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Sample records for frequency sweeper seeded

  1. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  2. Plasma sweeper. [Patents

    DOEpatents

    Motley, R.W.; Glanz, J.

    1982-10-25

    A device is described for coupling RF power (a plasma sweeper) from RF power introducing means to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the RF power introducing means. Means are described for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  3. The quantum sweeper effect

    NASA Astrophysics Data System (ADS)

    Grössing, G.; Fussy, S.; Mesa Pascasio, J.; Schwabl, H.

    2015-07-01

    We show that during stochastic beam attenuation in double slit experiments, there appear unexpected new effects for transmission factors below a ≤ 10-4, which can eventually be observed with the aid of weak measurement techniques. These are denoted as quantum sweeper effects, which are characterized by the bunching together of low counting rate particles within very narrow spatial domains. We employ a “superclassical” modeling procedure which we have previously shown to produce predictions identical with those of standard quantum theory. Thus it is demonstrated that in reaching down to ever weaker channel intensities, the nonlinear nature of the probability density currents becomes ever more important. We finally show that the resulting unexpected effects nevertheless implicitly also exist in standard quantum mechanics.

  4. Risk factors for chronic diseases among road sweepers in Bangkok.

    PubMed

    Phonrat, B; Pongpaew, P; Tungtrongchitr, R; Horsawat, V; Supanaranond, W; Vutikes, S; Vudhivai, N; Schelp, F P

    1997-03-01

    The nutritional and health status of road sweepers in Bangkok was investigated. Fifty-seven males and one hundred thirty-four females from 10 districts were selected for the study. The districts were sampled as cluster at random. From each district selected about 50% of road sweepers volunteered to participate in the investigation. Through questionnaires the age, marital status, place of origin, drinking and smoking habits were assessed. Anthropometric measurements, blood pressure and the lipid profile of these subjects were determined. According to a physical check-up and X-rays taken, all individuals investigated were apparently healthy. The age of the study group varied between 26 and 57 years. The median for the males was 47 years and for the females 37.5 years. Almost all the road sweepers were married. Smoking and alcohol drinking was widespread. Over- and undernutrition was found among the group investigated. 26.3% of the males and 1.5% of the females were undernourished. According to their systolic values, 15.8% of the males and 6.7% of the females were suffering from hypertension, and 38.6% of the males and 15.7% of the females had hypertension according to their diastolic values. 58.2% of the females and 29.3% of the males were overnourished. 57.9% of the males and 59.7% of the females had cholesterol levels above 200 mg/dl. Pathological values of LDL cholesterol were determined in 26.3% of the males and 28.4% of the females. The habit of consuming tonic drinks was widespread among the workers. The study concluded that behavior risk factors are highly prevalent in the group of workers belonging to the lower socio-economic class. Further investigations are presently being undertaken to study the after-effects of air pollution among this group of workers. The results will be subsequently reported in future publications.

  5. Narrowband alexandrite laser injection seeded with frequency dithered diode laser

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary; Lee, H. S.; Prasad, Coorg

    1991-01-01

    Narrowband radiation is produced from a pulsed alexandrite laser when injection seeded with the output of a low power, tunable, continuous wave single mode diode laser. Injection seeded power oscillators are easier to frequency stabilize than etalon narrowed lasers, are more efficient and less prone to optical damage. AlGaAs diode lasers are available with wavelengths from 760 to 770 nm in the oxygen A band that can be used for differential absorption lidar remote sensing of atmospheric pressure and temperature. Diodes with room temperature output at 740 nm may be cooled sufficiently to emit in the water vapor absorption band at 720-730 nm for humidity remote sensing. The diode laser linewidth of 200 MHz is sufficient to seed 2 or 3 longitudinal modes of the multi-transverse mode alexandrite laser, giving the pulsed laser a bandwidth of 0.007 to 0.014/cm.

  6. Disturbance frequency and vertical distribution of seeds affect long-term population dynamics: a mechanistic seed bank model.

    PubMed

    Eager, Eric Alan; Haridas, Chirakkal V; Pilson, Diana; Rebarber, Richard; Tenhumberg, Brigitte

    2013-08-01

    Seed banks are critically important for disturbance specialist plants because seeds of these species germinate only in disturbed soil. Disturbance and seed depth affect the survival and germination probability of seeds in the seed bank, which in turn affect population dynamics. We develop a density-dependent stochastic integral projection model to evaluate the effect of stochastic soil disturbances on plant population dynamics with an emphasis on mimicking how disturbances vertically redistribute seeds within the seed bank. We perform a simulation analysis of the effect of the frequency and mean depth of disturbances on the population's quasi-extinction probability, as well as the long-term mean and variance of the total density of seeds in the seed bank. We show that increasing the frequency of disturbances increases the long-term viability of the population, but the relationship between the mean depth of disturbance and the long-term viability of the population are not necessarily monotonic for all parameter combinations. Specifically, an increase in the probability of disturbance increases the long-term viability of the total seed bank population. However, if the probability of disturbance is too low, a shallower mean depth of disturbance can increase long-term viability, a relationship that switches as the probability of disturbance increases. However, a shallow disturbance depth is beneficial only in scenarios with low survival in the seed bank.

  7. Frequency stabilization of a single-frequency Q-switched Tm:YAG laser by using injection seeding technique.

    PubMed

    Zhang, Yunshan; Gao, Chunqing; Gao, Mingwei; Zheng, Yan; Wang, Lei; Wang, Ran

    2011-07-20

    A stable single-frequency Q-switched Tm:YAG laser was demonstrated. The laser was injection seeded by a monolithic nonplanar ring oscillator laser utilizing the ramp-hold-fire technique. The measurements of the output parameters were presented. This paper focused on investigation of the frequency stability of the injection-seeded laser, which was measured by optical heterodyne technique. A method used to restrict the frequency jitter of the laser was discussed. The fluctuation of the laser frequency was reduced from 2.36 MHz (rms) to 1.07 MHz (rms) in 1 h by optimizing the voltage of the piezoelectric translator. PMID:21772412

  8. Frequency stabilization of a single-frequency Q-switched Tm:YAG laser by using injection seeding technique.

    PubMed

    Zhang, Yunshan; Gao, Chunqing; Gao, Mingwei; Zheng, Yan; Wang, Lei; Wang, Ran

    2011-07-20

    A stable single-frequency Q-switched Tm:YAG laser was demonstrated. The laser was injection seeded by a monolithic nonplanar ring oscillator laser utilizing the ramp-hold-fire technique. The measurements of the output parameters were presented. This paper focused on investigation of the frequency stability of the injection-seeded laser, which was measured by optical heterodyne technique. A method used to restrict the frequency jitter of the laser was discussed. The fluctuation of the laser frequency was reduced from 2.36 MHz (rms) to 1.07 MHz (rms) in 1 h by optimizing the voltage of the piezoelectric translator.

  9. High Neotyphodium infection frequencies in tillers and seed of infected tall fescue plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research quantified frequencies of Neotyphodium infected (E+) tillers and mature seed from field-grown E+ plants of two wild tall fescue accessions from Morocco and Sardinia, Italy. Tiller infection rates were 100% (n = 50 from 10 E+ plants/accession) for each accession and over 99% of the seed...

  10. Effect of Finite Pulse Length and Laser Frequency Chirp on HGHG and EEHG Seeding

    SciTech Connect

    Stupakov, G.; /SLAC

    2011-11-18

    Theoretical studies of high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) often start from a simplified model in which the beam is assumed infinitely long and longitudinally uniform and the laser induced energy modulation is perfectly sinusoidal and of infinite duration. In such a model the resulting seed has a spectrum consisting of a collection of delta-functions (of zero width) located at the harmonics of the laser frequency. Being a useful tool for study of the seed bunching amplitudes, such a model cannot be used for realistic analysis the spectral properties of the seed. In this paper we take into account the finite duration of the laser pulse as well as some possible laser phase errors to study their effect on the spectrum of the seed.

  11. Injection seeding of a Q-switched alexandrite laser: Study of frequency stabilization

    NASA Technical Reports Server (NTRS)

    Brown, Lamarr A.

    1992-01-01

    AlGaAs diode lasers were used to injection seed a pulsed Q-switched alexandrite laser which produces a narrowband of radiation. Injection seeding is a method for achieving linewidths of less than 500 mega-Hz in the output of the broadband, tunable solid state laser. When the laser was set at a current of 59.8 milli-A and a temperature of 14.04 C, the wavelength was 767.6 nano-m. The Q-switched alexandrite laser was injection seeded and frequency stabilization was studied. The linewidth requirement was met, but the stability requirement was not due to drifting in the feedback voltage. Improvements on injection seeding should focus on increasing the feedback voltage to the laser diode, filtering the laser diode by using temperature controlled narrowband filters, and the use of diamond (SiC) grating placed inside the alexandrite laser's resonator cavity.

  12. Self-seeded single-frequency laser peening method

    DOEpatents

    DAne, C.Brent; Hackey, Lloyd A.; Harris, Fritz B.

    2012-06-26

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  13. Self-seeded single-frequency laser peening method

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2009-08-11

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  14. Plasma sweeper to control the coupling of RF power to a magnetically confined plasma

    DOEpatents

    Motley, Robert W.; Glanz, James

    1985-01-01

    A device for coupling RF power (a plasma sweeper) from a phased waveguide array for introducing RF power to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the phased waveguide array; and a potential source coupled to the electrode for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  15. Wavemeter measurements of frequency stability of an injection seeded alexandrite laser for pressure and temperature lidar

    NASA Technical Reports Server (NTRS)

    Prasad, C. R.; Schwemmer, G. K.; Korb, C. L.

    1992-01-01

    The GSFC pressure-temperature lidar is a differential absorption lidar operating in the oxygen A band absorption region (760 to 770 nm), and utilizes two tunable pulsed alexandrite lasers. For obtaining temperature measurements with an accuracy of less than or = 1 K, it has been determined that the stability of the online laser frequency over a period of time corresponding to a set of measurements, 0.1 to 30 min, has to be better than +/- 0.002/cm. In addition, the requirements on laser spectral bandwidth and spectral purity are less than or = 0.02/cm and greater than or = 99.9 percent, respectively. Injection seeding with a stabilized AlGaAs diode laser was used to achieve the required frequency stability and spectral bandwidth. A high resolution Fizeau wavemeter was employed to determine the frequency stability of the pulsed alexandrite laser and determine its bandwidth, mode structure. We present the results of measurements of the frequency stability and the spectrum of the injection seeded alexandrite laser.

  16. Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

    SciTech Connect

    Nong, Hanond Markmann, Sergej; Hekmat, Negar; Jukam, Nathan; Pal, Shovon; Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A.; Wieck, Andreas D.

    2014-09-15

    A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunes the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.

  17. Observation of a 100-MHz frequency variation across the output of a frequency-doubled injection-seeded unstable-resonator Q-switched Nd:YAG laser.

    PubMed

    Forkey, J N; Lempert, W R; Miles, R B

    1997-02-15

    We report high-resolution measurements of the spatial variation of the optical frequency of an injection-seeded unstable-resonator Q-switched Nd:YAG laser. Images of the second harmonic taken through a molecular-iodine notch filter show frequency variations of as much as 100 MHz (second harmonic) between the center and the edge of the beam. PMID:18183159

  18. Spectral linewidth preservation in parametric frequency combs seeded by dual pumps.

    PubMed

    Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2012-07-30

    We demonstrate new technique for generation of programmable-pitch, wideband frequency combs with low phase noise. The comb generation was achieved using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds. The approach relies on phase-correlated continuous-wave pumps in order to cancel spectral linewidth broadening inherent to parametric comb generation. Parametric combs with over 200-nm bandwidth were obtained and characterized with respect to phase noise scaling to demonstrate linewidth preservation over 100 generated tones.

  19. Spectral linewidth preservation in parametric frequency combs seeded by dual pumps.

    PubMed

    Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2012-07-30

    We demonstrate new technique for generation of programmable-pitch, wideband frequency combs with low phase noise. The comb generation was achieved using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds. The approach relies on phase-correlated continuous-wave pumps in order to cancel spectral linewidth broadening inherent to parametric comb generation. Parametric combs with over 200-nm bandwidth were obtained and characterized with respect to phase noise scaling to demonstrate linewidth preservation over 100 generated tones. PMID:23038314

  20. Increasing the stearate content in seed oil of Brassica juncea by heterologous expression of MlFatB affects lipid content and germination frequency of transgenic seeds.

    PubMed

    Bhattacharya, Surajit; Sinha, Saheli; Das, Natasha; Maiti, Mrinal K

    2015-11-01

    Fatty acids from dietary lipids can impart both beneficial and harmful health effects. The compositional balance between saturated and unsaturated fatty acids plays a decisive role in maintaining the physiological harmony, proper growth and development in the human system. In case of Brassica juncea seed oil, the level of saturated fatty acid, especially desirable stearate is very much lower than the recommended value, along with a high content of nutritionally undesirable erucic acid. Therefore, in order to shift the carbon flux towards the production of stearate at the expense of erucate, the MlFatB gene encoding a FatB thioesterase from Madhuca longifolia (latifolia) was expressed heterologously in seed tissues of B. juncea. The functional MlFatB competed with the highly active endogenous BjFatA thioesterase, and the transgenic B. juncea lines showed noteworthy changes in their seed fatty acid profiles. The proportion of stearate increased up to 16-fold, constituting almost 31% of the total fatty acids along with the production of arachidic acid in significant amount (up to ∼11%). Moreover, the content of erucate was reduced up to 71% in the seed oils of transgenic lines. Although a nutritionally desirable fatty acid profile was achieved, the transgenic seeds exhibit reduction or abolition of seed germination in addition to a decrease in seed lipid content. The findings of the present study revealing the stearoyl-ACP thioesterase-mediated enhancement of the stearate content that is associated with reduced germination frequency of transgenic B. juncea seeds, may explain why no natural or induced stearate-rich Brassica has been found or developed. Furthermore, this study also suggests that the newly characterized MlFatB is a potential candidate gene for refined metabolic engineering strategy in B. juncea or other plant species for increasing stearate content in seed oil. PMID:26351151

  1. Increasing the stearate content in seed oil of Brassica juncea by heterologous expression of MlFatB affects lipid content and germination frequency of transgenic seeds.

    PubMed

    Bhattacharya, Surajit; Sinha, Saheli; Das, Natasha; Maiti, Mrinal K

    2015-11-01

    Fatty acids from dietary lipids can impart both beneficial and harmful health effects. The compositional balance between saturated and unsaturated fatty acids plays a decisive role in maintaining the physiological harmony, proper growth and development in the human system. In case of Brassica juncea seed oil, the level of saturated fatty acid, especially desirable stearate is very much lower than the recommended value, along with a high content of nutritionally undesirable erucic acid. Therefore, in order to shift the carbon flux towards the production of stearate at the expense of erucate, the MlFatB gene encoding a FatB thioesterase from Madhuca longifolia (latifolia) was expressed heterologously in seed tissues of B. juncea. The functional MlFatB competed with the highly active endogenous BjFatA thioesterase, and the transgenic B. juncea lines showed noteworthy changes in their seed fatty acid profiles. The proportion of stearate increased up to 16-fold, constituting almost 31% of the total fatty acids along with the production of arachidic acid in significant amount (up to ∼11%). Moreover, the content of erucate was reduced up to 71% in the seed oils of transgenic lines. Although a nutritionally desirable fatty acid profile was achieved, the transgenic seeds exhibit reduction or abolition of seed germination in addition to a decrease in seed lipid content. The findings of the present study revealing the stearoyl-ACP thioesterase-mediated enhancement of the stearate content that is associated with reduced germination frequency of transgenic B. juncea seeds, may explain why no natural or induced stearate-rich Brassica has been found or developed. Furthermore, this study also suggests that the newly characterized MlFatB is a potential candidate gene for refined metabolic engineering strategy in B. juncea or other plant species for increasing stearate content in seed oil.

  2. Single frequency operation of a tunable injection-seeded Nd:GSAG Q-switched laser around 942nm.

    PubMed

    Lin, Zhifeng; Wang, Xin; Kallmeyer, Frank; Eichler, Hans Joachim; Gao, Chunqing

    2010-03-15

    Single frequency operation of a diode-pumped tunable injection-seeded Nd:GSAG Q-switched laser around 942nm was demonstrated. With a three-mirror ring cavity, the single frequency laser pulse with output energy of 13.2mJ was obtained at a repetition rate of 10Hz. The linewidth of the single frequency laser was less than 100MHz. The wavelength of the single frequency Nd:GSAG laser can be tuned from 942.38nm to 943.10nm.

  3. Single-frequency, injection-seeded Q-switched operation of resonantly pumped Er:YAG ceramic laser at 1645 nm

    NASA Astrophysics Data System (ADS)

    Ye, Qing; Gao, Chunqing; Wang, Shuo; Na, Quanxin; Shi, Yang; Wang, Qing; Gao, Mingwei; Zhang, Jian

    2016-07-01

    A single-frequency Q-switched Er:YAG polycrystalline ceramic laser is reported for the first time. The `Ramp-Hold-Fire' injection-seeding technique was employed to obtain single-frequency pulses, with an Er:YAG NPRO as a seed laser. Single-frequency laser operation was obtained with pulse energy of 4.7 mJ, pulse width of 250 ns and pulse repetition rate of 200 Hz.

  4. H{sup -} beam extraction from a cesium seeded field effect transistor based radio frequency negative hydrogen ion source

    SciTech Connect

    Ando, A.; Matsuno, T.; Funaoi, T.; Tanaka, N.; Tsumori, K.; Takeiri, Y.

    2012-02-15

    H{sup -} beam was successfully extracted from a cesium seeded ion source operated using a field effect transistor inverter power supply as a radio frequency (RF) wave source. High density hydrogen plasma more than 10{sup 19} m{sup -3} was obtained using an external type antenna with RF frequency of lower than 0.5 MHz. The source was isolated by an isolation transformer and H{sup -} ion beam was extracted from a single aperture. Acceleration current and extraction current increased with the increase of extraction voltage. Addition of a small amount of cesium vapor into the source enhanced the currents.

  5. Generation of wideband frequency combs by continuous-wave seeding of multistage mixers with synthesized dispersion.

    PubMed

    Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2012-01-30

    We numerically and experimentally demonstrate efficient generation of an equalized optical comb with 150-nm bandwidth. The comb was generated by low-power, continuous-wave seeds, eliminating the need for pulsed laser sources. The new architecture relies on efficient creation of higher-order mixing tones in phase-matched nonlinear fiber stages separated by a linear compressor. Wideband generation was enabled by precise dispersion engineering of multiple-stage parametric mixers.

  6. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse

    PubMed Central

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-01-01

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse. PMID:26463195

  7. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse.

    PubMed

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-Ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-05-12

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse.

  8. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse.

    PubMed

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-Ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-01-01

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse. PMID:26463195

  9. Frequency stabilization and transverse mode discrimination in injection-seeded unstable resonator TEA CO2 lasers

    NASA Technical Reports Server (NTRS)

    Ancellet, G. M.; Menzies, R. T.; Brothers, A. M.

    1987-01-01

    Longitudinal mode selection by injection has been demonstrated as a viable technique for TEA-CO2 lasers with pulse energies of a Joule or greater. Once reliable generation of single-longitudinal-mode (SLM) pulses is obtained, the characteristics and the causes of intrapulse frequency variation can be studied. These include the effect of the decaying plasma, the thermal gradient due to the energy dissipation associated with the laser mechanism itself, and the pressure shift of the center frequency of the laser transition. The use of the positive-branch unstable resonator as an efficient means of coupling a discharge with large spatial dimensions to an optical cavity mode introduces another concern: namely, what can be done to emphasize transverse mode discrimination in an unstable resonator cavity while maintaining high coupling efficiency. These issues are discussed in this paper, and relevant experimental results are included.

  10. Self-seeded single-frequency solid-state ring laser and system using same

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-02-20

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  11. Multiple-frequency injection-seeded nanosecond pulsed laser without parasitic intensity modulation.

    PubMed

    Penninckx, D; Luce, J; Diaz, R; Bonville, O; Courchinoux, R; Lamaignère, L

    2016-07-15

    Thanks to a phase-modulated injection seeder, we report the operation of a nanosecond Nd:YAG Q-switched laser with pulses having both a large spectral bandwidth and a smooth temporal waveform. Because of the smooth temporal waveform, such pulses allow, for instance, reducing the impact of the Kerr effect and, because of the large spectral bandwidth, suppressing stimulated Brillouin scattering. We conducted a parametric study of the features of the generated pulses versus the injection conditions. We show that, as opposed to the central frequency (wavelength) of the seeder, the phase modulation frequency has to be carefully chosen, but it is not a critical parameter and does not require any particular feedback. PMID:27420504

  12. Motor disturbances and thalamic electrical power of frequency bands' improve by grape seed extract in animal model of Parkinson's disease

    PubMed Central

    Sarkaki, Alireza; Eidypour, Zainab; Motamedi, Freshteh; keramati, keivan; Farbood, Yaghoub

    2012-01-01

    Objective: Previous studies showed that grape seed extract (GSE) is an excellent natural substance with potent antioxidant effect and free radical scavenger. This study aimed to evaluate the effect of GSE on motor dysfunctions and thalamic local Electroencephalography (EEG) frequency bands' powers in rats with Parkinson's disease (PD). Materials and Methods: In this study 8 µg 6-hydroxydopamine (6-OHDA) dissolved in 2 µl normal saline containing 0.01% ascorbic acid was infused into right medial forebrain bundle (MFB) to make an animal model of PD. Rats with PD received four weeks GSE (100 mg/kg, p.o.) after apomorphine-induced rotation test. Spontaneous motor tests and also thalamic ventroanterior nucleus (AV) local EEG recording were done in freely moving rats in all groups. Results: Chronic treatment of PD rats with GSE could influence potentially frequency bands' powers of thalamic VA and improve post-lesion motor dysfunctions significantly (p<0.05 and p<0.01, respectively). Conclusion: Our findings suggest that GSE modulates the CNS function and has beneficial effects on the direct and indirect striato-thalamo-cortical pathways in PD. GSE acts as a new and potent natural free radical scavenger which removes oxidants produced by neurotoxin 6-OHDA in brain. Therefore, it reinforces electrical power of remained thalamic VA neurons and thereby improves post-lesion motor disorders. PMID:25050252

  13. High frequency plant regeneration from mature seed of elite, recalcitrant Malaysian indica rice ( Oryza sativa L.) CV. MR 219.

    PubMed

    Sivakumar, P; Law, Y S; Ho, C-L; Harikrishna, Jennifer Ann

    2010-09-01

    An efficient in vitro plant regeneration system was established for elite, recalcitrant Malaysian indica rice, Oryza sativa L. CV. MR 219 using mature seeds as explant on Murashige and Skoog and Chu N6 media containing 2,4-dichlorophenoxy acetic acid and kinetin either alone or in different combinations. L-proline, casein hydrolysate and L-glutamine were added to callus induction media for enhancement of embryogenic callus induction. The highest frequency of friable callus induction (84%) was observed in N6 medium containing 2.5 mg l(-1) 2,4-dichlorophenoxy acetic acid, 0.2 mg l(-1) kinetin, 2.5 mg l(-1) L-proline, 300 mg l(-1) casein hydrolysate, 20 mg l(-1) L-glutamine and 30 g l(-1) sucrose under culture in continuous lighting conditions. The maximum regeneration frequency (71%) was observed, when 30-day-old N6 friable calli were cultured on MS medium supplemented with 3 mg l(-1) 6-benzyl aminopurine, 1 mg l(-1) naphthalene acetic acid, 2.5 mg l(-1) L-proline, 300 mg l(-1) casein hydrolysate and 3% maltose. Developed shoots were rooted in half strength MS medium supplemented with 2% sucrose and were successfully transplanted to soil with 95% survival. This protocol may be used for other recalcitrant indica rice genotypes and to transfer desirable genes in to Malaysian indica rice cultivar MR219 for crop improvement.

  14. High efficiency intra-cavity sum-frequency-generation in a self-seeded image-rotating nanosecond optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Armstrong, Darrell J.; Smith, Arlee V.

    2005-03-01

    We have built and tested a highly efficient source of pulsed 320 nm light based on intra-cavity sum-frequency-generation in a self-injection-seeded image-rotating nanosecond optical parametric oscillator. The four-mirror nonplanar ring optical cavity uses the RISTRA geometry, denoting rotated-image singly-resonant twisted rectangle. The cavity contains a type-II xz-cut KTP crystal pumped by the 532 nm second harmonic of Nd:YAG to generate an 803~nm signal and 1576 nm idler, and a type-II BBO crystal to sum-frequency mix the 532 nm pump and cavity-resonant 803 nm signal to generate 320 nm light. The cavity is configured so pump light passes first through the BBO crystal and then through the KTP crystal with the 320 nm light exiting through the output coupler following the BBO sum-frequency crystal. The cavity output coupler is designed to be a high reflector at 532 nm, have high transmission at 320 nm, and reflect approximately 85% at 803 nm. With this configuration we've obtained 1064 nm to 320 nm optical-to-optical conversion efficiency of 24% and generated single-frequency λ = 320 nm pulses with energies up to 140 mJ.

  15. High-efficiency intra-cavity sum-frequency-generation in a self-seeded image-rotating nanosecond optical parametric oscillator.

    SciTech Connect

    Armstrong, Darrell Jewell; Smith, Arlee Virgil

    2005-02-01

    We have built and tested a highly efficient source of pulsed 320 nm light based on intra-cavity sum-frequency-generation in a self-injection-seeded image-rotating nanosecond optical parametric oscillator. The four-mirror nonplanar ring optical cavity uses the RISTRA geometry, denoting rotated-image singly-resonant twisted rectangle. The cavity contains a type-II xz-cut KTP crystal pumped by the 532 nm second harmonic of Nd:YAG to generate an 803{approx}nm signal and 1576 nm idler, and a type-II BBO crystal to sum-frequency mix the 532 nm pump and cavity-resonant 803 nm signal to generate 320 nm light. The cavity is configured so pump light passes first through the BBO crystal and then through the KTP crystal with the 320 nm light exiting through the output coupler following the BBO sum-frequency crystal. The cavity output coupler is designed to be a high reflector at 532 nm, have high transmission at 320 nm, and reflect approximately 85% at 803 nm. With this configuration we've obtained 1064 nm to 320 nm optical-to-optical conversion efficiency of 24% and generated single-frequency {lambda} = 320 nm pulses with energies up to 140 mJ.

  16. Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser

    SciTech Connect

    Zastrau, Ulf; Fletcher, Luke B.; Galtier, Eric Ch.; Gamboa, Eliseo; Glenzer, Siegfried H.; Heimann, Philipp; Nagler, Bob; Schropp, Andreas; Lee, Hae Ja; Förster, Eckhart; Marschner, Heike; Wehrhan, Ortrud

    2014-09-15

    We present a cylindrically curved GaAs x-ray spectrometer with energy resolution ΔE/E = 1.1 × 10{sup −4} and wave-number resolution of Δk/k = 3 × 10{sup −3}, allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to 5.2/Å in 100 separate bins, with only 0.34% wavenumber blurring. The dispersion of 0.418 eV/13.5 μm agrees with predictions within 1.3%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic highly annealed pyrolytic graphite spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1 eV and a significant range of wavenumbers must be covered in one exposure.

  17. Study of phase coherence degradation induced by a tapered semiconductor amplifier with frequency-modulated continuous-wave and pulsed seed lasers.

    PubMed

    Qi, Xiang Hui; Yi, Lin; Ma, Qian Li; Zhou, Da Wei; Zhou, Xiao Ji; Chen, Xu Zong

    2009-08-01

    We investigate the phase coherence between a seed laser and a laser amplified by a tapered semiconductor amplifier (TSA) when the seed laser is either continuous wave (CW) or pulsed. The phase fluctuations in the time domain are employed to describe the degradation of phase coherence induced by a TSA. The amplified laser is measured to be approximately 99.98% coherent with the seed, when the CW or pulsed laser is seeded, at different supplying currents of the TSA. Furthermore, the phase coherence is measured when the seed laser is modulated. The results reveal that the phase coherence degradations induced by the TSA remain the same for a seed laser with and without modulation, when different supplying currents of the TSA are applied. PMID:19649040

  18. Analysis of the plasma sweeper

    SciTech Connect

    Glanz, J.; Motley, R.W.

    1982-09-01

    The coupling of lower hybrid waves to a plasma can be modified by placing potentials on electrodes near the mouth of a phased array. Positive potentials on the electrodes create an electric field that sweeps the plasma away at a velocity c anti E x anti B/B/sup 2/. In this paper we derive the electric field created by the applied potential from the nondivergent character of the current flow and the ion momentum equation, in which ion-neutral charge-exchange collisions are retained, and we compare the predictions with experimental data.

  19. Fast optical frequency sweeping using voltage controlled oscillator driven single sideband modulation combined with injection locking.

    PubMed

    Wang, Jian; Chen, Dijun; Cai, Haiwen; Wei, Fang; Qu, Ronghui

    2015-03-23

    An ultrafast optical frequency sweeping technique for narrow linewidth lasers is reported. This technique exploits the large frequency modulation bandwidth of a wideband voltage controlled oscillator (VCO) and a high speed electro-optic dual parallel Mach-Zehnder modulator (DPMZM) which works on the state of carrier suppressed single sideband modulation(CS-SSB). Optical frequency sweeping of a narrow linewidth fiber laser with 3.85 GHz sweeping range and 80 GHz/μs tuning speed is demonstrated, which is an extremely high tuning speed for frequency sweeping of narrow linewidth lasers. In addition, injection locking technique is adopted to improve the sweeper's low optical power output and small side-mode suppression ratio (SMSR). PMID:25837048

  20. High-power continuous-wave mid-infrared radiation generated by difference frequency mixing of diode-laser-seeded fiber amplifiers and its application to dual-beam spectroscopy

    NASA Technical Reports Server (NTRS)

    Lancaster, D. G.; Richter, D.; Curl, R. F.; Tittel, F. K.; Goldberg, L.; Koplow, J.

    1999-01-01

    We report the generation of up to 0.7 mW of narrow-linewidth (<60-MHz) radiation at 3.3 micrometers by difference frequency mixing of a Nd:YAG-seeded 1.6-W Yb fiber amplifier and a 1.5-micrometers diode-laser-seeded 0.6-W Er/Yb fiber amplifier in periodically poled LiNbO3. A conversion efficiency of 0.09%/W (0.47 mWW-2 cm-1) was achieved. A room-air CH4 spectrum acquired with a compact 80-m multipass cell and a dual-beam spectroscopic configuration indicates an absorption sensitivity of +/-2.8 x 10(-5) (+/-1 sigma), corresponding to a sub-parts-in-10(9) (ppb) CH4 sensitivity (0.8 ppb).

  1. High-power frequency comb in the range of 2-2.15  μm based on a holmium fiber amplifier seeded by wavelength-shifted Raman solitons from an erbium-fiber laser.

    PubMed

    Coluccelli, Nicola; Cassinerio, Marco; Gambetta, Alessio; Laporta, Paolo; Galzerano, Gianluca

    2014-03-15

    We demonstrate a room-temperature high-power frequency comb source covering the spectral region from 2 to 2.15 μm. The source is based on a femtosecond erbium-fiber laser operating at 1.55 μm with a repetition rate of 250 MHz, wavelength-shifted up to 2.06 μm by the solitonic Raman effect, seeding a large-mode-area holmium (Ho) fiber amplifier pumped by a thulium (Tm) fiber laser emitting at 1.94 μm. The frequency comb has an integrated power of 2 W, with overall power fluctuations as low as 0.3%. The beatnote between the comb and a high-spectral-purity, single-frequency Tm-Ho laser has a linewidth of 32 kHz over 1 ms observation time, with a signal-to-noise ratio in excess of 30 dB.

  2. Magnetic-seeding filtration

    SciTech Connect

    Ying, T.Y.; Chin, C.J.; Lu, S.C.; Yiacoumi, S.

    1997-10-01

    Magnetic-seeding filtration consists of two steps: heterogeneous particle flocculation of magnetic and nonmagnetic particles in a stirred tank and high-gradient magnetic filtration (HGMF). The effects of various parameters affecting magnetic-seeding filtration (HGMF). The effects of various parameters affecting magnetic seeding filtration are theoretically and experimentally investigated. A trajectory model that includes hydrodynamic resistance, van der Waals, and electrostatic forces is developed to calculate the flocculation frequency in a turbulent-shear regime. Fractal dimension is introduced to simulate the open structure of aggregates. A magnetic-filtration model that consists of trajectory analysis, a particle build-up model, a breakthrough model, and a bivariate population-balance model is developed to predict the breakthrough curve of magnetic-seeding filtration. A good agreement between modeling results and experimental data is obtained. The results show that the model developed in this study can be used to predict the performance of magnetic-seeding filtration without using empirical coefficients or fitting parameters. 35 refs., 7 figs., 1 tab.

  3. Verticillium dahliae race 2-specific PCR reveals a high frequency of race 2 strains in commercial spinach seed lots and delineates race structure.

    PubMed

    Short, Dylan P G; Gurung, Suraj; Maruthachalam, Karunakaran; Atallah, Zahi K; Subbarao, Krishna V

    2014-07-01

    Two pathogenic races of Verticillium dahliae have been described on lettuce and tomato. Host resistance to race 1 is governed by plant immune receptors that recognize the race 1-specific fungal effector Ave1. Only partial resistance to race 2 exists in lettuce. Although polymerase chain reaction (PCR) assays are available to identify race 1, no complementary test exists to positively identify race 2, except for lengthy pathogenicity assays on host differentials. Using the genome sequences of two isolates of V. dahliae, one each from races 1 and 2, we identified potential markers and PCR primers to distinguish the two races. Several primer pairs based on polymorphisms between the races were designed and tested on reference isolates of known race. One primer pair, VdR2F-VdR2R, consistently yielded a 256-bp amplicon in all race 2 isolates exclusively. We screened DNA from 677 V. dahliae isolates, including 340 from spinach seedlots, with the above primer pair and a previously published race 1-specific primer pair. DNA from isolates that did not amplify with race 1-specific PCRs amplified with the race 2-specific primers. To validate this, two differential lines of lettuce were inoculated with 53 arbitrarily selected isolates from spinach seed and their pathogenicity and virulence were assessed in a greenhouse. The reactions of the differential cultivars strongly supported the PCR data. V. dahliae race structure was investigated in crops in coastal California and elsewhere using primers specific to the two races. All artichoke isolates from California were race 1, whereas nearly all tomato isolates were race 2. Isolates from lettuce, pepper, and strawberry from California as well as isolates from spinach seed from two of four countries comprised both races, whereas only race 2 was observed in cotton, mint, olive, and potato. This highlights the importance of identifying resistance against race 2 in different hosts. The technique developed in this study will benefit

  4. Verticillium dahliae race 2-specific PCR reveals a high frequency of race 2 strains in commercial spinach seed lots and delineates race structure.

    PubMed

    Short, Dylan P G; Gurung, Suraj; Maruthachalam, Karunakaran; Atallah, Zahi K; Subbarao, Krishna V

    2014-07-01

    Two pathogenic races of Verticillium dahliae have been described on lettuce and tomato. Host resistance to race 1 is governed by plant immune receptors that recognize the race 1-specific fungal effector Ave1. Only partial resistance to race 2 exists in lettuce. Although polymerase chain reaction (PCR) assays are available to identify race 1, no complementary test exists to positively identify race 2, except for lengthy pathogenicity assays on host differentials. Using the genome sequences of two isolates of V. dahliae, one each from races 1 and 2, we identified potential markers and PCR primers to distinguish the two races. Several primer pairs based on polymorphisms between the races were designed and tested on reference isolates of known race. One primer pair, VdR2F-VdR2R, consistently yielded a 256-bp amplicon in all race 2 isolates exclusively. We screened DNA from 677 V. dahliae isolates, including 340 from spinach seedlots, with the above primer pair and a previously published race 1-specific primer pair. DNA from isolates that did not amplify with race 1-specific PCRs amplified with the race 2-specific primers. To validate this, two differential lines of lettuce were inoculated with 53 arbitrarily selected isolates from spinach seed and their pathogenicity and virulence were assessed in a greenhouse. The reactions of the differential cultivars strongly supported the PCR data. V. dahliae race structure was investigated in crops in coastal California and elsewhere using primers specific to the two races. All artichoke isolates from California were race 1, whereas nearly all tomato isolates were race 2. Isolates from lettuce, pepper, and strawberry from California as well as isolates from spinach seed from two of four countries comprised both races, whereas only race 2 was observed in cotton, mint, olive, and potato. This highlights the importance of identifying resistance against race 2 in different hosts. The technique developed in this study will benefit

  5. Synchronous Photoinjection Using a Frequency-Doubled Gain-Switched Fiber-Coupled Seed Laser and ErYb-Doped Fiber Amplifier

    SciTech Connect

    John Hansknecht; Benard Poelker

    2006-06-01

    Light at 1.56 um from a gain-switched fiber-coupled diode laser and ErYb-doped fiber amplifier was frequency doubled to obtain over 2W average power at 780 nm with {approx} 40ps pulses and pulse repetition rate of 499 MHz. This light was used to drive the 100kV DC high voltage GaAs photoemission gun at CEBAF at Jefferson Laboratory to produce a high average current beam (100uA) of highly spin-polarized electrons (>80%). This new drive laser system represents a significant advance over laser systems used previously, providing significantly higher power and enhanced reliability.

  6. Seed rain, soil seed bank, seed loss and regeneration of Castanopsis fargesii (Fagaceae) in a subtropical evergreen broad-leaved forest

    USGS Publications Warehouse

    Du, X.; Guo, Q.; Gao, X.; Ma, K.

    2007-01-01

    Understanding the seed rain and seed loss dynamics in the natural condition has important significance for revealing the natural regeneration mechanisms. We conducted a 3-year field observation on seed rain, seed loss and natural regeneration of Castanopsis fargesii Franch., a dominant tree species in evergreen broad-leaved forests in Dujiangyan, southwestern China. The results showed that: (1) there were marked differences in (mature) seed production between mast (733,700 seeds in 2001) and regular (51,200 and 195,600 seeds in 2002 and 2003, respectively) years for C. fargesii. (2) Most seeds were dispersed in leaf litter, humus and 0-2 cm depth soil in seed bank. (3) Frequency distributions of both DBH and height indicated that C. fargesii had a relatively stable population. (4) Seed rain, seed ground density, seed loss, and leaf fall were highly dynamic and certain quantity of seeds were preserved on the ground for a prolonged time due to predator satiation in both the mast and regular years so that the continuous presence of seed bank and seedling recruitments in situ became possible. Both longer time observations and manipulative experiments should be carried out to better understand the roles of seed dispersal and regeneration process in the ecosystem performance. ?? 2006 Elsevier B.V. All rights reserved.

  7. Indirect interactions between browsers and seed predators affect the seed bank dynamics of a chaparral shrub.

    PubMed

    Deveny, Adrian J; Fox, Laurel R

    2006-11-01

    Interactions between herbivores and seed predators may have long-term consequences for plant populations that rely on persistent seed banks for recovery after unpredictable fires. We assessed the effects of browsing by deer and seed predation by rodents, ants and birds on the densities of seeds entering the seed bank of Ceanothus cuneatus var. rigidus, a maritime chaparral shrub in coastal California. Ceanothus produced many more seeds when protected from browsers in long-term experimental exclosures than did browsed plants, but the seed densities in the soil beneath browsed and unbrowsed Ceanothus were the same at the start of an intensive one-year study. The density of seeds in the soil initially increased in both treatments following summer seed drop: while densities returned to pre-drop levels within a few weeks under browsed plants, soil seed densities remained high for 5-8 months beneath unbrowsed plants. Rodent abundance (especially deer mice) was higher near unbrowsed plants than >30 m away, and rodents removed Ceanothus seeds from dishes in the experimental plots. At least in the short term, rodent density and rates of seed removal were inversely related to the intensity of browsing. Our data have management implications for maintaining viable Ceanothus populations by regulating the intensity of browsing and the timing, intensity and frequency of fires.

  8. Seed Treatment. Bulletin 760.

    ERIC Educational Resources Information Center

    Lowery, Harvey C.

    This manual gives a definition of seed treatment, the types of seeds normally treated, diseases and insects commonly associated with seeds, fungicides and insecticides used, types of equipment used for seed treatment, and information on labeling and coloring of treated seed, pesticide carriers, binders, stickers, and safety precautions. (BB)

  9. What Are Chia Seeds?

    MedlinePlus

    ... Men For Women For Seniors What Are Chia Seeds? Published February 05, 2014 Print Email When you ... number of research participants. How to Eat Chia Seeds Chia seeds can be eaten raw or prepared ...

  10. Bean Seed Imbibition.

    ERIC Educational Resources Information Center

    Hershey, David R.

    1998-01-01

    Enables students to examine the time course for seed imbibition and the pressure generated by imbibing seeds. Provides background information, detailed procedures, and ideas for further investigation. (DDR)

  11. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  12. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  13. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  14. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  15. 7 CFR 201.18 - Other agricultural seeds (crop seeds).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Other agricultural seeds (crop seeds). 201.18 Section... SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.18 Other agricultural seeds...

  16. Seed Treatment. Sale Publication 4076.

    ERIC Educational Resources Information Center

    Wamsley, Mary Ann, Ed.; Vermeire, Donna M., Ed.

    This guide gives information about types of seeds that may require chemical protection against pests, seed treatment pesticide formulations, seed treatment methods, labeling treated seed, and safety and environmental precautions. (Author/BB)

  17. Healthy food trends -- chia seeds

    MedlinePlus

    ... Healthy food trends - salvia; Healthy snacks - Chia seeds; Weight loss - Chia seeds; Healthy diet - Chia seeds; Wellness - Chia ... fiber. Some think chia seeds may help with weight loss and other risk factors, but this has not ...

  18. Seed Proteomics"

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteomic analysis of seeds encounters some specific problems that do not impinge on analyses of other plant cells, tissues, or organs. There are anatomic considerations. Seeds comprise the seed coat, the storage organ(s), and the embryonic axis. Are these to be studied individually or as a compo...

  19. Going to Seed.

    ERIC Educational Resources Information Center

    Powell, Richard R.

    1984-01-01

    Describes a unit on seeds designed to introduce students to their scientific and nutritional uses. Unit activities are easily done, employ a variety of process skills, and can be used at various grade levels. Suggests field trips to gather seeds, seed sprouting, and making cookies out of various whole grains. (JM)

  20. Needs of Seeds

    ERIC Educational Resources Information Center

    Keeley, Page

    2011-01-01

    The "Needs of Seeds" formative assessment probe can be used to find out whether students recognize that seeds have needs both similar to and different from plants and other living organisms (Keeley, Eberle, and Tugel 2007). The probe reveals whether students overgeneralize the needs of seeds by assuming they have the same needs as the adult plants…

  1. Injection Seeding Of A Q-Switched Alexandrite Laser

    NASA Technical Reports Server (NTRS)

    Zukowski, Barbara J. K.; Glesne, Thomas R.; Schwemmer, Geary; Czechanski, James P.; Kay, Richard B.

    1992-01-01

    Experiment demonstrates that standing-wave, Q-switched, tunable alexandrite laser can be injection-seeded to increase stability of output frequency and significantly reduce bandwidth from 750 GHz to 180 MHz. Injecting laser acts as oscillator or master, while Q-switched laser into which ouput of seed laser injected acts as amplifier or slave.

  2. Occurrence and trends of weed seed and ergot contaminants in Oregon grown Poa pratensis and Poa trivialis seed lots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to assess the diversity and frequency of occurrence of weed seeds and sclerotia of the fungus Claviceps purpurea (ergot) in certified seed lots of P. pratensis (Kentucky bluegrass) and P. trivialis (rough bluegrass) based on purity analysis at the Oregon State University See...

  3. Postfire seeding and plant community recovery in the Great Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As wildland fire frequency increases around the globe, increased understanding of plant community recovery in burned landscapes is needed to improve effectiveness of rehabilitation efforts. We measured establishment of seeded species, colonization of Bromus tectorum L. (cheatgrass), and recovery of ...

  4. The seed nuclear proteome

    PubMed Central

    Repetto, Ombretta; Rogniaux, Hélène; Larré, Colette; Thompson, Richard; Gallardo, Karine

    2012-01-01

    Understanding the regulatory networks coordinating seed development will help to manipulate seed traits, such as protein content and seed weight, in order to increase yield and seed nutritional value of important food crops, such as legumes. Because of the cardinal role of the nucleus in gene expression, sub-proteome analyses of nuclei from developing seeds were conducted, taking advantage of the sequences available for model species. In this review, we discuss the strategies used to separate and identify the nuclear proteins at a stage when the seed is preparing for reserve accumulation. We present how these data provide an insight into the complexity and distinctive features of the seed nuclear proteome. We discuss the presence of chromatin-modifying enzymes and proteins that have roles in RNA-directed DNA methylation and which may be involved in modifying genome architecture in preparation for seed filling. Specific features of the seed nuclei at the transition between the stage of cell divisions and that of cell expansion and reserve deposition are described here which may help to manipulate seed quality traits, such as seed weight. PMID:23267364

  5. CW dual-frequency MOPA laser with frequency separation of 45 GHz.

    PubMed

    Hu, Miao; Zheng, Yaoyuan; Cai, Ju; Zhang, Guiju; Li, Qiliang; Zhou, Xuefang; Wei, Yizhen; Lu, Yang

    2015-04-20

    A CW dual-frequency master oscillator power amplifier (MOPA) laser system with dozens of gigahertz (GHz) frequency separation is presented. The MOPA system consists of a monolithic microchip seed laser and a double-end pumped traveling wave power amplifier. The short length of seed laser cavity guarantees the seed signal with a large frequency separation (above 53 GHz) but low output power (below 247.8 mW). By adding a long and low-doped active medium laser amplifier stage, a significant increase in laser power and an improvement in beam quality are obtained. After fine temperature tuning of seed laser cavity for "spectra matching", a 2.40 W dual-frequency laser signal with 45 GHz frequency separation is achieved.

  6. Anthropogenic fire drives the evolution of seed traits

    PubMed Central

    Gómez-González, Susana; Torres-Díaz, Cristian; Bustos-Schindler, Carlos; Gianoli, Ernesto

    2011-01-01

    Fire is a major disturbance affecting ecosystems worldwide. Phylogenetic studies have shown that the evolution of seed persistence (fire resistance) is associated with fire frequency or severity. However, the existence of specific seed traits resulting from natural selection mediated by fire remains a key question in plant evolution. We evaluated the role of fire in the evolution of seed traits from a microevolutionary perspective, using as a study system a native forb from the Chilean matorral, where fire is a novel, anthropogenic disturbance. We show that anthropogenic fires are shaping the evolution of seed traits such as pubescence and shape. Among-population variation in seed pubescence, shape, and pericarp thickness was strongly associated with fire frequency, and within a population, fire selected those plants with more pubescent seeds, thicker pericarps, and less rounded seeds. Seed pubescence and shape were shown to be heritable traits. Our findings provide insights into the understanding of the evolution of seed traits in fire-prone environments and demonstrate that human-made fires can be driving evolutionary changes in plant species from ecosystems where fires do not occur naturally. PMID:22065739

  7. Mutational effects of space flight on Zea mays seeds

    NASA Technical Reports Server (NTRS)

    Mei, M.; Qiu, Y.; He, Y.; Bucker, H.; Yang, C. H.

    1994-01-01

    The growth and development of more than 500 Zea mays seeds flown on Long Duration Exposure Facility (LDEF) were studied. Somatic mutations, including white-yellow stripes on leaves, dwarfing, change of leaf sheath color or seedling color were observed in plants developed from these seeds. When the frequency of white-yellow formation was used as the endpoint and compared with data from ground based studies, the dose to which maize seeds might be exposed during the flight was estimated to be equivalent to 635 cGy of gamma rays. Seeds from one particular holder gave a high mutation frequency and a wide mutation spectrum. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed somatic mutation. Electron microscopy studies showed that the damage of chloroplast development in the white-yellow stripe on leaves was similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground.

  8. Mutational effects of space flight on Zea mays seeds

    NASA Astrophysics Data System (ADS)

    Mei, M.; Qiu, Y.; He, Y.; Bucker, H.; Yang, C. H.

    1994-10-01

    The growth and development of more than 500 Zea mays seeds flown on LDEF were studied. Somatic mutations, including white-yellow stripes on leaves, dwarfing, change of leaf sheath color or seedling color were observed in plants developed from these seeds. When the frequency of white-yellow formation was used as the endpoint and compared with data from ground based studies, the dose to which maize seeds might be exposed during the flight was estimated to be equivalent to 635 cGy of gamma rays. Seeds from one particular holder gave a high mutation frequency and a wide mutation spectrum. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed somatic mutation. Electron microscopy studies showed that the damage of chroloplast development in the white-yellow stripe on leaves was similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground.

  9. Mutational effects of space flight on Zea mays seeds.

    PubMed

    Mei, M; Qiu, Y; He, Y; Bucker, H; Yang, C H

    1994-10-01

    The growth and development of more than 500 Zea mays seeds flown on LDEF were studied. Somatic mutations, including white-yellow stripes on leaves, dwarfing, change of leaf sheath color or seedling color were observed in plants developed from these seeds. When the frequency of white-yellow formation was used as the endpoint and compared with data from ground based studies, the dose to which maize seeds might be exposed during the flight was estimated to be equivalent to 635 cGy of gamma rays. Seeds from one particular holder gave a high mutation frequency and a wide mutation spectrum. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed somatic mutation. Electron microscopy studies showed that the damage of chloroplast development in the white-yellow stripe on leaves was similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground.

  10. Highly efficient narrow-line generation by difference-frequency mixing of a green pump and the stokes seed in RbTiOPO4 crystals: excitation of 943-nm emission.

    PubMed

    Kuznetsov, Sergey; Pasmanik, Guerman; Shilov, Alexander; Tiour, Larissa

    2004-04-15

    An efficient and compact scheme for diode-pumped Nd:YLF laser wavelength conversion to 943 nm was demonstrated by use of difference-frequency mixing and stimulated Raman scattering. We believe that this is the highest conversion efficiency from the laser fundamental wavelength reported to date. It is shown that RbTiOPO4 crystals are capable of providing highly efficient frequency mixing as a nonlinear medium. PMID:15119398

  11. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues

    PubMed Central

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E.

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  12. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

    PubMed

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  13. Physiology of Oil Seeds

    PubMed Central

    Ketring, D. L.; Morgan, P. W.

    1971-01-01

    Germination, ethylene production, and carbon dioxide production by dormant Virginia-type peanuts were determined during treatments with plant growth regulators. Kinetin, benzylaminopurine, and 2-chloroethylphosphonic acid induced extensive germination above the water controls. Benzylaminopurine and 2-chloroethylphosphonic acid increased the germination of the more dormant basal seeds to a larger extent above the controls than the less dormant apical seeds. Coumarin induced a slight stimulation of germination while abscisic acid, 2,4-dichlorophenoxyacetic acid, and succinic acid 2,2-dimethylhydrazide did not stimulate germination above the controls. In addition to stimulating germination, the cytokinins also stimulated ethylene production by the seeds. In the case of benzylaminopurine, where the more dormant basal seeds were stimulated to germinate above the control to a larger extent than the less dormant apical seeds, correspondingly more ethylene production was induced in the basal seeds. However, the opposite was true of kinetin for both germination and ethylene production. When germination was extensively stimulated by the cytokinins, maximal ethylene and carbon dioxide evolution occurred at 24 and 72 hours, respectively. Abscisic acid inhibited ethylene production and germinaton of the seeds while carbon dioxide evolution was comparatively high. The crucial physiological event for germination of dormant peanut seeds was enhancement of ethylene production by the seeds. PMID:16657647

  14. A role for seed storage proteins in Arabidopsis seed longevity.

    PubMed

    Nguyen, Thu-Phuong; Cueff, Gwendal; Hegedus, Dwayne D; Rajjou, Loïc; Bentsink, Leónie

    2015-10-01

    Proteomics approaches have been a useful tool for determining the biological roles and functions of individual proteins and identifying the molecular mechanisms that govern seed germination, vigour and viability in response to ageing. In this work the dry seed proteome of four Arabidopsis thaliana genotypes, that carry introgression fragments at the position of seed longevity quantitative trait loci and as a result display different levels of seed longevity, was investigated. Seeds at two physiological states, after-ripened seeds that had the full germination ability and aged (stored) seeds of which the germination ability was severely reduced, were compared. Aged dry seed proteomes were markedly different from the after-ripened and reflected the seed longevity level of the four genotypes, despite the fact that dry seeds are metabolically quiescent. Results confirmed the role of antioxidant systems, notably vitamin E, and indicated that protection and maintenance of the translation machinery and energy pathways are essential for seed longevity. Moreover, a new role for seed storage proteins (SSPs) was identified in dry seeds during ageing. Cruciferins (CRUs) are the most abundant SSPs in Arabidopsis and seeds of a triple mutant for three CRU isoforms (crua crub cruc) were more sensitive to artificial ageing and their seed proteins were highly oxidized compared with wild-type seeds. These results confirm that oxidation is involved in seed deterioration and that SSPs buffer the seed from oxidative stress, thus protecting important proteins required for seed germination and seedling formation.

  15. A quick SEED tutorial

    USGS Publications Warehouse

    Ringler, Adam; Evans, John R.

    2015-01-01

    A number of different government-funded seismic data centers offer free open-access data (e.g., U.S. Geological Survey, National Earthquake Information Center, the Incorporated Research Institutions for Seismology (IRIS), and Data Management System), which can be freely downloaded and shared among different members of the community (Lay, 2009). To efficiently share data, it is important that different data providers follow a common format. The Standard for the Exchange of Earthquake Data (SEED) provides one such format for storing seismic and other geophysical data. The SEED format is widely used in earthquake seismology; however, SEED and its structure can be difficult for many first-time users (ourselves included). Below is a quick tutorial that outlines the basic structure of SEED format. This write-up is in no way intended to replace the comprehensive SEED manual (Ahern et al., 2009), and instead of going into the details of any specific part of the SEED format we refer the reader to the manual for additional details. The goal of this write-up is to succinctly explain the basic structure of SEED format as well as the associated jargon, as most commonly used now, in a colloquial way so that novice users of SEED can become more familiar with the format and its application quickly. Our goal is to give the reader the necessary background so that when problems or questions about SEED format arise they will have some understanding of where they should look for more details or from where the problem might be stemming. As a secondary goal, we hope to help the reader become familiar with the SEED manual (Ahern et al., 2009), which contains detailed information about all aspects of the SEED format.

  16. Examining Children's Models of Seed.

    ERIC Educational Resources Information Center

    Jewell, Natalie

    2002-01-01

    Reports research that examines children's models of seed. Explores the conceptions held by children (N=75) of germination and seed formation. Concludes that children hold a restricted meaning for the term 'seed'. (DDR)

  17. GROWING SEEDS, TEACHER'S GUIDE.

    ERIC Educational Resources Information Center

    Elementary Science Study, Newton, MA.

    THIS TEACHER'S GUIDE IS DESIGNED FOR USE WITH AN ELEMENTARY SCIENCE STUDY UNIT, "GROWING SEEDS," IN WHICH SUCH BASIC SCIENCE SKILLS AND PROCESSES AS MEASUREMENT, OBSERVATION, AND HYPOTHESIS FORMATION ARE INTRODUCED THROUGH STUDENT ACTIVITIES INVOLVING SEEDS, GERMINATION, AND SEEDLING GROWTH. THE MATERIALS WERE DEVELOPED FOR USE IN ELEMENTARY…

  18. [Quality classification criteria of Paeonia suffruticosa seeds].

    PubMed

    Cao, Ya-yue; Zhu, Zai-biao; Guo, Qiao-sheng; Liu, Li; Wang, Chang-lin

    2015-02-01

    In order to establish the quality classification criteria of Paeonia suffruticosa seeds, thirty-one batches of P. suffruticosa seeds from different provenances were selected. The seed rooting rate, seed germination rate, seed purity, seed viability, 1,000-seed weight and moisture content were determined and analyzed through SPSS 20.0 software. Seed rooting rate, seed germination rate and seed purity were selected as the main index for classification, while 1,000-seed weight, seed viability and moisture content could be used as important references. The seed quality grading of P. suffruticosa was set as three grades. The seed quality of each grade should meet following requirements: For the first grade seeds, seed rooting rate ≥ 80%, seed germination rate ≥ 80%, seed purity ≥ 90%, seed viability ≥ 80%, 1,000-seed weight ≥ 250 g, moisture content, ≤ 10. For the second grade seeds, seed rooting rate ≥ 50%, seed germination rate ≥ 60%, seed purity ≥ 70%, seed viability ≥ 75%, 1,000-seed weight ≥ 225 g, moisture content ≤ 10. For the third grade seeds, seed rooting rate ≥ 20%, seed germination rate ≥ 45%, seed purity ≥ 60%, seed viability ≥ 45%, 1,000-seed weight ≥ 205 g, moisture content ≤ 10. The quality classification criteria of P. suffruticosa seeds have been initially established.

  19. The earliest seeds

    USGS Publications Warehouse

    Gillespie, W.H.; Rothwell, G.W.; Scheckler, S.E.

    1981-01-01

    Lagenostomalean-type seeds in bifurcating cupule systems have been discovered in the late Devonian Hampshire Formation of Randolph County, West Virginia, USA (Fig. 1). The associated megaflora, plants from coal balls, and vertebrate and invertebrate faunas demonstrate that the material is Famennian; the microflora indicates a more specific Fa2c age. Consequently, these seeds predate Archaeosperma arnoldii1 from the Fa2d of northeastern Pennsylvania, the oldest previously reported seed. By applying precision fracture, transfer, de??gagement, and thin-section techniques to selected cupules from the more than 100 specimens on hand, we have determined the three-dimensional morphology and histology of the seeds (Fig. 2a-h, k) and cupule systems. A comparison with known late Devonian to early Carboniferous seeds reveals that ours are more primitively organized than all except Genomosperma2,3. ?? 1981 Nature Publishing Group.

  20. The effect of burial depth on removal of seeds of Phytolacca americana.

    SciTech Connect

    Orrock, John, L.: Damschen, Ellen, I.

    2007-04-01

    Abstract - Although burial is known to have important effects on seed predation in a variety of habitats, the role of burial depth in affecting the removal of seeds in early successional systems is poorly known. Phytolacca American (pokeweed) is a model species to examine the role of burial depth in affecting seed removal because it is common in early-successional habitats, studies suggest that seed removal is indicative of seed predation, and seed predation is related to the recruitment of mature plants. To determine how burial depth affects P. americana seed removal, 20 seeds of P. americana were buried at depths of 0, 1, or 3 cm in early-successional habitats at the Savannah River Site in South Carolina for over 6 weeks. The frequency with which seeds were encountered (as measured by the removal of at least one seed) and the proportion of seeds removed was significantly greater when seeds were on the soil surface (0 cm depth) compared to seeds that were buried 1 cm or 3 cm; there was no difference in encounter or removal between seeds at 1 cm or 3 cm. Our findings suggest that burial may have important consequences for P. americana population dynamics, because seed survival depends upon whether or not the seed is buried, and relatively shallow burial can yield large increases in seed survival. Because seed limitation is known to be an important determinant of plant community composition in early successional systems, our work suggests that burial may play an unappreciated role in the dynamics of these communities by reducing predator-mediated seed limitation.

  1. Magnetic stimulation of marigold seed

    NASA Astrophysics Data System (ADS)

    Afzal, I.; Mukhtar, K.; Qasim, M.; Basra, S. M. A.; Shahid, M.; Haq, Z.

    2012-10-01

    The effects of magnetic field treatments of French marigold seeds on germination, early seedling growth and biochemical changes of seedlings were studied under controlled conditions. For this purpose, seeds were exposed to five different magnetic seed treatments for 3 min each. Most of seed treatments resulted in improved germination speed and spread, root and shoot length, seed soluble sugars and a-amylase activity. Magnetic seed treatment with 100 mT maximally improved germination, seedling vigour and starch metabolism as compared to control and other seed treatments. In emergence experiment, higher emergence percentage (4-fold), emergence index (5-fold) and vigorous seedling growth were obtained in seeds treated with 100 mT. Overall, the enhancement of marigold seeds by magnetic seed treatment with 100 mT could be related to enhanced starch metabolism. The results suggest that magnetic field treatments of French marigold seeds have the potential to enhance germination, early growth and biochemical parameters of seedlings.

  2. Defoliation effects on Bromus tectorum seed production: Implications for grazing

    USGS Publications Warehouse

    Hempy-Mayer, K.; Pyke, D.A.

    2008-01-01

    Cheatgrass (Bromus tectorum L.) is an invasive annual grass that creates near-homogenous stands in areas throughout the Intermountain sagebrush steppe and challenges successful native plant restoration in these areas. A clipping experiment carried out at two cheatgrass-dominated sites in eastern Oregon (Lincoln Bench and Succor Creek) evaluated defoliation as a potential control method for cheatgrass and a seeding preparation method for native plant reseeding projects. Treatments involved clipping plants at two heights (tall = 7.6 cm, and short = 2.5 cm), two phenological stages (boot and purple), and two frequencies (once and twice), although purple-stage treatments were clipped only once. Treatments at each site were replicated in a randomized complete block design that included a control with no defoliation. End-of-season seed density (seeds??m-2) was estimated by sampling viable seeds from plants, litter, and soil of each treatment. Undipped control plants produced an average of approximately 13 000 and 20 000 seeds??m-2 at Lincoln Bench and Succor Creek, respectively. Plants clipped short at the boot stage and again 2 wk later had among the lowest mean seed densities at both sites, and were considered the most successful treatments (Lincoln Bench: F 6,45 = 47.07, P < 0.0001; Succor Creek: F6,40 = 19.60, P < 0.0001). The 95% confidence intervals for seed densities were 123-324 seeds??m-2 from the Lincoln Bench treatment, and 769-2256 seeds??m-2 from the Succor Creek treatment. Literature suggests a maximum acceptable cheatgrass seed density of approximately 330 seeds??m-2 for successful native plant restoration through reseeding. Thus, although this study helped pinpoint optimal defoliation parameters for cheatgrass control, it also called into question the potential for livestock grazing to be an effective seed-bed preparation technique in native plant reseeding projects in cheatgrass-dominated areas.

  3. Photoacoustic Study of Fungal Disease of Acai ( Euterpe oleracea) Seeds

    NASA Astrophysics Data System (ADS)

    Rezende, Denise V.; Nunes, O. A. C.; Oliveira, A. C.

    2009-10-01

    Photoacoustic spectroscopy is introduced as a promising experimental technique to investigate fungus infected Acai ( Euterpe oleracea) seeds. Photoacoustic spectra of healthy and infected Acai seeds with the fungus Colletotrichum gloeosporioides were recorded firstly in the modulation frequency range of 5Hz to 700 Hz, while keeping the wavelength of excitation radiation of a Xe arc-lamp constant, to ascertain the depth of penetration of infection within the seed and secondly, at variable wavelength (wavelength scanning) in the interval 250nm to 1,000 nm, while keeping the modulation frequency constant. In the former, the photoacoustic signal strength from the infected seed was found higher than that of the healthy one, and has been associated with the appearance of new biomolecules associated with the pathogen infection. In the latter, characteristics peaks and bands were observed in the range from 650 nm to 900 nm ascribed to organic compounds with carboxylates and amines (functional groups) forming the typical metabolic structures of the fungus.

  4. Seed output and the seed bank in Vallisneria americana (Hydrocharitaceae).

    PubMed

    Lokker, C; Lovett-Doust, L; Lovett-Doust, J

    1997-10-01

    Seed banks and sexual reproduction are known to be significant in colonization and re-establishment of some aquatic macrophyte communities. For highly clonal aquatic macrophytes, however, there is a lack of information on seed production and seed fate as compared with annual sexual species. The seed bank for three populations of Vallisneria americana in the Huron-Erie corridor of the Great Lakes was sampled and quantified in the spring of 1994, and related to seed production in the previous season at these sites. Seed deposition rates during 1994 were also assessed. Sites varied in the proportion of plants flowering and in their tertiary sex ratios, but did not differ in seed numbers produced per unit area. The size of the seed bank was not significantly related to the previous season's seed output, and estimates of seed deposition in the following year tended to be approximately tenfold greater than seed densities found in the seed bank. The stages between seed production and subsequent seed germination are generally very dynamic, with dispersal, mortality, and predation as likely regulating factors. The potential for seedling establishment in V. americana needs to be assessed more fully before the role of seeds in population processes can be determined. PMID:21708549

  5. Fishing for Seeds.

    ERIC Educational Resources Information Center

    Science and Children, 2001

    2001-01-01

    Describes a method to collect seeds that are dispersed from weeds while avoiding some outdoor hazards such as rough terrain or animals. Describes a plan for creating a weed fishing pole and includes a materials list. (SAH)

  6. Seeds in Flight

    ERIC Educational Resources Information Center

    Martin, Willard K.

    1978-01-01

    Discussed are the seed dispersal mechanisms of six different plants: big-leaf maple, pincushion tree, tree of heaven, squirting cucumber, digger pine, and bull thistle. Elaborate color and black-and-white drawings illustrate the text. (MA)

  7. Tomato seeds for LDEF

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Tomato seeds are prepared for their launch aboard the Langley's Long Duration Exposure Facility. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 119), by James Schultz.

  8. Investigation of the effect of space flight factors on chromosomes in seeds

    NASA Technical Reports Server (NTRS)

    Dubinina, L. G.

    1980-01-01

    Frequency of mutations in postflight air-dry Crepis capillaris seeds, kept for five days aboard an artificial satellite was 36.0 + or - 1.9%, vs. 19.01 + or - 1.2% for seeds in a similar ground experiment. Both groups of seeds were prepared in identical concentrations and were treated by the same mutagen. The spectrum of mutations in postflight Crepis capillaris seeds contained a large number of chromosome-type mutations and some cells showed multiple alterations. Postflight seeds not treated with mutagens had a slightly higher level of mutability.

  9. Seed dispersal in fens

    USGS Publications Warehouse

    Middleton, B.; Van Diggelen, R.; Jensen, K.

    2006-01-01

    Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and reducing genetic exchange. Species in fragmented wetlands may have lower reproductive success, which can lead to biodiversity loss. While fens may have always been relatively isolated from each other, they have become increasingly fragmented in modern times within agricultural and urban landscapes in both Europe and North America. Dispersal by water, animals and wind has been hampered by changes related to development in landscapes surrounding fens. Because the seeds of certain species are long-lived in the seed bank, frequent episodes of dispersal are not always necessary to maintain the biodiversity of fens. However, of particular concern to restoration is that some dominant species, such as the tussock sedge Carex stricta, may not disperse readily between fens. Conclusions: Knowledge of seed dispersal can be used to maintain and restore the biodiversity of fens in fragmented landscapes. Given that development has fragmented landscapes and that this situation is not likely to change, the dispersal of seeds might be enhanced by moving hay or cattle from fens to damaged sites, or by reestablishing lost hydrological connections. ?? IAVS; Opulus Press.

  10. Evaluation of Seed Transmission of Turnip yellow mosaic virus and Tobacco mosaic virus in Arabidopsis thaliana.

    PubMed

    de Assis Filho, F M; Sherwood, J L

    2000-11-01

    ABSTRACT The mechanism of virus transmission through seed was studied in Arabidopsis thaliana infected with Turnip yellow mosaic virus (TYMV) and Tobacco mosaic virus (TMV). Serological and biological tests were conducted to identify the route by which the viruses reach the seed and subsequently are located in the seed. Both TYMV and TMV were detected in seed from infected plants, however only TYMV was seed-transmitted. This is the first report of transmission of TYMV in seed of A. thaliana. Estimating virus seed transmission by grow-out tests was more accurate than enzyme-linked immunosorbent assay due to the higher frequency of antigen in the seed coat than in the embryo. Virus in the seed coat did not lead to seedling infection. Thus, embryo invasion is necessary for seed transmission of TYMV in A. thaliana. Crosses between healthy and virus-infected plants indicated that TYMV from either the female or the male parent could invade the seed. Conversely, invasion from maternal tissue was the only route for TMV to invade the seed. Pollination of flowers on healthy A. thaliana with pollen from TYMV-infected plants did not result in systemic infection of healthy plants, despite TYMV being carried by pollen to the seed.

  11. Optically seeded stimulated Raman scattering of aqueous sulfate microdroplets

    NASA Astrophysics Data System (ADS)

    Pasternack, Louise; Fleming, James W.; Owrutsky, Jeffrey C.

    1996-07-01

    Optically seeded, stimulated Raman scattering is demonstrated for 25- mu m -radius water droplets containing sulfate. Frequency-doubled Nd:YAG laser-excited Stokes radiation from the 3450- cm -1 O-H-stretching vibration of water provides the seed for morphology-dependent stimulated Raman scattering from the nu 1 vibration of sulfate that is excited by a dye laser. Seeding enhances the otherwise weaker signal for low concentrations of the anion, thereby reducing the solute detection limit, by a method that does not require changing of the droplet composition.

  12. Seed coat color and seed weight contribute differential responses of targeted metabolites in soybean seeds.

    PubMed

    Lee, Jinwook; Hwang, Young-Sun; Kim, Sun Tae; Yoon, Won-Byong; Han, Won Young; Kang, In-Kyu; Choung, Myoung-Gun

    2017-01-01

    The distribution and variation of targeted metabolites in soybean seeds are affected by genetic and environmental factors. In this study, we used 192 soybean germplasm accessions collected from two provinces of Korea to elucidate the effects of seed coat color and seeds dry weight on the metabolic variation and responses of targeted metabolites. The effects of seed coat color and seeds dry weight were present in sucrose, total oligosaccharides, total carbohydrates and all measured fatty acids. The targeted metabolites were clustered within three groups. These metabolites were not only differently related to seeds dry weight, but also responded differentially to seed coat color. The inter-relationship between the targeted metabolites was highly present in the result of correlation analysis. Overall, results revealed that the targeted metabolites were diverged in relation to seed coat color and seeds dry weight within locally collected soybean seed germplasm accessions. PMID:27507473

  13. Mechanisms of long-distance dispersal of seeds by wind.

    PubMed

    Nathan, Ran; Katul, Gabriel G; Horn, Henry S; Thomas, Suvi M; Oren, Ram; Avissar, Roni; Pacala, Stephen W; Levin, Simon A

    2002-07-25

    Long-distance dispersal (LDD) is central to species expansion following climate change, re-colonization of disturbed areas and control of pests. The current paradigm is that the frequency and spatial extent of LDD events are extremely difficult to predict. Here we show that mechanistic models coupling seed release and aerodynamics with turbulent transport processes provide accurate probabilistic descriptions of LDD of seeds by wind. The proposed model reliably predicts the vertical distribution of dispersed seeds of five tree species observed along a 45-m high tower in an eastern US deciduous forest. Simulations show that uplifting above the forest canopy is necessary and sufficient for LDD, hence, they provide the means to define LDD quantitatively rather than arbitrarily. Seed uplifting probability thus sets an upper bound on the probability of long-distance colonization. Uplifted yellow poplar seeds are on average lighter than seeds at the forest floor, but also include the heaviest seeds. Because uplifting probabilities are appreciable (as much as 1 5%), and tree seed crops are commonly massive, some LDD events will establish individuals that can critically affect plant dynamics on large scales.

  14. Seeds in space experiment results

    NASA Technical Reports Server (NTRS)

    Alston, Jim A.

    1991-01-01

    Two million seeds of 120 different varieties representing 106 species, 97 genera, and 55 plant families were flown aboard the Long Duration Exposure Facility (LDEF). The seeds were housed on the space exposed experiment developed for students (SEEDS) tray in sealed canister number six and in two small vented canisters. The tray was in the F-2 position. The seeds were germinated and the germination rates and development of the resulting plants compared to the control seed that stayed in Park Seed's seed storage facility. The initial results are presented. There was a better survival rate in the sealed canister in space than in the storage facility at Park Seed. At least some of the seeds in each of the vented canisters survived the exposure to vacuum for almost six years. The number of observed apparent mutations was very low.

  15. Seed Transmission of Pseudoperonospora cubensis

    PubMed Central

    Cohen, Yigal; Rubin, Avia E.; Galperin, Mariana; Ploch, Sebastian; Runge, Fabian; Thines, Marco

    2014-01-01

    Pseudoperonospora cubensis, an obligate biotrophic oomycete causing devastating foliar disease in species of the Cucurbitaceae family, was never reported in seeds or transmitted by seeds. We now show that P. cubensis occurs in fruits and seeds of downy mildew-infected plants but not in fruits or seeds of healthy plants. About 6.7% of the fruits collected during 2012–2014 have developed downy mildew when homogenized and inoculated onto detached leaves and 0.9% of the seeds collected developed downy mildew when grown to the seedling stage. This is the first report showing that P. cubensis has become seed-transmitted in cucurbits. Species-specific PCR assays showed that P. cubensis occurs in ovaries, fruit seed cavity and seed embryos of cucurbits. We propose that international trade of fruits or seeds of cucurbits might be associated with the recent global change in the population structure of P. cubensis. PMID:25329308

  16. Automated seed manipulation and planting

    NASA Technical Reports Server (NTRS)

    Garcia, Ray; Herrera, Javier; Holcomb, Scott; Kelly, Paul; Myers, Scott; Rosendo, Manny; Sivitz, Herbert; Wolsefer, Dave

    1988-01-01

    The Mechanical Division fabricated three seed separators utilizing pressure gradients to move and separate wheat seeds. These separators are called minnow buckets and use air, water, or a combination of both to generate the pressure gradient. Electrostatic fields were employed in the seed separator constructed by the Electrical Division. This separator operates by forcing a temporary electric dipole on the wheat seeds and using charged electrodes to attract and move the seeds. Seed delivery to the hydroponic growth tray is accomplished by the seed cassette. The cassette is compatible with all the seed separators, and it consists of a plastic tube threaded with millipore filter paper. During planting operations, the seeds are placed in an empty cassette. The loaded cassette is then placed in the growth tray and nutrient solution provided. The solution wets the filter paper and capillary action draws the nutrients up to feed the seeds. These seeding systems were tested and showed encouraging results. Seeds were effectively separated and the cassette can support the growth of wheat plants. Problems remaining to be investigated include improving the success of delivering the seeds to the cassette and providing adequate spacing between seeds for the electric separator.

  17. Linearly frequency-modulated pulsed single-frequency fiber laser at 1083 nm.

    PubMed

    Zhang, Yuanfei; Yang, Changsheng; Li, Can; Feng, Zhouming; Xu, Shanhui; Deng, Huaqiu; Yang, Zhongmin

    2016-02-22

    A linearly frequency-modulated, actively Q-switched, single-frequency ring fiber laser based on injection seeding from an ultra-short cavity is demonstrated at 1083 nm. A piezoelectric transducer is employed to obtain linearly frequency-modulating performance and over 1.05 GHz frequency-tuning range is achieved with a modulating frequency reaching tens of kilohertz. A maximum peak power of the stable output pulse is over 3.83 W during frequency-modulating process. This type of pulsed fiber laser provides a promising candidate for coherent LIDAR in the measurement of thermosphere.

  18. Magnetic-seeding filtration

    SciTech Connect

    Depaoli, D.

    1996-10-01

    This task will investigate the capabilities of magnetic-seeding filtration for the enhanced removal of magnetic and nonmagnetic particulates from liquids. This technology appies to a wide range of liquid wastes, including groundwater, process waters, and tank supernatant. Magnetic-seeding filtration can be used in several aspects of treatment, such as (1) removal of solids, particularly those in the colloidal-size range that are difficult to remove by conventional means; (2) removal of contaminants by precipitation processes; and (3) removal of contaminants by sorption processes.

  19. Seed Dormancy and Germination

    PubMed Central

    Bentsink, Leónie; Koornneef, Maarten

    2008-01-01

    Seed dormancy allows seeds to overcome periods that are unfavourable for seedling established and is therefore important for plant ecology and agriculture. Several processes are known to be involved in the induction of dormancy and in the switch from the dormant to the germinating state. The role of plant hormones, the different tissues and genes involved, including newly identified genes in dormancy and germination are described in this chapter, as well as the use transcriptome, proteome and metabolome analyses to study these mechanistically not well understood processes. PMID:22303244

  20. Fiber and seed loss from seed cotton cleaning machinery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fiber and seed loss from seed cotton cleaning equipment in cotton gins occurs, but the quantity of material lost, factors affecting fiber and seed loss, and the mechanisms that cause material loss are not well understood. Two experiments were conducted to evaluate the effects of different factors on...

  1. Multiple seeds sensitivity using a single seed with threshold.

    PubMed

    Egidi, Lavinia; Manzini, Giovanni

    2015-08-01

    Spaced seeds are a fundamental tool for similarity search in biosequences. The best sensitivity/selectivity trade-offs are obtained using many seeds simultaneously: This is known as the multiple seed approach. Unfortunately, spaced seeds use a large amount of memory and the available RAM is a practical limit to the number of seeds one can use simultaneously. Inspired by some recent results on lossless seeds, we revisit the approach of using a single spaced seed and considering two regions homologous if the seed hits in at least t sufficiently close positions. We show that by choosing the locations of the don't care symbols in the seed using quadratic residues modulo a prime number, we derive single seeds that when used with a threshold t > 1 have competitive sensitivity/selectivity trade-offs, indeed close to the best multiple seeds known in the literature. In addition, the choice of the threshold t can be adjusted to modify sensitivity and selectivity a posteriori, thus enabling a more accurate search in the specific instance at issue. The seeds we propose also exhibit robustness and allow flexibility in usage. PMID:25747382

  2. Fast-switching system for injection seeding of a high-power Ti:sapphire laser.

    PubMed

    Khalesifard, Hamid R; Fix, Andreas; Ehret, Gerhard; Schiller, Max; Wulfmeyer, Volker

    2009-07-01

    A high frequency switching and tunable seed laser system has been designed and constructed for injection seeding of a high-power pulsed Ti:sapphire laser. The whole laser system operates as the transmitter of a scanning, ground-based, water-vapor differential absorption lidar (DIAL). The output of two seed lasers can be tuned in the wavelength range of 815-840 nm up to the power of 20 mW and switched between the online and offline wavelengths of the DIAL at frequencies of 0-1 kHz. The frequency stability of online and offline seed lasers is better than +/-20 MHz rms and the mode-hop-free tuning range is greater than 40 GHz with external cavity diode lasers. The advantage of this system for efficient injection seeding of the Ti:sapphire cavity is that it is modular, robust, fully fiber-coupled, and polarization maintaining.

  3. Fast-switching system for injection seeding of a high-power Ti:sapphire laser.

    PubMed

    Khalesifard, Hamid R; Fix, Andreas; Ehret, Gerhard; Schiller, Max; Wulfmeyer, Volker

    2009-07-01

    A high frequency switching and tunable seed laser system has been designed and constructed for injection seeding of a high-power pulsed Ti:sapphire laser. The whole laser system operates as the transmitter of a scanning, ground-based, water-vapor differential absorption lidar (DIAL). The output of two seed lasers can be tuned in the wavelength range of 815-840 nm up to the power of 20 mW and switched between the online and offline wavelengths of the DIAL at frequencies of 0-1 kHz. The frequency stability of online and offline seed lasers is better than +/-20 MHz rms and the mode-hop-free tuning range is greater than 40 GHz with external cavity diode lasers. The advantage of this system for efficient injection seeding of the Ti:sapphire cavity is that it is modular, robust, fully fiber-coupled, and polarization maintaining. PMID:19655946

  4. [Spatial patterns of seed dispersal in Hemiptelea davidii woodland in Keerqin sandy land, China].

    PubMed

    Yang, Yun-Fei; Bai, Yun-Peng; Li, Jian-Dong; Li, Li

    2010-08-01

    In order to reveal the space expansion potential of Hemiptelea davidii woodland in Keerqin sandy land in China, the quantitative spatial characteristics of the seed rain in the understory and at the woodsides, as well as the seed dispersal patterns at the woodsides and of the isolating trees, were analyzed through survey on sequential sampling away from seed source in different directions at the woodsides and isolating trees and random sampling in the understory. The results showed that among three sampling plots, the average density of the seed rain in the understory was the highest (13732.5 +/- 3106.2 seeds x m(-2)). For isolating trees, the seed rain had the highest density (5449.4 +/- 1429.3 seeds x m(-2)) in southeast transect, being significantly higher than that in other directions, and the lowest one (650.2 +/- 631.6 seeds x m(-2)) in the northwest transect, being significantly lower than that in other directions. At the woodsides, the seed rain density was significantly higher in the east and south transects than in the west and north transects. The variation of the seed density was greater, with the variation coefficient being 25.7%-106.3% in different directions in the two plots of isolating trees and woodsides. Same as other anemochorous plants, H. davidii had the characteristics of seed dispersal away from the seed source. In the eight sampling transects, there existed diversity in the patterns of the seed dispersal away from the seed source in per unit area and in accumulated area, including linear, power, exponential, quadratic parabola, and logarithmic functions. It was suggested that the space expansion potential of H. davidii woodland in Keerqin sandy land would be greater in more frequency down wind directions such as the south, southeast, and east than in more frequency upwind directions such as the north, northwest, and west.

  5. The SEED Initiative

    ERIC Educational Resources Information Center

    Teich, Carolyn R.

    2011-01-01

    Committed to fulfilling the promise of the green economy, the American Association of Community Colleges (AACC) launched the Sustainability Education and Economic Development (SEED) initiative (www.theseedcenter.org) in October 2010. The project advances sustainability and clean energy workforce development practices at community colleges by…

  6. Magnetic-seeding filtration

    SciTech Connect

    DePaoli, D.W.; Tsouris, C.; Yiacoumi, Sotira

    1997-10-01

    Magnetic-seeding filtration is a technology under development for the enhanced removal of magnetic and non-magnetic particulates from liquids. This process involves the addition of a small amount of magnetic seed particles (such as naturally occurring iron oxide) to a waste suspension, followed by treatment with a magnetic filter. Non-magnetic and weakly magnetic particles are made to undergo nonhomogeneous flocculation with the seed particles, forming flocs of high magnetic susceptibility that are readily removed by a conventional high-gradient magnetic filter. This technology is applicable to a wide range of liquid wastes, including groundwater, process waters, and tank supernatants. Magnetic-seeding filtration may be used in several aspects of treatment, such as (1) removal of solids, particularly those in the colloidal size range that are difficult to remove by conventional means; (2) removal of contaminants by precipitation processes; and (3) removal of contaminants by sorption processes. Waste stream characteristics for which the technology may be applicable include (1) particle sizes ranging from relatively coarse (several microns) to colloidal particles, (2) high or low radiation levels, (3) broad-ranging flow rates, (4) low to moderate solids concentration, (5) cases requiring high decontamination factors, and (6) aqueous or non-aqueous liquids. At this point, the technology is at the bench-scale stage of development; laboratory studies and fundamental modeling are currently being employed to determine the capabilities of the process.

  7. Seeds: A Celebration of Science.

    ERIC Educational Resources Information Center

    Melton, Bob

    The Space Exposed Experiment Developed for Students (SEEDS) Project offered science classes at the 5-12 and college levels the opportunity to conduct experiments involving tomato seeds that had been space-exposed over long periods of time. SEEDS kits were complete packages obtained from the National Aeronautics and Space Administration (NASA) for…

  8. Corridors cause differential seed predation.

    SciTech Connect

    Orrock, John L.; Damschen, Ellen I.

    2005-06-01

    Orrock, John, L., and Ellen I. Damschen. 2005. Corridors cause differential seed predation. Ecol. Apps. 15(3):793-798. Abstract. Corridors that connect disjunct populations are heavily debated in conservation, largely because the effects of corridors have rarely been evaluated by replicated, large-scale studies. Using large-scale experimental landscapes, we found that, in addition to documented positive effects, corridors also have negative impacts on bird-dispersed plants by affecting seed predation, and that overall predation is a function of the seeds primary consumer (rodents or arthropods). Both large-seeded Prunus serotina and small-seeded Rubus allegheniensis experienced greater predation in connected patches. However, P. serotina experienced significantly less seed predation compared to R. allegheniensis in unconnected patches, due to decreased impacts of rodent seed predators on this large-seeded species. Viewed in light of previous evidence that corridors have beneficial impacts by increasing pollination and seed dispersal, this work demonstrates that corridors may have both positive and negative effects for the same plant species at different life stages. Moreover, these effects may differentially affect plant species within the same community: seeds primarily consumed by rodents suffer less predation in unconnected patches. By shifting the impact of rodent and arthropod seed predators, corridors constructed for plant conservation could lead to shifts in the seed bank.

  9. Dispersal of Transgenes through Maize Seed Systems in Mexico

    PubMed Central

    Dyer, George A.; Serratos-Hernández, J. Antonio; Perales, Hugo R.; Gepts, Paul; Piñeyro-Nelson, Alma; Chávez, Angeles; Salinas-Arreortua, Noé; Yúnez-Naude, Antonio; Taylor, J. Edward; Alvarez-Buylla, Elena R.

    2009-01-01

    Objectives Current models of transgene dispersal focus on gene flow via pollen while neglecting seed, a vital vehicle for gene flow in centers of crop origin and diversity. We analyze the dispersal of maize transgenes via seeds in Mexico, the crop's cradle. Methods We use immunoassays (ELISA) to screen for the activity of recombinant proteins in a nationwide sample of farmer seed stocks. We estimate critical parameters of seed population dynamics using household survey data and combine these estimates with analytical results to examine presumed sources and mechanisms of dispersal. Results Recombinant proteins Cry1Ab/Ac and CP4/EPSPS were found in 3.1% and 1.8% of samples, respectively. They are most abundant in southeast Mexico but also present in the west-central region. Diffusion of seed and grain imported from the United States might explain the frequency and distribution of transgenes in west-central Mexico but not in the southeast. Conclusions Understanding the potential for transgene survival and dispersal should help design methods to regulate the diffusion of germplasm into local seed stocks. Further research is needed on the interactions between formal and informal seed systems and grain markets in centers of crop origin and diversification. PMID:19503610

  10. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  11. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  12. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  13. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  14. 7 CFR 201.15 - Weed seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation...

  15. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hard seed. 201.30 Section 201.30 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed,...

  16. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hard seed. 201.30 Section 201.30 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed,...

  17. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hard seed. 201.30 Section 201.30 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed,...

  18. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seed. 201.30 Section 201.30 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed,...

  19. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hard seed. 201.30 Section 201.30 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed,...

  20. Tree Seed Technology Training Course: Student Outline.

    ERIC Educational Resources Information Center

    Bonner, F. T.; And Others

    This manual is intended primarily to train seed collectors, seed-plant managers, seed analysts, and nursery managers, but can serve as a resource for any training course in forest regeneration. It includes both temperate and tropical tree species of all intended uses and covers the following topics: seed biology, seed collection, seed handling,…

  1. Seed priming to alleviate salinity stress in germinating seeds.

    PubMed

    Ibrahim, Ehab A

    2016-03-15

    Salinity is one of the major abiotic stresses that affect crop production in arid and semiarid areas. Seed germination and seedling growth are the stages most sensitive to salinity. Salt stress causes adverse physiological and biochemical changes in germinating seeds. It can affect the seed germination and stand establishment through osmotic stress, ion-specific effects and oxidative stress. The salinity delays or prevents the seed germination through various factors, such as a reduction in water availability, changes in the mobilization of stored reserves and affecting the structural organization of proteins. Various techniques can improve emergence and stand establishment under salt conditions. One of the most frequently utilized is seed priming. The process of seed priming involves prior exposure to an abiotic stress, making a seed more resistant to future exposure. Seed priming stimulates the pre-germination metabolic processes and makes the seed ready for radicle protrusion. It increases the antioxidant system activity and the repair of membranes. These changes promote seed vigor during germination and emergence under salinity stress. The aim of this paper is to review the recent literature on the response of plants to seed priming under salinity stress. The mechanism of the effect of salinity on seed germination is discussed and the seed priming process is summarized. Physiological, biochemical and molecular changes induced by priming that lead to seed enhancement are covered. Plants' responses to some priming agents under salinity stress are reported based on the best available data. For a great number of crops, little information exists and further research is needed. PMID:26812088

  2. Seed priming to alleviate salinity stress in germinating seeds.

    PubMed

    Ibrahim, Ehab A

    2016-03-15

    Salinity is one of the major abiotic stresses that affect crop production in arid and semiarid areas. Seed germination and seedling growth are the stages most sensitive to salinity. Salt stress causes adverse physiological and biochemical changes in germinating seeds. It can affect the seed germination and stand establishment through osmotic stress, ion-specific effects and oxidative stress. The salinity delays or prevents the seed germination through various factors, such as a reduction in water availability, changes in the mobilization of stored reserves and affecting the structural organization of proteins. Various techniques can improve emergence and stand establishment under salt conditions. One of the most frequently utilized is seed priming. The process of seed priming involves prior exposure to an abiotic stress, making a seed more resistant to future exposure. Seed priming stimulates the pre-germination metabolic processes and makes the seed ready for radicle protrusion. It increases the antioxidant system activity and the repair of membranes. These changes promote seed vigor during germination and emergence under salinity stress. The aim of this paper is to review the recent literature on the response of plants to seed priming under salinity stress. The mechanism of the effect of salinity on seed germination is discussed and the seed priming process is summarized. Physiological, biochemical and molecular changes induced by priming that lead to seed enhancement are covered. Plants' responses to some priming agents under salinity stress are reported based on the best available data. For a great number of crops, little information exists and further research is needed.

  3. Crop protection by seed coating.

    PubMed

    Ehsanfar, S; Modarres-Sanavy, S A M

    2005-01-01

    Providence of sufficient and healthy food for increasing human population clears the importance of notice to increasing crop production in company with environmental loss reduction. Growth and yield of every plant with sexual reproduction, depends on germination & emergence of sown seeds. Seed is a small alive plant that its biological function is protection and nutrition of embryo. Biological, chemical and physiological characteristics of seed, affect on plant performance & its resistance to undesirable environmental conditions, and even on its total yield. So attention to seed and try to increase its performance is so important. One of the factors that cause reduction in germination percentage and seedling establishment, is seed disease. It's possible to control these diseases by treating the seed before planting it. Coating the seed with pesticides, is one of the ways to gain this goal. Seed coating is a technique in which several material as fertilizers, nutritional elements, moisture attractive or repulsive agents, plant growth regulators, rhizobium inocolum, chemical & pesticide etc, add to seed by adhesive agents and cause to increase seed performance and germination. Seed coating, leads to increase benefits in seed industry, because seeds can use all of their genetic vigor. This technique is used for seeds of many garden plants, valuable crops (such as corn, sunflower, canola, alfalfa,...) and some of the grasses. In this technique that was first used in coating cereal seeds in 1930, a thin and permeable layer of pesticide is stuck on seed surface and prevent damage of seedborn pathogens. This layer is melted or splited after absorption of moisture and suitable temperature by seed, and let the radical to exit the seed. In this approach materials are used accurately with seed, evaporation & leakage of pesticide and also adverse effects of some pesticides on seeds are diminished, and these factors cause to increase the accuracy and performance of pesticide

  4. Reduced seed germination in Arabidopsis over-expressing SWI/SNF2 ATPase genes.

    PubMed

    Leeggangers, Hendrika A C F; Folta, Adam; Muras, Aleksandra; Nap, Jan-Peter; Mlynarova, Ludmila

    2015-02-01

    In the life of flowering plants, seed germination is a critical step to ensure survival into the next generation. Generally the seed prior to germination has been in a dormant state with a low rate of metabolism. In the transition from a dormant seed to a germinating seed, various epigenetic mechanisms play a regulatory role. Here, we demonstrate that the over-expression of chromatin remodeling ATPase genes (AtCHR12 or AtCHR23) reduced the frequency of seed germination in Arabidopsis thaliana up to 30% relative to the wild-type seeds. On the other hand, single loss-of-function mutations of the two genes did not affect seed germination. The reduction of germination in over-expressing mutants was more pronounced in stress conditions (salt or high temperature), showing the impact of the environment. Reduced germinations upon over-expression coincided with increased transcript levels of seed maturation genes and with reduced degradation of their mRNAs stored in dry seeds. Our results indicate that repression of AtCHR12/23 gene expression in germinating wild-type Arabidopsis seeds is required for full germination. This establishes a functional link between chromatin modifiers and regulatory networks towards seed maturation and germination.

  5. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  6. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  7. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  8. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  9. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  10. Dielectric characterization of the seeds of invasive Chinese tallow tree.

    PubMed

    Fennell, Laura Picou; Boldor, Dorin

    2013-01-01

    Biofuels have the potential to replace a significant portion of the transportation needs of the USA and the world. Low-cost lipid feedstock (i.e. tallow tree seeds) can be used for production of biodiesel, but these seeds need to be dried. Microwave drying is utilized to dry various seeds and grain, but for this process to be most efficient the dielectric properties of the materials need to be known. This study presents, for the first time, the dielectric properties of the seeds of the Chinese tallow tree. The dielectric constant and dielectric loss factor were determined using a modified free-space method for different moisture contents at frequency ranges centered around 915 and 2450 MHz respectively. The dielectric constant decreased with frequency in those respective ranges, and increased linearly with increasing moisture content, from 1.96 at 0% m.c. to 2.3 at 7% m.c. at 915 MHz, and from 2.08 at 0% m.c. to 2.42 at 7.6% m.c. at 2450 MHz. The dielectric loss factor generally decreased with frequency in both frequency ranges, and increased linearly with moisture content from a low of 0.16 at 0% m.c. to 0.21 at 7.56% at 915 MHz, respectively from a low of 0.13 at 0% m.c. to 0.2 at 7.6% m.c. at 2450 MHz. These results can be used to design microwave processing operations and systems for drying of tallow tree seeds, as well as for non-destructive determination of theses seeds' moisture content. PMID:24779226

  11. Pollination, seed set and seed predation on a landscape scale.

    PubMed

    Steffan-Dewenter, I; Münzenberg, U; Tscharntke, T

    2001-08-22

    We analysed the combined effects of pollination and seed predation on seed set of Centaurea jacea in 15 landscapes differing in structural complexity. In the centre of each landscape, a patch of Centaurea plants was established for standardized measurements of flower visitation, seed predation and seed set. Both the number of flower-visiting bees and the proportion of flower heads damaged by seed predators increased with landscape complexity, which was measured as the proportion of semi-natural habitats. The mean number of seeds per flower head did not increase with the proportion of semi-natural habitats, presumably because of the counterbalancing effects of pollination and seed predation. For a subset of undamaged flower heads, the number of seeds per flower head was positively correlated with the number of flower visits. Further reasons for the unexpected failure to detect a correlation between landscape complexity and seed set appeared to be changes in flower-visitor behaviour and the contrasting responses of honeybees and wild bees to habitat context. Landscape analyses at eight spatial scales (radius of landscape sectors, 250-3000 m) showed that different groups perceived the landscape at different spatial scales. Changes in pollinator numbers could be explained only at small scales (up to 1000 m), while the seed predators also responded to large scales (up to 2500 m).

  12. Sensitive Technique For Detecting Alignment Of Seed Laser

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    1994-01-01

    Frequency response near resonance measured. Improved technique for detection and quantification of alignment of injection-seeding laser with associated power-oscillator laser proposed. Particularly useful in indicating alignment at spectral purity greater than 98 percent because it becomes more sensitive as perfect alignment approached. In addition, implemented relatively easily, without turning on power-oscillator laser.

  13. Empty seeds are not always bad: simultaneous effect of seed emptiness and masting on animal seed predation.

    PubMed

    Perea, Ramón; Venturas, Martin; Gil, Luis

    2013-01-01

    Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal) and in two contrasting microsites (open vs. sheltered) to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis). In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P). Parthenocarpy (non-fertilized seeds) was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds) did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators) consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed. PMID:23776503

  14. Empty Seeds Are Not Always Bad: Simultaneous Effect of Seed Emptiness and Masting on Animal Seed Predation

    PubMed Central

    Perea, Ramón; Venturas, Martin; Gil, Luis

    2013-01-01

    Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal) and in two contrasting microsites (open vs. sheltered) to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis). In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P). Parthenocarpy (non-fertilized seeds) was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds) did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators) consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed. PMID:23776503

  15. Acute toxicity and genotoxic activity of avocado seed extract (Persea americana Mill., c.v. Hass).

    PubMed

    Padilla-Camberos, Eduardo; Martínez-Velázquez, Moisés; Flores-Fernández, José Miguel; Villanueva-Rodríguez, Socorro

    2013-01-01

    The use of vegetal extracts requires toxicological and genotoxic evaluations to establish and verify safety before being added to human cosmetic, pharmaceutical medicine, or alimentary products. Persea americana seeds have been used in traditional medicine as treatment for several diseases. In this work, the ethanolic seed extract of Persea americana was evaluated with respect to its genotoxic potential through micronucleus assay in rodents. The frequency of micronuclei in groups of animals treated with avocado seed extract showed no differences compared to the negative control (vehicle); therefore, it is considered that the avocado seed extract showed no genotoxic activity in the micronucleus test. PMID:24298206

  16. Acute toxicity and genotoxic activity of avocado seed extract (Persea americana Mill., c.v. Hass).

    PubMed

    Padilla-Camberos, Eduardo; Martínez-Velázquez, Moisés; Flores-Fernández, José Miguel; Villanueva-Rodríguez, Socorro

    2013-01-01

    The use of vegetal extracts requires toxicological and genotoxic evaluations to establish and verify safety before being added to human cosmetic, pharmaceutical medicine, or alimentary products. Persea americana seeds have been used in traditional medicine as treatment for several diseases. In this work, the ethanolic seed extract of Persea americana was evaluated with respect to its genotoxic potential through micronucleus assay in rodents. The frequency of micronuclei in groups of animals treated with avocado seed extract showed no differences compared to the negative control (vehicle); therefore, it is considered that the avocado seed extract showed no genotoxic activity in the micronucleus test.

  17. Acute Toxicity and Genotoxic Activity of Avocado Seed Extract (Persea americana Mill., c.v. Hass)

    PubMed Central

    Padilla-Camberos, Eduardo; Martínez-Velázquez, Moisés; Flores-Fernández, José Miguel; Villanueva-Rodríguez, Socorro

    2013-01-01

    The use of vegetal extracts requires toxicological and genotoxic evaluations to establish and verify safety before being added to human cosmetic, pharmaceutical medicine, or alimentary products. Persea americana seeds have been used in traditional medicine as treatment for several diseases. In this work, the ethanolic seed extract of Persea americana was evaluated with respect to its genotoxic potential through micronucleus assay in rodents. The frequency of micronuclei in groups of animals treated with avocado seed extract showed no differences compared to the negative control (vehicle); therefore, it is considered that the avocado seed extract showed no genotoxic activity in the micronucleus test. PMID:24298206

  18. Frequency spirals

    NASA Astrophysics Data System (ADS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-09-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call "frequency spirals." These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  19. Seed-to-Seed-to-Seed Growth and Development of Arabidopsis in Microgravity

    PubMed Central

    Link, Bruce M.; Busse, James S.

    2014-01-01

    Abstract Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-to-back) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves. Key Words: Arabidopsis—Branch—Inflorescence—Microgravity—Morphology—Seed—Space. Astrobiology 14, 866–875. PMID:25317938

  20. Seed-to-seed-to-seed growth and development of Arabidopsis in microgravity.

    PubMed

    Link, Bruce M; Busse, James S; Stankovic, Bratislav

    2014-10-01

    Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-to-back) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves. PMID:25317938

  1. Seed-to-seed-to-seed growth and development of Arabidopsis in microgravity.

    PubMed

    Link, Bruce M; Busse, James S; Stankovic, Bratislav

    2014-10-01

    Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-to-back) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves.

  2. S-SEED Simulator

    2008-11-21

    This code simulates the transient response of two self-electrooptic-effect devices (SEEDs) connected in series to form an S-SEED pair as used in all-optical high-speed switching. Both optical beam propagation and carrier motion is assumed to be normal to the epi plane, so the code is inherently 1D in nature. For each SEED, an optical input in W/cm**2 is specified as a function of time (usually a step function input). The signal is absorbed during amore » double pass through the intrinsic region, with a spatially-dependent absorption coefficient that is dependent on the transient local electric field. This absorption generates electron-hole pairs that then contribute to the device current, and a transient optical output is predicted. Carriers in the semiconductor layers are generated through thermal excitation or optical absorption, move under the action of diffusion and self-consistent electric fields updated at each time step by a 1D Poisson solver, and recombine at density-dependent rates. The different epi layers are independently specified by position, thickness, doping type and density, and thus space charge effects and junction capacitance are included automatically.« less

  3. Glycinebetaine enhances the tolerance of tomato plants to high temperature during germination of seeds and growth of seedlings.

    PubMed

    Li, Shufen; Li, Feng; Wang, Jianwei; Zhang, Wen; Meng, Qingwei; Chen, Tony H H; Murata, Norio; Yang, Xinghong

    2011-11-01

    Tomato (Lycopersicon esculentum cv. 'Moneymaker') was transformed with a codA gene, from Arthrobacter globiformis, for choline oxidase that had been modified to allow targeting to both chloroplasts and the cytosol. Glycinebetaine (GB) accumulated in seeds of transformed plants up to 1 µmol g(-1) dry weight (DW), while no detectable GB was found in wild-type (WT) seeds. The codA-transgenic seeds germinated faster and at higher frequency than WT seeds with high temperature treatment. After heat stress, levels of expression of a mitochondrial small heat-shock protein (MT-sHSP), heat-shock protein 70 (HSP70) and heat-shock cognate 70 (HSC70) were higher in transgenic seeds than in WT seeds during heat stress, and the accumulation of HSP70 was more prominent in codA-transgenic seeds than in WT seeds. Addition of GB to the germination medium or imbibition of seeds in a solution of GB enhanced the tolerance of WT seeds to high temperatures. WT seeds treated with exogenous GB also expressed heat-shock genes at elevated levels and accumulated more HSP70 than controls. Our results suggest that GB, either applied exogenously or accumulated in vivo in codA-transgenic seeds, enhanced the expression of heat-shock genes in and improved the tolerance to high temperature of tomato seeds during germination. PMID:21711358

  4. Sunflower seed allergy.

    PubMed

    Ukleja-Sokołowska, Natalia; Gawrońska-Ukleja, Ewa; Żbikowska-Gotz, Magdalena; Bartuzi, Zbigniew; Sokołowski, Łukasz

    2016-09-01

    Sunflower seeds are a rare source of allergy, but several cases of occupational allergies to sunflowers have been described. Sunflower allergens on the whole, however, still await precise and systematic description. We present an interesting case of a 40-year-old male patient, admitted to hospital due to shortness of breath and urticaria, both of which appeared shortly after the patient ingested sunflower seeds. Our laryngological examination revealed swelling of the pharynx with retention of saliva and swelling of the mouth and tongue. During diagnostics, 2 months later, we found that skin prick tests were positive to mugwort pollen (12/9 mm), oranges (6/6 mm), egg protein (3/3 mm), and hazelnuts (3/3 mm). A native prick by prick test with sunflower seeds was strongly positive (8/5 mm). Elevated concentrations of specific IgE against weed mix (inc. lenscale, mugwort, ragweed) allergens (1.04 IU/mL), Artemisia vulgaris (1.36 IU/mL), and Artemisia absinthium (0.49 IU/mL) were found. An ImmunoCap ISAC test found an average level of specific IgE against mugwort pollen allergen component Art v 1 - 5,7 ISU-E, indicating an allergy to mugwort pollen and low to medium levels of specific IgE against lipid transfer proteins (LTP) found in walnuts, peanuts, mugwort pollen, and hazelnuts. Through the ISAC inhibition test we proved that sunflower seed allergen extracts contain proteins cross-reactive with patients' IgE specific to Art v 1, Art v 3, and Jug r 3. Based on our results and the clinical pattern of the disease we confirmed that the patient is allergic to mugwort pollen and that he had an anaphylactic reaction as a result of ingesting sunflower seeds. We suspected that hypersensitivity to sunflower LTP and defensin-like proteins, both cross-reactive with mugwort pollen allergens, were the main cause of the patient's anaphylactic reaction. PMID:27222528

  5. Network models of frugivory and seed dispersal: Challenges and opportunities

    NASA Astrophysics Data System (ADS)

    Carlo, Tomás A.; Yang, Suann

    2011-11-01

    Network analyses have emerged as a new tool to study frugivory and seed dispersal (FSD) mutualisms because networks can model and simplify the complexity of multiple community-wide species interactions. Moreover, network theory suggests that structural properties, such as the presence of highly generalist species, are linked to the stability of mutualistic communities. However, we still lack empirical validation of network model predictions. Here we outline new research avenues to connect network models to FSD processes, and illustrate the challenges and opportunities of this tool with a field study. We hypothesized that generalist frugivores would be important for forest stability by dispersing seeds into deforested areas and initiating reforestation. We then constructed a network of plant-frugivore interactions using published data and identified the most generalist frugivores. To test the importance of generalists we measured: 1) the frequency with which frugivores moved between pasture and forest, 2) the bird-generated seed rain under perches in the pasture, and 3) the perching frequency of birds above seed traps. The generalist frugivores in the forest network were not important for seed dispersal into pastures, and thus for forest recovery, because the forest network excluded habitat heterogeneities, frugivore behavior, and movements. More research is needed to develop ways to incorporate relevant FSD processes into network models in order for these models to be more useful to community ecology and conservation. The network framework can serve to spark and renew interest in FSD and further our understanding of plant-animal communities.

  6. Differential seed handling by two African primates affects seed fate and establishment of large-seeded trees

    NASA Astrophysics Data System (ADS)

    Gross-Camp, Nicole D.; Kaplin, Beth A.

    2011-11-01

    We examined the influence of seed handling by two semi-terrestrial African forest primates, chimpanzees ( Pan troglodytes) and l'Hoest's monkeys ( Cercopithecus lhoesti), on the fate of large-seeded tree species in an afromontane forest. Chimpanzees and l'Hoest's monkeys dispersed eleven seed species over one year, with quantity and quality of dispersal varying through time. Primates differed in their seed handling behaviors with chimpanzees defecating large seeds (>0.5 cm) significantly more than l'Hoest's. Furthermore, they exhibited different oral-processing techniques with chimpanzees discarding wadges containing many seeds and l'Hoest's monkeys spitting single seeds. A PCA examined the relationship between microhabitat characteristics and the site where primates deposited seeds. The first two components explained almost half of the observed variation. Microhabitat characteristics associated with sites where seeds were defecated had little overlap with those characteristics describing where spit seeds arrived, suggesting that seed handling in part determines the location where seeds are deposited. We monitored a total of 552 seed depositions through time, recording seed persistence, germination, and establishment. Defecations were deposited significantly farther from an adult conspecific than orally-discarded seeds where they experienced the greatest persistence but poorest establishment. In contrast, spit seeds were deposited closest to an adult conspecific but experienced the highest seed establishment rates. We used experimental plots to examine the relationship between seed handling, deposition site, and seed fate. We found a significant difference in seed handling and fate, with undispersed seeds in whole fruits experiencing the lowest establishment rates. Seed germination differed by habitat type with open forest experiencing the highest rates of germination. Our results highlight the relationship between primate seed handling and deposition site and seed

  7. Seed size selection by olive baboons.

    PubMed

    Kunz, Britta Kerstin; Linsenmair, Karl Eduard

    2008-10-01

    Seed size is an important plant fitness trait that can influence several steps between fruiting and the establishment of a plant's offspring. Seed size varies considerably within many plant species, yet the relevance of the trait for intra-specific fruit choice by primates has received little attention. Primates may select certain seed sizes within a species for a number of reasons, e.g. to decrease indigestible seed load or increase pulp intake per fruit. Olive baboons (Papio anubis, Cercopithecidae) are known to select seed size in unripe and mature pods of Parkia biglobosa (Mimosaceae) differentially, so that pods with small seeds, and an intermediate seed number, contribute most to dispersal by baboons. We tested whether olive baboons likewise select for smaller ripe seeds within each of nine additional fruit species whose fruit pulp baboons commonly consume, and for larger seeds in one species in which baboons feed on the seeds. Species differed in fruit type and seed number per fruit. For five of these species, baboons dispersed seeds that were significantly smaller than seeds extracted manually from randomly collected fresh fruits. In contrast, for three species, baboons swallowed seeds that were significantly longer and/or wider than seeds from fresh fruits. In two species, sizes of ingested seeds and seeds from fresh fruits did not differ significantly. Baboons frequently spat out seeds of Drypetes floribunda (Euphorbiaceae) but not those of other plant species having seeds of equal size. Oral processing of D. floribunda seeds depended on seed size: seeds that were spat out were significantly larger and swallowed seeds smaller, than seeds from randomly collected fresh fruits. We argue that seed size selection in baboons is influenced, among other traits, by the amount of pulp rewarded per fruit relative to seed load, which is likely to vary with fruit and seed shape.

  8. Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Anikeeva, I. D.; Akatov, Yu. A.; Vaulina, E. N.; Kostina, L. N.; Marenny, A.; Portman, A. I.; Rusin, S. V.

    1995-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied. The seeds were located inside the satellite in an open space, protected with aluminum foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminum foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival rate and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can thus be regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  9. Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887

    NASA Technical Reports Server (NTRS)

    Anikeeva, I. D.; Vaulina, E. N.; Kostina, L. N.; Marenny, A. M.; Portman, A. I.; Rusin, S. V.; Benton, E. V.

    1990-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  10. Functional importance of avian seed dispersers changes in response to human-induced forest edges in tropical seed-dispersal networks.

    PubMed

    Saavedra, Francisco; Hensen, Isabell; Beck, Stephan G; Böhning-Gaese, Katrin; Lippok, Denis; Töpfer, Till; Schleuning, Matthias

    2014-11-01

    Although seed-dispersal networks are increasingly used to infer the functioning of ecosystems, few studies have investigated the link between the properties of these networks and the ecosystem function of seed dispersal by animals. We investigate how frugivore communities and seed dispersal change with habitat disturbance and test whether relationships between morphological traits and functional roles of seed dispersers change in response to human-induced forest edges. We recorded interaction frequencies between fleshy fruited plants and frugivorous bird species in tropical montane forests in the Bolivian Andes and recorded functional bird traits (body mass, gape width and wing tip length) associated with quantitative (seed-removal rate) and qualitative (seed-deposition pattern) components of seed-dispersal effectiveness. We found that the abundance and richness of frugivorous birds were higher at forest edges. More fruits were removed and dispersed seeds were less clustered at edges than in the interior. Additionally, functional and interaction diversity were higher at edges than in the interior, but functional and interaction evenness did not differ. Interaction strength of bird species increased with body mass, gape width and wing tip length in the forest interior, but was not related to bird morphologies at forest edges. Our study suggests that increases in functional and interaction diversity and an even distribution of interaction strength across bird morphologies lead to enhanced quantity and tentatively enhanced quality of seed dispersal. It also suggests that the effects of species traits on ecosystem functions can vary along small-scale gradients of human disturbance.

  11. Commercial Seed Lots Exhibit Reduced Seed Dormancy in Comparison to Wild Seed Lots of Echinacea purpurea

    PubMed Central

    Qu, Luping; Wang, Xiping; Chen, Ying; Scalzo, Richard; Widrlechner, Mark P.; Davis, Jeanine M.; Hancock, James F.

    2005-01-01

    Seed germination patterns were studied in E. purpurea (L.) Moench grouped by seed source, one group of seven lots from commercially cultivated populations and a second group of nine lots regenerated from ex situ conserved wild populations. Germination tests were conducted in a growth chamber in light (40 μmol·m−2·s−1) or darkness at 25 °C for 20 days after soaking the seeds in water for 10 minutes. Except for two seed lots from wild populations, better germination was observed for commercially cultivated populations in light (90% mean among seed lots, ranging from 82% to 95%) and in darkness (88% mean among seed lots, ranging from 82% to 97%) than for wild populations in light (56% mean among seed lots, ranging from 9% to 92%) or in darkness (37% mean among seed lots, ranging from 4% to 78%). No germination difference was measured between treatments in light and darkness in the commercially cultivated populations, but significant differences were noted for treatments among wild populations. These results suggest that repeated cycles of sowing seeds during cultivation without treatments for dormancy release resulted in reduced seed dormancy in E. purpurea. PMID:16429595

  12. Frequency-shifted feedback amplifier for broadband laser cooling

    NASA Astrophysics Data System (ADS)

    Lim, Michael; van Kooy, Alexander; Yanakas, Michael

    2014-03-01

    We have developed a compact, all-solid state laser amplifier for generating asymmetric sidebands with controlled number and spacing of optical frequencies. The gain element is a tapered semiconductor amplifier, used in conjunction with an acousto-optic modulator that generates red-detuned feedback frequencies. This results in asymmetric sidebands that are all lower in optical frequency than the narrowband seed laser frequency. The output laser spectrum has a well-defined edge (the input laser frequency) and multiple sidebands whose number, frequency spacing, and power are fully controlled by the seed laser characteristics and a single radio frequency input. The number of sidebands can be varied in a controlled way, and the output optical power is variable up to the Watt level of the amplifier chip. The system will be used for broadband laser cooling.

  13. Does seeding after wildfires in rangelands reduce erosion or invasive species?

    USGS Publications Warehouse

    Pyke, David A.; Wirth, Troy A.; Beyers, Jan L.

    2013-01-01

    Mitigation of ecological damage caused by rangeland wildfires has historically been an issue restricted to the western United States. It has focused on conservation of ecosystem function through reducing soil erosion and spread of invasive plants. Effectiveness of mitigation treatments has been debated recently. We reviewed recent literature to conduct a meta-analysis of seeding after wildfires to determine if seedings may (1) protect ecosystems against soil erosion and (2) reduce invasion or abundance of undesirable nonnative plant species. Effectiveness of postfire seedings was examined in 8 erosion and 19 invasive species cases. Seeding has little effect on erosion during the first year after fire and is highly dependent upon initial establishment and coverage of species in successive years. Among all seeding cases, 28% reduced, 67% were neutral, and 5% increased invasive species abundance. Older seedings were more likely to show reductions in invasives than younger seedings. Seedings with high plant establishment were more likely to reduce invasives than those with low establishment. Studies are needed that examine (1) frequency of adequate establishment of postfire seedings and causal factors of success or failure, (2) long-term impacts of seeding along a range of initial establishment and concomitant plant coverage over time as it relates to erosion and abundance of invasive plant species, and (3) auxiliary treatments designed to increase likelihood of germination and establishment given the inevitable variability of environmental conditions. These studies would aid land managers in deciding when postfire treatments are required and their likely level of success.

  14. [Dynamics of the induced chromosomal instability in welsh onion (Allium fistulosum L.): gamma irradiation of the seeds of different storage periods].

    PubMed

    Lazarenko, L M; Bezrukov, V F

    2006-01-01

    The chromosome aberrations in root meristem cells of welsh onion (Allium fistulosum L.) seeds after gamma-irradiation (5 and 10 Gy) of different-aged seeds (7, 19, 31, 43 and 55 months of storage) were studied. The irradiation dose of 5 Gy significantly increased the frequency of aberrant anaphases (FAA) for 31- and 43-months seeds; the dose of 10 Gy significantly increased the FAA in seeds of all age groups. The irradiation of young (7 months) seeds resulted in decreasing of the fraction of bridges to the control level of the old (55-months) seeds for the dose of 5 Gy and below the control level of the old seeds--for the dose of 10 Gy. Some peculiarities of cytogenetic parameters of genome instability and the germinating capacity of the seeds made it possible to suppose that the third year of storage is a critical period for the welsh onion seeds. PMID:17100278

  15. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  16. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  17. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  18. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  19. 7 CFR 201.50 - Weed seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Weed seed. 201.50 Section 201.50 Agriculture... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or tubers) of plants shall be considered weed seeds when recognized as weed seeds by the law or rules...

  20. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hard seed. 201.21 Section 201.21 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard...

  1. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hard seed. 201.21 Section 201.21 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard...

  2. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seed. 201.21 Section 201.21 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard...

  3. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hard seed. 201.21 Section 201.21 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard...

  4. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hard seed. 201.21 Section 201.21 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard...

  5. Metal deposition using seed layers

    DOEpatents

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  6. Seed to Seed, The Secret Life of Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This is a book review of "Seed to Seed, The Secret Life of Plants", by Nicholas Harberd. The book is a diary of ruminations/introspections about plant development and about the main research topic of Nick Harberd’s laboratory. His intended audience is initially nonscientists; many of the explanation...

  7. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  8. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  9. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  10. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  11. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading...

  12. A guide to forest seed handling

    SciTech Connect

    Willan, R.L.

    1986-01-01

    This guide to forest seed handling focuses on seed quality, i.e., the physiological viability and vigor of the seeds. Seed and fruit development, germination, and dormancy and the fundamentals of planning seed collections are covered. The guide includes discussions on seed collection of fallen fruits or seeds from the forest floor from the crowns of felled trees, and from standing trees with access from the ground and with other means of access. Also considered are precautions to be followed during fruit and seed handling between collection and processing. The different stages in seed processing are detailed, including extraction, depulping, drying, tumbling and threshing, dewinging, cleaning, grading, and mixing. Factors affecting seed longevity in storage and the choice of storage methods are reviewed. Different forms of seed pretreatment and seed testing methods are described.

  13. Automated seed manipulation and planting

    NASA Technical Reports Server (NTRS)

    Garcia, Ray; Herrera, Javier; Holcomb, Scott; Kelly, Paul; Myers, Scott; Rosendo, Manny; Sivitz, Herbert; Wolsefer, Dave

    1988-01-01

    Activities for the Fall Semester, 1987 focused on investigating the mechanical/electrical properties of wheat seeds and forming various Seed Planting System (SPS) concepts based on those properties. The Electrical Division of the design group was formed to devise an SPS using electrostatic charge fields for seeding operations. Experiments concerning seed separation using electrical induction (rearranging of the charges within the seed) were conducted with promising results. The seeds, when exposed to the high voltage and low current field produced by a Van de Graff generator, were observed to move back and forth between two electrodes. An SPS concept has been developed based on this phenomena, and will be developed throughout the Spring Semester, 1988. The Mechanical Division centered on SPS concepts involving valves, pumps, and fluids to separate and deliver seeds. An SPS idea utilizing the pressure difference caused by air as it rushes out of holes drilled in the wall of a closed container has been formulated and will be considered for future development. Also, a system of seed separation and delivery employing a combination of centrifugal force, friction, and air flow was considered.

  14. Chapter 3: Seed and Varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed is one of the most important factors in sugarbeet production. Seed selection is one of the most important decisions a grower can make. Without a uniform plant population of a sugarbeet variety adapted to the growing region, the producer will have difficulty achieving economical crop production....

  15. Training for Certification: Seed Treatment.

    ERIC Educational Resources Information Center

    Mississippi State Univ., State College. Cooperative Extension Service.

    This Cooperative Extension Service publication from Mississippi State University is a training guide for commercial pesticide applicators. Focusing specifically on the treatment of seeds with pesticides, this publication is meant to prepare one to take the written examination for Environmental Protection Agency Seed Treatment certification.…

  16. Insecticide seed treatments for sugarbeet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pest feeding and vectoring of viruses cause serious problems in sugarbeet production worldwide. In order to ameliorate pest and disease problems on sugarbeet, two seed treatments, Poncho Beta (60 g a.i. clothianidin + 8 g a.i. beta-cyfluthrin/100,000 seed) and Cruiser Tef (60 g a.i. thiamethoxam + 8...

  17. Seed dormancy in alpine species

    PubMed Central

    Schwienbacher, Erich; Navarro-Cano, Jose Antonio; Neuner, Gilbert; Erschbamer, Brigitta

    2011-01-01

    In alpine species the classification of the various mechanisms underlying seed dormancy has been rather questionable and controversial. Thus, we investigated 28 alpine species to evaluate the prevailing types of dormancy. Embryo type and water impermeability of seed coats gave an indication of the potential seed dormancy class. To ascertain the actual dormancy class and level, we performed germination experiments comparing the behavior of seeds without storage, after cold-dry storage, after cold-wet storage, and scarification. We also tested the light requirement for germination in some species. Germination behavior was characterized using the final germination percentage and the mean germination time. Considering the effects of the pretreatments, a refined classification of the prevailing dormancy types was constructed based on the results of our pretreatments. Only two out of the 28 species that we evaluated had predominantly non-dormant seeds. Physiological dormancy was prevalent in 20 species, with deep physiological dormancy being the most abundant, followed by non-deep and intermediate physiological dormancy. Seeds of four species with underdeveloped embryos were assigned to the morphophysiologial dormancy class. An impermeable seed coat was identified in two species, with no additional physiological germination block. We defined these species as having physical dormancy. Light promoted the germination of seeds without storage in all but one species with physiological dormancy. In species with physical dormancy, light responses were of minor importance. We discuss our new classification in the context of former germination studies and draw implications for the timing of germination in the field. PMID:24415831

  18. Seed dormancy in Mexican teosinte

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed dormancy in wild Zea species may affect fitness and relate to ecological adaptation. The primary objective of this study was to characterize the variation in seed germination of the wild species of the genus Zea that currently grow in Mexico, and to relate this variation to their ecological zon...

  19. Ripening events in seeded watermelons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeded watermelons generally start color development in the locule (seed cavity), with color progressing to the center of the fruit during the ripening process. Soluble solids content (SSR) is thought to be highest at the blossom end. In large-fruited watermelon where only a portion of the fruit is...

  20. Morphological Analysis of Rubus Seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Rubus exhibits morphological diversity and a wide range of reproductive systems and habitats. We examined seed coat ultrastructural morphology of seed accessions of 10 subgenera preserved at the US Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Reposito...

  1. Microwave drying of seed cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A small lab dryer was designed for use in drying seed cotton with components of a microwave generator mounted thereon. The magnetron emitted radiation directly into the seed cotton and a fan directed air cross-flow to the radiation direction. The microwave components were a 1.1 kW magnetron, trans...

  2. Genebanking seeds from natural populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional storage protocols have been developed to preserve genetic diversity of seeds of crops in genebanks. These same principles have been applied to preserve seeds from wild populations. While most principles for conventional storage protocols are applicable to a broad range of wild species...

  3. Seed Dispersal by Ants in the Semi-arid Caatinga of North-east Brazil

    PubMed Central

    Leal, Inara R.; Wirth, Rainer; Tabarelli, Marcelo

    2007-01-01

    Background and Aims Myrmecochory is a conspicuous feature of several sclerophyll ecosystems around the world but it has received little attention in the semi-arid areas of South America. This study addresses the importance of seed dispersal by ants in a 2500-km2 area of the Caatinga ecosystem (north-east Brazil) and investigates ant-derived benefits to the plant through myrmecochory. Methods Seed manipulation and dispersal by ants was investigated during a 3-year period in the Xingó region. Both plant and ant assemblages involved in seed dispersal were described and ant behaviour was characterized. True myrmecochorous seeds of seven Euphorbiaceae species (i.e. elaiosome-bearing seeds) were used in experiments designed to: (1) quantify the rates of seed cleaning/removal and the influence of both seed size and elaiosome presence on seed removal; (2) identify the fate of seeds dispersed by ants; and (3) document the benefits of seed dispersal by ants in terms of seed germination and seedling growth. Key Results Seed dispersal by ants involved one-quarter of the woody flora inhabiting the Xingó region, but true myrmecochory was restricted to 12·8 % of the woody plant species. Myrmecochorous seeds manipulated by ants faced high levels of seed removal (38–84 %) and 83 % of removed seeds were discarded on ant nests. Moreover, seed removal positively correlated with the presence of elaiosome, and elaiosome removal increased germination success by at least 30 %. Finally, some Euphorbiaceae species presented both increased germination and seedling growth on ant-nest soils. Conclusions Myrmecochory is a relevant seed dispersal mode in the Caatinga ecosystem, and is particularly frequent among Euphorbiaceae trees and shrubs. The fact that seeds reach micro-sites suitable for establishment (ant nests) supports the directed dispersal hypothesis as a possible force favouring myrmecochory in this ecosystem. Ecosystems with a high frequency of myrmecochorous plants appear not

  4. Simulation of free-electron lasers seeded with broadband radiation

    SciTech Connect

    Bajlekov, Svetoslav; Fawley, William; Schroeder, Carl; Bartolini, Riccardo; Hooker, Simon

    2011-03-10

    The longitudinal coherence of free-electron laser (FEL) radiation can be enhanced by seeding the FEL with high harmonics of an optical laser pulse. The radiation produced by high-harmonic generation (HHG), however, has a fast-varying temporal profile that can violate the slowly varying envelope approximation and limited frequency window that is employed in conventional free-electron laser simulation codes. Here we investigate the implications of violating this approximation on the accuracy of simulations. On the basis of both analytical considerations and 1D numerical studies, it is concluded that, for most realistic scenarios, conventional FEL codes are capable of accurately simulating the FEL process even when the seed radiation violates the slowly varying envelope approximation. We additionally discuss the significance of filtering the harmonic content of broadband HHG seeds.

  5. [Metabolic control of seed germination].

    PubMed

    Catusse, Julie; Strub, Jean-Marc; Job, Claudette; Van Dorsselaer, Alain; Job, Dominique

    2008-01-01

    We have used proteomics to better characterize germination and early seedling vigor in sugarbeet. Our strategy includes (1) construction of proteome reference maps for dry and germinating seeds of a high-vigor reference seed lot; (2) investigation of the specific tissue accumulation of proteins (root, cotyledon, perisperm); (3) investigation of changes in protein expression profiles detected in the reference seed lot subjected to different vigor-modifying treatments, e.g. aging and/or priming. More than 1 000 sugarbeet seed proteins have been identified by LC/MS-MS mass spectrometry (albumins, globulins and glutelins have been analyzed separately). Due to the conservation of protein sequences and the quality of MS sequencing (more than 10 000 peptide sequences have been obtained), the success rate of protein identification was on the average of 80%. This is to our knowledge the best detailed proteome analysis ever carried out in seeds. The data allowed us to build a detailed metabolic chart of the sugarbeet seed, generating new insights into the molecular mechanisms determining the development of a new seedling. Also, the proteome of a seed-storage tissue as the perisperm is described for the first time.

  6. Ultrahigh harmonics generation in a FEL with a seed laser

    SciTech Connect

    Goloviznin, V.V.; Amersfoort, P.W. van

    1995-12-31

    One of the most challenging problems in modern FEL technology is to operate in the X-ray region, especially in the {open_quotes}water window{close_quotes}. Because of the absence of optical resonators in this range of wavelengths, only a single-pass device may be suitable for this task. The Self-Amplified Spontaneous Emission (SASE) mechanism is now under active discussion as a realistic way to provide high-power coherent emission in the X-ray range. Both the undulator parameters and the electron beam parameters required for the lasing are achieveable at today`s technological level. On the other hand, the SASE approach implies a very long and expensive periodic magnetic structure, typically several tens of meters long. This is mainly because of the rather long build-up time necessary to establish a coherent mode from incoherent noise. A mechanism of shortening this time would be therefore highly desirable. In the present paper we consider a scheme using two undulators and a seed-laser to produce coherent X-ray emission. The first undulator and the seed-laser provide a pre-modulation of the beam while the second undulator serves as a source of coherent spontaneous radiation at a very high harmonic of the seed-laser frequency; the whole scheme may then be considered to be an FEL-based frequency upconvertor. The total length of the periodic magnetic structure is shown to be of the order of several meters, nearly an order of magnitude shorter than in the SASE case. For the same beam quality as in the SASE scheme and with realistic seed-laser parameters, the efficiency of the beam pre-modulation at the 50-th (!) harmonic is shown to be as high as 15%. The output radiation is tunable between discrete harmonics of the seed-frequency.

  7. Wet deposition of the seeding agent after weather modification activities.

    PubMed

    Curić, Mladjen; Janc, Dejan

    2013-09-01

    Weather modification activities are performed mostly by cloud seeding. Some operational projects have been conducted for more than a half century and cover planetary scales. These activities have led to large amounts of seeding agents being deposited on the ground in precipitation. The main intent of this paper is to identify the spatial pattern of silver iodide deposits after hail suppression. The spatial pattern of silver iodide deposits is determined using the weather modification project measurements from seeding agent reports, two weather radars and 316 launching sites during a 5-year period. The estimated spatial distribution of the deposits is not uniform, with the maximum silver iodide amount located in the southern part of the study area (up to 140 μg m(-2)). Our results are comparable with the measurements performed by chemical analyses during other cloud seeding experiments. The maximum location coincides well with that of the maximum seeded hailstorm precipitation frequency. A new method for identifying the spatial pattern of wet-deposited material has been established. The location with the maximum amount is found. This method would be important as a means of placing samplers and monitoring at the representative sites because those are where most weather modification projects would be performed in the future.

  8. Why cirrus cloud seeding cannot substantially cool the planet

    NASA Astrophysics Data System (ADS)

    Gasparini, Blaž; Lohmann, Ulrike

    2016-05-01

    The net warming effect of cirrus clouds has driven part of the geoengineering research toward the idea of decreasing their occurrence frequency by seeding them with efficient ice nucleating particles. We study responses of cirrus clouds to simplified global seeding strategies in terms of their radiative fluxes with the help of the ECHAM-HAM general circulation model. Our cirrus scheme takes into account the competition between homogeneous and heterogeneous freezing, preexisting ice crystals, and the full spectrum of updraft velocities. While we find that the cirrus cloud radiative effect evaluated from our model is positive and large enough (5.7 W/m2) to confirm their geoengineering potential, none of the seeding strategies achieves a significant cooling due to complex microphysical mechanisms limiting their climatic responses. After globally uniform seeding is applied, we observe an increase in cirrus cloud cover, a decrease in ice crystal number concentration, and a decrease in ice crystal radius. An analysis of their respective radiative contributions points to the ice crystal radius decrease as the main factor limiting seeding effectiveness.

  9. Birds as suppliers of seed dispersal in temperate ecosystems: conservation guidelines from real-world landscapes.

    PubMed

    Garcia, Daniel; Zamora, Regino; Amico, Guillermo C

    2010-08-01

    Seed dispersal by animals is considered a pivotal ecosystem function that drives plant-community dynamics in natural habitats and vegetation recovery in human-altered landscapes. Nevertheless, there is a lack of suitable ecological knowledge to develop basic conservation and management guidelines for this ecosystem service. Essential questions, such as how well the abundance of frugivorous animals predicts seeding function in different ecosystems and how anthropogenic landscape heterogeneity conditions the role of dispersers, remain poorly answered. In three temperate ecosystems, we studied seed dispersal by frugivorous birds in landscape mosaics shaped by human disturbance. By applying a standardized design across systems, we related the frequency of occurrence of bird-dispersed seeds throughout the landscape to the abundance of birds, the habitat features, and the abundance of fleshy fruits. Abundance of frugivorous birds in itself predicted the occurrence of dispersed seeds throughout the landscape in all ecosystems studied. Even those landscape patches impoverished due to anthropogenic disturbance received some dispersed seeds when visited intensively by birds. Nonetheless, human-caused landscape degradation largely affected seed-deposition patterns by decreasing cover of woody vegetation or availability of fruit resources that attracted birds and promoted seed dispersal. The relative role of woody cover and fruit availability in seed dispersal by birds differed among ecosystems. Our results suggest that to manage seed dispersal for temperate ecosystem preservation or restoration one should consider abundance of frugivorous birds as a surrogate of landscape-scale seed dispersal and an indicator of patch quality for the dispersal function; woody cover and fruit resource availability as key landscape features that drive seedfall patterns; and birds as mobile links that connect landscape patches of different degrees of degradation and habitat quality via seed

  10. Implications of nonrandom seed abscission and global stilling for migration of wind-dispersed plant species.

    PubMed

    Thompson, Sally E; Katul, Gabriel G

    2013-06-01

    Migration of plant populations is a potential survival response to climate change that depends critically on seed dispersal. Biological and physical factors determine dispersal and migration of wind-dispersed species. Recent field and wind tunnel studies demonstrate biological adaptations that bias seed release toward conditions of higher wind velocity, promoting longer dispersal distances and faster migration. However, another suite of international studies also recently highlighted a global decrease in near-surface wind speeds, or 'global stilling'. This study assessed the implications of both factors on potential plant population migration rates, using a mechanistic modeling framework. Nonrandom abscission was investigated using models of three seed release mechanisms: (i) a simple drag model; (ii) a seed deflection model; and (iii) a 'wear and tear' model. The models generated a single functional relationship between the frequency of seed release and statistics of the near-surface wind environment, independent of the abscission mechanism. An Inertial-Particle, Coupled Eulerian-Lagrangian Closure model (IP-CELC) was used to investigate abscission effects on seed dispersal kernels and plant population migration rates under contemporary and potential future wind conditions (based on reported global stilling trends). The results confirm that nonrandom seed abscission increased dispersal distances, particularly for light seeds. The increases were mitigated by two physical feedbacks: (i) although nonrandom abscission increased the initial acceleration of seeds from rest, the sensitivity of the seed dispersal to this initial condition declined as the wind speed increased; and (ii) while nonrandom abscission increased the mean dispersal length, it reduced the kurtosis of seasonal dispersal kernels, and thus the chance of long-distance dispersal. Wind stilling greatly reduced the modeled migration rates under biased seed release conditions. Thus, species that require

  11. Banking on the past: seed banks as a reservoir for rare and native species in restored vernal pools

    PubMed Central

    Faist, Akasha M.; Ferrenberg, Scott; Collinge, Sharon K.

    2013-01-01

    Soil seed banks serve as reservoirs for future plant communities, and when diverse and abundant can buffer vegetation communities against environmental fluctuations. Sparse seed banks, however, may lead to future declines of already rare species. Seed banks in wetland communities are often robust and can persist over long time periods making wetlands model systems for studying the spatial and temporal links between above- and belowground communities. Using collected soils and germination trials, we assessed species diversity and density in the seed banks of restored, ephemeral wetlands (vernal pools) in California's Central Valley, USA. Using long-term vegetation surveys, we compared the community structure of seed banks to that of aboveground vegetation and assessed the temporal links between below- and aboveground communities. We also compared the proportional abundances of different cover classes as well as the abundance of native plants in seed banks to aboveground communities. The proportional abundances of both rare and native species were greater in seed bank samples than in aboveground samples, yet the seed bank had lower species richness than aboveground vegetation. However, the seed bank had greater levels of differentiation among pools (beta diversity; β) than aboveground samples. Additionally, the seed bank was more similar to the earlier (2003–06) aboveground community than the more recent (2007–10) aboveground community. The correlation of species composition in the current seed bank to an earlier aboveground community suggests that seed banks exhibit storage effects while aboveground species composition in this system is not driven by seed bank composition, but is perhaps due to environmental filtering. We conclude that the seed bank of these pools is neither prone to the same temporal rates of invasion as the aboveground community, nor is seed abundance presently a limiting factor in the aboveground frequency of native species or a promoting

  12. Soil seed bank composition in different successional stages of a species rich wooded meadow in Laelatu, western Estonia

    NASA Astrophysics Data System (ADS)

    Kalamees, Rein; Zobel, Martin

    1998-04-01

    We studied the seed bank of a calcareous grassland in four sites with different management history: original old grassland, which has been described as one of the richest plant communities in Europe, long-term restored grassland, which has been overgrown in the seventies, recently overgrown ( ca. 20 years ago) and long-term overgrown grasslands. The seed banks in grassland sites at Laelatu were small both in size and number of species. The number of species and seeds in the seed bank declined significantly from managed grasslands to closed overgrown community. The highest species richness of the soil seed bank (number of species per soil volume) was found in the managed grassland sites, the seed density in the bank was the highest in the long-term restored grassland site. About one third of all the grassland species were found in the seed bank. The proportion of species in the established vegetation — represented also in the bank — was higher in overgrown sites. However, ordination (Correspondence Analysis), which also took into account species frequencies, showed that the similarity between established vegetation on plots and seed bank samples decreased from original grassland to closed overgrown grassland. The persistence of the seeds of only 8-10 typical grassland species in the seed bank of overgrown grassland sites makes the significance of the seed bank for community restoration quite small.

  13. [Effect of decimeter polarized electromagnetic radiation on germinating capacity of seeds].

    PubMed

    Polevik, N D

    2013-01-01

    The effect of a polarization structure of electromagnetic radiation on the germinating capacity of seeds of such weeds as Green foxtail (Setaria viridis) and Green amaranth (Amaranthus retroflexus) has been studied. Seeds have been exposed to impulse electromagnetic radiation in a frequency of 896 MHz with linear, elliptical right-handed and elliptical left-handed polarizations at different power flux density levels. It is determined that the effect of the right-handed polarized electromagnetic radiation increases and the influence of the left-handed polarized one reduces the germinating capacity of seeds compared to the effect of the linearly polarized electromagnetic radiation. It is shown that the seeds have an amplitude polarization selectivity as evinced by the major effect of the right-handed polarized radiation on seeds. An electrodynamic model as the right-handed elliptically polarized antenna with the given quantity of the ellipticity of polarization is suggested to use in description of this selectivity.

  14. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  15. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  16. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  17. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  18. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  19. Programmed cell death in seeds of angiosperms.

    PubMed

    López-Fernández, María Paula; Maldonado, Sara

    2015-12-01

    During the diversification of angiosperms, seeds have evolved structural, chemical, molecular and physiologically developing changes that specially affect the nucellus and endosperm. All through seed evolution, programmed cell death (PCD) has played a fundamental role. However, examples of PCD during seed development are limited. The present review examines PCD in integuments, nucellus, suspensor and endosperm in those representative examples of seeds studied to date.

  20. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  1. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  2. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  3. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  4. 7 CFR 948.6 - Seed potatoes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Seed potatoes. 948.6 Section 948.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Definitions § 948.6 Seed potatoes. Seed potatoes or seed means any...

  5. INTESPECIIC DIFFERENCES IN GRASS SEED IMBIBITION

    EPA Science Inventory

    Seeds from 12 grass species were studied relative to mode of wetting and time of exposure to water to document interspecific differences in imbibition characteristics. Imbibition causes seeds to become wet, and wet seeds are more detectable to consumers than dry seeds. Thus, ge...

  6. Materials used for Seed Storage Containers: Response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efficient seed storage is a shared concern among the growing number of seed banks established for crop improvement or ex situ conservation. Container properties greatly affect seed interactions with the environment and the overall cost and success of seed banking operations. Several material proper...

  7. Evaluation of Lettuce Genotypes for Seed Thermotolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermoinhibition of lettuce (Lactuca sativa L.) seed germination is a common problem associated with lettuce production. Depending on lettuce cultivars, seed germination may be inhibited when temperatures exceed 28oC. The delay or inhibition of seed germination at high temperatures may reduce seedli...

  8. Biotechnology of oil seed crops

    SciTech Connect

    James, A.T.

    1985-02-01

    A general summary of possibilities and limitation application of biotechnology processes to processing and/or production of fats and oils is presented. Enzymatic processes, cloning of premium perennial oil crops and genetic manipulation of oil seed compositions are discussed.

  9. Seeding for pervasively overlapping communities

    NASA Astrophysics Data System (ADS)

    Lee, Conrad; Reid, Fergal; McDaid, Aaron; Hurley, Neil

    2011-06-01

    In some social and biological networks, the majority of nodes belong to multiple communities. It has recently been shown that a number of the algorithms specifically designed to detect overlapping communities do not perform well in such highly overlapping settings. Here, we consider one class of these algorithms, those which optimize a local fitness measure, typically by using a greedy heuristic to expand a seed into a community. We perform synthetic benchmarks which indicate that an appropriate seeding strategy becomes more important as the extent of community overlap increases. We find that distinct cliques provide the best seeds. We find further support for this seeding strategy with benchmarks on a Facebook network and the yeast interactome.

  10. Ethylene, seed germination, and epinasty.

    PubMed

    Stewart, E R; Freebairn, H T

    1969-07-01

    Ethylene activity in lettuce seed (Lactuca satina) germination and tomato (Lycopersicon esculentum) petiole epinasty has been characterized by using heat to inhibit ethylene synthesis. This procedure enabled a separation of the production of ethylene from the effect of ethylene. Ethylene was required in tomato petioles to produce the epinastic response and auxin was found to be active in producing epinasty through a stimulation of ethylene synthesis with the resulting ethylene being responsible for the epinasty. In the same manner, it was shown that gibberellic acid stimulated ethylene synthesis in lettuce seeds. The ethylene produced then in turn stimulated the seeds to germinate. It was hypothesized that ethylene was the intermediate which caused epinasty or seed germination. Auxin and gibberellin primarily induced their response by stimulating ethylene production.

  11. Autoradiography for iodine-125 seeds

    SciTech Connect

    Alberti, W.; Divoux, S. ); Pothmann, B.; Tabor, P. ); Hermann, K.P.; Harder, D. )

    1993-04-02

    To study the interior design of model 6702 and 6711 iodine-125 seeds, contact autoradiographs were performed using mammography film. Improved resolution was obtained using a pin-hole camera with a hole of 0.1 mm [times] 0.1 mm. With these techniques, qualitative determination of the relative activity distribution within each seed was possible. The number of the activated resin spheres and the positions of the centers of these spheres can be exactly determined. A model calculation shows that variations in the arrangement of the activated spheres within a seed have a moderate influence on the dose distribution at source distances below 10 mm. Knowing the exact source configuration may be useful when comparing dose calculations with measured data for model 6702 [sup 125]I seeds which are currently employed in ophthalmic plaque and implant therapy of other tumors. 16 refs., 5 figs., 2 tabs.

  12. Maternal control of seed size in plants.

    PubMed

    Li, Na; Li, Yunhai

    2015-02-01

    Seed size is a key determinant of evolutionary fitness, and is also one of the most important components of seed yield. In angiosperms, seed development begins with double fertilization, which leads to the formation of a diploid embryo and a triploid endosperm. The outermost layer of the seed is the seed coat, which differentiates from maternal integuments. Therefore, the size of a seed is determined by the co-ordinated growth of the embryo, endosperm, and maternal tissue. Recent studies have identified several factors that act maternally or zygotically to regulate seed size, and revealed possible mechanisms that underlie seed size control in Arabidopsis and rice. In this review, we summarize current research progress in maternal control of seed size and discuss the roles of several newly identified regulators in maternal regulation of seed growth.

  13. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  14. Self-seeding of a pulsed double-grating Ti:sapphire laser oscillator.

    PubMed

    Tamura, Koji

    2008-04-01

    A self-seeded pulsed double-grating Ti:sapphire laser oscillator consisting of a grazing incidence cavity geometry with a pair of gratings and a standing-wave cavity pumped by a frequency-doubled Nd:YAG laser was developed and characterized. With self-seeding, narrow-linewidth single-longitudinal-mode (SLM) operation and SLM scanning were possible with a reduced lasing threshold, which was desirable for the intended applications.

  15. Effects of prolonged exposure to space flight factors for 175 days on lettuce seeds

    NASA Astrophysics Data System (ADS)

    Nevzgodina, L. V.; Maximova, E. N.; Akatov, Yu. A.

    We have studied the effects of prolonged (up to 175 days) exposure of Lactuca sativa seeds to space flight factors, including primary cosmic radiation heavy ions. The data obtained evidence a significant fourfold increase ofs pontaneous mutagenesis in seeds both with regard to the total number of aberrant cells as well as the formation of single cells with multiple aberrations. Comparison of the present experiment with earlier works shows that the frequency of such aberrations increases with the duration of the flight.

  16. Self-seeding of a pulsed double-grating Ti:sapphire laser oscillator

    SciTech Connect

    Tamura, Koji

    2008-04-01

    A self-seeded pulsed double-grating Ti:sapphire laser oscillator consisting of a grazing incidence cavity geometry with a pair of gratings and a standing-wave cavity pumped by a frequency-doubled Nd:YAG laser was developed and characterized. With self-seeding, narrow-linewidth single-longitudinal-mode (SLM) operation and SLM scanning were possible with a reduced lasing threshold, which was desirable for the intended applications.

  17. Effects of prolonged exposure to space flight factors for 175 days on lettuce seeds

    SciTech Connect

    Nevzgodina, L.V.; Maximova, E.N.; Akatov, Yu.A.

    1981-01-01

    The effects of prolonged (up to 175 days) exposure of Lactuca sativa seeds to space flight factors, including primary cosmic radiation heavy ions have been studied. The data obtained evidence a significant fourfold increase of spontaneous mutagenesis in seeds both with regard to the total number of aberrant cells as well as the formation of single cells with multiple aberrations. Comparison of the present experiment with earlier works shows that the frequency of such aberrations increases with the duration of the flight.

  18. Seed dormancy and ABA signaling

    PubMed Central

    del Carmen Rodríguez-Gacio, María; Matilla-Vázquez, Miguel A

    2009-01-01

    The seed is an important organ in higher plants, it is an important organ for plant survival and species dispersion. The transition between seed dormancy and germination represents a critical stage in the plant life cycle and it is an important ecological and commercial trait. A dynamic balance of synthesis and catabolism of two antagonistic hormones, abscisic acid (ABA) and giberellins (GAs), controls the equilibrium between seed dormancy and germination. Embryonic ABA plays a central role in induction and maintenance of seed dormancy and also inhibits the transition from embryonic to germination growth. Therefore, the ABA metabolism must be highly regulated at both temporal and spatial levels during phase of dessication tolerance. On the other hand, the ABA levels do not depend exclusively on the seeds because sometimes it becomes a strong sink and imports it from the roots and rhizosphere through the xylem and/or phloem. These events are discussed in depth here. Likewise, the role of some recently characterized genes belonging to seeds of woody species and related to ABA signaling are also included. Finally, although four possible ABA receptors have been reported, not much is known about how they mediate ABA signaling transduction. However, new publications seem to show that almost all these receptors lack several properties to consider them as such. PMID:19875942

  19. Depth Profiles in Maize ( Zea mays L.) Seeds Studied by Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Zepeda-Bautista, R.

    2015-06-01

    Photoacoustic spectroscopy (PAS) has been used to analyze agricultural seeds and can be applied to the study of seed depth profiles of these complex samples composed of different structures. The sample depth profile can be obtained through the photoacoustic (PA) signal, amplitude, and phase at different light modulation frequencies. The PA signal phase is more sensitive to changes of thermal properties in layered samples than the PA signal amplitude. Hence, the PA signal phase can also be used to characterize layers at different depths. Thus, the objective of the present study was to obtain the optical absorption spectra of maize seeds ( Zea mays L.) by means of PAS at different light modulation frequencies (17 Hz, 30 Hz, and 50 Hz) and comparing these spectra with the ones obtained from the phase-resolved method in order to separate the optical absorption spectra of seed pericarp and endosperm. The results suggest the possibility of using the phase-resolved method to obtain optical absorption spectra of different seed structures, at different depths, without damaging the seed. Thus, PAS could be a nondestructive method for characterization of agricultural seeds and thus improve quality control in the food industry.

  20. Echo-Enabled Harmonic Generation for Seeded FELs

    SciTech Connect

    Stupakov, G.; /SLAC

    2011-05-19

    In the x-ray wavelengths, the two leading FEL concepts are the self-amplified spontaneous emission (SASE) configuration and the high-gain harmonic generation (HGHG) scheme. While the radiation from a SASE FEL is coherent transversely, it typically has rather limited temporal coherence. Alternatively, the HGHG scheme allows generation of fully coherent radiation by up-converting the frequency of a high-power seed laser. However, due to the relatively low up-frequency conversion efficiency, multiple stages of HGHG FEL are needed in order to generate x-rays from a UV laser. The up-frequency conversion efficiency can be greatly improved with the recently proposed echo-enabled harmonic generation (EEHG) technique. In this work we will present the concept of EEHG, and address some practically important issues that affect the performance of the seeding. We show how the EEHG can be incorporated in the FEL scheme and what is the expected performance of the EEHG seeded FEL. We will then briefly describe the first proof-of-principle EEHG experiment carried out at the Next Linear Collider Test Accelerator (NLCTA) at SLAC. We will also discuss latest advances in the echo-scheme approach, and refer to subsequent modifications of the original concept.

  1. Optimum harvest maturity for Leymus chinensis seed.

    PubMed

    Lin, Jixiang; Wang, Yingnan; Qi, Mingming; Li, Xiaoyu; Yang, Chunxue; Wang, Yongcui; Mu, Chunsheng

    2016-01-01

    Timely harvest is critical to achieve maximum seed viability and vigour in agricultural production. However, little information exists concerning how to reap the best quality seeds of Leymus chinensis, which is the dominant and most promising grass species in the Songnen Grassland of Northern China. The objective of this study was to investigate and evaluate possible quality indices of the seeds at different days after peak anthesis. Seed quality at different development stages was assessed by the colours of the seed and lemmas, seed weight, moisture content, electrical conductivity of seed leachate and germination indices. Two consecutive years of experimental results showed that the maximum seed quality was recorded at 39 days after peak anthesis. At this date, the colours of the seed and lemmas reached heavy brown and yellow, respectively. The seed weight was highest and the moisture content and the electrical conductivity of seed leachate were lowest. In addition, the seed also reached its maximum germination percentage and energy at this stage, determined using a standard germination test (SGT) and accelerated ageing test (AAT). Thus, Leymus chinensis can be harvested at 39 days after peak anthesis based on the changes in parameters. Colour identification can be used as an additional indicator to provide a more rapid and reliable measure of optimum seed maturity; approximately 10 days after the colour of the lemmas reached yellow and the colour of the seed reached heavy brown, the seed of this species was suitable for harvest. PMID:27170257

  2. Optimum harvest maturity for Leymus chinensis seed

    PubMed Central

    Lin, Jixiang; Wang, Yingnan; Qi, Mingming; Li, Xiaoyu; Yang, Chunxue; Wang, Yongcui

    2016-01-01

    ABSTRACT Timely harvest is critical to achieve maximum seed viability and vigour in agricultural production. However, little information exists concerning how to reap the best quality seeds of Leymus chinensis, which is the dominant and most promising grass species in the Songnen Grassland of Northern China. The objective of this study was to investigate and evaluate possible quality indices of the seeds at different days after peak anthesis. Seed quality at different development stages was assessed by the colours of the seed and lemmas, seed weight, moisture content, electrical conductivity of seed leachate and germination indices. Two consecutive years of experimental results showed that the maximum seed quality was recorded at 39 days after peak anthesis. At this date, the colours of the seed and lemmas reached heavy brown and yellow, respectively. The seed weight was highest and the moisture content and the electrical conductivity of seed leachate were lowest. In addition, the seed also reached its maximum germination percentage and energy at this stage, determined using a standard germination test (SGT) and accelerated ageing test (AAT). Thus, Leymus chinensis can be harvested at 39 days after peak anthesis based on the changes in parameters. Colour identification can be used as an additional indicator to provide a more rapid and reliable measure of optimum seed maturity; approximately 10 days after the colour of the lemmas reached yellow and the colour of the seed reached heavy brown, the seed of this species was suitable for harvest. PMID:27170257

  3. Multiple frequency optical mixer and demultiplexer and apparatus for remote sensing

    NASA Technical Reports Server (NTRS)

    Chen, Jeffrey R. (Inventor)

    2010-01-01

    A pulsed laser system includes a modulator module configured to provide pulsed electrical signals and a plurality of solid-state seed sources coupled to the modulator module and configured to operate, responsive to the pulsed electrical signals, in a pulse mode. Each of the plurality of solid-state seed sources is tuned to a different frequency channel separated from any adjacent frequency channel by a frequency offset. The pulsed laser system also includes a combiner that combines outputs from each of the solid state seed sources into a single optical path and an optical doubler and demultiplexer coupled to the single optical path and providing each doubled seed frequency on a separate output path.

  4. Phenolics in the seed coat of wild soybean (Glycine soja) and their significance for seed hardness and seed germination.

    PubMed

    Zhou, San; Sekizaki, Haruo; Yang, Zhihong; Sawa, Satoko; Pan, Jun

    2010-10-27

    Hardseededness in annual wild soybean (Glycine soja Sieb. Et Zucc.) is a valuable trait that affects the germination, viability, and quality of stored seeds. Two G. soja ecotypes native to Shandong Province of China have been used to identify the phenolics in the seed coat that correlate with the seed hardness and seed germination. Three major phenolics from the seed coat were isolated and identified as epicatechin, cyanidin 3-O-glucoside, and delphinidin 3-O-glucoside. Of the three phenolics, only the change of epicatechin exhibited a significant positive correlation with the change of hard seed percentages both under different water conditions during seed development and under different gas conditions during seed storage. Epicatechin also reveals a hormesis-like effect on the seed germination of G. soja. Epicatechin is suggested to be functionally related to coat-imposed hardseededness in G. soja.

  5. Catalyst-free growth of ZnO nanowires on ITO seed/glass by thermal evaporation method: Effects of ITO seed layer thickness

    NASA Astrophysics Data System (ADS)

    Alsultany, Forat H.; Hassan, Z.; Ahmed, Naser M.

    2016-07-01

    A seed/catalyst-free growth of ZnO nanowires (ZnO-NWs) on a glass substrate were successfully fabricated using thermal evaporation technique. These nanowires were grown on ITO seed layers of different thicknesses of 25 and 75 nm, which were deposited on glass substrates by radio frequency (RF) magnetron sputtering. Prior to synthesized ITO nanowires, the sputtered ITO seeds were annealed using the continuous wave (CW) CO2 laser at 450 °C in air for 15 min. The effect of seed layer thickness on the morphological, structural, and optical properties of ZnO-NWs were systematically investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Vis spectrophotometer.

  6. Pre-dispersal predation effect on seed packaging strategies and seed viability.

    PubMed

    DeSoto, Lucía; Tutor, David; Torices, Rubén; Rodríguez-Echeverría, Susana; Nabais, Cristina

    2016-01-01

    An increased understanding of intraspecific seed packaging (i.e. seed size/number strategy) variation across different environments may improve current knowledge of the ecological forces that drive seed evolution in plants. In particular, pre-dispersal seed predation may influence seed packaging strategies, triggering a reduction of the resources allocated to undamaged seeds within the preyed fruits. Assessing plant reactions to pre-dispersal seed predation is crucial to a better understanding of predation effects, but the response of plants to arthropod attacks remains unexplored. We have assessed the effect of cone predation on the size and viability of undamaged seeds in populations of Juniperus thurifera with contrasting seed packaging strategies, namely, North African populations with single-large-seeded cones and South European populations with multi-small-seeded cones. Our results show that the incidence of predation was lower on the single-large-seeded African cones than on the multi-small-seeded European ones. Seeds from non-preyed cones were also larger and had a higher germination success than uneaten seeds from preyed cones, but only in populations with multi-seeded cones and in cones attacked by Trisetacus sp., suggesting a differential plastic response to predation. It is possible that pre-dispersal seed predation has been a strong selective pressure in European populations with high cone predation rates, being a process which maintains multi-small-seeded cones and empty seeds as a strategy to save some seeds from predation. Conversely, pre-dispersal predation might not have a strong effect in the African populations with single-large-seeded cones characterized by seed germination and filling rates higher than those in the European populations. Our results indicate that differences in pre-dispersal seed predators and predation levels may affect both selection on and intraspecific variation in seed packaging.

  7. Pre-dispersal predation effect on seed packaging strategies and seed viability.

    PubMed

    DeSoto, Lucía; Tutor, David; Torices, Rubén; Rodríguez-Echeverría, Susana; Nabais, Cristina

    2016-01-01

    An increased understanding of intraspecific seed packaging (i.e. seed size/number strategy) variation across different environments may improve current knowledge of the ecological forces that drive seed evolution in plants. In particular, pre-dispersal seed predation may influence seed packaging strategies, triggering a reduction of the resources allocated to undamaged seeds within the preyed fruits. Assessing plant reactions to pre-dispersal seed predation is crucial to a better understanding of predation effects, but the response of plants to arthropod attacks remains unexplored. We have assessed the effect of cone predation on the size and viability of undamaged seeds in populations of Juniperus thurifera with contrasting seed packaging strategies, namely, North African populations with single-large-seeded cones and South European populations with multi-small-seeded cones. Our results show that the incidence of predation was lower on the single-large-seeded African cones than on the multi-small-seeded European ones. Seeds from non-preyed cones were also larger and had a higher germination success than uneaten seeds from preyed cones, but only in populations with multi-seeded cones and in cones attacked by Trisetacus sp., suggesting a differential plastic response to predation. It is possible that pre-dispersal seed predation has been a strong selective pressure in European populations with high cone predation rates, being a process which maintains multi-small-seeded cones and empty seeds as a strategy to save some seeds from predation. Conversely, pre-dispersal predation might not have a strong effect in the African populations with single-large-seeded cones characterized by seed germination and filling rates higher than those in the European populations. Our results indicate that differences in pre-dispersal seed predators and predation levels may affect both selection on and intraspecific variation in seed packaging. PMID:26400794

  8. Q-switched fiber laser based on an acousto-optic modulator with injection seeding technique.

    PubMed

    Li, Wencai; Liu, Haowei; Zhang, Ji; Long, Hu; Feng, Sujuan; Mao, Qinghe

    2016-06-10

    The operation mechanism and the pulse property of an actively Q-switched erbium-doped fiber laser based on an acousto-optic modulator (AOM) switch with the injection seeding technique are investigated. Our results show that the Q-switched pulses can be locked to oscillate near a fixed frequency higher than that of the seed laser, though the frequency-shift effect of the AOM impedes stable cavity mode oscillations. The operation mechanism of such Q-switch fiber lasers can be explained by the mutual locking-in among the shifted frequency components originated from the injected coherence seed with the help of the gain dynamics of the Q-switch cavity. Moreover, narrow-linewidth Q-switched pulses with different repetition rates can be obtained with different cavity lengths for incredibly stable output pulses without any use of cavity-stabilized techniques. PMID:27409015

  9. Male fitness of oilseed rape (Brassica napus), weedy B. rapa and their F(1) hybrids when pollinating B. rapa seeds.

    PubMed

    Pertl, M; Hauser, T P; Damgaard, C; Jørgensen, R B

    2002-09-01

    The likelihood that two species hybridise and backcross may depend strongly on environmental conditions, and possibly on competitive interactions between parents and hybrids. We studied the paternity of seeds produced by weedy Brassica rapa growing in mixtures with oilseed rape (B. napus) and their F(1) hybrids at different frequencies and densities. Paternity was determined by the presence of a transgene, morphology, and AFLP markers. In addition, observations of flower and pollen production, and published data on pollen fertilisation success, zygote survival, and seed germination, allowed us to estimate an expected paternity. The frequency and density of B. napus, B. rapa, and F(1) plants had a strong influence on flower, pollen, and seed production, and on the paternity of B. rapa seeds. Hybridisation and backcrossing mostly occurred at low densities and at high frequencies of B. napus and F(1), respectively. F(1) and backcross offspring were produced mainly by a few B. rapa mother plants. The observed hybridisation and backcrossing frequencies were much lower than expected from our compilation of fitness components. Our results show that the male fitness of B. rapa, B. napus, and F(1) hybrids is strongly influenced by their local frequencies, and that male fitness of F(1)hybrids, when pollinating B. rapa seeds, is low even when their female fitness (seed set) is high.

  10. Laser Phase Errors in Seeded FELs

    SciTech Connect

    Ratner, D.; Fry, A.; Stupakov, G.; White, W.; /SLAC

    2012-03-28

    Harmonic seeding of free electron lasers has attracted significant attention from the promise of transform-limited pulses in the soft X-ray region. Harmonic multiplication schemes extend seeding to shorter wavelengths, but also amplify the spectral phase errors of the initial seed laser, and may degrade the pulse quality. In this paper we consider the effect of seed laser phase errors in high gain harmonic generation and echo-enabled harmonic generation. We use simulations to confirm analytical results for the case of linearly chirped seed lasers, and extend the results for arbitrary seed laser envelope and phase.

  11. Frequency domain optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-05-01

    Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength.

  12. Frequency domain optical parametric amplification

    PubMed Central

    Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-01-01

    Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength. PMID:24805968

  13. Dual-frequency injection-locked continuous-wave near-infrared laser.

    PubMed

    Gavara, Trivikramarao; Ohashi, Takeru; Sasaki, Yusuke; Kawashima, Takuya; Hamano, Hiroaki; Yoshizaki, Ryo; Fujimura, Yuki; Yoshii, Kazumichi; Ohae, Chiaki; Katsuragawa, Masayuki

    2016-07-01

    We report a dual-frequency injection-locked continuous-wave near-infrared laser. The entire system consists of a Ti:sapphire ring laser as a power oscillator, two independent diode lasers employed as seed lasers, and a master cavity providing a frequency reference. Stable dual-frequency injection-locked oscillation is achieved with a maximum output power of 2.8 W. We show its single longitudinal/transverse mode characteristics and practical power stability, as fundamental performance features of this laser system. We also demonstrate arbitrary selectivity of the two frequencies and flexible control of their relative powers by simply manipulating the seed lasers, as advanced features.

  14. Functional importance of avian seed dispersers changes in response to human-induced forest edges in tropical seed-dispersal networks.

    PubMed

    Saavedra, Francisco; Hensen, Isabell; Beck, Stephan G; Böhning-Gaese, Katrin; Lippok, Denis; Töpfer, Till; Schleuning, Matthias

    2014-11-01

    Although seed-dispersal networks are increasingly used to infer the functioning of ecosystems, few studies have investigated the link between the properties of these networks and the ecosystem function of seed dispersal by animals. We investigate how frugivore communities and seed dispersal change with habitat disturbance and test whether relationships between morphological traits and functional roles of seed dispersers change in response to human-induced forest edges. We recorded interaction frequencies between fleshy fruited plants and frugivorous bird species in tropical montane forests in the Bolivian Andes and recorded functional bird traits (body mass, gape width and wing tip length) associated with quantitative (seed-removal rate) and qualitative (seed-deposition pattern) components of seed-dispersal effectiveness. We found that the abundance and richness of frugivorous birds were higher at forest edges. More fruits were removed and dispersed seeds were less clustered at edges than in the interior. Additionally, functional and interaction diversity were higher at edges than in the interior, but functional and interaction evenness did not differ. Interaction strength of bird species increased with body mass, gape width and wing tip length in the forest interior, but was not related to bird morphologies at forest edges. Our study suggests that increases in functional and interaction diversity and an even distribution of interaction strength across bird morphologies lead to enhanced quantity and tentatively enhanced quality of seed dispersal. It also suggests that the effects of species traits on ecosystem functions can vary along small-scale gradients of human disturbance. PMID:25182931

  15. Unique Method for Generating Design Earthquake Time History Seeds

    SciTech Connect

    R. E. Spears

    2008-07-01

    A method has been developed which takes a single seed earthquake time history and produces multiple similar seed earthquake time histories. These new time histories possess important frequency and cumulative energy attributes of the original while having a correlation less than 30% (per the ASCE/SEI 43-05 Section 2.4 [1]). They are produced by taking the fast Fourier transform of the original seed. The averaged amplitudes are then pared with random phase angles and the inverse fast Fourier transform is taken to produce a new time history. The average amplitude through time is then adjusted to encourage a similar cumulative energy curve. Next, the displacement is modified to approximate the original curve using Fourier techniques. Finally, the correlation is checked to ensure it is less than 30%. This process does not guarantee that the correlation will be less than 30% for all of a given set of new curves. It does provide a simple tool where a few additional iterations of the process should produce a set of seed earthquake time histories meeting the correlation criteria.

  16. Spaced Seed Data Structures for De Novo Assembly

    PubMed Central

    Birol, Inanç; Chu, Justin; Mohamadi, Hamid; Jackman, Shaun D.; Raghavan, Karthika; Vandervalk, Benjamin P.; Raymond, Anthony; Warren, René L.

    2015-01-01

    De novo assembly of the genome of a species is essential in the absence of a reference genome sequence. Many scalable assembly algorithms use the de Bruijn graph (DBG) paradigm to reconstruct genomes, where a table of subsequences of a certain length is derived from the reads, and their overlaps are analyzed to assemble sequences. Despite longer subsequences unlocking longer genomic features for assembly, associated increase in compute resources limits the practicability of DBG over other assembly archetypes already designed for longer reads. Here, we revisit the DBG paradigm to adapt it to the changing sequencing technology landscape and introduce three data structure designs for spaced seeds in the form of paired subsequences. These data structures address memory and run time constraints imposed by longer reads. We observe that when a fixed distance separates seed pairs, it provides increased sequence specificity with increased gap length. Further, we note that Bloom filters would be suitable to implicitly store spaced seeds and be tolerant to sequencing errors. Building on this concept, we describe a data structure for tracking the frequencies of observed spaced seeds. These data structure designs will have applications in genome, transcriptome and metagenome assemblies, and read error correction. PMID:26539459

  17. Seed Mucilage Improves Seedling Emergence of a Sand Desert Shrub

    PubMed Central

    Yang, Xuejun; Baskin, Carol C.; Baskin, Jerry M.; Liu, Guangzheng; Huang, Zhenying

    2012-01-01

    The success of seedling establishment of desert plants is determined by seedling emergence response to an unpredictable precipitation regime. Sand burial is a crucial and frequent environmental stress that impacts seedling establishment on sand dunes. However, little is known about the ecological role of seed mucilage in seedling emergence in arid sandy environments. We hypothesized that seed mucilage enhances seedling emergence in a low precipitation regime and under conditions of sand burial. In a greenhouse experiment, two types of Artemisia sphaerocephala achenes (intact and demucilaged) were exposed to different combinations of burial depth (0, 5, 10, 20, 40 and 60 mm) and irrigation regimes (low, medium and high, which simulated the precipitation amount and frequency in May, June and July in the natural habitat, respectively). Seedling emergence increased with increasing irrigation. It was highest at 5 mm sand burial depth and ceased at burial depths greater than 20 mm in all irrigation regimes. Mucilage significantly enhanced seedling emergence at 0, 5 and 10 mm burial depths in low irrigation, at 0 and 5 mm burial depths in medium irrigation and at 0 and 10 mm burial depths in high irrigation. Seed mucilage also reduced seedling mortality at the shallow sand burial depths. Moreover, mucilage significantly affected seedling emergence time and quiescence and dormancy percentages. Our findings suggest that seed mucilage plays an ecologically important role in successful seedling establishment of A. sphaerocephala by improving seedling emergence and reducing seedling mortality in stressful habitats of the sandy desert environment. PMID:22511952

  18. Fluorescent Screening of Transgenic Arabidopsis Seeds without Germination1

    PubMed Central

    Wei, Shu; Bravdo, Ben-Ami; Shoseyov, Oded

    2004-01-01

    In this paper, we describe a reliable method for the screening and selection of Arabidopsis transgenic seeds within minutes without germination. Expression of the Aspergillus niger β-glucosidase gene BGL1 in the plant's endoplasmic reticulum was used as a visual marker, together with 4-methylumbelliferyl-β-d-glucopyranoside (MUGluc) as a substrate. Subsequent to incubation in a solution of MUGluc at room temperature for 2 to 15 min, transgenic seeds expressing BGL1 demonstrated a distinct fluorescent signal under UV light. Optimal screening conditions at room temperature were achieved between 75 and 450 μm MUGluc, at a pH of 2.5 to 5.0 and 2 to 5 min of incubation. No significant loss of viability was detected in transgenic seeds that were redried and stored for 45 d after incubation in MUGluc solution for 2 to 150 min. Transgenic plants expressing BGL1 displayed normal phenotypes relative to the wild type. Selection frequency was 3.1% ± 0.34% for the fluorescence selection method, while kanamycin resistant selection resulted in only 0.56% ± 0.13% using the same seed batch. This novel selection method is nondestructive, practical, and efficient, and eliminates the use of antibiotic genes. In addition, the procedure shortens the selection time from weeks to minutes. PMID:15208418

  19. Spaced Seed Data Structures for De Novo Assembly.

    PubMed

    Birol, Inanç; Chu, Justin; Mohamadi, Hamid; Jackman, Shaun D; Raghavan, Karthika; Vandervalk, Benjamin P; Raymond, Anthony; Warren, René L

    2015-01-01

    De novo assembly of the genome of a species is essential in the absence of a reference genome sequence. Many scalable assembly algorithms use the de Bruijn graph (DBG) paradigm to reconstruct genomes, where a table of subsequences of a certain length is derived from the reads, and their overlaps are analyzed to assemble sequences. Despite longer subsequences unlocking longer genomic features for assembly, associated increase in compute resources limits the practicability of DBG over other assembly archetypes already designed for longer reads. Here, we revisit the DBG paradigm to adapt it to the changing sequencing technology landscape and introduce three data structure designs for spaced seeds in the form of paired subsequences. These data structures address memory and run time constraints imposed by longer reads. We observe that when a fixed distance separates seed pairs, it provides increased sequence specificity with increased gap length. Further, we note that Bloom filters would be suitable to implicitly store spaced seeds and be tolerant to sequencing errors. Building on this concept, we describe a data structure for tracking the frequencies of observed spaced seeds. These data structure designs will have applications in genome, transcriptome and metagenome assemblies, and read error correction. PMID:26539459

  20. Spaced Seed Data Structures for De Novo Assembly.

    PubMed

    Birol, Inanç; Chu, Justin; Mohamadi, Hamid; Jackman, Shaun D; Raghavan, Karthika; Vandervalk, Benjamin P; Raymond, Anthony; Warren, René L

    2015-01-01

    De novo assembly of the genome of a species is essential in the absence of a reference genome sequence. Many scalable assembly algorithms use the de Bruijn graph (DBG) paradigm to reconstruct genomes, where a table of subsequences of a certain length is derived from the reads, and their overlaps are analyzed to assemble sequences. Despite longer subsequences unlocking longer genomic features for assembly, associated increase in compute resources limits the practicability of DBG over other assembly archetypes already designed for longer reads. Here, we revisit the DBG paradigm to adapt it to the changing sequencing technology landscape and introduce three data structure designs for spaced seeds in the form of paired subsequences. These data structures address memory and run time constraints imposed by longer reads. We observe that when a fixed distance separates seed pairs, it provides increased sequence specificity with increased gap length. Further, we note that Bloom filters would be suitable to implicitly store spaced seeds and be tolerant to sequencing errors. Building on this concept, we describe a data structure for tracking the frequencies of observed spaced seeds. These data structure designs will have applications in genome, transcriptome and metagenome assemblies, and read error correction.

  1. Smoke signals and seed dormancy

    PubMed Central

    Waters, Mark T; Nelson, David C

    2011-01-01

    The Arabidopsis thaliana F-box protein MAX2 has been discovered in four separate genetic screens, indicating that it has roles in leaf senescence, seedling photosensitivity, shoot outgrowth and seed germination. Both strigolactones and karrikins can regulate A. thaliana seed germination and seedling photomorphogenesis in a MAX2-dependent manner, but only strigolactones inhibit shoot branching. How MAX2 mediates specific responses to both classes of structurally-related signals, and the origin of its dual role remains unknown. The moss Physcomitrella patens utilizes strigolactones and MAX2 orthologs are present across the land plants, suggesting that this signaling system could have an ancient origin. The seed of parasitic Orobanchaceae species germinate preferentially in response to strigolactones over karrikins, and putative Orobanchaceae MAX2 orthologs form a sub-clade distinct from those of other dicots. These observations suggest that lineage-specific evolution of MAX2 may have given rise to specialized responses to these signaling molecules. PMID:22019642

  2. CT, MR, and ultrasound image artifacts from prostate brachytherapy seed implants: The impact of seed size

    SciTech Connect

    Robertson, Andrew K. H.; Basran, Parminder S.; Thomas, Steven D.; Wells, Derek

    2012-04-15

    Purpose: To investigate the effects of brachytherapy seed size on the quality of x-ray computed tomography (CT), ultrasound (US), and magnetic resonance (MR) images and seed localization through comparison of the 6711 and 9011 {sup 125}I sources. Methods: For CT images, an acrylic phantom mimicking a clinical implantation plan and embedded with low contrast regions of interest (ROIs) was designed for both the 0.774 mm diameter 6711 (standard) and the 0.508 mm diameter 9011 (thin) seed models (Oncura, Inc., and GE Healthcare, Arlington Heights, IL). Image quality metrics were assessed using the standard deviation of ROIs between the seeds and the contrast to noise ratio (CNR) within the low contrast ROIs. For US images, water phantoms with both single and multiseed arrangements were constructed for both seed sizes. For MR images, both seeds were implanted into a porcine gel and imaged with pelvic imaging protocols. The standard deviation of ROIs and CNR values were used as metrics of artifact quantification. Seed localization within the CT images was assessed using the automated seed finder in a commercial brachytherapy treatment planning system. The number of erroneous seed placements and the average and maximum error in seed placements were recorded as metrics of the localization accuracy. Results: With the thin seeds, CT image noise was reduced from 48.5 {+-} 0.2 to 32.0 {+-} 0.2 HU and CNR improved by a median value of 74% when compared with the standard seeds. Ultrasound image noise was measured at 50.3 {+-} 17.1 dB for the thin seed images and 50.0 {+-} 19.8 dB for the standard seed images, and artifacts directly behind the seeds were smaller and less prominent with the thin seed model. For MR images, CNR of the standard seeds reduced on average 17% when using the thin seeds for all different imaging sequences and seed orientations, but these differences are not appreciable. Automated seed localization required an average ({+-}SD) of 7.0 {+-} 3.5 manual

  3. SEEDS Moving Group Status Update

    NASA Technical Reports Server (NTRS)

    McElwain, Michael

    2011-01-01

    I will summarize the current status of the SEEDS Moving Group category and describe the importance of this sub-sample for the entire SEEDS survey. This presentation will include analysis of the sensitivity for the Moving Groups with general a comparison to other the other sub-categories. I will discuss the future impact of the Subaru SCExAO system for these targets and the advantage of using a specialized integral field spectrograph. Finally, I will present the impact of a pupil grid mask in order to produce fiducial spots in the focal plane that can be used for both photometry and astrometry.

  4. [Nutritional value of sesame seeds].

    PubMed

    Martinchik, A N

    2011-01-01

    Literature data on the nutritional value of sesame seeds (Sesamum indicum L.), their use in feeding the world population and food production are presented. Sesame seeds contain up to 55% oil and 20% protein. Sesame proteins are limited by lysine but rich in tryptophan and methionine. Sesame oil is rich in linoleic and oleic acids, the predominance of gamma-tocopherol over the other isomers of vitamin E and high content of fat-soluble lignans (sesamin and sesamolin). Thanks to recent sesame oil has a phytoestrogen activity; it has a cholesterol-lowering effect.

  5. SEEDS: A Celebration of Science

    NASA Technical Reports Server (NTRS)

    Melton, Bob

    1991-01-01

    The major goal of the project of Space Exposed Experiment Developed for Students (SEEDS) was to stimulate interest in science through the active involvement of all participants. Youthful investigators utilized the basic and integrated science process skills as they conducted the research necessary to complete the data reports used in the compilation of this document. Participants described many unique activities designed to promote critical thinking and problem solving. Seeds made a significant impact toward enhancing the teaching, learning, and enjoyment of science for students worldwide.

  6. Soil warming increases plant species richness but decreases germination from the alpine soil seed bank.

    PubMed

    Hoyle, Gemma L; Venn, Susanna E; Steadman, Kathryn J; Good, Roger B; McAuliffe, Edward J; Williams, Emlyn R; Nicotra, Adrienne B

    2013-05-01

    Global warming is occurring more rapidly above the treeline than at lower elevations and alpine areas are predicted to experience above average warming in the future. Temperature is a primary factor in stimulating seed germination and regulating changes in seed dormancy status. Thus, plant regeneration from seed will be crucial to the persistence, migration and post disturbance recruitment of alpine plants in future climates. Here, we present the first assessment of the impact of soil warming on germination from the persistent alpine soil seed bank. Contrary to expectations, soil warming lead to reduced overall germination from the soil seed bank. However, germination response to soil temperature was species specific such that total species richness actually increased by nine with soil warming. We further explored the system by assessing the prevalence of seed dormancy and germination response to soil disturbance, the frequency of which is predicted to increase under climate change. Seeds of a significant proportion of species demonstrated physiological dormancy mechanisms and germination of several species appeared to be intrinsically linked to soil disturbance. In addition, we found no evidence of subalpine species and little evidence of exotic weed species in the soil, suggesting that the soil seed bank will not facilitate their invasion of the alpine zone. In conclusion, changes in recruitment via the alpine soil seed bank can be expected under climate change, as a result of altered dormancy alleviation and germination cues. Furthermore, the alpine soil seed bank, and the species richness therein, has the potential to help maintain local species diversity, support species range shift and moderate species dominance. Implications for alpine management and areas for further study are also discussed.

  7. Mechanism of particle flocculation by magnetic seeding

    SciTech Connect

    Yiacoumi, S.; Rountree, D.A.; Tsouris, C.

    1996-12-25

    Magnetic seeding flocculation of micrometer-sized particles in liquid suspensions is investigated. Primary forces acting on individual particles, including gravity and magnetic attraction, as well as van der Waals, electrostatic, magnetic dipole, and hydrodynamic interparticle forces, are examined and quantified. A mathematical statement of the overall relative velocity is developed from the net force acting on a particle. From this, the equation of relative motion for two particles in cylindrical coordinates is derived. A computer model is then used to solve this equation repeatedly to find the particle trajectory borderline between collision and noncollision, thus determining the collision efficiency and collision frequency. The effects of a variety of parameters on flocculation performance are then explored. It is found that some factors have unexpected and complex influences on the collision efficiency and collision frequency, particularly the particle size ratio and the direction of the magnetic field. Magnetic separation has been used for desulfurization of coal, and separation and concentration of mining ores and wastes, and nuclear reactor coolant water filtration.

  8. Updated Methods for Seed Shape Analysis

    PubMed Central

    Cervantes, Emilio; Martín, José Javier; Saadaoui, Ezzeddine

    2016-01-01

    Morphological variation in seed characters includes differences in seed size and shape. Seed shape is an important trait in plant identification and classification. In addition it has agronomic importance because it reflects genetic, physiological, and ecological components and affects yield, quality, and market price. The use of digital technologies, together with development of quantification and modeling methods, allows a better description of seed shape. Image processing systems are used in the automatic determination of seed size and shape, becoming a basic tool in the study of diversity. Seed shape is determined by a variety of indexes (circularity, roundness, and J index). The comparison of the seed images to a geometrical figure (circle, cardioid, ellipse, ellipsoid, etc.) provides a precise quantification of shape. The methods of shape quantification based on these models are useful for an accurate description allowing to compare between genotypes or along developmental phases as well as to establish the level of variation in different sets of seeds. PMID:27190684

  9. We're Having a Seed Sale.

    ERIC Educational Resources Information Center

    Riss, Pam Helfers

    1994-01-01

    Botany meets computer science in this activity, which challenges students to create a computerized seed catalog. Class members work together to develop a database of plants, much like the major seed companies do. (PR)

  10. Observation of frequency doubling in tantalum doped silica fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    Second harmonic conversion efficients of 3 x 0,0001 in tantalum-doped silica fibers prepared by the seeding technique are reported. A series of experiments were conducted to characterize the frequency doubling in this fiber and to compare the results to the behavior observed in germanosilicate and rare earth-doped aluminosilicate fibers.

  11. Handling System for Iridium-192 Seeds

    NASA Technical Reports Server (NTRS)

    Carpenter, W.; Wodicka, D.

    1973-01-01

    A complete system is proposed for safe handling of iridium-192 seeds used to internally irradiate malignant growths. A vibratory hopper feeds the seeds onto a transport system for deposit in a magazine or storage area. A circular magazine consisting of segmented plastic tubing with holes in the walls to accommodate the seeds seems feasible. The magazine is indexed to stop and release a seed for calibration and deposition.

  12. Nutrient content of Prosopis africana seeds.

    PubMed

    Barminas, J T; Maina, H M; Ali, J

    1998-01-01

    The proximate and mineral compositions of Prosopis africana seeds used in the preparation of a local condiment in Nigeria and as animal feed were investigated. The proximate analysis showed that protein, ash and fiber values were comparable to Parkia africana seeds. However, the crude lipid content was lower than Parkia filicoidea seeds and decorticated groundnut. Phosphorus, potassium and calcium were the major mineral elements of the seeds, thereby suggesting that they could contribute partially to the overall daily intake of these elements.

  13. Frequency signature of water activity by biospeckle laser

    NASA Astrophysics Data System (ADS)

    Cardoso, Rafael Rodrigues; Costa, Anderson Gomide; Nobre, Cassia Marques Batista; Braga, Roberto Alves

    2011-04-01

    Biospeckle laser technique has become an important tool to investigate biological activity in several areas of science. However, due to the complexity of biological materials it is necessary to develop research processes that ensure greater efficiency in isolating areas of different activities in the same material using the biospeckle. Thus, alternative techniques, such as those related to spectral domain, allow approaches that provide a means for frequency and isolation marking of various observed phenomena. The possibility of creating frequency markers related to physical or chemical phenomena under biospeckle laser monitoring opens the way for important applications in the analysis of biological materials. In seeds, for example, one research challenge is the creation of a methodology to analyze their vigor undermining the influence of water activity. This study aimed to use wavelet transform to create maps in frequency of biological material, particularly from maize and bean seeds, seeking to isolate water activity. Wavelet transform was used in conjunction with traditional biospeckle laser methods, Fujii, Generalized Differences and Time History Speckle Patterns. The data analysis allowed access of information in different frequencies, making it possible to map activities that only occur at certain frequencies in the seeds associated to particular areas they operate, as in the case of activities present in the embryo as well as those present in the endosperm. Thus the work enabled the identification of frequency bands where water activity may be operating creating a signature useful in further works.

  14. Reversible Seeding in Storage Rings

    SciTech Connect

    Ratner, Daniel; Chao, Alex; /SLAC

    2011-12-14

    We propose to generate steady-state microbunching in a storage ring with a reversible seeding scheme. High gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) are two promising methods for microbunching linac electron beams. Because both schemes increase the energy spread of the seeded beam, they cannot drive a coherent radiator turn-by-turn in a storage ring. However, reversing the seeding process following the radiator minimizes the impact on the electron beam and may allow coherent radiation at or near the storage ring repetition rate. In this paper we describe the general idea and outline a proof-of-principle experiment. Electron storage rings can drive high average power light sources, and free-electron lasers (FELs) are now producing coherent light sources of unprecedented peak brightness While there is active research towards high repetition rate FELs (for example, using energy recovery linacs), at present there are still no convenient accelerator-based sources of high repetition rate, coherent radiation. As an alternative avenue, we recently proposed to establish steady-state microbunching (SSMB) in a storage ring. By maintaining steady-state coherent microbunching at one point in the storage ring, the beam generates coherent radiation at or close to the repetition rate of the storage ring. In this paper, we propose a method of generating a microbunched beam in a storage ring by using reversible versions of linac seeding schemes.

  15. The Seed Is the Law

    ERIC Educational Resources Information Center

    Antone, Eileen M.

    2005-01-01

    Since humanities arise from a specific place and from the people of that place, this article will focus on Peacemaker's revolutionary teachings about the seed of law. Long before the people from across the ocean arrived here on Turtle Island (North America) there was much warfare happening. According to John Mohawk (2001, para. 1), an Iroquoian…

  16. Seed coat darkening in Cowpea bean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed coat of cowpea bean (Vigna unguiculata L. Walp) slowly browns to a darker color during storage. High temperature and humidity during storage might contribute to this color change. Variation in browning rate among seeds in a lot leads to a mixture of seed colors creating an unacceptable product...

  17. 9 CFR 101.7 - Seed organisms.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Seed organisms. 101.7 Section 101.7..., SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms. When used in conjunction with or in reference to seed organisms, the following shall mean: (a) Master...

  18. 9 CFR 101.7 - Seed organisms.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Seed organisms. 101.7 Section 101.7..., SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms. When used in conjunction with or in reference to seed organisms, the following shall mean: (a) Master...

  19. 9 CFR 101.7 - Seed organisms.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Seed organisms. 101.7 Section 101.7..., SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms. When used in conjunction with or in reference to seed organisms, the following shall mean: (a) Master...

  20. 9 CFR 101.7 - Seed organisms.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Seed organisms. 101.7 Section 101.7..., SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms. When used in conjunction with or in reference to seed organisms, the following shall mean: (a) Master...

  1. Weed Research in Alfalfa Seed Production 2007

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed control in alfalfa seed production is important to produce high quality and high yield of alfalfa seed. Herbicides were tested on a commercial field of alfalfa seed in central Washington in 2007. Flumioxzin slightly injured alfalfa when applied at 0.125 and 0.25 lb ai/a. to dormant alfalfa in M...

  2. 7 CFR 947.12 - Seed potatoes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Seed potatoes. 947.12 Section 947.12 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN MODOC AND... Definitions § 947.12 Seed potatoes. Seed potatoes means and includes all potatoes officially certified...

  3. 7 CFR 947.12 - Seed potatoes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Seed potatoes. 947.12 Section 947.12 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN MODOC AND... Definitions § 947.12 Seed potatoes. Seed potatoes means and includes all potatoes officially certified...

  4. 7 CFR 947.12 - Seed potatoes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Seed potatoes. 947.12 Section 947.12 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN MODOC AND... Definitions § 947.12 Seed potatoes. Seed potatoes means and includes all potatoes officially certified...

  5. 7 CFR 947.12 - Seed potatoes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Seed potatoes. 947.12 Section 947.12 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN MODOC AND... Definitions § 947.12 Seed potatoes. Seed potatoes means and includes all potatoes officially certified...

  6. 7 CFR 946.12 - Seed potatoes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Seed potatoes. 946.12 Section 946.12 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Order Regulating Handling Definitions § 946.12 Seed potatoes. Seed potatoes means and includes...

  7. 7 CFR 946.12 - Seed potatoes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Seed potatoes. 946.12 Section 946.12 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Order Regulating Handling Definitions § 946.12 Seed potatoes. Seed potatoes means and includes...

  8. 7 CFR 947.12 - Seed potatoes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Seed potatoes. 947.12 Section 947.12 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN MODOC AND... Definitions § 947.12 Seed potatoes. Seed potatoes means and includes all potatoes officially certified...

  9. 7 CFR 946.12 - Seed potatoes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Seed potatoes. 946.12 Section 946.12 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Order Regulating Handling Definitions § 946.12 Seed potatoes. Seed potatoes means and includes...

  10. 7 CFR 946.12 - Seed potatoes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Seed potatoes. 946.12 Section 946.12 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Order Regulating Handling Definitions § 946.12 Seed potatoes. Seed potatoes means and includes...

  11. 7 CFR 946.12 - Seed potatoes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Seed potatoes. 946.12 Section 946.12 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Order Regulating Handling Definitions § 946.12 Seed potatoes. Seed potatoes means and includes...

  12. Frequency-Rank Distributions

    ERIC Educational Resources Information Center

    Brookes, Bertram C.; Griffiths, Jose M.

    1978-01-01

    Frequency, rank, and frequency rank distributions are defined. Extensive discussion on several aspects of frequency rank distributions includes the Poisson process as a means of exploring the stability of ranks; the correlation of frequency rank distributions; and the transfer coefficient, a new measure in frequency rank distribution. (MBR)

  13. 7 CFR 201.69 - Classes of certified seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Classes of certified seed. 201.69 Section 201.69..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.69 Classes of certified seed. (a) Classes of certified seed are as...

  14. 7 CFR 201.24a - Inoculated seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Inoculated seed. 201.24a Section 201.24a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.24a Inoculated seed. Seed claimed to be inoculated shall...

  15. 7 CFR 201.69 - Classes of certified seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Classes of certified seed. 201.69 Section 201.69..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.69 Classes of certified seed. (a) Classes of certified seed are as...

  16. 7 CFR 201.24a - Inoculated seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Inoculated seed. 201.24a Section 201.24a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.24a Inoculated seed. Seed claimed to be inoculated shall...

  17. 7 CFR 201.24a - Inoculated seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Inoculated seed. 201.24a Section 201.24a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.24a Inoculated seed. Seed claimed to be inoculated shall...

  18. 7 CFR 201.24a - Inoculated seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Inoculated seed. 201.24a Section 201.24a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.24a Inoculated seed. Seed claimed to be inoculated shall...

  19. 7 CFR 201.69 - Classes of certified seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Classes of certified seed. 201.69 Section 201.69..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.69 Classes of certified seed. (a) Classes of certified seed are as...

  20. 7 CFR 201.69 - Classes of certified seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Classes of certified seed. 201.69 Section 201.69..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.69 Classes of certified seed. (a) Classes of certified seed are as...

  1. 7 CFR 201.69 - Classes of certified seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Classes of certified seed. 201.69 Section 201.69..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Certified Seed § 201.69 Classes of certified seed. (a) Classes of certified seed are as...

  2. 7 CFR 201.24a - Inoculated seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Inoculated seed. 201.24a Section 201.24a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.24a Inoculated seed. Seed claimed to be inoculated shall...

  3. The poppy seed defense: a novel solution.

    PubMed

    Chen, P; Braithwaite, R A; George, C; Hylands, P J; Parkin, M C; Smith, N W; Kicman, A T

    2014-03-01

    A major toxicological challenge is distinguishing whether morphine in urine, in the absence of 6-monoacetylmorphine (6-MAM), originates from 'street' heroin use or poppy seed ingestion. Manufacturing byproducts from the synthesis of illicit heroin include those that originate from the reaction of acetic anhydride with the alkaloid impurity, thebaine, which undergoes skeletal rearrangement, resulting in compounds with a 2-(N-methylacetamido)ethyl side-chain. The hypothesis that the tertiary amide in this side-chain is resistant to endogenous hydrolysis was supported from in-vitro experiments; a glucuronide metabolite (designated 'ATM4G') was identified that may be used as a marker of 'street' heroin administration. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for this metabolite was then performed on selected urine specimens from 22 known heroin users, these being negative on routine testing for 6-MAM by gas chromatography-mass spectrometry (GC-MS), using the generally applied reporting threshold of 10 ng/mL, but positive for the presence of morphine. Peaks corresponding to the retention time for the metabolite marker were clearly observed for 16 of the 22 samples, with variations of the ratios of its three dependent ions being within ± 30% of that produced in vitro. Conversely, 6-MAM was detected in only 3 samples, but at concentrations <1 ng/mL. Such a high frequency for the presence of the metabolite marker in urine, in the absence of 6-MAM, is noteworthy and suggests that detection of this metabolite may offer an important advance in forensic toxicology, allowing the development of a new and more definitive test for heroin abuse and thus a potential solution to the so-called 'poppy seed defense'.

  4. Diversity of plant oil seed-associated fungi isolated from seven oil-bearing seeds and their potential for the production of lipolytic enzymes.

    PubMed

    Venkatesagowda, Balaji; Ponugupaty, Ebenezer; Barbosa, Aneli M; Dekker, Robert F H

    2012-01-01

    Commercial oil-yielding seeds (castor, coconut, neem, peanut, pongamia, rubber and sesame) were collected from different places in the state of Tamil Nadu (India) from which 1279 endophytic fungi were isolated. The oil-bearing seeds exhibited rich fungal diversity. High Shannon-Index H' was observed with pongamia seeds (2.847) while a low Index occurred for coconut kernel-associated mycoflora (1.018). Maximum Colonization Frequency (%) was observed for Lasiodiplodia theobromae (176). Dominance Index (expressed in terms of the Simpson's Index D) was high (0.581) for coconut kernel-associated fungi, and low for pongamia seed-borne fungi. Species Richness (Chao) of the fungal isolates was high (47.09) in the case of neem seeds, and low (16.6) for peanut seeds. All 1279 fungal isolates were screened for lipolytic activity employing a zymogram method using Tween-20 in agar. Forty isolates showed strong lipolytic activity, and were morphologically identified as belonging to 19 taxa (Alternaria, Aspergillus, Chalaropsis, Cladosporium, Colletotrichum, Curvularia, Drechslera, Fusarium, Lasiodiplodia, Mucor, Penicillium, Pestalotiopsis, Phoma, Phomopsis, Phyllosticta, Rhizopus, Sclerotinia, Stachybotrys and Trichoderma). These isolates also exhibited amylolytic, proteolytic and cellulolytic activities. Five fungal isolates (Aspergillus niger, Chalaropsis thielavioides, Colletotrichum gloeosporioides, Lasiodiplodia theobromae and Phoma glomerata) exhibited highest lipase activities, and the best producer was Lasiodiplodia theobromae (108 U/mL), which was characterized by genomic sequence analysis of the ITS region of 18S rDNA. PMID:22806781

  5. [Seed rain, soil seed bank, and natural regeneration of natural Toona ciliata var. pubescens forest].

    PubMed

    Huang, Hong-Lan; Zhang, Lu; Liao, Cheng-Kai

    2012-04-01

    Taking the natural Toona ciliata var. pubescens forest in the Jiujiangshan National Nature Reserve in Jiangxi Province of China as test object, an investigation was conducted on the seed rain, soil seed bank, and seedlings number in 2008-2011. The seed rain of the forest was dispersed from late October to the end of December. In 2010, the seed rain intensity in different sampling plots was in the order of Xiagongtang observatory (320.3 +/- 23.5 seeds x m(-2)) > Xiagongtang protection station (284.7 +/- 24.2 seeds x m(-2)) > Daqiutian protection station (251.6 +/- 24.7 seeds x m(-2)), and the quantity of the intact seeds in soil supplied for seed germination and regeneration was 222.0, 34.3, and 22.6 seeds x m(-2), respectively. The seed bank reserves was affected by the seed production amount, bird feeding, and seed viability, etc., of which, bird feeding was the prime factor for the substantial drop of the seed bank reserves. Due to the low resistance against storage and a large number of rot during storage, the seeds in soil could hardly be effectively stored beyond one month. The seedlings germinated in December were averagely less than 2 stands x m(-2), and the soil seed reserves in the next January was the least (6.7-11.8 seeds x m(-2)), with the germinated seedlings averagely 0.4-0.6 stands x m(-2), which was consistent with the rare distribution of natural seedlings in the forest. It was concluded that the small seed rain reserves, low seed vigor of soil seed bank, and low seedling establishment were the important factors impacting the natural regeneration of T. ciliata var. pubescens.

  6. Myrmecochory and short-term seed fate in Rhamnus alaternus: Ant species and seed characteristics

    NASA Astrophysics Data System (ADS)

    Bas, J. M.; Oliveras, J.; Gómez, C.

    2009-05-01

    Benefits conferred on plants in ant-mediated seed dispersal mutualisms (myrmecochory) depend on the fate of transported seeds. We studied the effects of elaiosome presence, seed size and seed treatment (with and without passage through a bird's digestive tract) on short-term seed fate in Rhamnus alaternus. In our study, we define short-term seed, or initial, seed fate, as the location where ants release the seeds after ant contact with it. The elaiosomes had the most influence on short-term fate, i.e. whether or not seeds were transported to the nest. The workers usually transported big seeds more often than small ones, but small ants did not transport large seeds. Effect of seed size on transport depended on the ant species and on the treatment of the seed (manual extraction simulating a direct fall from the parent plant vs. bird deposition corresponding to preliminary primary dispersal). Probability of removal of elaiosome-bearing seeds to the nest by Aphaenogaster senilis increased with increasing seed weight.

  7. Thermal Images of Seeds Obtained at Different Depths by Photoacoustic Microscopy (PAM)

    NASA Astrophysics Data System (ADS)

    Domínguez-Pacheco, A.; Hernández-Aguilar, C.; Cruz-Orea, A.

    2015-06-01

    The objective of the present study was to obtain thermal images of a broccoli seed ( Brassica oleracea) by photoacoustic microscopy, at different modulation frequencies of the incident light beam ((0.5, 1, 5, and 20) Hz). The thermal images obtained in the amplitude of the photoacoustic signal vary with each applied frequency. In the lowest light frequency modulation, there is greater thermal wave penetration in the sample. Likewise, the photoacoustic signal is modified according to the structural characteristics of the sample and the modulation frequency of the incident light. Different structural components could be seen by photothermal techniques, as shown in the present study.

  8. Stimulation of lettuce seed germination by ethylene.

    PubMed

    Abeles, F B; Lonski, J

    1969-02-01

    Ethylene increased the germination of freshly imbibed lettuce (Lactuca sativa L. var. Grand Rapids) seeds. Seeds receiving either red or far-red light or darkness all showed a positive response to the gas. However, ethylene was apparently without effect on dormant seeds, those which failed to germinate after an initial red or far-red treatment. Carbon dioxide, which often acts as a competitive inhibitor of ethylene, failed to clearly reverse ethylene-enhanced seed germination. While light doubled ethylene production from the lettuce seeds, its effect was not mediated by the phytochrome system since both red and far-red light had a similar effect.

  9. Self-seeding ring optical parametric oscillator

    DOEpatents

    Smith, Arlee V.; Armstrong, Darrell J.

    2005-12-27

    An optical parametric oscillator apparatus utilizing self-seeding with an external nanosecond-duration pump source to generate a seed pulse resulting in increased conversion efficiency. An optical parametric oscillator with a ring configuration are combined with a pump that injection seeds the optical parametric oscillator with a nanosecond duration, mJ pulse in the reverse direction as the main pulse. A retroreflecting means outside the cavity injects the seed pulse back into the cavity in the direction of the main pulse to seed the main pulse, resulting in higher conversion efficiency.

  10. Performance of laser Doppler velocimeter with polydisperse seed particles in high-speed flows

    NASA Technical Reports Server (NTRS)

    Samimy, M.; Abu-Hijleh, B. A. K.

    1989-01-01

    The flowfield behind an oblique shock wave, where the LDV measured velocities are seed-particle-size dependent, was used to investigate the effects of LDV system parameters on the range of detectable polydisperse seed particles. The parameters included frequency shifting, laser power, scattered signal amplification level, and number of required fringe crossings. The results showed that with polydisperse seed particles ranging from 0.1 to 4.0 microns available in the flow, the average diameter of the detected particles could change from 0.2 to 3.0 microns by changing different LDV system parameters. The effects of this shift in the range of detectable particles on the frequency response of LDV are discussed.

  11. Performance of laser Doppler velocimeter with polydisperse seed particles in high speed flows

    NASA Technical Reports Server (NTRS)

    Samimy, M.; Bhattacharyya, S.; Abu-Hijleh, B. A./K.

    1988-01-01

    The flowfield behind an oblique shock wave, where the LDV measured velocities are seed particle size dependent, was used to investigate the effects of LDV system parameters on the range of detectable polydisperse seed particles. The parameters included frequency shifting, laser power, scattered signal amplification level, and number of required fringe crossings. The results showed that with polydisperse seed particles ranging from 0.1 to 4.0 microns available in the flow, the average diameter of the detected particles could change from 0.2 to 3.0 microns by changing different LDV system parameters. The effects of this shift in the range of detectable particles on the frequency response of LDV was discussed.

  12. In vitro seed to seed growth on clinostats

    NASA Technical Reports Server (NTRS)

    Hoshizaki, T.

    1984-01-01

    The effect of a long term micro-gravity environment on the life cycle of plants is unknown. Whether higher plants have evolved to a stage where removal or reduction of gravity is detrimental to plant life cycle and thus fatal to the plant species, is an unanswered question in space plants which were successfully grown through the various stages of their life cycle. Attempts to grow plants as a continuous integral process from seed to seed through one generation were successful until recently. Culture of plants through multiple generations was not accomplished in space nor in ground based studies. The effect of long term simulated weightlessness by growing consecutive generations of plants continuously on clinostats using the cruciferous plants, Arabidopsis thaliana (L.) Heyn. and Cardamine oligosperma Nutt. is being investigated.

  13. Morphological rates of angiosperm seed size evolution.

    PubMed

    Sims, Hallie J

    2013-05-01

    The evolution of seed size among angiosperms reflects their ecological diversification in a complex fitness landscape of life-history strategies. The lineages that have evolved seeds beyond the upper and lower boundaries that defined nonflowering seed plants since the Paleozoic are more dispersed across the angiosperm phylogeny than would be expected under a neutral model of phenotypic evolution. Morphological rates of seed size evolution estimated for 40 clades based on 17,375 species ranged from 0.001 (Garryales) to 0.207 (Malvales). Comparative phylogenetic analysis indicated that morphological rates are not associated with the clade's seed size but are negatively correlated with the clade's position in the overall distribution of angiosperm seed sizes; clades with seed sizes closer to the angiosperm mean had significantly higher morphological rates than clades with extremely small or extremely large seeds. Likewise, per-clade taxonomic diversification rates are not associated with the seed size of the clade but with where the clade falls within the angiosperm seed size distribution. These results suggest that evolutionary rates (morphological and taxonomic) are elevated in densely occupied regions of the seed morphospace relative to lineages whose ecophenotypic innovations have moved them toward the edges.

  14. Determination of oil in sunflower seeds

    SciTech Connect

    Kochlar, S.P.; Rossell, J.B.

    1987-06-01

    Oil content measurement in sunflower seeds on an ''as is'' basis by current official methods is often associated with poor reproducibility. This study shows that the main factor contributing to this poor agreement is the particle size to which seeds are ground. This invariably influences the homogeneity of the bulk ground sample from which subsequent subsamples are taken. It is therefore suggested that oil content determinations on sunflower seeds should be carried out on seed samples that have been evenly and finely ground, to a particle size not greater than 2.0 mm, in a mechanical mill such as the Ultra-Centrifugal mill. Other factors investigated were seed composition (free husk, empty husk, crude fiber and seed meats) and structural differences in the seeds by light microscopy. (Refs. 16).

  15. Savanna fires increase rates and distances of seed dispersal by ants.

    PubMed

    Parr, C L; Andersen, A N; Chastagnol, C; Duffaud, C

    2007-02-01

    Myrmecochory (seed dispersal by ants) is a prominent dispersal mechanism in many environments, and can play a key role in local vegetation dynamics. Here we investigate its interaction with another key process in vegetation dynamics-fire. We examine ant dispersal of seeds immediately before and after experimental burning in an Australian tropical savanna, one of the world's most fire-prone ecosystems. Specifically, our study addressed the effects of burning on: (1) the composition of ants removing seeds, (2) number of seed removals, and (3) distance of seed dispersal. Fire led to higher rates of seed removal post-fire when compared with unburnt habitat, and markedly altered dispersal distance, with mean dispersal distance increasing more than twofold (from 1.6 to 3.8 m), and many distance dispersal events greater than the pre-fire maximum (7.55 m) being recorded. These changes were due primarily to longer foraging ranges of species of Iridomyrmex, most likely in response to the simplification of their foraging landscape. The significance of enhanced seed-removal rates and distance dispersal for seedling establishment is unclear because the benefits to plants in having their seeds dispersed by ants in northern Australia are poorly known. However, an enhanced removal rate would enhance any benefit of reduced predation by rodents. Similarly, the broader range of dispersal distances would appear to benefit plants in terms of reduced parent-offspring conflict and sibling competition, and the location of favourable seedling microsites. Given the high frequency of fire in Australian tropical savannas, enhanced benefits of seed dispersal by ants would apply for much of the year. PMID:17033801

  16. [The dynamics of chromosomal instability of welsh onion (Allium fistulosum L.): the influence of seed storage temperature].

    PubMed

    Lazarenko, L M; Bezrukov, V F

    2008-01-01

    The age-related dynamics of chromosomal instability and germination capacity of welsh onion (Allium fistulosum L.) seeds have been studied under two different storage temperatures during six years after harvesting. Seeds that were kept at the room temperature (14-28 degrees C) during 6 years of storage have lost their germination capacity. The frequencies of aberrant anaphases grew from 2% on the first month of storage up to 80% on the 75th month of storage. The germination capacity of seeds kept at the lower temperature (4-9 degrees C) was 73-77% on the 6th year of storage and the frequency of aberrant anaphases remained within the limits of 2-4%. Thus, storage of welsh onion seeds during 6 years at the lower temperature allows to retain germination capacity and restrains the augmentation of chromosomal instability in root meristem cells of seedlings during this period. PMID:19140441

  17. Endozoochorous seed dispersal by Japanese macaques (Macaca fuscata): Effects of temporal variation in ranging and seed characteristics on seed shadows.

    PubMed

    Tsuji, Yamato; Morimoto, Mayumi

    2016-02-01

    Variation in seed shadows generated by frugivores is caused by daily, seasonal, and inter-annual variation in ranging, as well as inter-specific variability in gut passage times according to seed characteristics. We studied the extent to which seed weight, specific gravity, and daily (morning, afternoon, and evening) and inter-annual (2004 vs. 2005) variation in ranging affected seed shadows generated by wild Japanese macaques (Macaca fuscata) in northern Japan. The macaques ingested fleshy fruits of 11 species during the two year study period; Viburnum dilatatum (Caprifoliaceae: heavier seeds with higher specific gravity) and Rosa multiflora (Rosaceae: lighter seeds with lower specific gravity) were eaten frequently in both years. The travel distances of macaques after feeding on V. dilatatum and R. multiflora fruits were estimated by combining feeding locations and ranging patterns measured in the field with gut passage times of model seeds in captive animals. Median travel distances after fruit feeding were 431 (quantile range: 277-654) and 478 m (265-646), respectively, with a maximum of 1,261 m. Neither year nor time of day affected travel distances. The gut passage time of model V. dilatatum seeds was longer than that of model R. multiflora seed, but this did not affect dispersal distances. Seed shadows for both species over 2 years showed unimodal distribution (peak: 101-500 m) and more than 90%, 20%, and 3% of ingested seeds were estimated to be dispersed >100, >500, and >1000 m, respectively, the longest known distances among macaque species. R. multiflora seeds tended to be dispersed further in 2004 than 2005, but V. dilatatum seeds were not, implying that inter-annual variations in ranging pattern due to the distribution and abundance of nut fruiting could affect dispersal distance.

  18. Diatom response to extremely low-frequency magnetic fields

    SciTech Connect

    Parkinson, W.C.; Sulik, G.L. )

    1992-06-01

    Reports that extremely low-frequency magnetic fields can interfere with normal biological cell function continue to stimulate experimental activity as well as investigations into the possible mechanism of the interaction. The cyclotron resonance' model of Liboff has been tested by Smith et al. using as the biological test system the diatom Amphora coffeiformis. They report enhanced motility of the diatom in response to a low-frequency electromagnetic field tuned to the cyclotron resonance condition for calcium ions. We report here an attempt to reproduce their results. Following their protocol diatoms were seeded onto agar plates containing varying amounts of calcium and exposed to colinear DC and AC magnetic fields tuned to the cyclotron resonant condition for frequencies of 16, 30, and 60 Hz. The fractional motility was compared with that of control plates seeded at the same time from the same culture. We find no evidence of a cyclotron resonance effect.

  19. Water binding in legume seeds

    NASA Technical Reports Server (NTRS)

    Vertucci, C. W.; Leopold, A. C.

    1987-01-01

    The physical status of water in seeds has a pivotal role in determining the physiological reactions that can take place in the dry state. Using water sorption isotherms from cotyledon and axis tissue of five leguminous seeds, the strength of water binding and the numbers of binding sites have been estimated using van't Hoff analyses and the D'Arcy/Watt equation. These parameters of water sorption are calculated for each of the three regions of water binding and for a range of temperatures. Water sorption characteristics are reflective of the chemical composition of the biological materials as well as the temperature at which hydration takes place. Changes in the sorption characteristics with temperature and hydration level may suggest hydration-induced structural changes in cellular components.

  20. MHD seed recovery and regeneration

    NASA Astrophysics Data System (ADS)

    1988-10-01

    The TRW Econoseed MHD Seed Regeneration Process is based on the reaction of calcium formate with potassium sulfate spent seed from an MHD electric power generation plant. The process was tested at bench scale, design a proof of concept (POC) test plant, plan and cost a Phase 2 project for a POC plant evaluation and prepare a conceptual design of a 300 MW (t) commercial plant. The results of the project are as follows: (1) each of the unit operations is demonstrated, and (2) the data are incorporated into a POC plant design and project cost, as well as a 300 MW (t) commercial retrofit plant design and cost estimate. Specific results are as follows: (1) calcium formate can be produced at 100 percent yield in a total retention time of less than 5 minutes, (2) utilizing the calcium formate, spent seed can quantitatively be converted to potassium formate, potassium carbonate or mixtures of these with potassium sulfate as per the commercial design without measurable loss of potassium to insolubles at a total retention time under 20 minutes and ambient pressure, (3) the solid rejects form the process meet RCRA EP Toxicity requirements for safe disposal, and (4) filtration and evaporation data, as well as reaction data cited above, show that the Econoseed technology is ready for scale up to POC plant scale. Economics forecast studies show that the total cost per unit of potassium for seed regeneration by the Econoseed Process is in the range of $0.23 to $0.27/lb, a cost which is less than half the potassium cost of $0.63/lb for purchasing new potassium carbonate.

  1. Generation of Particles and Seeding

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    1991-01-01

    One of the most important elements in laser velocimetry, yet the most neglected, is the small particle embedded in the flow field that scatters the light necessary to make velocity measurements. An attempt to remove the confusion in choosing a seeding method by assessing many of the techniques currently used is presented. Their characteristics and typical limitations imposed by various applications are outlined. The ramifications of these methods on measurement accuracy are addressed.

  2. Low-Cost, Single-Frequency Sources for Spectroscopy Using Conventional Fabry-Perot Diode Lasers

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Duerksen, Gary L.

    1999-01-01

    Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

  3. Low-Cost, Single-Frequency Sources for Spectroscopy using Conventional Fabry-Perot Diode Lasers

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

  4. Hierarchical mechanisms of spatially contagious seed dispersal in complex seed-disperser networks.

    PubMed

    Fedriani, José M; Wiegand, Thorsten

    2014-02-01

    Intra- and interspecific spatially contagious seed dispersal has far-reaching implications for plant recruitment, distribution, and community assemblage. However, logistical and analytical limitations have curtailed our understanding concerning the mechanisms and resulting spatial patterns of contagious seed dispersal in most systems and, especially, in complex seed-disperser networks. We investigated mechanisms of seed aggregation using techniques of spatial point pattern analysis and extensive data sets on mutispecific endozoochorous seed rain generated by five frugivorous mammals in three Mediterranean shrublands over two seasons. Our novel analytical approach revealed three hierarchical and complementary mechanisms of seed aggregation acting at different levels (fecal samples, seeds, pairs of seed species) and spatial scales. First, the three local guilds of frugivores tended to deliver their feces highly aggregated at small and intermediate spatial scales, and the overall pattern of fecal delivery could be described well by a nested double-cluster Thomas process. Second, once the strong observed fecal aggregation was accounted for, the distribution of mammal feces containing seeds was clustered within the pattern of all feces (i.e., with and without seeds), and the density of fecal samples containing seeds was higher than expected around other feces containing seeds in two out of the three studied seed-disperser networks. Finally, at a finer level, mark correlation analyses revealed that for some plant species pairs, the number of dispersed seeds was positively associated either at small or large spatial scales. Despite the relatively invariant patterning of nested double-clustering, some attributes of endozoochorous seed rain (e.g., intensity, scales of aggregation) were variable among study sites due to changes in the ecological context in which seeds and their dispersers interact. Our investigation disentangles for the first time the hierarchy of synergic

  5. Development of a versatile high temperature top seeded solution growth unit for growing cesium lithium borate crystals.

    PubMed

    Reddy, Babu; Elizabeth, Suja; Bhat, H L; Karnal, A K

    2009-01-01

    The design and fabrication of a state of the art high temperature top seeded solution growth (HTTSSG) unit with seed and crucible rotation options is discussed. Crystals from solid solutions of high viscosity could be grown using the setup. The fabricated setup is used to grow high optical quality single crystals of cesium lithium borate with dimensions 50x40x40 mm(3) for frequency conversion of ir to UV laser through harmonic generation.

  6. Experimental and Numerical Investigation of Single Frequency Amplifier with Photonic Bandgap Fiber at 1178 nm

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Hua; Cui, Shu-Zhen; Hu, Jin-Meng; Cao, Fen; Fang, Yong; Lu, Hui-Ling

    2014-06-01

    A single frequency photonic bandgap fiber amplifier at 1178 nm is investigated experimentally and numerically. With a pump power of 81 W, a single frequency 1178 nm fiber laser of 10.3 W is obtained with a 3W seed laser and a 20 m gain fiber. Numerical simulation is conducted with a rate equation model taking amplified spontaneous emission and stimulated Brillouin scattering (SBS) into consideration. Temperature distribution along the fiber is applied for SBS suppression, more than 50 W single frequency fiber laser at 1178 nm is predicted theoretically with a 5W seed laser and a 40 m long gain fiber with five temperature steps.

  7. MHD seed recovery/regeneration

    NASA Astrophysics Data System (ADS)

    Task 1 calls for the design, procurement, construction, and installation of the Seed Regeneration Proof-of-Concept Facility (SRPF) that will produce tonnage quantities of recyclable potassium formate seed at a design rate of 250 lb/hr for testing in the channel at the CDIF while collecting data that will be used to upgrade the design of a 300 MW(sub t) system. Approximately 12 tons of KCOOH (dry basis) as 70-75 wt percent solution were produced. The front end of the plant (potassium sulfate reaction and solids separation/washing units) was operated for five days in March. Most of the operations were conducted at a spent seed feed rate of 250 pounds/hour. A total of 8,500 gallons of dilute KCOOH solution was generated containing approximately 2.6 tons of potassium formate (dry basis). The average KCOOH content of this solution was 7 wt percent. The design KCOOH solution concentration for the front end of the plant is 8.5 wt percent. The evaporation unit was operated for a total of six days during March. Approximately 2.5 tons of potassium formate (dry basis) were processed through the evaporator and concentrated to greater then 7 wt percent.

  8. Achromatically injection-seeded terahertz-wave parametric generator.

    PubMed

    Imai, Kazuhiro; Kawase, Kodo; Minamide, Hiroaki; Ito, Hiromasa

    2002-12-15

    An achromatically injection-seeded terahertz-wave parametric generator was constructed with MgO:LiNbO (3) crystals and a tunable seeder in a stationary dispersion-compensated optical arrangement. Without readjusting the mirrors, we obtained smooth tuning of the terahertz wave over the 0.6-2.6 THz range by adjusting the seeder wavelength alone. We have successfully demonstrated the feasibility of this system for terahertz-wave absorption measurements over a wide frequency range by using low-pressure water vapor. PMID:18033473

  9. Proteome Analysis of Poplar Seed Vigor

    PubMed Central

    Zhang, Hong; Wang, Wei-Qing; Liu, Shu-Jun; Møller, Ian Max; Song, Song-Quan

    2015-01-01

    Seed vigor is a complex property that determines the seed’s potential for rapid uniform emergence and subsequent growth. However, the mechanism for change in seed vigor is poorly understood. The seeds of poplar (Populus × Canadensis Moench), which are short-lived, were stored at 30°C and 75±5% relative humidity for different periods of time (0–90 days) to obtain different vigor seeds (from 95 to 0% germination). With decreasing seed vigor, the temperature range of seed germination became narrower; the respiration rate of the seeds decreased markedly, while the relative electrolyte leakage increased markedly, both levelling off after 45 days. A total of 81 protein spots showed a significant change in abundance (≥ 1.5-fold, P < 0.05) when comparing the proteomes among seeds with different vigor. Of the identified 65 proteins, most belonged to the groups involved in metabolism (23%), protein synthesis and destination (22%), energy (18%), cell defense and rescue (17%), and storage protein (15%). These proteins accounted for 95% of all the identified proteins. During seed aging, 53 and 6 identified proteins consistently increased and decreased in abundance, respectively, and they were associated with metabolism (22%), protein synthesis and destination (22%), energy (19%), cell defense and rescue (19%), storage proteins (15%), and cell growth and structure (3%). These data show that the decrease in seed vigor (aging) is an energy-dependent process, which requires protein synthesis and degradation as well as cellular defense and rescue. PMID:26172265

  10. Electrophysiology of pumpkin seeds: Memristors in vivo.

    PubMed

    Volkov, Alexander G; Nyasani, Eunice K; Tuckett, Clayton; Greeman, Esther A; Markin, Vladislav S

    2016-01-01

    Leon Chua, the discoverer of a memristor, theoretically predicted that voltage gated ion channels can be memristors. We recently found memristors in different plants such as the Venus flytrap, Mimosa pudica, Aloe vera, apple fruits, and in potato tubers. There are no publications in literature about the existence of memristors in seeds. The goal of this work was to discover if pumpkin seeds might have memristors. We selected Cucurbita pepo L., cv. Cinderella, Cucurbita maxima L. cv Warty Goblin, and Cucurbita maxima L., cv. Jarrahdale seeds for this analysis. In these seeds, we found the presence of resistors with memory. The analysis was based on cyclic voltammetry where a memristor should manifest itself as a nonlinear two-terminal electrical element, which exhibits a pinched hysteresis loop on a current-voltage plane for any bipolar cyclic voltage input signal. Dry dormant pumpkin seeds have very high electrical resistance without memristive properties. The electrostimulation by bipolar sinusoidal or triangular periodic waves induces electrical responses in imbibed pumpkin seeds with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K(+) channels, transforms a memristor to a resistor in pumpkin seeds. NPPB (5-Nitro-2-(3-phenylpropylamino)benzoic acid) inhibits the memristive properties of imbibed pumpkin seeds. The discovery of memristors in pumpkin seeds creates a new direction in the understanding of electrophysiological phenomena in seeds.

  11. Electrophysiology of pumpkin seeds: Memristors in vivo

    PubMed Central

    Volkov, Alexander G.; Nyasani, Eunice K.; Tuckett, Clayton; Greeman, Esther A.; Markin, Vladislav S.

    2016-01-01

    ABSTRACT Leon Chua, the discoverer of a memristor, theoretically predicted that voltage gated ion channels can be memristors. We recently found memristors in different plants such as the Venus flytrap, Mimosa pudica, Aloe vera, apple fruits, and in potato tubers. There are no publications in literature about the existence of memristors in seeds. The goal of this work was to discover if pumpkin seeds might have memristors. We selected Cucurbita pepo L., cv. Cinderella, Cucurbita maxima L. cv Warty Goblin, and Cucurbita maxima L., cv. Jarrahdale seeds for this analysis. In these seeds, we found the presence of resistors with memory. The analysis was based on cyclic voltammetry where a memristor should manifest itself as a nonlinear two-terminal electrical element, which exhibits a pinched hysteresis loop on a current-voltage plane for any bipolar cyclic voltage input signal. Dry dormant pumpkin seeds have very high electrical resistance without memristive properties. The electrostimulation by bipolar sinusoidal or triangular periodic waves induces electrical responses in imbibed pumpkin seeds with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K+ channels, transforms a memristor to a resistor in pumpkin seeds. NPPB (5-Nitro-2-(3-phenylpropylamino)benzoic acid) inhibits the memristive properties of imbibed pumpkin seeds. The discovery of memristors in pumpkin seeds creates a new direction in the understanding of electrophysiological phenomena in seeds. PMID:26926652

  12. Local evolution of seed flotation in Arabidopsis.

    PubMed

    Saez-Aguayo, Susana; Rondeau-Mouro, Corinne; Macquet, Audrey; Kronholm, Ilkka; Ralet, Marie-Christine; Berger, Adeline; Sallé, Christine; Poulain, Damien; Granier, Fabienne; Botran, Lucy; Loudet, Olivier; de Meaux, Juliette; Marion-Poll, Annie; North, Helen M

    2014-03-01

    Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 β-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR) relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed. PMID:24625826

  13. Local Evolution of Seed Flotation in Arabidopsis

    PubMed Central

    Saez-Aguayo, Susana; Rondeau-Mouro, Corinne; Macquet, Audrey; Kronholm, Ilkka; Ralet, Marie-Christine; Berger, Adeline; Sallé, Christine; Poulain, Damien; Granier, Fabienne; Botran, Lucy; Loudet, Olivier; de Meaux, Juliette; Marion-Poll, Annie; North, Helen M.

    2014-01-01

    Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 β-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR) relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed. PMID:24625826

  14. Electrophysiology of pumpkin seeds: Memristors in vivo.

    PubMed

    Volkov, Alexander G; Nyasani, Eunice K; Tuckett, Clayton; Greeman, Esther A; Markin, Vladislav S

    2016-01-01

    Leon Chua, the discoverer of a memristor, theoretically predicted that voltage gated ion channels can be memristors. We recently found memristors in different plants such as the Venus flytrap, Mimosa pudica, Aloe vera, apple fruits, and in potato tubers. There are no publications in literature about the existence of memristors in seeds. The goal of this work was to discover if pumpkin seeds might have memristors. We selected Cucurbita pepo L., cv. Cinderella, Cucurbita maxima L. cv Warty Goblin, and Cucurbita maxima L., cv. Jarrahdale seeds for this analysis. In these seeds, we found the presence of resistors with memory. The analysis was based on cyclic voltammetry where a memristor should manifest itself as a nonlinear two-terminal electrical element, which exhibits a pinched hysteresis loop on a current-voltage plane for any bipolar cyclic voltage input signal. Dry dormant pumpkin seeds have very high electrical resistance without memristive properties. The electrostimulation by bipolar sinusoidal or triangular periodic waves induces electrical responses in imbibed pumpkin seeds with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K(+) channels, transforms a memristor to a resistor in pumpkin seeds. NPPB (5-Nitro-2-(3-phenylpropylamino)benzoic acid) inhibits the memristive properties of imbibed pumpkin seeds. The discovery of memristors in pumpkin seeds creates a new direction in the understanding of electrophysiological phenomena in seeds. PMID:26926652

  15. Galactinol as marker for seed longevity.

    PubMed

    de Souza Vidigal, Deborah; Willems, Leo; van Arkel, Jeroen; Dekkers, Bas J W; Hilhorst, Henk W M; Bentsink, Leónie

    2016-05-01

    Reduced seed longevity or storability is a major problem in seed storage and contributes to increased costs in crop production. Here we investigated whether seed galactinol contents could be predictive for seed storability behavior in Arabidopsis, cabbage and tomato. The analyses revealed a positive correlation between galactinol content and seed longevity in the three species tested, which indicates that this correlation is conserved in the Brassicaceae and beyond. Quantitative trait loci (QTL) mapping in tomato revealed a co-locating QTL for galactinol content and seed longevity on chromosome 2. A candidate for this QTL is the GALACTINOL SYNTHASE gene (Solyc02g084980.2.1) that is located in the QTL interval. GALACTINOL SYNTHASE is a key enzyme of the raffinose family oligosaccharide (RFO) pathway. To investigate the role of enzymes in the RFO pathway in more detail, we applied a reverse genetics approach using T-DNA knock-out lines in genes encoding enzymes of this pathway (GALACTINOL SYNTHASE 1, GALACTINOL SYNTHASE 2, RAFFINOSE SYNTHASE, STACHYOSE SYNTHASE and ALPHA-GALACTOSIDASE) and overexpressors of the cucumber GALACTINOL SYNTHASE 2 gene in Arabidopsis. The galactinol synthase 2 mutant and the galactinol synthase 1 galactinol synthase 2 double mutant contained the lowest seed galactinol content which coincided with lower seed longevity. These results show that galactinol content of mature dry seed can be used as a biomarker for seed longevity in Brassicaceae and tomato. PMID:26993241

  16. Effects of rodent species, seed species, and predator cues on seed fate

    USGS Publications Warehouse

    Sivy, Kelly J.; Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan

    2011-01-01

    Seed selection, removal and subsequent management by granivorous animals is thought to be a complex interaction of factors including qualities of the seeds themselves (e.g., seed size, nutritional quality) and features of the local habitat (e.g. perceived predator risk). At the same time, differential seed selection and dispersal is thought to have profound effects on seed fate and potentially vegetation dynamics. In a feeding arena, we tested whether rodent species, seed species, and indirect and direct predation cues influence seed selection and handling behaviors (e.g., scatter hoarding versus larder hoarding) of two heteromyid rodents, Ord's kangaroo rat (Dipodomys ordii) and the Great Basin pocket mouse (Perognathus parvus). The indirect cue was shrub cover, a feature of the environment. Direct cues, presented individually, were (1) control, (2) coyote (Canis latrans) vocalization, (3) coyote scent, (4) red fox (Vulpes vulpes) scent, or (5) short-eared owl (Asio flammeus) vocalization. We offered seeds of three sizes: two native grasses, Indian ricegrass (Achnatherum hymenoides) and bluebunch wheatgrass (Pseudoroegneria spicata), and the non-native cereal rye (Secale cereale), each in separate trays. Kangaroo rats preferentially harvested Indian ricegrass while pocket mice predominately harvested Indian ricegrass and cereal rye. Pocket mice were more likely to scatter hoard preferred seeds, whereas kangaroo rats mostly consumed and/or larder hoarded preferred seeds. No predator cue significantly affected seed preferences. However, both species altered seed handling behavior in response to direct predation cues by leaving more seeds available in the seed pool, though they responded to different predator cues. If these results translate to natural dynamics on the landscape, the two rodents are expected to have different impacts on seed survival and plant recruitment via their different seed selection and seed handling behaviors.

  17. Seed source, seed traits, and frugivore habits: Implications for dispersal quality of two sympatric primates.

    PubMed

    Benítez-Malvido, Julieta; González-Di Pierro, Ana Ma; Lombera, Rafael; Guillén, Susana; Estrada, Alejandro

    2014-06-11

    • Premise of the study: Frugivore selection of fruits and treatment of seeds together with seed deposition site are crucial for the population dynamics of vertebrate-dispersed plants. However, frugivore species may influence dispersal quality differently even when feeding on the same fruit species and, while animals disperse some seeds, others simply fall beneath the parent plant.• Methods: In southern Mexico, we investigated to see if within-species seed traits (i.e., length, width, weight, and volume) and germination success differed according to seed source. For five tropical tree species we obtained ingested seeds from two sources, howler monkey (Alouatta pigra) and spider monkey (Ateles geoffroyi) feces; and noningested seeds from two sources, the ground and tree crowns (with predispersed seeds used as control).• Key results: A principal components' analysis showed that traits of seeds ingested by howler monkeys differed from other sources while seeds ingested by spider monkeys were similar to noningested seeds. Howlers consumed on average the larger seeds in Ampelocera hottlei, Brosimum lactescens, and Dialium guianense. Both primate species consumed the smaller seeds in Spondias mombin, while no seed trait differences among seed sources were found in Spondias radlkoferi. For all five tree species, germination rate was greatest for seeds ingested by howler monkeys.• Conclusions: For the studied plant species, seed ingestion by howler monkeys confers higher dispersal quality than ingestion by spider monkeys or nondispersal. Dispersal services of both primate species, however, are not redundant and may contribute to germination heterogeneity within plant populations in tropical forests. PMID:24920763

  18. Effects of rodent species, seed species, and predator cues on seed fate

    NASA Astrophysics Data System (ADS)

    Sivy, Kelly J.; Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan

    2011-07-01

    Seed selection, removal and subsequent management by granivorous animals is thought to be a complex interaction of factors including qualities of the seeds themselves (e.g., seed size, nutritional quality) and features of the local habitat (e.g. perceived predator risk). At the same time, differential seed selection and dispersal is thought to have profound effects on seed fate and potentially vegetation dynamics. In a feeding arena, we tested whether rodent species, seed species, and indirect and direct predation cues influence seed selection and handling behaviors (e.g., scatter hoarding versus larder hoarding) of two heteromyid rodents, Ord's kangaroo rat ( Dipodomys ordii) and the Great Basin pocket mouse ( Perognathus parvus). The indirect cue was shrub cover, a feature of the environment. Direct cues, presented individually, were (1) control, (2) coyote ( Canis latrans) vocalization, (3) coyote scent, (4) red fox ( Vulpes vulpes) scent, or (5) short-eared owl ( Asio flammeus) vocalization. We offered seeds of three sizes: two native grasses, Indian ricegrass ( Achnatherum hymenoides) and bluebunch wheatgrass ( Pseudoroegneria spicata), and the non-native cereal rye ( Secale cereale), each in separate trays. Kangaroo rats preferentially harvested Indian ricegrass while pocket mice predominately harvested Indian ricegrass and cereal rye. Pocket mice were more likely to scatter hoard preferred seeds, whereas kangaroo rats mostly consumed and/or larder hoarded preferred seeds. No predator cue significantly affected seed preferences. However, both species altered seed handling behavior in response to direct predation cues by leaving more seeds available in the seed pool, though they responded to different predator cues. If these results translate to natural dynamics on the landscape, the two rodents are expected to have different impacts on seed survival and plant recruitment via their different seed selection and seed handling behaviors.

  19. Joshua tree (Yucca brevifolia) seeds are dispersed by seed-caching rodents

    USGS Publications Warehouse

    Vander Wall, S. B.; Esque, T.; Haines, D.; Garnett, M.; Waitman, B.A.

    2006-01-01

    Joshua tree (Yucca brevifolia) is a distinctive and charismatic plant of the Mojave Desert. Although floral biology and seed production of Joshua tree and other yuccas are well understood, the fate of Joshua tree seeds has never been studied. We tested the hypothesis that Joshua tree seeds are dispersed by seed-caching rodents. We radioactively labelled Joshua tree seeds and followed their fates at five source plants in Potosi Wash, Clark County, Nevada, USA. Rodents made a mean of 30.6 caches, usually within 30 m of the base of source plants. Caches contained a mean of 5.2 seeds buried 3-30 nun deep. A variety of rodent species appears to have prepared the caches. Three of the 836 Joshua tree seeds (0.4%) cached germinated the following spring. Seed germination using rodent exclosures was nearly 15%. More than 82% of seeds in open plots were removed by granivores, and neither microsite nor supplemental water significantly affected germination. Joshua tree produces seeds in indehiscent pods or capsules, which rodents dismantle to harvest seeds. Because there is no other known means of seed dispersal, it is possible that the Joshua tree-rodent seed dispersal interaction is an obligate mutualism for the plant.

  20. Microencapsulation of chia seed oil using chia seed protein isolate-chia seed gum complex coacervates.

    PubMed

    Timilsena, Yakindra Prasad; Adhikari, Raju; Barrow, Colin J; Adhikari, Benu

    2016-10-01

    Chia seed oil (CSO) microcapsules were produced by using chia seed protein isolate (CPI)-chia seed gum (CSG) complex coacervates aiming to enhance the oxidative stability of CSO. The effect of wall material composition, core-to-wall ratio and method of drying on the microencapsulation efficiency (MEE) and oxidative stability (OS) was studied The microcapsules produced using CPI-CSG complex coacervates as wall material had higher MEE at equivalent payload, lower surface oil and higher OS compared to the microcapsules produced by using CSG and CPI individually. CSO microcapsules produced by using CSG as wall material had lowest MEE (67.3%) and oxidative stability index (OSI=6.6h), whereas CPI-CSG complex coacervate microcapsules had the highest MEE (93.9%) and OSI (12.3h). The MEE and OSI of microcapsules produced by using CPI as wall materials were in between those produced by using CSG and CPI-CSG complex coacervates as wall materials. The CSO microcapsules produced by using CPI-CSG complex coacervate as shell matrix at core-to-wall ratio of 1:2 had 6 times longer storage life compared to that of unencapsulated CSO. The peroxide value of CSO microcapsule produced using CPI-CSG complex coacervate as wall material was <10meq O2/kg oil during 30 days of storage. PMID:27212219

  1. Microencapsulation of chia seed oil using chia seed protein isolate-chia seed gum complex coacervates.

    PubMed

    Timilsena, Yakindra Prasad; Adhikari, Raju; Barrow, Colin J; Adhikari, Benu

    2016-10-01

    Chia seed oil (CSO) microcapsules were produced by using chia seed protein isolate (CPI)-chia seed gum (CSG) complex coacervates aiming to enhance the oxidative stability of CSO. The effect of wall material composition, core-to-wall ratio and method of drying on the microencapsulation efficiency (MEE) and oxidative stability (OS) was studied The microcapsules produced using CPI-CSG complex coacervates as wall material had higher MEE at equivalent payload, lower surface oil and higher OS compared to the microcapsules produced by using CSG and CPI individually. CSO microcapsules produced by using CSG as wall material had lowest MEE (67.3%) and oxidative stability index (OSI=6.6h), whereas CPI-CSG complex coacervate microcapsules had the highest MEE (93.9%) and OSI (12.3h). The MEE and OSI of microcapsules produced by using CPI as wall materials were in between those produced by using CSG and CPI-CSG complex coacervates as wall materials. The CSO microcapsules produced by using CPI-CSG complex coacervate as shell matrix at core-to-wall ratio of 1:2 had 6 times longer storage life compared to that of unencapsulated CSO. The peroxide value of CSO microcapsule produced using CPI-CSG complex coacervate as wall material was <10meq O2/kg oil during 30 days of storage.

  2. Seed localization in ultrasound and registration to C-arm fluoroscopy using matched needle tracks for prostate brachytherapy.

    PubMed

    Moradi, Mehdi; Mahdavi, S Sara; Dehghan, Ehsan; Lobo, Julio R; Deshmukh, Sanchit; Morris, William James; Fichtinger, Gabor; Salcudean, Septimiu Tim E

    2012-09-01

    We propose a novel fiducial-free approach for the registration of C-arm fluoroscopy to 3-D ultrasound images of prostate brachytherapy implants to enable dosimetry. The approach involves the reliable detection of a subset of radioactive seeds from 3-D ultrasound, and the use of needle tracks in both ultrasound and fluoroscopy for registration. Seed detection in ultrasound is achieved through template matching in 3-D radio frequency ultrasound signals, followed by thresholding and spatial filtering. The resulting subset of seeds is registered to the complete reconstruction of the brachytherapy implant from multiple C-arm fluoroscopy views. To compensate for the deformation caused by the ultrasound probe, simulated warping is applied to the seed cloud from fluoroscopy. The magnitude of the applied warping is optimized within the registration process. The registration is performed in two stages. First, the needle track projections from fluoroscopy and ultrasound are matched. Only the seeds in the matched needles are then used as fiducials for point-based registration. We report results from a physical phantom with a realistic implant (average postregistration seed distance of 1.6 ± 1.2 mm) and from five clinical patient datasets (average error: 2.8 ± 1.5 mm over 128 detected seeds). We conclude that it is feasible to use RF ultrasound data, template matching, and spatial filtering to detect a reliable subset of brachytherapy seeds from ultrasound to enable registration to fluoroscopy for dosimetry.

  3. Myiarchus flycatchers are the primary seed dispersers of Bursera longipes in a Mexican dry forest.

    PubMed

    Almazán-Núñez, R Carlos; Eguiarte, Luis E; Arizmendi, María Del Coro; Corcuera, Pablo

    2016-01-01

    We evaluated the seed dispersal of Bursera longipes by birds along a successional gradient of tropical dry forest (TDF) in southwestern Mexico. B. longipes is an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits to B. longipes and the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature) characterized by distinct floristic and structural elements. Flycatchers of the Myiarchus and Tyrannus genera removed the majority of fruits at each site. Overall, visits to B. longipes were less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers: M. cinerascens and M. nutingii. Perch plants, mainly composed of legumes (e.g., Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha), serve also as nurse plants since the number of young individuals recruited from B. longipes was higher under these than expected by chance. This study shows that Myiarchus flycatchers are the most efficient seed dispersers of B. longipes across all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution.

  4. Myiarchus flycatchers are the primary seed dispersers of Bursera longipes in a Mexican dry forest

    PubMed Central

    Almazán-Núñez, R. Carlos; Eguiarte, Luis E.; Arizmendi, María del Coro

    2016-01-01

    We evaluated the seed dispersal of Bursera longipes by birds along a successional gradient of tropical dry forest (TDF) in southwestern Mexico. B. longipes is an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits to B. longipes and the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature) characterized by distinct floristic and structural elements. Flycatchers of the Myiarchus and Tyrannus genera removed the majority of fruits at each site. Overall, visits to B. longipes were less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers: M. cinerascens and M. nutingii. Perch plants, mainly composed of legumes (e.g., Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha), serve also as nurse plants since the number of young individuals recruited from B. longipes was higher under these than expected by chance. This study shows that Myiarchus flycatchers are the most efficient seed dispersers of B. longipes across all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution. PMID:27326382

  5. Myiarchus flycatchers are the primary seed dispersers of Bursera longipes in a Mexican dry forest.

    PubMed

    Almazán-Núñez, R Carlos; Eguiarte, Luis E; Arizmendi, María Del Coro; Corcuera, Pablo

    2016-01-01

    We evaluated the seed dispersal of Bursera longipes by birds along a successional gradient of tropical dry forest (TDF) in southwestern Mexico. B. longipes is an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits to B. longipes and the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature) characterized by distinct floristic and structural elements. Flycatchers of the Myiarchus and Tyrannus genera removed the majority of fruits at each site. Overall, visits to B. longipes were less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers: M. cinerascens and M. nutingii. Perch plants, mainly composed of legumes (e.g., Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha), serve also as nurse plants since the number of young individuals recruited from B. longipes was higher under these than expected by chance. This study shows that Myiarchus flycatchers are the most efficient seed dispersers of B. longipes across all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution. PMID:27326382

  6. Oxidative signaling in seed germination and dormancy

    PubMed Central

    El-Maarouf-Bouteau, Hayat

    2008-01-01

    Reactive Oxygen Species (ROS) play a key role in various events of seed life. In orthodox seeds, ROS are produced from embryogenesis to germination, i.e., in metabolically active cells, but also in quiescent dry tissues during after ripening and storage, owing various mechanisms depending on the seed moisture content. Although ROS have been up to now widely considered as detrimental to seeds, recent advances in plant physiology signaling pathways has lead to reconsider their role. ROS accumulation can therefore be also beneficial for seed germination and seedling growth by regulating cellular growth, ensuring a protection against pathogens or controlling the cell redox status. ROS probably also act as a positive signal in seed dormancy release. They interact with abscisic acid and gibberellins transduction pathway and are likely to control numerous transcription factors and properties of specific protein through their carbonylation. PMID:19513212

  7. Tamarind seed: properties, processing and utilization.

    PubMed

    Kumar, Chandini S; Bhattacharya, Sila

    2008-01-01

    Tamarind seed is an underutilized byproduct of the tamarind pulp industry. Only a small portion of the seed, in the form of tamarind kernel powder (TKP), is used as a sizing material in the textile, paper, and jute industries. Though many applications of this seed are possible, there have been hardly any other uses for it including using it as an additive in food formulations. The excellent gelling cum adhesive characteristics of the decorticated seed powder can lead to several applications in food and pharmaceutical industries which are evident by the number of research papers as well as patent applications. This article thus focuses on the possibilities of using the seed in several food and non-food industries with particular reference to physical and engineering properties, hydration behavior, rheological properties, functional and nutritional characteristics, and the processing of the tamarind seed for wider applications.

  8. Arborescent palm seed morphology and seedling distribution.

    PubMed

    Salm, Rodolfo

    2005-11-01

    This study examines how the seed morphology of two large arborescent palms, Attalea maripa (Aubl.) Mart. and Astrocaryum aculeatum G. Mey, may affect their seed shadow in a seasonally dry Amazonian forest. In addition to being smaller and produced in larger numbers than those of A. aculeatum, A. maripa seeds also presented a substantially lower amount of nutritional reserves available for the embryo. However, A. maripa seedlings were found in much higher numbers than those of A. aculeatum. The results suggest that, within the spatial scale considered, the seed rain of A. maripa is more restricted to the area surrounding around reproductive conspecifics than that of A. aculeatum. Furthermore, in comparison with those of A. aculeatum, the smaller seeds of A. maripa might be less attractive to scatterhoarding rodents (e.g. Dasyprocta aguti). The pattern observed emphasizes the importance of scatterhoarding rodents as dispersers of large-seeded plant species in Neotropical forests. PMID:16532195

  9. [Seed geography: its concept and basic scientific issues].

    PubMed

    Yu, Shun-Li; Wang, Zong-Shuai; Zeren, Wangmu

    2010-01-01

    In this paper, a new concept 'seed geography' was provided, and its definition, research contents, and scientific issues were put forward. Seed geography is a newly developed interdisciplinary science from plant geography, seed ecology, and phytosociology, which studies the geographic variation patterns of seed biological traits as well as their relationships with environmental factors from macroscopic to microscopic, and the seed formation, development, and change trends. The main research contents would include geography of seed mass, geography of seed chemical components, geography of seed morphology, geography of seed cell biological characteristics, geography of seed physiological characteristics, geography of seed genetic characteristics, and geography of flower and fruit. To explore the scientific issues in seed geography would help us to better understand the long-term adaptation and evolution of seed characteristics to natural environments.

  10. A study of autorotating plant seeds.

    PubMed

    Sunada, S; Ide, A; Hoshino, Y; Okamoto, M

    2015-12-01

    A leading edge vortex exists on the upper surface of an autorotating plant seed. The vortex enhances the vertical aerodynamic force acting on the seed and decreases the rate of descent. We analyzed the flight data of rotary seeds and revealed that the lift-drag ratio affects the descent factor more strongly than the vertical force coefficient. This has also been confirmed by falling tests of model rotors, which have various aspect ratios, airfoil shapes and total masses. PMID:26382230

  11. A study of autorotating plant seeds.

    PubMed

    Sunada, S; Ide, A; Hoshino, Y; Okamoto, M

    2015-12-01

    A leading edge vortex exists on the upper surface of an autorotating plant seed. The vortex enhances the vertical aerodynamic force acting on the seed and decreases the rate of descent. We analyzed the flight data of rotary seeds and revealed that the lift-drag ratio affects the descent factor more strongly than the vertical force coefficient. This has also been confirmed by falling tests of model rotors, which have various aspect ratios, airfoil shapes and total masses.

  12. Incorporating seed orientation in brachytherapy implant reconstruction

    NASA Astrophysics Data System (ADS)

    Zhou, Yu; Jain, Ameet K.; Chirikjian, Gregory S.; Fichtinger, Gabor

    2006-03-01

    Intra-operative quality assurance and dosimetry optimization in prostate brachytherapy critically depends on the ability of discerning the locations of implanted seeds. Various methods exist for seed matching and reconstruction from multiple segmented C-arm images. Unfortunately, using three or more images makes the problem NP-hard, i.e. no polynomial-time algorithm can provably compute the complete matching. Typically, a statistical analysis of performance is considered sufficient. Hence it is of utmost importance to exploit all the available information in order to minimize the matching and reconstruction errors. Current algorithms use only the information about seed centers, disregarding the information about the orientations and length of seeds. While the latter has little dosimetric impact, it can positively contribute to improving seed matching rate and 3D implant reconstruction accuracy. It can also become critical information when hidden and spuriously segmented seeds need to be matched, where reliable and generic methods are not yet available. Expecting orientation information to be useful in reconstructing large and dense implants, we have developed a method which incorporates seed orientation information into our previously proposed reconstruction algorithm (MARSHAL). Simulation study shows that under normal segmentation errors, when considering seed orientations, implants of 80 to 140 seeds with the density of 2.0- 3.0 seeds/cc give an average matching rate >97% using three-image matching. It is higher than the matching rate of about 96% when considering only seed positions. This means that the information of seed orientations appears to be a valuable additive to fluoroscopy-based brachytherapy implant reconstruction.

  13. Chemical solution seed layer for rabits tapes

    SciTech Connect

    Goyal, Amit; Paranthaman, Mariappan; Wee, Sung-Hun

    2014-06-10

    A method for making a superconducting article includes the steps of providing a biaxially textured substrate. A seed layer is then deposited. The seed layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different rare earth or transition metal cations. A superconductor layer is grown epitaxially such that the superconductor layer is supported by the seed layer.

  14. AUTOMATIC FREQUENCY CONTROL SYSTEM

    DOEpatents

    Hansen, C.F.; Salisbury, J.D.

    1961-01-10

    A control is described for automatically matching the frequency of a resonant cavity to that of a driving oscillator. The driving oscillator is disconnected from the cavity and a secondary oscillator is actuated in which the cavity is the frequency determining element. A low frequency is mixed with the output of the driving oscillator and the resultant lower and upper sidebands are separately derived. The frequencies of the sidebands are compared with the secondary oscillator frequency. deriving a servo control signal to adjust a tuning element in the cavity and matching the cavity frequency to that of the driving oscillator. The driving oscillator may then be connected to the cavity.

  15. Conflicting selection from fire and seed predation drives fine-scaled phenotypic variation in a widespread North American conifer.

    PubMed

    Talluto, Matthew V; Benkman, Craig W

    2014-07-01

    Recent work has demonstrated that evolutionary processes shape ecological dynamics on relatively short timescales (eco-evolutionary dynamics), but demonstrating these effects at large spatial scales in natural landscapes has proven difficult. We used empirical studies and modeling to investigate how selective pressures from fire and predispersal seed predation affect the evolution of serotiny, an ecologically important trait. Serotiny is a highly heritable key reproductive trait in Rocky Mountain lodgepole pine (Pinus contorta subsp. latifolia), a conifer that dominates millions of hectares in western North America. In these forests, the frequency of serotiny determines postfire seedling density with corresponding community- and ecosystem-level effects. We found that serotinous individuals have a selective advantage at high fire frequencies and low predation pressure; however, very high seed predation shifted the selective advantage to nonserotinous individuals even at high fire frequencies. Simulation modeling suggests that spatial variation in the frequency of serotiny results from heterogeneity in these two selective agents. These results, combined with previous findings showing a negative association between the density of seed predators and the frequency of serotiny at both landscape and continental scales, demonstrate that contemporary patterns in serotiny reflect an evolutionary response to conflicting selection pressures from fire and seed predation. Thus, we show that variation in the frequency of a heritable polygenic trait depends on spatial variation in two dominant selective agents, and, importantly, the effects of the local trait variation propagate with profound consequences to the structure and function of communities and ecosystems across a large landscape. PMID:24979772

  16. Conflicting selection from fire and seed predation drives fine-scaled phenotypic variation in a widespread North American conifer

    PubMed Central

    Talluto, Matthew V.; Benkman, Craig W.

    2014-01-01

    Recent work has demonstrated that evolutionary processes shape ecological dynamics on relatively short timescales (eco-evolutionary dynamics), but demonstrating these effects at large spatial scales in natural landscapes has proven difficult. We used empirical studies and modeling to investigate how selective pressures from fire and predispersal seed predation affect the evolution of serotiny, an ecologically important trait. Serotiny is a highly heritable key reproductive trait in Rocky Mountain lodgepole pine (Pinus contorta subsp. latifolia), a conifer that dominates millions of hectares in western North America. In these forests, the frequency of serotiny determines postfire seedling density with corresponding community- and ecosystem-level effects. We found that serotinous individuals have a selective advantage at high fire frequencies and low predation pressure; however, very high seed predation shifted the selective advantage to nonserotinous individuals even at high fire frequencies. Simulation modeling suggests that spatial variation in the frequency of serotiny results from heterogeneity in these two selective agents. These results, combined with previous findings showing a negative association between the density of seed predators and the frequency of serotiny at both landscape and continental scales, demonstrate that contemporary patterns in serotiny reflect an evolutionary response to conflicting selection pressures from fire and seed predation. Thus, we show that variation in the frequency of a heritable polygenic trait depends on spatial variation in two dominant selective agents, and, importantly, the effects of the local trait variation propagate with profound consequences to the structure and function of communities and ecosystems across a large landscape. PMID:24979772

  17. Yellowstone grizzly bear mortality, human habituation, and whitebark pine seed crops

    USGS Publications Warehouse

    Mattson, David J.; Blanchard, Bonnie M.; Knight, Richard R.

    1992-01-01

    The Yellowstone grizzly bear (Ursus arctos horribilis) population may be extirpated during the next 100-200 years unless mortality rates stabilize and remain at acceptable low levels. Consequently, we analyzed relationships between Yellowstone grizzly bear mortality and frequency of human habituation among bears and size of the whitebark pine (Pinus albicaulis) seed crop. During years of large seed crops, bears used areas within 5 km of roads and 8 km of developments half as intensively as during years of small seed crops because whitebark pine's high elevation distribution is typically remote from human facilities. On average, management trappings of bears were 6.2 times higher, mortality of adult females 2.3 times higher, and mortality of subadult males 3.3 times higher during years of small seed crops. We hypothesize that high mortality of adult females and subadult males during small seed crop years was a consequence of their tendency to range closest (of all sex-age cohorts) to human facilities; they also had a higher frequency of human habituation compared with adult males. We also hypothesize that low morality among subadult females during small seed crop years was a result of fewer energetic stressors compared with adult females and greater familiarity with their range compared with subadult males; mortality was low even though they ranged close to humans and exhibited a high frequency of human habituation. Human-habituated and food-conditioned bears were 2.9 times as likely to range within 4 km of developments and 3.1 times as often killed by humans compared with nonhabituated bears. We argue that destruction of habituated bears that use native foods near humans results in a decline in the overall ability of bears to use available habitat; and that the number and extent of human facilities in occupied grizzly bear habitat needs to be minimized unless habituated bears are preserved and successful ways to manage the associated risks to humans are developed.

  18. 7 CFR 201.57a - Dormant seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57a Dormant seeds. Dormant seeds are viable seeds, other than hard seeds, which fail to germinate when provided the specified germination..., or application of germination promoting chemicals. (b) The percentage of dormant seed, if...

  19. 7 CFR 201.57a - Dormant seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57a Dormant seeds. Dormant seeds are viable seeds, other than hard seeds, which fail to germinate when provided the specified germination..., or application of germination promoting chemicals. (b) The percentage of dormant seed, if...

  20. 7 CFR 201.57a - Dormant seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57a Dormant seeds. Dormant seeds are viable seeds, other than hard seeds, which fail to germinate when provided the specified germination..., or application of germination promoting chemicals. (b) The percentage of dormant seed, if...

  1. 7 CFR 201.57a - Dormant seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57a Dormant seeds. Dormant seeds are viable seeds, other than hard seeds, which fail to germinate when provided the specified germination..., or application of germination promoting chemicals. (b) The percentage of dormant seed, if...

  2. 7 CFR 201.57a - Dormant seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57a Dormant seeds. Dormant seeds are viable seeds, other than hard seeds, which fail to germinate when provided the specified germination..., or application of germination promoting chemicals. (b) The percentage of dormant seed, if...

  3. 7 CFR 361.6 - Noxious weed seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 5 2011-01-01 2011-01-01 false Noxious weed seeds. 361.6 Section 361.6 Agriculture..., DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.6 Noxious weed... considered noxious weed seeds. (1) Seeds with no tolerances applicable to their introduction: Acacia...

  4. 7 CFR 201.16 - Noxious-weed seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Noxious-weed seeds. 201.16 Section 201.16 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.16 Noxious-weed seeds. (a) Except for those kinds of noxious-weed seeds shown in paragraph (b) of this section, the names of the kinds of noxious-weed seeds and...

  5. 7 CFR 201.16 - Noxious-weed seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Noxious-weed seeds. 201.16 Section 201.16 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.16 Noxious-weed seeds. (a) Except for those kinds of noxious-weed seeds shown in paragraph (b) of this section, the names of the kinds of noxious-weed seeds and...

  6. 7 CFR 361.6 - Noxious weed seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Noxious weed seeds. 361.6 Section 361.6 Agriculture..., DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.6 Noxious weed... considered noxious weed seeds. (1) Seeds with no tolerances applicable to their introduction: Aeginetia...

  7. 7 CFR 201.16 - Noxious-weed seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Noxious-weed seeds. 201.16 Section 201.16 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.16 Noxious-weed seeds. (a) Except for those kinds of noxious-weed seeds shown in paragraph (b) of this section, the names of the kinds of noxious-weed seeds and...

  8. 7 CFR 361.6 - Noxious weed seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 5 2014-01-01 2014-01-01 false Noxious weed seeds. 361.6 Section 361.6 Agriculture..., DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.6 Noxious weed... considered noxious weed seeds. (1) Seeds with no tolerances applicable to their introduction: Acacia...

  9. 7 CFR 201.16 - Noxious-weed seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Noxious-weed seeds. 201.16 Section 201.16 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.16 Noxious-weed seeds. (a) Except for those kinds of noxious-weed seeds shown in paragraph (b) of this section, the names of the kinds of noxious-weed seeds and...

  10. 7 CFR 201.16 - Noxious-weed seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Noxious-weed seeds. 201.16 Section 201.16 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.16 Noxious-weed seeds. (a) Except for those kinds of noxious-weed seeds shown in paragraph (b) of this section, the names of the kinds of noxious-weed seeds and...

  11. 7 CFR 361.6 - Noxious weed seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 5 2013-01-01 2013-01-01 false Noxious weed seeds. 361.6 Section 361.6 Agriculture..., DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.6 Noxious weed... considered noxious weed seeds. (1) Seeds with no tolerances applicable to their introduction: Acacia...

  12. 7 CFR 361.6 - Noxious weed seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 5 2012-01-01 2012-01-01 false Noxious weed seeds. 361.6 Section 361.6 Agriculture..., DEPARTMENT OF AGRICULTURE IMPORTATION OF SEED AND SCREENINGS UNDER THE FEDERAL SEED ACT § 361.6 Noxious weed... considered noxious weed seeds. (1) Seeds with no tolerances applicable to their introduction: Acacia...

  13. Applicator Training Manual for: Seed Treatment Pest Control.

    ERIC Educational Resources Information Center

    TeKrony, Dennis M.

    This manual gives general information on seed treatment and type of seeds which can be treated. Also discussed are the problems and pests commonly associated with seed diseases and the fungicides and insecticides used for seed treatment. Information is also given on seed treatment equipment such as dust treaters, slurry treaters, and direct…

  14. 7 CFR 201.64 - Pure live seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Pure live seed. 201.64 Section 201.64 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.64 Pure live seed. The tolerance for pure live seed shall be determined...

  15. 7 CFR 201.64 - Pure live seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Pure live seed. 201.64 Section 201.64 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.64 Pure live seed. The tolerance for pure live seed shall be determined...

  16. 7 CFR 201.7a - Treated seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Treated seed. 201.7a Section 201.7a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Records for Agricultural and Vegetable Seeds § 201.7a Treated seed. The complete record for...

  17. 7 CFR 201.64 - Pure live seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Pure live seed. 201.64 Section 201.64 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.64 Pure live seed. The tolerance for pure live seed shall be determined...

  18. 7 CFR 201.47a - Seed unit.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Seed unit. 201.47a Section 201.47a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.47a Seed unit. The seed unit is...

  19. 7 CFR 201.7a - Treated seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Treated seed. 201.7a Section 201.7a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Records for Agricultural and Vegetable Seeds § 201.7a Treated seed. The complete record for...

  20. 7 CFR 201.47a - Seed unit.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Seed unit. 201.47a Section 201.47a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.47a Seed unit. The seed unit is...

  1. 7 CFR 201.64 - Pure live seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Pure live seed. 201.64 Section 201.64 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.64 Pure live seed. The tolerance for pure live seed shall be determined...

  2. 7 CFR 201.49 - Other crop seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Other crop seed. 201.49 Section 201.49 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.49 Other crop seed. (a) Seeds of...

  3. 7 CFR 201.47a - Seed unit.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Seed unit. 201.47a Section 201.47a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.47a Seed unit. The seed unit is...

  4. 7 CFR 201.64 - Pure live seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Pure live seed. 201.64 Section 201.64 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.64 Pure live seed. The tolerance for pure live seed shall be determined...

  5. 7 CFR 201.47a - Seed unit.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Seed unit. 201.47a Section 201.47a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.47a Seed unit. The seed unit is...

  6. 7 CFR 201.49 - Other crop seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Other crop seed. 201.49 Section 201.49 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.49 Other crop seed. (a) Seeds of...

  7. 7 CFR 201.7a - Treated seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Treated seed. 201.7a Section 201.7a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Records for Agricultural and Vegetable Seeds § 201.7a Treated seed. The complete record for...

  8. 7 CFR 201.7a - Treated seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Treated seed. 201.7a Section 201.7a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Records for Agricultural and Vegetable Seeds § 201.7a Treated seed. The complete record for...

  9. 7 CFR 201.49 - Other crop seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Other crop seed. 201.49 Section 201.49 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.49 Other crop seed. (a) Seeds of...

  10. 7 CFR 201.7a - Treated seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Treated seed. 201.7a Section 201.7a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Records for Agricultural and Vegetable Seeds § 201.7a Treated seed. The complete record for...

  11. 7 CFR 201.47a - Seed unit.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Seed unit. 201.47a Section 201.47a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Purity Analysis in the Administration of the Act § 201.47a Seed unit. The seed unit is...

  12. Phase sensitive Raman process with correlated seeds

    SciTech Connect

    Chen, Bing; Qiu, Cheng; Chen, L. Q. Zhang, Kai; Guo, Jinxian; Yuan, Chun-Hua; Zhang, Weiping; Ou, Z. Y.

    2015-03-16

    A phase sensitive Raman scattering was experimentally demonstrated by injecting a Stokes light seed into an atomic ensemble, whose internal state is set in such a way that it is coherent with the input Stokes seed. Such phase sensitive characteristic is a result of interference effect due to the phase correlation between the injected Stokes light field and the internal state of the atomic ensemble in the Raman process. Furthermore, the constructive interference leads to a Raman efficiency larger than other kinds of Raman processes such as stimulated Raman process with Stokes seed injection alone or uncorrelated light-atom seeding. It may find applications in precision spectroscopy, quantum optics, and precise measurement.

  13. Parasitoid wasps indirectly suppress seed production by stimulating consumption rates of their seed-feeding hosts.

    PubMed

    Xi, Xinqiang; Eisenhauer, Nico; Sun, Shucun

    2015-07-01

    In parasitoid-herbivore-plant food chains, parasitoids may be simultaneously linked with both herbivore hosts and plants, as occurs when herbivores attacked by parasitoids continue to consume plants although they are destined to die. This peculiar property may cause parasitoids to confer a differential trophic cascading effect on plants than that known for typical predators. We hypothesized that larval koinobiont parasitoids would confer an immediate negative effect on plant seed production by stimulating consumption of their seed-predator hosts. We tested this hypothesis in an alpine parasitic food chain of plant seeds, pre-dispersal seed predators (tephritid fly larvae) and koinobiont parasitoids using field observations, a field experiment and a microcosm study. We first compared observed seed production in (i) non-infected capitula, (ii) capitula infected only by seed predators (tephritid flies) and (iii) capitula infected by both seed predators and their parasitoids in five Asteraceae species. Consistent with our hypothesis, seed loss in the capitula with both seed predators and parasitoids was significantly greater than in the capitula infested only by seed predators. This effect was replicated in a controlled field experiment focusing on the most common parasitoid-seed predator-plant interaction chain in our system, in which confounding factors (e.g. density and phenology) were excluded. Here, we show that parasitoids indirectly decreased plant seed production by changing the behaviour of seed predators. In a microcosm study, we show that larval parasitoids significantly extended the growth period and increased the terminal size of their host tephritid maggots. Thus, parasitoids suppressed plant seed production by stimulating the growth and consumption of the fly maggots. In contrast to the typical predator-induced trophic cascade, we highlight the significance of parasitoids indirectly decreasing plant fitness by stimulating consumption by seed predators

  14. Parasitoid wasps indirectly suppress seed production by stimulating consumption rates of their seed-feeding hosts.

    PubMed

    Xi, Xinqiang; Eisenhauer, Nico; Sun, Shucun

    2015-07-01

    In parasitoid-herbivore-plant food chains, parasitoids may be simultaneously linked with both herbivore hosts and plants, as occurs when herbivores attacked by parasitoids continue to consume plants although they are destined to die. This peculiar property may cause parasitoids to confer a differential trophic cascading effect on plants than that known for typical predators. We hypothesized that larval koinobiont parasitoids would confer an immediate negative effect on plant seed production by stimulating consumption of their seed-predator hosts. We tested this hypothesis in an alpine parasitic food chain of plant seeds, pre-dispersal seed predators (tephritid fly larvae) and koinobiont parasitoids using field observations, a field experiment and a microcosm study. We first compared observed seed production in (i) non-infected capitula, (ii) capitula infected only by seed predators (tephritid flies) and (iii) capitula infected by both seed predators and their parasitoids in five Asteraceae species. Consistent with our hypothesis, seed loss in the capitula with both seed predators and parasitoids was significantly greater than in the capitula infested only by seed predators. This effect was replicated in a controlled field experiment focusing on the most common parasitoid-seed predator-plant interaction chain in our system, in which confounding factors (e.g. density and phenology) were excluded. Here, we show that parasitoids indirectly decreased plant seed production by changing the behaviour of seed predators. In a microcosm study, we show that larval parasitoids significantly extended the growth period and increased the terminal size of their host tephritid maggots. Thus, parasitoids suppressed plant seed production by stimulating the growth and consumption of the fly maggots. In contrast to the typical predator-induced trophic cascade, we highlight the significance of parasitoids indirectly decreasing plant fitness by stimulating consumption by seed predators

  15. Effects of elevated CO2 and temperature on seed quality.

    PubMed

    Hampton, J G; Boelt, B; Rolston, M P; Chastain, T G

    2013-04-01

    Successful crop production depends initially on the availability of high-quality seed. By 2050 global climate change will have influenced crop yields, but will these changes affect seed quality? The present review examines the effects of elevated carbon dioxide (CO2) and temperature during seed production on three seed quality components: seed mass, germination and seed vigour. In response to elevated CO2, seed mass has been reported to both increase and decrease in C3 plants, but not change in C4 plants. Increases are greater in legumes than non-legumes, and there is considerable variation among species. Seed mass increases may result in a decrease of seed nitrogen (N) concentration in non-legumes. Increasing temperature may decrease seed mass because of an accelerated growth rate and reduced seed filling duration, but lower seed mass does not necessarily reduce seed germination or vigour. Like seed mass, reported seed germination responses to elevated CO2 have been variable. The reported changes in seed C/N ratio can decrease seed protein content which may eventually lead to reduced viability. Conversely, increased ethylene production may stimulate germination in some species. High-temperature stress before developing seeds reach physiological maturity (PM) can reduce germination by inhibiting the ability of the plant to supply the assimilates necessary to synthesize the storage compounds required for germination. Nothing is known concerning the effects of elevated CO2 on seed vigour. However, seed vigour can be reduced by high-temperature stress both before and after PM. High temperatures induce or increase the physiological deterioration of seeds. Limited evidence suggests that only short periods of high-temperature stress at critical seed development stages are required to reduce seed vigour, but further research is required. The predicted environmental changes will lead to losses of seed quality, particularly for seed vigour and possibly germination. The seed

  16. Effects of elevated CO2 and temperature on seed quality.

    PubMed

    Hampton, J G; Boelt, B; Rolston, M P; Chastain, T G

    2013-04-01

    Successful crop production depends initially on the availability of high-quality seed. By 2050 global climate change will have influenced crop yields, but will these changes affect seed quality? The present review examines the effects of elevated carbon dioxide (CO2) and temperature during seed production on three seed quality components: seed mass, germination and seed vigour. In response to elevated CO2, seed mass has been reported to both increase and decrease in C3 plants, but not change in C4 plants. Increases are greater in legumes than non-legumes, and there is considerable variation among species. Seed mass increases may result in a decrease of seed nitrogen (N) concentration in non-legumes. Increasing temperature may decrease seed mass because of an accelerated growth rate and reduced seed filling duration, but lower seed mass does not necessarily reduce seed germination or vigour. Like seed mass, reported seed germination responses to elevated CO2 have been variable. The reported changes in seed C/N ratio can decrease seed protein content which may eventually lead to reduced viability. Conversely, increased ethylene production may stimulate germination in some species. High-temperature stress before developing seeds reach physiological maturity (PM) can reduce germination by inhibiting the ability of the plant to supply the assimilates necessary to synthesize the storage compounds required for germination. Nothing is known concerning the effects of elevated CO2 on seed vigour. However, seed vigour can be reduced by high-temperature stress both before and after PM. High temperatures induce or increase the physiological deterioration of seeds. Limited evidence suggests that only short periods of high-temperature stress at critical seed development stages are required to reduce seed vigour, but further research is required. The predicted environmental changes will lead to losses of seed quality, particularly for seed vigour and possibly germination. The seed

  17. Effects of seed origin and irrigation on survival and growth of transplanted shrubs

    SciTech Connect

    Winkel, V.K.

    1995-10-01

    Revegetation is difficult in the Mojave Desert due to limited, erratic precipitation and extreme temperatures. Establishing plant cover by transplanting native shrubs is known to be a promising technique, but many questions still remain regarding its use on a large operational scale. A study was initiated on the US Department of Energy Nevada Test Site (NTS) to determine the effects of seed origin and irrigation on survival and growth of transplanted shrubs. Plants of three species (Larrea tridentata, Ambrosia dumosa, and Atriplex canescens) were grown in a greenhouse and hardened outdoors. Plants of all three species were produced from two seed sources: (1) seed collected from the NTS (Mojave Desert), and (2) commercially available seed collected from outside the NTS. One-year-old containerized plants (180 of each species) were transplanted to a site on the NTS and irrigated with two liters of water at one of the following frequencies: (1) at time of planting only, (2) at time of planting and monthly during the first growing season, and (3) at time of planting and twice monthly during the first growing season. After 16 months, survival of all species was generally greater than 80% and was unaffected by irrigation treatments. Survival of fourwing saltbush was significantly greater from local versus non-local seed. Survival of bursage and creosotebush was generally unaffected by seed origin. Shrub volumes regardless of species or seed origin increased during the first growing season, and then decreased during the second growing season. Shrub volumes for fourwing saltbush were significantly greater for shrubs from local versus non-local seed.

  18. Accumulation and degradation of thiamin-binding protein and level of thiamin in wheat seeds during seed maturation and germination.

    PubMed

    Watanabe, Katsumi; Nishida, Naoko; Adachi, Takashi; Ueda, Motoko; Mitsunaga, Toshio; Kawamura, Yukio

    2004-06-01

    Changes in the levels of thiamin-binding globulin and thiamin in wheat seeds during maturation and germination were studied. The thiamin-binding activity of the seed proteins increased with seed development after flowering. The thiamin content of the seeds also increased with development. Thiamin-binding activity decreased during seed germination. On the other hand, immunological analysis using an antibody directed against the thiamin-binding protein isolated from wheat seeds showed that the thiamin-binding globulin accumulated in the aleurone layer of the seeds during maturation, and then the protein was degraded and disappeared during seed germination. These results suggested that the thiamin-binding globulin of wheat seeds was synthesized and accumulated in the aleurone layer of the seeds with seed development, similar to the thiamin-binding albumin in sesame seeds, and that thiamin bound to the thiamin-binding globulin in the dormant wheat seeds for germ growth during germination.

  19. Effects of mechanical vibration on seed germination of Arabidopsis thaliana (L.) Heynh.

    PubMed

    Uchida, Ayuho; Yamamoto, Kotaro T

    2002-06-01

    The effects of sinusoidal vibration (40-120 Hz, amplitude equal to or smaller than 0.42 mm) on seed germination of Arabidopsis thaliana were examined. When the amplitude of vibration was fixed at 0.42 mm, vibration with frequencies higher than 70 Hz increased the rate of seed germination. When the frequency of vibration was fixed at 100 Hz, vibration with amplitudes larger than 0.33 mm also increased the rate of germination. The increase in the rate of germination appeared dependent on acceleration calculated from the frequency and amplitude of vibration. Vibration with a maximum acceleration of 70 m s(-2) increased the rate of germination, but the promotive effects leveled off at higher accelerations. Vibration had little effect on seed germination in a starch-deficient mutant, pgm. Thus, the amyloplasts appeared to act as a susceptor that senses mechanical vibrations. No vibration-induced promotion of germination was seen in an ethylene-insensitive mutant, etr1, or in the wild type in the presence of aminoethoxyvinylglycine, an inhibitor of ethylene synthesis, suggesting that vibration increased the rate of seed germination through the action of ethylene.

  20. The seeded growth of graphene.

    PubMed

    Lee, Jae-Kap; Lee, Sohyung; Kim, Yong-Il; Kim, Jin-Gyu; Min, Bong-Ki; Lee, Kyung-Il; Park, Yeseul; John, Phillip

    2014-01-01

    In this paper, we demonstrate the seeded growth of graphene under a plasma chemical vapor deposition condition. First, we fabricate graphene nanopowders (~5 nm) by ball-milling commercial multi-wall carbon nanotubes. The graphene nanoparticles were subsequently subject to a direct current plasma generated in a 100 Torr 10%CH4 - 90%H2 gas mixture. The plasma growth enlarged, over one hour, the nuclei to graphene sheets larger than one hundred nm(2) in area. Characterization by electron and X-ray diffraction, high-resolution transmission electron microscopy images provide evidence for the presence of monolayer graphene sheets. PMID:25022816

  1. Comparisons of seed longevity under simulated aging and genebank storage conditions using brassicaceae seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeds survive for years under dry conditions but then viability crashes without warning. Efforts to provide high quality seeds to customers, breed longer-living seeds, or to investigate the underlying causes of deterioration during storage prompt the need for a reliable measure of the longevity phe...

  2. Breaking seed coat dormancy with physical and chemical methods in tamarind (Tamarindus indica L.) seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tamarind (Tamarindus indica L.) is an important tree crop in Africa and Asia. It is primarily propagated by grafting, which involves the generation of rootstock material. Tamarind seeds have an impermeable seed coat and need scarification for improved germination. In this study, tamarind seeds colle...

  3. Increasing seed size and quality by manipulating BIG SEEDS 1 in legume species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant organs such as seeds are primary sources of food for both humans and animals. Seed size is one of the major agronomic traits that have been selected in crop plants during their domestication. Legume seeds are a major source of dietary proteins and oils. Here, we report a novel and conserved ro...

  4. Dimensional specific physical properties of fan palm fruits, seeds and seed coats (Washingtonia robusta)

    NASA Astrophysics Data System (ADS)

    Coşkuner, Yalçın; Gökbudak, Ayşe

    2016-07-01

    In this study some physical properties of fan palm (Washingtonia robusta) fruits, seeds and seed coats were determined using dimensional, bulk and single kernel physical analysis. The moisture content of whole fruits, seeds and seed coats was 12.0, 9.86 and 13.87% (d.b.), respectively. The sphericity values showed that seed shape (0.86) is close to a sphere, similar as the fruit shape (0.83), both of which were close to a scalene ellipsoid shape. The surface area values of fruits and seeds were obtained as 163.27 and 80.25 mm2, and volume values were obtained as 190.96 and 66.32 mm3, respectively. Bulk densities of fruits, seeds and seed coats were 559, 783 and 272 kg m-3, and the corresponding true densities were 1143, 1147 and 864 kg m-3, whereas the corresponding porosities were 48.87, 54.12, and 31.52%, respectively. The values of the static coefficient of friction and the angle of repose of fruits, seeds and seed coats of palm fruits were studied on aluminium, canvas, galvanised iron, plywood, PP knitted bag, PVC and stainless steel surfaces. As expected, seed coat has higher values of coefficient of static friction on the all surfaces than fruit and seed.

  5. Supplementing seed banks to rehabilitate disturbed Mojave Desert shrublands: where do all the seeds go?

    USGS Publications Warehouse

    DeFalco, Lesley A.; Esque, Todd C.; Nicklas, Melissa B.; Kane, Jeffrey M.

    2012-01-01

    Revegetation of degraded arid lands often involves supplementing impoverished seed banks and improving the seedbed, yet these approaches frequently fail. To understand these failures, we tracked the fates of seeds for six shrub species that were broadcast across two contrasting surface disturbances common to the Mojave Desert—sites compacted by concentrated vehicle use and trenched sites where topsoil and subsurface soils were mixed. We evaluated seedbed treatments that enhance soil-seed contact (tackifier) and create surface roughness while reducing soil bulk density (harrowing). We also explored whether seed harvesting by granivores and seedling suppression by non-native annuals influence the success of broadcast seeding in revegetating degraded shrublands. Ten weeks after treatments, seeds readily moved off of experimental plots in untreated compacted sites, but seed movements were reduced 32% by tackifier and 55% through harrowing. Harrowing promoted seedling emergence in compacted sites, particularly for the early-colonizing species Encelia farinosa, but tackifier was largely ineffective. The inherent surface roughness of trenched sites retained three times the number of seeds than compacted sites, but soil mixing during trench development likely altered the suitability of the seedbed thus resulting in poor seedling emergence. Non-native annuals had little influence on seed fates during our study. In contrast, the prevalence of harvester ants increased seed removal on compacted sites, whereas rodent activity influenced removal on trenched sites. Future success of broadcast seeding in arid lands depends on evaluating disturbance characteristics prior to seeding and selecting appropriate species and seasons for application.

  6. The effect of twig architecture and seed number on seed size variation in subtropical woody species.

    PubMed

    Chen, Hong; Niklas, Karl J; Yang, Dongmei; Sun, Shucun

    2009-01-01

    This study aims to determine the effect of twig (current year shoot) size on seed size variation and to test whether a seed size vs number tradeoff occurs for the twigs of subtropical broad-leaved species. Fruit-bearing twigs were sampled for 55 woody species (including 33 evergreen and 22 deciduous dicot species) from a southwest Chinese forest. Twig size, fruit size and number, and seed size and number were measured for each species. The relationships among these functional traits were determined both across species and across correlated phyletic divergences. Total fruit mass and total seed mass were positively correlated with twig size. Seed size was positively associated with fruit size, which was, in turn, positively correlated with twig diameter, but negatively correlated with the ratio of twig length to diameter. The effect of twig size on seed size variation was not significant, possibly as a result of the large variation in seed number per fruit. Cross-species and across-phyletic divergence analyses revealed that seed size was negatively and isometrically correlated with seed number per twig mass in both the evergreen and deciduous species groupings, demonstrating the existence of tradeoff between seed size and number. A seed size vs number tradeoff is detectable in the twigs of woody species. Comparatively little of the variance in seed size was attributable to twig size variation.

  7. Buried Seed Banks as Indicators of Seed Output along an Altitudinal Gradient.

    ERIC Educational Resources Information Center

    Thompson, K.

    1985-01-01

    Study of buried seed banks (viable seeds deposited in the soil near parent plants) provides a relatively easy way of determining cumulative effects on seed production and species' altitudinal limits. Sites, methods, validity, interpretation, problems of collection on a mountain, and germination techniques are discussed. (Author/DH)

  8. Bulk YBCO seeded with 45°-45° bridge-seeds of different lengths

    NASA Astrophysics Data System (ADS)

    Shi, Y.-H.; Durrell, J. H.; Dennis, A. R.; Cardwell, D. A.

    2013-01-01

    Single grain, (RE)BCO (rare earth-barium-copper oxide) bulk superconductors in large or complicated geometries are required for a variety of potential applications, such as in motors and generators and magnetic shielding devices. As a result, top, multi-seeded, melt growth has been investigated over the past 15 years in an attempt to enlarge the size of (RE)BCO single grains specifically for such applications. Of these multi-seeding techniques, so-called bridge-seeding provides the best alignment of two seeds in a single grain growth process. Here we report, for the first time, the successful growth of YBCO (yttrium-barium-copper oxide) using a special, 45°-45°, arrangement of bridge-seeds. The superconducting properties, including trapped field, of the multi-seeded YBCO grains have been measured for different bridge lengths of the 45°-45° bridge-seeds. The boundaries at the impinging growth front and the growth features of the top, multi-seeded surface and cross-section of the multi-seeded, samples have been analysed using optical microscopy. The results suggest that an impurity-free boundary between the two seeds of each leg of the bridge-seed can form when 45°-45° bridge-seeds are used to enlarge the size of YBCO grains.

  9. Frequency stability review

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    1987-01-01

    Certain aspects of the description and measurement of oscillator stability are treated. Topics covered are time and frequency deviations, Allan variance, the zero-crossing counter measurement technique, frequency drift removal, and the three-cornered hat.

  10. Modeling Frequency Comb Sources

    NASA Astrophysics Data System (ADS)

    Li, Feng; Yuan, Jinhui; Kang, Zhe; Li, Qian; Wai, P. K. A.

    2016-06-01

    Frequency comb sources have revolutionized metrology and spectroscopy and found applications in many fields. Stable, low-cost, high-quality frequency comb sources are important to these applications. Modeling of the frequency comb sources will help the understanding of the operation mechanism and optimization of the design of such sources. In this paper,we review the theoretical models used and recent progress of the modeling of frequency comb sources.

  11. Two-Color Radiation Generated in a Seeded Free-Electron Laser with Two Electron Beams.

    PubMed

    Petralia, A; Anania, M P; Artioli, M; Bacci, A; Bellaveglia, M; Carpanese, M; Chiadroni, E; Cianchi, A; Ciocci, F; Dattoli, G; Di Giovenale, D; Di Palma, E; Di Pirro, G P; Ferrario, M; Giannessi, L; Innocenti, L; Mostacci, A; Petrillo, V; Pompili, R; Rau, J V; Ronsivalle, C; Rossi, A R; Sabia, E; Shpakov, V; Vaccarezza, C; Villa, F

    2015-07-01

    We present the experimental evidence of the generation of coherent and statistically stable two-color free-electron laser radiation obtained by seeding an electron beam double peaked in energy with a laser pulse single spiked in frequency. The radiation presents two neat spectral lines, with time delay, frequency separation, and relative intensity that can be accurately controlled. The analysis of the emitted radiation shows a temporal coherence and a shot-to-shot regularity in frequency significantly enhanced with respect to the self-amplified spontaneous emission.

  12. Rheological and microstructural properties of the chia seed polysaccharide.

    PubMed

    Timilsena, Yakindra Prasad; Adhikari, Raju; Kasapis, Stefan; Adhikari, Benu

    2015-11-01

    Chia seed polysaccharide (CSP) was extracted from chia (Salvia hispanica) seeds, and its rheological and microstructural properties in aqueous solutions were studied. CSP solution exhibited Newtonian and shear thinning flow patterns depending on shear rate when the concentration was ≤0.06% (w/v). CSP solutions at concentrations >0.06% (w/v) exhibited strong shear thinning behaviour within the shear rate tested (0.001-300s(-1)). The transition from dilute to semi-dilute regime occurred at a critical concentration (C*) of 0.03gdL(-1). The intrinsic viscosity was high (∼16dLg(-1)) and concentration dependence of zero shear viscosity in the semi-dilute regime followed η0∝C(2.7) relationship. The storage modulus (G') was higher than the loss modulus (G″) at all experimental frequencies and their frequency dependence was negligible at all tested concentrations. Apparent shear viscosity was smaller than dynamic complex viscosity at equivalent values of deformation and G' varied with the square of concentration indicating a gel-like behaviour in CSP solutions within 0.02-3.0% (w/v) concentrations. Controlled acid hydrolysis of purified CSP yielded various low molecular fractions with fairly uniform polydispersity giving a Mark-Houwink-Sakurada relationship of intrinsic viscosity equaling to 1.52×10(-4) (molecular weight)(0.803) (dLg(-1)).

  13. Eastern Frequency Response Study

    SciTech Connect

    Miller, N.W.; Shao, M.; Pajic, S.; D'Aquila, R.

    2013-05-01

    This study was specifically designed to investigate the frequency response of the Eastern Interconnection that results from large loss-of-generation events of the type targeted by the North American Electric Reliability Corp. Standard BAL-003 Frequency Response and Frequency Bias Setting (NERC 2012a), under possible future system conditions with high levels of wind generation.

  14. Frequency Response Tool

    SciTech Connect

    Etingov, Pavel; Chassin, PNNL David; Zhang, PNNL Yu; PNNL,

    2014-03-13

    According to the North American Electric Reliability Corporation (NERC) definition: “Frequency response is a measure of an Interconnection’s ability to stabilize frequency immediately following the sudden loss of generation or load, and is a critical component of the reliable operation of the Bulk-Power System, particularly during disturbances and recoveries. Failure to maintain frequency can disrupt the operation of equipment and initiate disconnection of power plant equipment to prevent it from being damaged, which could lead to wide-spread blackouts.” Frequency Response Tool automates the power system frequency response analysis process. The tool performs initial estimation of the system frequency parameters (initial frequency, minimum frequency, settling point). User can visually inspect and adjust these parameters. The tool also calculates the frequency response performance metrics of the system, archives the historic events and baselines the system performance. Frequency response performance characteristics of the system are calculated using phasor measurement unit (PMU) information. Methodology of the frequency response performance assessment implemented in the tool complies with the NERC Frequency response standard.

  15. Frequency Response Tool

    2014-03-13

    According to the North American Electric Reliability Corporation (NERC) definition: “Frequency response is a measure of an Interconnection’s ability to stabilize frequency immediately following the sudden loss of generation or load, and is a critical component of the reliable operation of the Bulk-Power System, particularly during disturbances and recoveries. Failure to maintain frequency can disrupt the operation of equipment and initiate disconnection of power plant equipment to prevent it from being damaged, which could leadmore » to wide-spread blackouts.” Frequency Response Tool automates the power system frequency response analysis process. The tool performs initial estimation of the system frequency parameters (initial frequency, minimum frequency, settling point). User can visually inspect and adjust these parameters. The tool also calculates the frequency response performance metrics of the system, archives the historic events and baselines the system performance. Frequency response performance characteristics of the system are calculated using phasor measurement unit (PMU) information. Methodology of the frequency response performance assessment implemented in the tool complies with the NERC Frequency response standard.« less

  16. Dispersal of mimetic seeds of three species of Ormosia (Leguminosae)

    USGS Publications Warehouse

    Foster, M.S.; DeLay, L.S.

    1998-01-01

    Seeds with 'imitation arils' appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard 'mimetic' seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae) were observed to ascertain mechanisms of seed dispersal and the role of seemingly mimetic characteristics of the seeds in that dispersal. Seed predation and seed germination were also examined. Ormosia isthamensis and O. macrocalyx (but not O. bopiensis) deceived arboreally-foraging frugivorous birds into taking their mimetic seeds, although rates of seed dispersal were low. These results are consistent with the mimetic seed hypothesis. On the other hand, the rates of disappearance of seeds from the ground under the Ormosia trees, hardness of the seeds, and enhancement of germination with the abrasion of the seed coat are all consistent with the hard-seed for grit hypothesis.

  17. Seed Anatomy and Water Uptake in Relation to Seed Dormancy in Opuntia tomentosa (Cactaceae, Opuntioideae)

    PubMed Central

    Orozco-Segovia, A.; Márquez-Guzmán, J.; Sánchez-Coronado, M. E.; Gamboa de Buen, A.; Baskin, J. M.; Baskin, C. C.

    2007-01-01

    Background and Aims There is considerable confusion in the literature concerning impermeability of seeds with ‘hard’ seed coats, because the ability to take up (imbibe) water has not been tested in most of them. Seeds of Opuntia tomentosa were reported recently to have a water-impermeable seed coat sensu lato (i.e. physical dormancy), in combination with physiological dormancy. However, physical dormancy is not known to occur in Cactaceae. Therefore, the aim of this study was to determine if seeds of O. tomentosa are water-permeable or water-impermeable, i.e. if they have physical dormancy. Methods The micromorphology of the seed coat and associated structures were characterized by SEM and light microscopy. Permeability of the seed-covering layers was assessed by an increase in mass of seeds on a wet substrate and by dye-tracking and uptake of tritiated water by intact versus scarified seeds. Key Results A germination valve and a water channel are formed in the hilum–micropyle region during dehydration and ageing in seeds of O. tomentosa. The funicular envelope undoubtedly plays a role in germination of Opuntia seeds via restriction of water uptake and mechanical resistance to expansion of the embryo. However, seeds do not exhibit any of three features characteristic of those with physical dormancy. Thus, they do not have a water-impermeable layer(s) of palisade cells (macrosclereids) or a water gap sensu stricto and they imbibe water without the seed coat being disrupted. Conclusions Although dormancy in seeds of this species can be broken by scarification, they have physiological dormancy only. Further, based on information in the literature, it is concluded that it is unlikely that any species of Opuntia has physical dormancy. This is the first integrative study of the anatomy, dynamics of water uptake and dormancy in seeds of Cactaceae subfamily Opuntioideae. PMID:17298989

  18. Harmonic Frequency Lowering

    PubMed Central

    Kirchberger, Martin

    2016-01-01

    A novel algorithm for frequency lowering in music was developed and experimentally tested in hearing-impaired listeners. Harmonic frequency lowering (HFL) combines frequency transposition and frequency compression to preserve the harmonic content of music stimuli. Listeners were asked to make judgments regarding detail and sound quality in music stimuli. Stimuli were presented under different signal processing conditions: original, low-pass filtered, HFL, and nonlinear frequency compressed. Results showed that participants reported perceiving the most detail in the HFL condition. In addition, there was no difference in sound quality across conditions. PMID:26834122

  19. Regional flood frequency analysis

    SciTech Connect

    Singh, V.P.

    1987-01-01

    This book, the fourth of a four volume set, contains five sections encompassing major aspects of regional flood frequency analysis. Each section starts usually with an invited state-of-the-art paper followed by contributed papers. The first section provides an assessment of regional flood frequency analysis. Methods for performing regional frequency analysis for ungaged watersheds are presented in Section 2. More discussion on regional frequency analysis is provided in Section 3. Selection and comparison of regional frequency methods are dealt with in Section 4; these are of great interest to the user. Increasing attention is being focused these days on paleohydrologic flood analysis. This topic is covered in Section 5.

  20. Frequency selective infrared sensors

    SciTech Connect

    Davids, Paul; Peters, David W

    2014-11-25

    A frequency selective infrared (IR) photodetector having a predetermined frequency band. The exemplary frequency selective photodetector includes: a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface; an electrode electrically coupled to the first surface of the dielectric IR absorber; and a frequency selective surface plasmonic (FSSP) structure formed on the second surface of the dielectric IR absorber. The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band that is incident on the FSSP structure substantially independent of the angle of incidence of the incident radiation on the FSSP structure.

  1. Frequency selective infrared sensors

    DOEpatents

    Davids, Paul; Peters, David W

    2013-05-28

    A frequency selective infrared (IR) photodetector having a predetermined frequency band. The exemplary frequency selective photodetector includes: a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface; an electrode electrically coupled to the first surface of the dielectric IR absorber; and a frequency selective surface plasmonic (FSSP) structure formed on the second surface of the dielectric IR absorber. The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band that is incident on the FSSP structure substantially independent of the angle of incidence of the incident radiation on the FSSP structure.

  2. Frequency set on systems

    NASA Astrophysics Data System (ADS)

    Wilby, W. A.; Brett, A. R. H.

    Frequency set on techniques used in ECM applications include repeater jammers, frequency memory loops (RF and optical), coherent digital RF memories, and closed loop VCO set on systems. Closed loop frequency set on systems using analog phase and frequency locking are considered to have a number of cost and performance advantages. Their performance is discussed in terms of frequency accuracy, bandwidth, locking time, stability, and simultaneous signals. Some experimental results are presented which show typical locking performance. Future ECM systems might require a response to very short pulses. Acoustooptic and fiber-optic pulse stretching techniques can be used to meet such requirements.

  3. Frequency discriminator/phase detector

    NASA Technical Reports Server (NTRS)

    Crow, R. B.

    1974-01-01

    Circuit provides dual function of frequency discriminator/phase detector which reduces frequency acquisition time without adding to circuit complexity. Both frequency discriminators, in evaluated frequency discriminator/phase detector circuits, are effective two decades above and below center frequency.

  4. Occurrence of Physical Dormancy in Seeds of Australian Sapindaceae: A Survey of 14 Species in Nine Genera

    PubMed Central

    Cook, A.; Turner, S. R.; Baskin, J. M.; Baskin, C. C.; Steadman, K. J.; Dixon, K. W.

    2008-01-01

    Background and Aims Sapindaceae is one of 16 angiosperm families whose seeds have physical dormancy (PY). However, the extent and nature of PY within this family is poorly known. The primary aims of this study were: (1) to evaluate seed characteristics and determine presence (or not) of PY within nine genera of Australian Sapindaceae; and (2) to compare the frequency of PY across the phylogenetic tree within Australian Sapindaceae. Methods Viability, imbibition and seed characteristics were assessed for 14 taxa from nine genera of Sapindaceae. For five species of Dodonaea, optimal conditions for germination and dormancy break were evaluated. An in situ burial experiment was performed on D. hackettiana seeds to identify the factor(s) responsible for overcoming PY. Classes of dormancy and of non-dormancy for 26 genera of Sapindaceae were mapped onto a phylogenetic tree for the family. Key Results Mean seed viability across all taxa was 69·7 %. Embryos were fully developed and folded (seven genera) or bent (two genera); no endosperm was present. Seeds of all five Dodonaea spp. and of Distichostemon hispidulus had PY. Hot-water treatment released PY in these six species. Optimal germination temperature for seeds of the four Dodonaea spp. that germinated was 15–20 °C. Following 5 months burial in soil, 36·4 % of D. hackettiana seeds had lost PY and germinated by the beginning of the winter wet season (May). Laboratory and field data indicate that dormancy was broken by warm, moist temperatures (≥50 °C) during summer. Conclusions PY occurs infrequently in genera of Sapindaceae native to Australia. Seeds of Dodonaea and Distichostemon had PY, whereas those of the other seven genera did not. Seeds of these two genera and of Diplopeltis (a previous study) are the only three of the 20 native Australian genera of Sapindaceae for which germination has been studied that have PY; all three belong to subfamily Dodonaeoideae. PMID:18369237

  5. Comparative Effects of Pollen and Seed Migration on the Cytonuclear Structure of Plant Populations. II. Paternal Cytoplasmic Inheritance

    PubMed Central

    Schnabel, A.; Asmussen, M. A.

    1992-01-01

    We continue our study of the effects of pollen and seed migration on the cytonuclear structure of mixed-mating plant populations by analyzing two deterministic continent-island models under the critical assumption of paternal cytoplasmic inheritance. The major results of this study that contrast with our previous conclusions based on maternal cytoplasmic inheritance are (i) pollen gene flow can significantly affect the cytonuclear structure of the island population, and in particular can help to generate cytonuclear disequilibria that greatly exceed the magnitude of those that would be produced by seed migration or mixed mating alone; (ii) with simultaneous pollen and seed migration, nonzero cytonuclear disequilibria will be maintained not only when there is disequilibrium in the immigrant pollen or seeds, but also through a variety of intermigrant admixture effects when the two pools of immigrants differ appropriately in their cytonuclear compositions; (iii) either immigrant pollen or immigrant seeds can generate disequilibria de novo in populations with initially random cytonuclear associations, but pollen migration alone generally produces lower levels of disequilibrium than does comparable seed migration, especially at high levels of self-fertilization when the overall fraction of immigrant pollen is low; (iv) the equilibrium state of the island population will be influenced by the rate of pollen gene flow whenever there is either allelic disequilibrium in the immigrant pollen or simultaneous seed migration coupled with different cytoplasmic or nuclear allele frequencies in immigrant pollen and seeds or nonzero allelic disequilibrium in either immigrant pool. The estimation of pollen migration should therefore be facilitated with paternal cytoplasmic inheritance relative to the case of maternal cytoplasmic inheritance. These basic conclusions hold whether the population is censused as seeds or as adults, but with simultaneous pollen and seed migration, the

  6. 9 CFR 101.7 - Seed organisms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Seed organisms. 101.7 Section 101.7 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS DEFINITIONS § 101.7 Seed organisms....

  7. Analysis of Peanut Seed Oil by NIR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near infrared reflectance spectra (NIRS) were collected from Arachis hypogaea seed samples and used in predictive models to rapidly identify varieties with high oleic acid. The method was developed for shelled peanut seeds with intact testa. Spectra were evaluated initially by principal component an...

  8. Hydration of Cuphea seeds containing crystallized triacylglycerols

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeds that exhibit intermediate storage behavior do not appear to survive under conventional -18C storage conditions. Cuphea wrightii, C. laminuligera, C. carthagenensis, and C. aequipetala are considered sensitive to low temperature storage. The seeds of these species have triacylglycerols (TAG) ...

  9. Puncturevine seed response to postemergence herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Puncturevine (Tribulus terrestris) continues to plague growers, vegetation managers, and home gardeners. Puncturevine is a summer annual weed with spiny fruits that split into five segments, each containing one to four seeds. The seed nearest the pointed end of the bur is the largest and usually ge...

  10. Improving photoacoustic imaging contrast of brachytherapy seeds

    NASA Astrophysics Data System (ADS)

    Pan, Leo; Baghani, Ali; Rohling, Robert; Abolmaesumi, Purang; Salcudean, Septimiu; Tang, Shuo

    2013-03-01

    Prostate brachytherapy is a form of radiotherapy for treating prostate cancer where the radiation sources are seeds inserted into the prostate. Accurate localization of seeds during prostate brachytherapy is essential to the success of intraoperative treatment planning. The current standard modality used in intraoperative seeds localization is transrectal ultrasound. Transrectal ultrasound, however, suffers in image quality due to several factors such speckle, shadowing, and off-axis seed orientation. Photoacoustic imaging, based on the photoacoustic phenomenon, is an emerging imaging modality. The contrast generating mechanism in photoacoustic imaging is optical absorption that is fundamentally different from conventional B-mode ultrasound which depicts changes in acoustic impedance. A photoacoustic imaging system is developed using a commercial ultrasound system. To improve imaging contrast and depth penetration, absorption enhancing coating is applied to the seeds. In comparison to bare seeds, approximately 18.5 dB increase in signal-to-noise ratio as well as a doubling of imaging depth are achieved. Our results demonstrate that the coating of the seeds can further improve the discernibility of the seeds.

  11. Abscisic Acid Levels and Seed Dormancy

    PubMed Central

    Sondheimer, E.; Tzou, D. S.; Galson, Eva C.

    1968-01-01

    Dormant seeds from Fraxinus species require cold-temperature after-ripening prior to germination. Earlier, we found that abscisic acid (ABA) will inhibit germination of excised nondormant embryos and that this can be reversed with a combination of gibberellic acid and kinetin. Using Milborrow's quantitative “racemate dilution” method the ABA concentration in 3 types of Fraxinus seed and pericarp were determined. While ABA was present in all tissues, the highest concentration was found in the seed and pericarp of dormant F. americana. During the chilling treatment of F. americana the ABA levels decreased 37% in the pericarp and 68% in the seed. The ABA concentration of the seed of the nondormant species, F. ornus, is as low as that found in F. americana seeds after cold treatment. Experiments with exogenously added ABA solutions indicate that it is unlikely that the ABA in the pericarp functions in the regulation of seed dormancy. However, the ABA in the seed does seem to have a regulatory role in germination. Images PMID:16656935

  12. Variation for seed phytosterols in sunflower germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunflower (Helianthus annuus L.) seeds and oils are rich sources of phytosterols, which are important compounds for human nutrition. There is limited information on variability for seed phytosterols in sunflower germplasm. The objective of the present research was to evaluate kernel phytosterol cont...

  13. Elastohydrodynamic Traction Properties of Seed Oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, PAO and hexadecane, were investigated using a ball-on disk traction apparatus. The seed oils were: castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and s...

  14. Elastohydrodynamic (EHD) traction properties of seed oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, PAO and hexadecane, were investigated using a ball-on disk traction apparatus. The seed oils were: castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and sev...

  15. Formative Assessment Probes: Seeds in a Bag

    ERIC Educational Resources Information Center

    Keeley, Page

    2014-01-01

    Many young children come to school with prior experiences planting seeds in a garden or in a pot, watering them, and seeing them grow. These early scientific investigations are designed to help children understand that seeds need water, something to grow in (such as soil), and the right temperature to sprout--if these conditions are met, a seed…

  16. Characterization of Milkweed (Asclepias spp.) Seed Proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Milkweed (Asclepias spp.) is a crop grown mainly for the production of floss used as hypoallergenic fillers in comforters and pillows. The seeds end up as by-products. Milkweed seed contains 21% oil and 30% crude protein (dry basis). The oil is similar in quality to soybean oil, but there is no i...

  17. MHD heat and seed recovery technology project

    SciTech Connect

    Petrick, M.; Johnson, T. R.

    1980-08-01

    The MHD Heat and Seed Recovery Technology Project at Argonne National Laboratory is obtaining information for the design and operation of the steam plant downstream of the MHD channel-diffuser, and of the seed regeneration process. The project goal is to supply the engineering data required in the design of components for prototype and demonstration MHD facilities. The work is being done in close cooperation with the Heat Recovery-Seed Recovery facility, which will be a 20-MW pilot plant of the MHD steam bottoming system. The primary effort of the HSR Technology Project is directed toward experimental investigations of critical issues, such as 1) NO/sub x/ behavior in the radiant boiler and secondary combustor; 2) radiant boiler design to meet the multiple requirements of steam generation, NO/sub x/ decomposition, and seed slag separation; 3) effects of solid or liquid seed deposits on heat transfer and gas flow in the steam and air heaters; 4) formation, growth, and deposition of seed-slag particles, 5) character of the combustion gas effluents, and 6) the corrosion and erosion of ceramic and metallic materials of construction. These investigations are performed primarily in a 2-MW test facility, Argonne MHD Process Engineering Laboratory (AMPEL). Other project activities are related to studies of the thermochemistry of the seed-slag combustion gas system, identification of ceramic and metallic materials for service in the MHD-steam plant, and evaluation of seed regeneration processes. Progress is reported.

  18. Towards a better monitoring of seed ageing under ex situ seed conservation

    PubMed Central

    Fu, Yong-Bi; Ahmed, Zaheer; Diederichsen, Axel

    2015-01-01

    Long-term conservation of 7.4 million ex situ seed accessions held in agricultural genebanks and botanic gardens worldwide is a challenging mission for human food security and ecosystem services. Recent advances in seed biology and genomics may have opened new opportunities for effective management of seed germplasm under long-term storage. Here, we review the current development of tools for assessing seed ageing and research advances in seed biology and genomics, with a focus on exploring their potential as better tools for monitoring of seed ageing. Seed ageing is found to be associated with the changes reflected in reactive oxygen species and mitochondria-triggered programmed cell deaths, expression of antioxidative genes and DNA and protein repair genes, chromosome telomere lengths, epigenetic regulation of related genes (microRNA and methylation) and altered organelle and nuclear genomes. Among these changes, the signals from mitochondrial and nuclear genomes may show the most promise for use in the development of tools to predict seed ageing. Non-destructive and non-invasive analyses of stored seeds through calorimetry or imaging techniques are also promising. It is clear that research into developing advanced tools for monitoring seed ageing to supplement traditional germination tests will be fruitful for effective conservation of ex situ seed germplasm. PMID:27293711

  19. Florivory Modulates the Seed Number-Seed Weight Relationship in Halenia elliptica (Gentianaceae)

    PubMed Central

    Wang, Linlin; Meng, Lihua; Luo, Jian

    2015-01-01

    Generally, plant reproductive success might be affected negatively by florivory, and the effects may vary depending on the timing and intensity of florivory. To clarify the impacts of florivory by the sawfly larvae (Tenthredinidae) on seed production of Halenia elliptica D. Don, we simulated florivory by removing different proportion of flowers at three reproductive stages in this alpine herb and then examined the seed number per fruit, the seed weight, and the seed mass per fruit of the remaining flowers. Seed number per fruit reduced significantly when flowers were removed at flowering and fruiting stages or when 15% and 60% of flowers were removed. However, seed weight increased significantly after flowers were removed, independent of treatments of reproductive stage and proportion. There was a similar seed mass per fruit between the plants subjected to simulation of florivory and control. The results indicated that florivory modulated the seed number-seed weight relationship in this alpine species. Our study suggested that selective seed abortion and resource reallocation within fruits may ensure fewer but larger seeds, which were expected to be adaptive in the harsh environments. PMID:26495428

  20. Seed birth to death: dual functions of reactive oxygen species in seed physiology

    PubMed Central

    Jeevan Kumar, S. P.; Rajendra Prasad, S.; Banerjee, Rintu; Thammineni, Chakradhar

    2015-01-01

    Background Reactive oxygen species (ROS) are considered to be detrimental to seed viability. However, recent studies have demonstrated that ROS have key roles in seed germination particularly in the release of seed dormancy and embryogenesis, as well as in protection from pathogens. Scope This review considers the functions of ROS in seed physiology. ROS are present in all cells and at all phases of the seed life cycle. ROS accumulation is important in breaking seed dormancy, and stimulating seed germination and protection from pathogens. However, excessive ROS accumulation can be detrimental. Therefore, knowledge of the mechanisms by which ROS influence seed physiology will provide insights that may not only allow the development of seed quality markers but also help us understand how dormancy can be broken in several recalcitrant species. Conclusions Reactive oxygen species have a dual role in seed physiology. Understanding the relative importance of beneficial and detrimental effects of ROS provides great scope for the improvement and maintenance of seed vigour and quality, factors that may ultimately increase crop yields. PMID:26271119

  1. Seed deposition patterns and the survival of seeds and seedlings of the palm Euterpe edulis

    NASA Astrophysics Data System (ADS)

    Pizo, Marco A.; Simão, Isaac

    2001-08-01

    The seed deposition pattern created by a seed disperser is one of the components of the efficiency of a species as seed disperser, and ultimately may influence the recruitment of a plant species. In this study, we used the seeds of a bird-dispersed forest palm, Euterpe edulis, to investigate the effects of two distinct seed deposition patterns created by birds that defecate (clumped pattern) and regurgitate seeds (loose-clumped pattern) on the survival of seeds experimentally set in an E. edulis-rich site, and of seedlings grown under shade-house conditions. The study was conducted in the lowland forest of Parque Estadual Intervales, SE Brazil. Clumped and loose-clumped seeds were equally preyed upon by rodents and insects. Although clumped and isolated seedlings had the same root weight after 1 year, the isolated seedlings survived better and presented more developed shoots, suggesting intraspecific competition among clumped seedlings. Our results indicate that animals that deposit E. edulis seeds in faecal clumps (e.g. cracids, tapirs) are less efficient seed dispersers than those that regurgitate seeds individually (e.g. trogons, toucans). Intraspecific competition among seedlings growing from faecal clumps is a likely process preventing the occurrence of clumps of adult palms.

  2. Seed Aging: Chromosome Stability and Extended Viability of Seeds Stored Fully Imbided 1

    PubMed Central

    Villiers, T. A.

    1974-01-01

    Increase in moisture content of seeds of Lactuca sativa L. and Fraxinus americana L. in air-dry storage caused a rapid decline in longevity and an increase in the rate of accumulation of chromosome aberrations. Storage of seeds fully imbibed but unable to germinate allowed a high germination capacity to be maintained for long periods, together with a very low incidence of chromosome aberrations. Seedlings grown from dry-stored seeds showed an increase in morphological abnormalities with length of storage, whereas seedlings from imbibed-stored seeds appeared normal. It is suggested that in dry tissues, enzyme-controlled turnover and repair may be temporarily suspended, and that this may be an important factor in the loss of seed viability in storage. The effect of increasing seed longevity by lowering the moisture content of dry-stored seeds is discussed in relation to this hypothesis. The relevance of the proposal is also discussed in relation to ecological studies. Images PMID:16658808

  3. Molecular regulation of seed and fruit set.

    PubMed

    Ruan, Yong-Ling; Patrick, John W; Bouzayen, Mondher; Osorio, Sonia; Fernie, Alisdair R

    2012-11-01

    Seed and fruit set are established during and soon after fertilization and determine seed and fruit number, their final size and, hence, yield potential. These processes are highly sensitive to biotic and abiotic stresses, which often lead to seed and fruit abortion. Here, we review the regulation of assimilate partitioning, including the potential roles of recently identified sucrose efflux transporters in seed and fruit set and examine the similarities of sucrose import and hydrolysis for both pollen and ovary sinks, and similar causes of abortion. We also discuss the molecular origins of parthenocarpy and the central roles of auxins and gibberellins in fruit set. The recently completed strawberry (Fragaria vesca) and tomato (Solanum lycopersicum) genomes have added to the existing crop databases, and new models are starting to be used in fruit and seed set studies. PMID:22776090

  4. S-Seed Switching, Noise, and Applications

    NASA Astrophysics Data System (ADS)

    Loh, Lup Meng

    The switching and noise characteristics of the Symmetric Self Electrooptic Effect Device (S-SEED) are studied in detail. The resulting analysis provides concise, closed form expressions for the S-SEED switching condition, the switching voltage of the device, and its switching time, all for a noiseless S-SEED model. A noise analysis, using a carrier state diagram, produced Bit Error Rate (BER) curves for the S-SEED that can be used in the design of a photonic switching system. This thesis also deals with application issues, demonstrating the versatility of the S-SEED as an optical logic device with memory. Two applications of the S-SEED are presented. A system to realize an All Optical Analog-to-Digital Converter (OADC) and an All Optical Digital-to-Analog Converter (ODAC) are conceived. The switching analysis presented here first models the noiseless S-SEED responsivity characteristics with a linear slope approximation. Such a model allows the derivation of a first order linear differential equation using a purely capacitive electric circuit model of an S-SEED. Similarly, an S-SEED model with series resistors results in a second order linear differential equation for the device. The resulting closed form solutions relate the noiseless S-SEED switching voltage and switching time to the operating parameters of the device. A discrete carrier approach is used to emulate S-SEED operation with shot noise. S-SEED state diagrams in conjunction with a Poisson probability density function (pdf), as well as an estimated Gaussian pdf, are used to determine both the probability of error P_ {E}, and the probability of abnormal operation P_{ABN}. The results provide a range of input parameter values for acceptable S-SEED performance when noise is included in the device model. Applications of S-SEEDs are presented that require logic and memory for their implementation. Experimental designs are detailed where S-SEEDs are the building blocks for an OADC and an ODAC. The inherent S-SEED

  5. Frequency dependent squeezed light at audio frequencies

    NASA Astrophysics Data System (ADS)

    Miller, John

    2015-04-01

    Following successful implementation in the previous generation of instruments, squeezed states of light represent a proven technology for the reduction of quantum noise in ground-based interferometric gravitational-wave detectors. As a result of lower noise and increased circulating power, the current generation of detectors places one further demand on this technique - that the orientation of the squeezed ellipse be rotated as function of frequency. This extension allows previously negligible quantum radiation pressure noise to be mitigated in addition to quantum shot noise. I will present the results of an experiment which performs the appropriate rotation by reflecting the squeezed state from a detuned high-finesse optical cavity, demonstrating frequency dependent squeezing at audio frequencies for the first time and paving the way for broadband quantum noise reduction in Advanced LIGO. Further, I will indicate how a realistic implementation of this approach will impact Advanced LIGO both alone and in combination with other potential upgrades.

  6. Seed treatment with Trichoderma harzianum alleviates biotic, abiotic, and physiological stresses in germinating seeds and seedlings.

    PubMed

    Mastouri, Fatemeh; Björkman, Thomas; Harman, Gary E

    2010-11-01

    Trichoderma spp. are endophytic plant symbionts that are widely used as seed treatments to control diseases and to enhance plant growth and yield. Although some recent work has been published on their abilities to alleviate abiotic stresses, specific knowledge of mechanisms, abilities to control multiple plant stress factors, their effects on seed and seedlings is lacking. We examined the effects of seed treatment with T. harzianum strain T22 on germination of seed exposed to biotic stress (seed and seedling disease caused by Pythium ultimum) and abiotic stresses (osmotic, salinity, chilling, or heat stress). We also evaluated the ability of the beneficial fungus to overcome physiological stress (poor seed quality induced by seed aging). If seed were not under any of the stresses noted above, T22 generally had little effect upon seedling performance. However, under stress, treated seed germinated consistently faster and more uniformly than untreated seeds whether the stress was osmotic, salt, or suboptimal temperatures. The consistent response to varying stresses suggests a common mechanism through which the plant-fungus association enhances tolerance to a wide range of abiotic stresses as well as biotic stress. A common factor that negatively affects plants under these stress conditions is accumulation of toxic reactive oxygen species (ROS), and we tested the hypothesis that T22 reduced damages resulting from accumulation of ROS in stressed plants. Treatment of seeds reduced accumulation of lipid peroxides in seedlings under osmotic stress or in aged seeds. In addition, we showed that the effect of exogenous application of an antioxidant, glutathione, or application of T22, resulted in a similar positive effect on seed germination under osmotic stress or in aged seed. This evidence supports the model that T. harzianum strain T22 increases seedling vigor and ameliorates stress by inducing physiological protection in plants against oxidative damage.

  7. Generation of Phase-Locked Pulses from a Seeded Free-Electron Laser.

    PubMed

    Gauthier, David; Ribič, Primož Rebernik; De Ninno, Giovanni; Allaria, Enrico; Cinquegrana, Paolo; Danailov, Miltcho Bojanov; Demidovich, Alexander; Ferrari, Eugenio; Giannessi, Luca

    2016-01-15

    In a coherent control experiment, light pulses are used to guide the real-time evolution of a quantum system. This requires the coherence and the control of the pulses' electric-field carrier waves. In this work, we use frequency-domain interferometry to demonstrate the mutual coherence of time-delayed pulses generated by an extreme ultraviolet seeded free-electron laser. Furthermore, we use the driving seed laser to lock and precisely control the relative phase between the two free-electron laser pulses. This new capability opens the way to a multitude of coherent control experiments, which will take advantage of the high intensity, short wavelength, and short duration of the pulses generated by seeded free-electron lasers. PMID:26824544

  8. Weed seeds on clothing: a global review.

    PubMed

    Ansong, Michael; Pickering, Catherine

    2014-11-01

    Weeds are a major threat to biodiversity including in areas of high conservation value. Unfortunately, people may be unintentionally introducing and dispersing weed seeds on their clothing when they visit these areas. To inform the management of these areas, we conducted a systematic quantitative literature review to determine the diversity and characteristics of species with seeds that can attach and be dispersed from clothing. Across 21 studies identified from systematic literature searches on this topic, seeds from 449 species have been recorded on clothing, more than double the diversity found in a previous review. Nearly all of them, 391 species, are listed weeds in one or more countries, with 58 classified as internationally-recognised environmental weeds. When our database was compared with weed lists from different countries and continents we found that clothing can carry the seeds of important regional weeds. A total of 287 of the species are listed as aliens in one or more countries in Europe, 156 are invasive species/noxious weeds in North America, 211 are naturalized alien plants in Australia, 97 are alien species in India, 33 are invasive species in China and 5 are declared weeds/invaders in South Africa. Seeds on the clothing of hikers can be carried to an average distance of 13 km, and where people travel in cars, trains, planes and boats, the seeds on their clothing can be carried much further. Factors that affect this type of seed dispersal include the type of clothing, the type of material the clothing is made from, the number and location of the seeds on plants, and seed traits such as adhesive and attachment structures. With increasing use of protected areas by tourists, including in remote regions, popular protected areas may be at great risk of biological invasions by weeds with seeds carried on clothing.

  9. Responses of Seed Germination, Seedling Growth, and Seed Yield Traits to Seed Pretreatment in Maize (Zea mays L.)

    PubMed Central

    Tian, Yu; Guan, Bo; Zhou, Daowei; Li, Guangdi; Lou, Yujie

    2014-01-01

    A series of seed priming experiments were conducted to test the effects of different pretreatment methods to seed germination, seedling growth, and seed yield traits in maize (Zea mays L.). Results indicated that the seeds primed by gibberellins (GA), NaCl, and polyethylene glycol (PEG) reagents showed a higher imbibitions rate compared to those primed with water. The final germination percentage and germination rate varied with different reagents significantly (P < 0.05). The recommended prime reagents were GA at 10 mg/L, NaCl at 50 mM, and PEG at 15% on account of germination experiment. 15% PEG priming reagent increased shoot and root biomass of maize seedling. The shoot biomass of seedlings after presoaking the seeds with NaCl reagent was significantly higher than the seedlings without priming treatment. No significant differences of plant height, leaf number, and hundred-grain weight were observed between control group and priming treatments. Presoaking with water, NaCl (50 mM), or PEG (15%) significantly increased the hundred-grain weight of maize. Therefore, seed pretreatment is proved to be an effective technique to improve the germination performance, seedling growth, and seed yield of maize. However, when compared with the two methods, if immediate sowing is possible, presoaking is recommended to harvest better benefits compared to priming method. PMID:25093210

  10. Seeds of hope, seeds of despair: towards a political economy of the seed industry in southern Africa.

    PubMed

    Zerbe, N

    2001-01-01

    The seed industry in Southern Africa has been radically transformed by a policy of liberalisation and privatisation started under structural adjustment. Traditionally under the domain of parastatals, seed research, production and distribution has been criticised for failing to provide modern variety seed to smallholder farmers. However, the private companies which have stepped in to replace seed parastatals in southern Africa have proven no more effective in meeting the demands of smallholders. The Trade Related Intellectual Property Rights (TRIPs) Agreement, concluded in 1994 as part of the Uruguay Rounds of GATT negotiations, as well as certain biotechnological innovations such as Terminator or Traitor technologies, threaten to further undermine local seed production and consumption by destroying the informal seed sector so central to agricultural production in the region. What alternatives exist? The success of Zimbabwe's maize seed network offers some insight. Resting on a unique relationship between government and nationally based producer co-operatives, Zimbabwe's maize programme was able to provide nearly every farmer in the country with hybrid maize suited for local growing conditions.

  11. Responses of seed germination, seedling growth, and seed yield traits to seed pretreatment in maize (Zea mays L.).

    PubMed

    Tian, Yu; Guan, Bo; Zhou, Daowei; Yu, Junbao; Li, Guangdi; Lou, Yujie

    2014-01-01

    A series of seed priming experiments were conducted to test the effects of different pretreatment methods to seed germination, seedling growth, and seed yield traits in maize (Zea mays L.). Results indicated that the seeds primed by gibberellins (GA), NaCl, and polyethylene glycol (PEG) reagents showed a higher imbibitions rate compared to those primed with water. The final germination percentage and germination rate varied with different reagents significantly (P < 0.05). The recommended prime reagents were GA at 10 mg/L, NaCl at 50 mM, and PEG at 15% on account of germination experiment. 15% PEG priming reagent increased shoot and root biomass of maize seedling. The shoot biomass of seedlings after presoaking the seeds with NaCl reagent was significantly higher than the seedlings without priming treatment. No significant differences of plant height, leaf number, and hundred-grain weight were observed between control group and priming treatments. Presoaking with water, NaCl (50 mM), or PEG (15%) significantly increased the hundred-grain weight of maize. Therefore, seed pretreatment is proved to be an effective technique to improve the germination performance, seedling growth, and seed yield of maize. However, when compared with the two methods, if immediate sowing is possible, presoaking is recommended to harvest better benefits compared to priming method.

  12. Radio frequency detection assembly and method for detecting radio frequencies

    DOEpatents

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  13. Narrowband cw injection seeded high power femtosecond double-pass optical parametric generator at 43 MHz: Gain and noise dynamics.

    PubMed

    Linnenbank, Heiko; Steinle, Tobias; Giessen, Harald

    2016-08-22

    We demonstrate narrowband cw injection seeding of a femtosecond double-pass optical parametric generator at 43 MHz repetition rate with a simple, low power external cavity diode laser. Up to 2.5 W of near-IR radiation (1.5 - 1.66 µm) as well as 800 mW of tunable mid-IR radiation (2.75 - 3.15 µm) with pulse durations below 300 fs are generated with a remarkable pulse-to-pulse and long term power stability. Compared to conventional, vacuum noise seeded optical parametric generators, the presented frequency conversion scheme does not only exhibit superior gain and noise dynamics, but also a high degree of flexibility upon control parameters such as pump power, seed power, or spectral position of the seed. PMID:27557233

  14. Seed germination and seedling fitness in Mesua ferrea L. in relation to fruit size and seed number per fruit

    NASA Astrophysics Data System (ADS)

    Khan, M. Latif; Bhuyan, Putul; Shankar, Uma; Todaria, Nagendra P.

    1999-11-01

    Effect of fruit size and seediness (seed number per fruit) was examined on germination and early growth of seedlings in Mesua ferrea L. Fruiting incidence (number of fruited trees in a population) and fruit loading (number of fruits per tree) vary from one year to the other, and were greater in 1997 than in 1998. Seeds from large fruits (> 40 g) are preferred for forestry plantations and those from small fruits (< 40 g) are discarded, despite a greater proportion of small fruits (63.2 %) than large fruits (36.8 %). A fruit, large or small in size, may contain one, two, three or four seeds. The germination percentage of seeds increased from 1-seeded through 4-seeded fruits both in laboratory and greenhouse conditions, and both in case of large and small fruits. Conversely, the mean seed weight and germination time decreased along this gradient, i.e. seeds from 1-seeded fruits were the heaviest and required maximum time for germination, and the seeds from 4-seeded fruits were the lightest and required minimum time for germination. The seeds from small fruits were lighter in weight, achieved lower germination percentages and required greater germination time than the seeds from large fruits in all four seeded categories. Seedlings from seeds from 1-seeded fruits survived better and with stronger vigour after 1 year of growth than seedlings from 2-, 3- and 4-seeded fruits. Further, seedling survival and vigour were greater for seeds from large rather than small fruits.

  15. Effects of seed abundance on seed scatter-hoarding of Edward's rat (Leopoldamys edwardsi Muridae) at the individual level.

    PubMed

    Zhang, Hongmao; Cheng, Jinrui; Xiao, Zhishu; Zhang, Zhibin

    2008-11-01

    Mast seeding is a common phenomenon, and has important effects on seed dispersal and hoarding by animals. At population level, the predator satiation hypothesis proposes that the satiating effect of a large amount of seeds on a relatively small number of predators benefits seed survival in mast-seeding years. However, the effect of mast seeding on the scatter-hoarding of rodents at the individual level is largely unknown. In this study, we investigated the effects of seed abundance (by simulating mast seeding and non-mast seeding) on the removal, consumption and scatter-hoarding of seeds of Camellia oleifera (Theaceae) by Edward's rat Leopoldamys edwardsi (Muridae) in seminatural enclosures in southwest China. We wanted to test the masting-enhanced hoarding hypothesis, which suggests that rodents tend to scatter-hoard more seeds in mast-seeding years in order to occupy more food resources. Our results indicate that L. edwardsi tended to disperse and scatter-hoard more seeds of C. oleifera per night with increasing seed abundance, and to eat less seeds per night when there was a high level of seed abundance in the enclosure experiments. These results support the masting-enhanced hoarding hypothesis. This capacity of rodents may be an evolutionary adaptation to the mast-seeding phenomenon. Our results suggest that mast seeding benefits forest regeneration not only through the predator satiation effect at the population level, but also through increased hoarding by animals at the individual level.

  16. Frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Waarts, Robert G. (Inventor)

    2001-01-01

    A frequency conversion system comprises first and second gain sources providing first and second frequency radiation outputs where the second gain source receives as input the output of the first gain source and, further, the second gain source comprises a Raman or Brillouin gain fiber for wave shifting a portion of the radiation of the first frequency output into second frequency radiation output to provided a combined output of first and second frequencies. Powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

  17. Laser frequency offset synthesizer

    NASA Astrophysics Data System (ADS)

    Lewis, D. A.; Evans, R. M.; Finn, M. A.

    1985-01-01

    A method is reported for locking the frequency difference of two lasers with an accuracy of 0.5 kHz or less over a one-second interval which is simple, stable, and relatively free from systematic errors. Two 633 nm He-Ne lasers are used, one with a fixed frequency and the other tunable. The beat frequency between the lasers is controlled by a voltage applied to a piezoelectric device which varies the cavity length of the tunable laser. This variable beat frequency, scaled by a computer-controlled modulus, is equivalent to a synthesizer. This approach eliminates the need for a separate external frequency synthesizer; furthermore, the phase detection process occurs at a relatively low frequency, making the required electronics simple and straightforward.

  18. The functional evaluation of waste yuzu (Citrus junos) seeds.

    PubMed

    Minamisawa, Mayumi; Yoshida, Shoichiro; Uzawa, Atsushi

    2014-02-01

    We have succeeded in extracting a large amount of expensive limonoids and the high total antioxidant capability yuzu seed oil from waste yuzu seed by simple methods. Yuzu seeds contain higher amounts of fat-soluble limonoid aglycone (330.6 mg g(-1) of dry seed), water-soluble limonoid glycoside (452.0 mg g(-1) of dry seed), and oil (40 mg g(-1) of green seed) than other citrus fruits. The antioxidant activities of yuzu seed aglycone, glycoside, and seed oil were evaluated in vitro. The potential antioxidant activity in oil solution, diphenylpicrylhydrazyl radical-scavenging activity, and hydrogen peroxide-scavenging activity effects of the seed extracts were also investigated. The antioxidant activity of yuzu seed oil was two times that of grapefruit seed oil, which has high activity. Yuzu glycoside produced the same high antioxidant activity as Luo Han Guo glycoside. PMID:24336775

  19. 7 CFR 361.7 - Special provisions for Canadian-origin seed and screenings.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... meets the noxious weed seed tolerances of § 361.6. Such seed will not be subject to the sampling... name the kinds of noxious weed seeds that are to be removed from the lot of seed. Seed being...

  20. 7 CFR 361.7 - Special provisions for Canadian-origin seed and screenings.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... meets the noxious weed seed tolerances of § 361.6. Such seed will not be subject to the sampling... name the kinds of noxious weed seeds that are to be removed from the lot of seed. Seed being...

  1. 7 CFR 361.7 - Special provisions for Canadian-origin seed and screenings.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... meets the noxious weed seed tolerances of § 361.6. Such seed will not be subject to the sampling... name the kinds of noxious weed seeds that are to be removed from the lot of seed. Seed being...

  2. 7 CFR 361.7 - Special provisions for Canadian-origin seed and screenings.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... meets the noxious weed seed tolerances of § 361.6. Such seed will not be subject to the sampling... name the kinds of noxious weed seeds that are to be removed from the lot of seed. Seed being...

  3. 7 CFR 361.7 - Special provisions for Canadian-origin seed and screenings.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... meets the noxious weed seed tolerances of § 361.6. Such seed will not be subject to the sampling... name the kinds of noxious weed seeds that are to be removed from the lot of seed. Seed being...

  4. A seed predator drives the evolution of a seed dispersal mutualism.

    PubMed

    Siepielski, Adam M; Benkman, Craig W

    2008-08-22

    Although antagonists are hypothesized to impede the evolution of mutualisms, they may simultaneously exert selection favouring the evolution of alternative mutualistic interactions. We found that increases in limber pine (Pinus flexilis) seed defences arising from selection exerted by a pre-dispersal seed predator (red squirrel Tamiasciurus hudsonicus) reduced the efficacy of limber pine's primary seed disperser (Clark's nutcracker Nucifraga columbiana) while enhancing seed dispersal by ground-foraging scatter-hoarding rodents (Peromyscus). Thus, there is a shift from relying on primary seed dispersal by birds in areas without red squirrels, to an increasing reliance on secondary seed dispersal by scatter-hoarding rodents in areas with red squirrels. Seed predators can therefore drive the evolution of seed defences, which in turn favour alternative seed dispersal mutualisms that lead to major changes in the mode of seed dispersal. Given that adaptive evolution in response to antagonists frequently impedes one kind of mutualistic interaction, the evolution of alternative mutualistic interactions may be a common by-product. PMID:18460433

  5. Timing of seed dispersal generates a bimodal seed bank depth distribution

    USGS Publications Warehouse

    Espinar, J.L.; Thompson, K.; Garcia, L.V.

    2005-01-01

    The density of soil seed banks is normally highest at the soil surface and declines monotonically with depth. Sometimes, for a variety of reasons, peak density occurs below the surface but, except in severely disturbed soils, it is generally true that deeper seeds are older. In seasonally dry habitats that develop deep soil cracks during the dry season, it is possible that some seeds fall down cracks and rapidly become deeply buried. We investigated this possibility for three dominant clonal perennials (Scirpus maritimus, S. litoralis, and Juncus subulatus) in the Don??ana salt marsh, a nontidal marsh with a Mediterranean climate located in southwest Spain. Two species, which shed most of their seed during the dry season and have seeds with low buoyancy, had bimodal viable seed depth distributions, with peak densities at the surface and at 16-20 cm. A third species, which shed most seeds after soil cracks had closed and had seeds with high buoyancy, had viable seeds only in surface soil. Bimodal seed bank depth distributions may be relatively common in seasonally dry habitats with fine-textured soils, but their ecological significance has not been investigated.

  6. Seed morphology characteristics in relation to seed loss by water erosion in the Loess Plateau.

    PubMed

    Jiao, Juying; Han, Luyan; Jia, Yanfeng; Lei, Dong; Wang, Ning; Li, Linyu

    2013-01-01

    The role of water erosion on seed loss and on plant establishment and distribution is unknown on the Chinese Loess Plateau, which suffers serious soil erosion. The seed susceptibility of 16 local species to removal by water erosion from loess slopes was determined by rainfall simulation experiments. The experiments were performed on slopes with gradients of 10°, 15°, 20° and 25° for a 60-min duration at an intensity of 50 mm/h, 100 mm/h and 150 mm/h, respectively. The total seed removal rate obviously increased with rainfall intensity but did not obviously change with slope gradient, and the responses were varied among the species. The morphological characteristics affecting seed loss of the various species are quite different. Our experiments showed that the seed removal from some species are mainly due to seed weight, some species are mainly affected by seed shape, some are affected by appendage, some by surface structure, some by the comprehensive effects of the different morphological characteristics, while seeds having mucilage secretion are not easily moved by water erosion. We argued that the seed removal during water erosion can clearly effect seed redistribution and deposition, and consequently, species composition and vegetation spatial distribution.

  7. A seed predator drives the evolution of a seed dispersal mutualism.

    PubMed

    Siepielski, Adam M; Benkman, Craig W

    2008-08-22

    Although antagonists are hypothesized to impede the evolution of mutualisms, they may simultaneously exert selection favouring the evolution of alternative mutualistic interactions. We found that increases in limber pine (Pinus flexilis) seed defences arising from selection exerted by a pre-dispersal seed predator (red squirrel Tamiasciurus hudsonicus) reduced the efficacy of limber pine's primary seed disperser (Clark's nutcracker Nucifraga columbiana) while enhancing seed dispersal by ground-foraging scatter-hoarding rodents (Peromyscus). Thus, there is a shift from relying on primary seed dispersal by birds in areas without red squirrels, to an increasing reliance on secondary seed dispersal by scatter-hoarding rodents in areas with red squirrels. Seed predators can therefore drive the evolution of seed defences, which in turn favour alternative seed dispersal mutualisms that lead to major changes in the mode of seed dispersal. Given that adaptive evolution in response to antagonists frequently impedes one kind of mutualistic interaction, the evolution of alternative mutualistic interactions may be a common by-product.

  8. Grazing impact on desert plants and soil seed banks: Implications for seed-eating animals

    NASA Astrophysics Data System (ADS)

    Pol, Rodrigo G.; Sagario, M. Cecilia; Marone, Luis

    2014-02-01

    We assess whether the knowledge of livestock diet helps to link grazing effects with changes in plant cover and soil seed bank size, aiming at inferring the consequences of grazing on seed-eating animals. Specifically, we test whether continuous and heavy grazing reduce the cover, number of reproductive structures and seed reserves of the same grass species whose seeds are selected and preferred by granivorous animals in the central Monte desert, Argentina. Grass cover and the number of grass spikes usually diminished under grazing conditions in the two localities studied (Telteca and Ñacuñán), and soil seed bank was consistently reduced in all three years evaluated owing to a decline of perennial grass and forb seeds. In particular, the abundance of those seeds selected and preferred by birds and ants (in all cases grass species) declined 70-92% in Ñacuñán, and 52-72% in Telteca. Reduction of perennial grass cover and spike number in grazed sites reinforced the causal link between livestock grazing and the decline of grass soil seed reserves throughout failed plant reproduction. Grass seed bank depletion suggests that grazing may trigger a "cascade" of mechanisms that affect the abundance and persistence of valuable fodder species as well as the availability of seed resources for granivorous animals.

  9. Anomalous, extreme weather disrupts obligate seed dispersal mutualism: snow in a subtropical forest ecosystem.

    PubMed

    Zhou, Youbing; Newman, Chris; Chen, Jin; Xie, Zongqiang; Macdonald, David W

    2013-09-01

    Ongoing global climate change is predicted to increase the frequency and magnitude of extreme weather events, impacting population dynamics and community structure. There is, however, a critical lack of case studies considering how climatic perturbations affect biotic interactions. Here, we document how an obligate seed dispersal mutualism was disrupted by a temporally anomalous and meteorologically extreme interlude of unseasonably frigid weather, with accompanying snowstorms, in subtropical China, during January-February 2008. Based on the analysis of 5892 fecal samples (representing six mammalian seed dispersers), this event caused a substantial disruption to the relative seed dispersal function for the raisin tree Hovenia dulcis from prestorm 6.29 (2006) and 11.47 (2007), down to 0.35 during the storm (2008). Crucially, this was due to impacts on mammalian seed dispersers and not due to a paucity of fruit, where 4.63 fruit per branch were available in January 2008, vs. 3.73 in 2006 and 3.58 in 2007. An induced dietary shift occurred among omnivorous carnivores during this event, from the consumption fruit to small mammals and birds, reducing their role in seed dispersal substantially. Induced range shift extinguished the functionality of herbivorous mammals completely, however, seed dispersal function was compensated in part by three omnivorous carnivores during poststorm years, and thus while the mutualism remained intact it was enacted by a narrower assemblage of species, rendering the system more vulnerable to extrinsic perturbations. The storm's extended effects also had anthropogenic corollaries - migrating ungulates becoming exposed to heightened levels of illegal hunting - causing long-term modification to the seed dispersal community and mutualism dynamics. Furthermore, degraded forests proved especially vulnerable to the storm's effects. Considering increasing climate variability and anthropogenic disturbance, the impacts of such massive, aberrant

  10. Nonlinear Frequency Compression

    PubMed Central

    Scollie, Susan; Glista, Danielle; Seelisch, Andreas

    2013-01-01

    Frequency lowering technologies offer an alternative amplification solution for severe to profound high frequency hearing losses. While frequency lowering technologies may improve audibility of high frequency sounds, the very nature of this processing can affect the perceived sound quality. This article reports the results from two studies that investigated the impact of a nonlinear frequency compression (NFC) algorithm on perceived sound quality. In the first study, the cutoff frequency and compression ratio parameters of the NFC algorithm were varied, and their effect on the speech quality was measured subjectively with 12 normal hearing adults, 12 normal hearing children, 13 hearing impaired adults, and 9 hearing impaired children. In the second study, 12 normal hearing and 8 hearing impaired adult listeners rated the quality of speech in quiet, speech in noise, and music after processing with a different set of NFC parameters. Results showed that the cutoff frequency parameter had more impact on sound quality ratings than the compression ratio, and that the hearing impaired adults were more tolerant to increased frequency compression than normal hearing adults. No statistically significant differences were found in the sound quality ratings of speech-in-noise and music stimuli processed through various NFC settings by hearing impaired listeners. These findings suggest that there may be an acceptable range of NFC settings for hearing impaired individuals where sound quality is not adversely affected. These results may assist an Audiologist in clinical NFC hearing aid fittings for achieving a balance between high frequency audibility and sound quality. PMID:23539261

  11. Frequency Response Analysis Tool

    SciTech Connect

    Etingov, Pavel V.; Kosterev, Dmitry; Dai, T.

    2014-12-31

    Frequency response has received a lot of attention in recent years at the national level, which culminated in the development and approval of North American Electricity Reliability Corporation (NERC) BAL-003-1 Frequency Response and Frequency Bias Setting Reliability Standard. This report is prepared to describe the details of the work conducted by Pacific Northwest National Laboratory (PNNL) in collaboration with the Bonneville Power Administration and Western Electricity Coordinating Council (WECC) Joint Synchronized Information Subcommittee (JSIS) to develop a frequency response analysis tool (FRAT). The document provides the details on the methodology and main features of the FRAT. The tool manages the database of under-frequency events and calculates the frequency response baseline. Frequency response calculations are consistent with frequency response measure (FRM) in NERC BAL-003-1 for an interconnection and balancing authority. The FRAT can use both phasor measurement unit (PMU) data, where available, and supervisory control and data acquisition (SCADA) data. The tool is also capable of automatically generating NERC Frequency Response Survey (FRS) forms required by BAL-003-1 Standard.

  12. The conservation physiology of seed dispersal

    PubMed Central

    Ruxton, Graeme D.; Schaefer, H. Martin

    2012-01-01

    At a time when plant species are experiencing increasing challenges from climate change, land-use change, harvesting and invasive species, dispersal has become a very important aspect of plant conservation. Seed dispersal by animals is particularly important because some animals disperse seeds to suitable sites in a directed fashion. Our review has two aims: (i) to highlight the various ways plant dispersal by animals can be affected by current anthropogenic change and (ii) to show the important role of plant and (particularly) animal physiology in shaping seed–dispersal interactions. We argue that large-bodied seed dispersers may be particularly important for plant conservation because seed dispersal of large-seeded plants is often more specialized and because large-bodied animals are targeted by human exploitation and have smaller population sizes. We further argue that more specialized seed-dispersal systems on island ecosystems might be particularly at risk from climate change both owing to small population sizes involved but also owing to the likely thermal specialization, particularly on tropical islands. More generally, the inherent vulnerability of seed-dispersal mutualisms to disruption driven by environmental change (as well as their ubiquity) demands that we continue to improve our understanding of their conservation physiology. PMID:22566677

  13. The efficient flight of Ruellia ciliatiflora seeds

    NASA Astrophysics Data System (ADS)

    Whitaker, Dwight; Marsh, Franklin; Chen, Peter; Vejar, David; Babb, Patrick; Castillo, Josue; Cordero, Sabrina; Lumban-Gaol, Maharani; Mora, Irlanda; Partida, Tania; Pineda, Julian; Rodriguez, Aaron

    2014-11-01

    The seeds of Ruellia ciliatiflora are small disks measuring approximately 3 mm in diameter and 0.3 mm in height, which are launched from exploding fruits at speeds exceeding 10 m/s. The seeds fly with backspin such that the axis of symmetry is parallel to the ground. With rotation rates that exceed 1 kHz they keep an aerodynamic profile and move through the air with a extremely low drag. Using high-speed video we have learned that the drag coefficients for these flying seeds can measure less than 0.01 for those launched with the least wobble. To understand the role of seed morphology and rotation rate on the flight of the seeds, we will also present work using 3D printed models of the seeds for studies in wind tunnels. Three-dimensional models are created by photographing seeds from many angles and inferring a shape using commercial software, which also creates a printable model. These studies should help guide work that compares explosions from fruits within the Acanthaceae family to which R. ciliatiflora belongs. This family consists of over 2000 species with exploding fruit with diverse habitats and morphologies.

  14. Oxygen requirement of germinating flax seeds

    NASA Technical Reports Server (NTRS)

    Kuznetsov, Oleg A.; Hasenstein, K. H.; Hasentein, K. H. (Principal Investigator)

    2003-01-01

    Plant experiments in earth orbit are typically prepared on the ground and germinated in orbit to study gravity effects on the developing seedlings. Germination requires the breakdown of storage compounds, and this metabolism depends upon respiration, making oxygen one of the limiting factors in seed germination. In microgravity lack of run-off of excess water requires careful testing of water dispensation and oxygen availability. In preparation for a shuttle experiment (MICRO on STS-107) we studied germination and growth of flax (Linum usitatissimum L.) seedlings in the developed hardware (Magnetic Field Chamber, MFC). We tested between four to 32 seeds per chamber (air volume=14 mL) and after 36 h measured the root length. At 90 microliters O2 per seed (32 seeds/chamber), the germination decreased from 94 to 69%, and the root length was reduced by 20%, compared to 8 seeds per chamber. Based on the percent germination and root length obtained in controlled gas mixtures between 3.6 and 21.6% O2 we determined the lower limit of reliable germination to be 10 vol. % O2 at atmospheric pressure. Although the oxygen available in the MFC's can support the intended number of seeds, the data show that seed storage and microgravity-related limitations may reduce germination. c2003 Published by Elsevier Ltd on behalf of COSPAR.

  15. Oxygen requirement of germinating flax seeds

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Oleg A.; Hasenstein, K. H.

    2003-05-01

    Plant experiments in earth orbit are typically prepared on the ground and germinated in orbit to study gravity effects on the developing seedlings. Germination requires the breakdown of storage compounds, and this metabolism depends upon respiration, making oxygen one of the limiting factors in seed germination. In microgravity lack of run-off of excess water requires careful testing of water dispensation and oxygen availability. In preparation for a shuttle experiment (MICRO on STS-107) we studied germination and growth of flax ( Linum usitatissimum L.) seedlings in the developed hardware (Magnetic Field Chamber, MFC). We tested between four to 32 seeds per chamber (air volume = 14 mL) and after 36 h measured the root length. At 90 μl O 2 per seed (32 seeds/chamber), the germination decreased from 94 to 69%, and the root length was reduced by 20%, compared to 8 seeds per chamber. Based on the percent germination and root length obtained in controlled gas mixtures between 3.6 and 21.6% O 2 we determined the lower limit of reliable germination to be 10 vol. % O 2 at atmospheric pressure. Although the oxygen available in the MFC's can support the intended number of seeds, the data show that seed storage and microgravity-related limitations may reduce germination.

  16. On the reaction coordinate for seeded crystallisation

    NASA Astrophysics Data System (ADS)

    Jungblut, Swetlana; Dellago, Christoph

    2015-09-01

    Small pre-structured seeds introduced into an undercooled fluid are known to increase the crystal nucleation rate by some orders of magnitude, if the structure of the seeds is commensurate with the bulk crystalline phase. The presence of such seeds also alters the crystallisation mechanism by favouring particular structures at the early stages of the nucleation process. Here, we study with computer simulations the effect of small face-centred cubic and body-centred cubic seeds on the crystallisation of a Lennard-Jones liquid in the strongly undercooled regime. We find that seeds with body-centred cubic structure lead to a larger enhancement of the crystallisation rate than face-centred cubic seeds. An analysis of recurrence times reveals that the size of the largest crystalline cluster used as reaction coordinate is affected by pronounced memory effects, which depend on the particular seed structure and point to the importance of structural information in the definition of a good reaction coordinate for crystallisation.

  17. Studies in Wild Oat Seed Dormancy

    PubMed Central

    Adkins, Stephen W.; Ross, James D.

    1981-01-01

    Seed of Avena fatua were shown to exhibit a characteristic loss of dormancy during dry storage at 25 C, whereas similar seed stored at 5 C maintained dormancy. 2-Chloroethylphosphonic acid was shown to increase germination of partly dormant seed imbibed under certain temperature regimes; a similar effect could not be established for fully dormant or fully nondormant seed. Using gas-liquid chromatography, natural ethylene levels were followed during imbibition of fully dormant and nondormant seed. A large peak in production was observed in the period prior to radicle emergence in the case of the nondormant seed. Measurements of ethylene production taken at 15 C, following periods of after-ripening in moist soil at either 5 or 25 C, indicated that endogenous production was unlikely to be a main cause of dormancy breakage in this species. The possibility that endogenous ethylene could play a role in natural dormancy breakage in aged seeds is discussed. The practical possibilities of 2-chloroethylphosphonic acid as a dormancy breaking agent in a field situation are outlined. PMID:16661675

  18. Sucrose metabolism in lima bean seeds

    SciTech Connect

    Xu, Dianpeng; Sung, Shijean, S.; Black, C.C. )

    1989-04-01

    Developing and germinating lima bean (Phaseolus lunatus var Cangreen) seeds were used for testing the sucrose synthase pathway, to examine the competition for uridine diphosphate (UDP) and pyrophosphate (PPi), and to identify adaptive and maintenance-type enzymes in glycolysis and gluconeogenesis. In developing seeds, sucrose breakdown was dominated by the sucrose synthase pathway; but in the seedling embryos, both the sucrose synthase pathway and acid invertase were active. UDPase activity was low and seemingly insufficient to compete for UDP during sucrose metabolism in seed development or germination. In contrast, both an acid and alkaline pyrophosphatase were active in seed development and germination. The set of adaptive enzymes identified in developing seeds were sucrose synthase, PPi-dependent phosphofructokinase, plus acid and alkaline pyrophosphatase; and, the adaptive enzymes identified in germinating seeds included the same set of enzymes plus acid invertase. The set of maintenance enzymes identified during development, in the dry seed, and during germination were UDP-glucopyrophosphorylase, neutral invertase, ATP and UTP-dependent fructokinase, glucokinase, phosphoglucomutase, ATP and UTP-dependent phosphofructokinase and sucrose-P synthase.

  19. Sucrose metabolism in lima bean seeds.

    PubMed

    Xu, D P; Sung, S J; Black, C C

    1989-04-01

    Developing and germinating lima bean (Phaseolus lunatus var Cangreen) seeds were used for testing the sucrose synthase pathway, to examine the competition for uridine diphosphate (UDP) and pyrophosphate (PPi), and to identify adaptive and maintenance-type enzymes in glycolysis and gluconeogenesis. In developing seeds, sucrose breakdown was dominated by the sucrose synthase pathway; but in the seedling embryos, both the sucrose synthase pathway and acid invertase were active. UDPase activity was low and seemingly insufficient to compete for UDP during sucrose metabolism in seed development or germination. In contrast, both an acid and alkaline pyrophosphatase were active in seed development and germination. The set of adaptive enzymes identified in developing seeds were sucrose synthase, PPi-dependent phosphofructokinase, plus acid and alkaline pyrophosphatase; and, the adaptive enzymes identified in germinating seeds included the same set of enzymes plus acid invertase. The set of maintenance enzymes identified during development, in the dry seed, and during germination were UDP-glucopyrophosphorylase, neutral invertase, ATP and UTP-dependent fructokinase, glucokinase, phosphoglucomutase, ATP and UTP-dependent phosphofructokinase and sucrose-P synthase.

  20. Triple Modulator-Chicane Scheme for Seeding Sub-Nanometer X-Ray Free Electron Lasers

    SciTech Connect

    Xiang, Dao; Stupakov, Gennady; /SLAC

    2011-07-06

    We propose a novel triple modulator-chicane (TMC) scheme to convert external input seed to shorter wavelengths. In the scheme high power seed lasers are used in the first and third modulator while only very low power seed is used in the second modulator. By properly choosing the parameters of the lasers and chicanes, we show that ultrahigh harmonics can be generated in the TMC scheme while simultaneously keeping the energy spread growth much smaller than beam's initial slice energy spread. As an example we show the feasibility of generating significant bunching at 1 nm and below from a low power ({approx} 100 kW) high harmonic generation seed at 20 nm assisted by two high power ({approx} 100 MW) UV lasers at 200 nm while keeping the energy spread growth within 40%. The supreme up-frequency conversion efficiency of the proposed TMC scheme together with its unique advantage in maintaining beam energy spread opens new opportunities for generating fully coherent x-rays at sub-nanometer wavelength from external seeds.

  1. Genotyping of endosperms to determine seed dormancy genes regulating germination through embryonic, endospermic, or maternal tissues in rice.

    PubMed

    Gu, Xing-You; Zhang, Jinfeng; Ye, Heng; Zhang, Lihua; Feng, Jiuhuan

    2014-12-04

    Seed dormancy is imposed by one or more of the embryo, endosperm, and maternal tissues that belong to two generations and represent two ploidy levels. Many quantitative trait loci (QTL) have been identified for seed dormancy as measured by gross effects on reduced germination rate or delayed germination in crop or model plants. This research developed an endosperm genotype-based genetic approach to determine specific tissues through which a mapped QTL regulates germination using rice as a model. This approach involves testing germination velocity for partially after-ripened seeds harvested from single plants heterozygous for a tested QTL and genotyping endosperms from individual germinated and nongerminated seeds with a codominant DNA marker located on the QTL peak region. Information collected about the QTL includes genotypic frequencies in germinated and/or nongerminated subpopulations; allelic frequency distributions during a germination period; endosperm or embryo genotypic differences in germination velocity; and genotypic frequencies for gametes involved in the double fertilization to form the sampled seeds. Using this approach, the seed dormancy loci SD12, SD1-2, and SD7-1 were determined to regulate germination through the embryo, endosperm, and maternal tissues, respectively; SD12 and SD1-2 acted additively on germination velocity in the offspring tissues; and SD12 also was associated with the preferential fertilization of male gametes in rice. This new genetic approach can be used to characterize mapped genes/QTL for tissue-specific functions in endospermic seeds and for marker-assisted selection of QTL alleles before or immediately after germination in crop breeding.

  2. Genotyping of Endosperms to Determine Seed Dormancy Genes Regulating Germination Through Embryonic, Endospermic, or Maternal Tissues in Rice

    PubMed Central

    Gu, Xing-You; Zhang, Jinfeng; Ye, Heng; Zhang, Lihua; Feng, Jiuhuan

    2014-01-01

    Seed dormancy is imposed by one or more of the embryo, endosperm, and maternal tissues that belong to two generations and represent two ploidy levels. Many quantitative trait loci (QTL) have been identified for seed dormancy as measured by gross effects on reduced germination rate or delayed germination in crop or model plants. This research developed an endosperm genotype−based genetic approach to determine specific tissues through which a mapped QTL regulates germination using rice as a model. This approach involves testing germination velocity for partially after-ripened seeds harvested from single plants heterozygous for a tested QTL and genotyping endosperms from individual germinated and nongerminated seeds with a codominant DNA marker located on the QTL peak region. Information collected about the QTL includes genotypic frequencies in germinated and/or nongerminated subpopulations; allelic frequency distributions during a germination period; endosperm or embryo genotypic differences in germination velocity; and genotypic frequencies for gametes involved in the double fertilization to form the sampled seeds. Using this approach, the seed dormancy loci SD12, SD1-2, and SD7-1 were determined to regulate germination through the embryo, endosperm, and maternal tissues, respectively; SD12 and SD1-2 acted additively on germination velocity in the offspring tissues; and SD12 also was associated with the preferential fertilization of male gametes in rice. This new genetic approach can be used to characterize mapped genes/QTL for tissue-specific functions in endospermic seeds and for marker-assisted selection of QTL alleles before or immediately after germination in crop breeding. PMID:25480961

  3. Chalazal seed coat development in Brassica napus.

    PubMed

    Millar, Jenna L; Khan, Deirdre; Becker, Michael G; Chan, Ainsley; Dufresne, André; Sumner, Michael; Belmonte, Mark F

    2015-12-01

    The chalazal seed coat (CZSC) is a maternal subregion adjacent to the funiculus which serves as the first point of entry into the developing seed. This subregion is of particular interest in Brassica napus (canola) because of its location within the seed and its putative contribution to seed filling processes. In this study, the CZSC of canola was characterized at an anatomical and molecular level to (i) describe the cellular and subcellular features of the CZSC throughout seed development, (ii) reveal cellular features of the CZSC that relate to transport processes, (iii) study gene activity of transporters and transcriptional regulators in the CZSC subregion over developmental time, and (iv) briefly investigate the contribution of the A and C constituent genomes to B. napus CZSC gene activity. We found that the CZSC contains terminating ends of xylem and phloem as well as a mosaic of endomembrane and plasmodesmatal connections, suggesting that this subregion is likely involved in the transport of material and information from the maternal tissues of the plant to other regions of the seed. Laser microdissection coupled with quantitative RT-PCR identified the relative abundance of sugar, water, auxin and amino acid transporter homologs inherited from the constituent genomes of this complex polyploid. We also studied the expression of three transcription factors that were shown to co-express with these biological processes providing a preliminary framework for the regulatory networks responsible for seed filling in canola and discuss the relationship of the CZSC to other regions and subregions of the seed and its role in seed development.

  4. The oxygen requirement of germinating flax seeds

    NASA Astrophysics Data System (ADS)

    Kuznetsov, O.; Hasenstein, K.

    Experiments for earth orbit are typically prepared on the ground and often germinated in orbit in order to study gravity effects on developing seedlings. Germination requires the breakdown of storage compounds and respiration. In orbit the formation of a water layer around the seed may further limit oxygen availability. Therefore, the oxygen content of the available gas volume is one of the limiting factors for seed germination. In preparation for an upcoming shuttle experiment (MICRO on STS-107) we studied germination and growth of flax (Linum usitatissimum L.) seedlings in the developed hardware. We tested per seed chamber (gas volume = 14 mL, O2 = 2.9 mL) between 4 to 32 seeds glued to germination paper by 1% (w/v) gum guar. A lexan cover and a gasket hermetically sealed each of the eight chambers. For imbibition of the seeds a previously optimized amount of distilled water was dispensed through sealed inlets. The seedlings were allowed to grow for either 32 to 48 h on a clinostat or without microgravity simulation. Then their root length was measured. With 32 seeds per chamber, four times the intended number of seeds for the flight, the germination rate decreased from 94 to 69%, and the root length was reduced by 20%. Experiments on the germination and root length in controlled atmospheres (5, 10, 15 and 21% O2 ) suggest that germination and growth for two days requires about 200 :l of O (1 mL air) per seed. Our2 experiments correlate oxygen dependency from seed mass and germination temperature, and analyze accumulation of gaseous metabolites (supported by NASA grant NAG10-0190).

  5. SUPERMASSIVE SEEDS FOR SUPERMASSIVE BLACK HOLES

    SciTech Connect

    Johnson, Jarrett L.; Whalen, Daniel J.; Li Hui; Holz, Daniel E.

    2013-07-10

    Recent observations of quasars powered by supermassive black holes (SMBHs) out to z {approx}> 7 constrain both the initial seed masses and the growth of the most massive black holes (BHs) in the early universe. Here we elucidate the implications of the radiative feedback from early generations of stars and from BH accretion for popular models for the formation and growth of seed BHs. We show that by properly accounting for (1) the limited role of mergers in growing seed BHs as inferred from cosmological simulations of early star formation and radiative feedback, (2) the sub-Eddington accretion rates of BHs expected at the earliest times, and (3) the large radiative efficiencies {epsilon} of the most massive BHs inferred from observations of active galactic nuclei at high redshift ({epsilon} {approx}> 0.1), we are led to the conclusion that the initial BH seeds may have been as massive as {approx}> 10{sup 5} M{sub Sun }. This presents a strong challenge to the Population III seed model, which calls for seed masses of {approx}100 M{sub Sun} and, even with constant Eddington-limited accretion, requires {epsilon} {approx}< 0.09 to explain the highest-z SMBHs in today's standard {Lambda}CDM cosmological model. It is, however, consistent with the prediction of the direct collapse scenario of SMBH seed formation, in which a supermassive primordial star forms in a region of the universe with a high molecule-dissociating background radiation field, and collapses directly into a 10{sup 4}-10{sup 6} M{sub Sun} seed BH. These results corroborate recent cosmological simulations and observational campaigns which suggest that these massive BHs were the seeds of a large fraction of the SMBHs residing in the centers of galaxies today.

  6. Stability and generalization in seed dispersal networks: a case study of frugivorous fish in Neotropical wetlands.

    PubMed

    Correa, Sandra Bibiana; Arujo, Joisiane K; Penha, Jerry; Nunes da Cunha, Catia; Bobier, Karen E; Anderson, Jill T

    2016-08-31

    When species within guilds perform similar ecological roles, functional redundancy can buffer ecosystems against species loss. Using data on the frequency of interactions between fish and fruit, we assessed whether co-occurring frugivores provide redundant seed dispersal services in three species-rich Neotropical wetlands. Our study revealed that frugivorous fishes have generalized diets; however, large-bodied fishes had greater seed dispersal breadth than small species, in some cases, providing seed dispersal services not achieved by smaller fish species. As overfishing disproportionately affects big fishes, the extirpation of these species could cause larger secondary extinctions of plant species than the loss of small specialist frugivores. To evaluate the consequences of frugivore specialization for network stability, we extracted data from 39 published seed dispersal networks of frugivorous birds, mammals and fish (our networks) across ecosystems. Our analysis of interaction frequencies revealed low frugivore specialization and lower nestedness than analyses based on binary data (presence-absence of interactions). In that case, ecosystems may be resilient to loss of any given frugivore. However, robustness to frugivore extinction declines with specialization, such that networks composed primarily of specialist frugivores are highly susceptible to the loss of generalists. In contrast with analyses of binary data, recently developed algorithms capable of modelling interaction strengths provide opportunities to enhance our understanding of complex ecological networks by accounting for heterogeneity of frugivore-fruit interactions. PMID:27581879

  7. Post-Fire Recovery in Coastal Sage Scrub: Seed Rain and Community Trajectory.

    PubMed

    Conlisk, Erin; Swab, Rebecca; Martínez-Berdeja, Alejandra; Daugherty, Matthew P

    2016-01-01

    Disturbance is a primary mechanism structuring ecological communities. However, human activity has the potential to alter the frequency and intensity of natural disturbance regimes, with subsequent effects on ecosystem processes. In Southern California, human development has led to increased fire frequency close to urban areas that can form a positive feedback with invasive plant spread. Understanding how abiotic and biotic factors structure post-fire plant communities is a critical component of post-fire management and restoration. In this study we considered a variety of mechanisms affecting post-fire vegetation recovery in Riversidean sage scrub. Comparing recently burned plots to unburned plots, we found that burning significantly reduced species richness and percent cover of exotic vegetation the first two years following a 100-hectare wildfire. Seed rain was higher in burned plots, with more native forb seeds, while unburned plots had more exotic grass seeds. Moreover, there were significant correlations between seed rain composition and plant cover composition the year prior and the year after. Collectively, this case study suggests that fire can alter community composition, but there was not compelling evidence of a vegetation-type conversion. Instead, the changes in the community composition were temporary and convergence in community composition was apparent within two years post-fire.

  8. Stability and generalization in seed dispersal networks: a case study of frugivorous fish in Neotropical wetlands.

    PubMed

    Correa, Sandra Bibiana; Arujo, Joisiane K; Penha, Jerry; Nunes da Cunha, Catia; Bobier, Karen E; Anderson, Jill T

    2016-08-31

    When species within guilds perform similar ecological roles, functional redundancy can buffer ecosystems against species loss. Using data on the frequency of interactions between fish and fruit, we assessed whether co-occurring frugivores provide redundant seed dispersal services in three species-rich Neotropical wetlands. Our study revealed that frugivorous fishes have generalized diets; however, large-bodied fishes had greater seed dispersal breadth than small species, in some cases, providing seed dispersal services not achieved by smaller fish species. As overfishing disproportionately affects big fishes, the extirpation of these species could cause larger secondary extinctions of plant species than the loss of small specialist frugivores. To evaluate the consequences of frugivore specialization for network stability, we extracted data from 39 published seed dispersal networks of frugivorous birds, mammals and fish (our networks) across ecosystems. Our analysis of interaction frequencies revealed low frugivore specialization and lower nestedness than analyses based on binary data (presence-absence of interactions). In that case, ecosystems may be resilient to loss of any given frugivore. However, robustness to frugivore extinction declines with specialization, such that networks composed primarily of specialist frugivores are highly susceptible to the loss of generalists. In contrast with analyses of binary data, recently developed algorithms capable of modelling interaction strengths provide opportunities to enhance our understanding of complex ecological networks by accounting for heterogeneity of frugivore-fruit interactions.

  9. Post-Fire Recovery in Coastal Sage Scrub: Seed Rain and Community Trajectory.

    PubMed

    Conlisk, Erin; Swab, Rebecca; Martínez-Berdeja, Alejandra; Daugherty, Matthew P

    2016-01-01

    Disturbance is a primary mechanism structuring ecological communities. However, human activity has the potential to alter the frequency and intensity of natural disturbance regimes, with subsequent effects on ecosystem processes. In Southern California, human development has led to increased fire frequency close to urban areas that can form a positive feedback with invasive plant spread. Understanding how abiotic and biotic factors structure post-fire plant communities is a critical component of post-fire management and restoration. In this study we considered a variety of mechanisms affecting post-fire vegetation recovery in Riversidean sage scrub. Comparing recently burned plots to unburned plots, we found that burning significantly reduced species richness and percent cover of exotic vegetation the first two years following a 100-hectare wildfire. Seed rain was higher in burned plots, with more native forb seeds, while unburned plots had more exotic grass seeds. Moreover, there were significant correlations between seed rain composition and plant cover composition the year prior and the year after. Collectively, this case study suggests that fire can alter community composition, but there was not compelling evidence of a vegetation-type conversion. Instead, the changes in the community composition were temporary and convergence in community composition was apparent within two years post-fire. PMID:27649564

  10. Effects of prolonged exposure of lettuce seeds to HZE particles on orbital stations

    NASA Astrophysics Data System (ADS)

    Nevzgodina, L. V.; Maksimova, E. N.; Kaminskaya, E. V.

    In a study of the biological effects of cosmic HZE particles, lettuce (Lactuca sativa) seeds were flown on the orbital stations Salyut 6 and 7 for varying periods of time (from 40 to 457 days). The dependence of the biological damage on flight duration, physical parameters and the fact of passage of an HZE particle through the seed was estimated using the criterion of the frequency of aberrant cells. The arrangement of the flight biological container Biobloc made it possible to trace the location of tracks of individual HZE particles with Z>=6 and LET 200 keV/um. In seeds hit by HZE particles, for all exposure times, a statistically significant much higher yield of aberrant cells and also of cells containing multiple chromosome aberrations was observed than in the control material. The frequency of aberrant cells is markedly higher (by a factor of 1,5) in seeds hit than in non-hit ones. The changes of the yield of aberrant cells as a function of the absorbed dose (3.2-63.4 mGy) and the fluence (4.8-44.2 particles/cm2) are linear for the exposure duration ranging from 40 to 457 days.

  11. Post-Fire Recovery in Coastal Sage Scrub: Seed Rain and Community Trajectory

    PubMed Central

    Conlisk, Erin; Swab, Rebecca; Martínez-Berdeja, Alejandra; Daugherty, Matthew P.

    2016-01-01

    Disturbance is a primary mechanism structuring ecological communities. However, human activity has the potential to alter the frequency and intensity of natural disturbance regimes, with subsequent effects on ecosystem processes. In Southern California, human development has led to increased fire frequency close to urban areas that can form a positive feedback with invasive plant spread. Understanding how abiotic and biotic factors structure post-fire plant communities is a critical component of post-fire management and restoration. In this study we considered a variety of mechanisms affecting post-fire vegetation recovery in Riversidean sage scrub. Comparing recently burned plots to unburned plots, we found that burning significantly reduced species richness and percent cover of exotic vegetation the first two years following a 100-hectare wildfire. Seed rain was higher in burned plots, with more native forb seeds, while unburned plots had more exotic grass seeds. Moreover, there were significant correlations between seed rain composition and plant cover composition the year prior and the year after. Collectively, this case study suggests that fire can alter community composition, but there was not compelling evidence of a vegetation-type conversion. Instead, the changes in the community composition were temporary and convergence in community composition was apparent within two years post-fire. PMID:27649564

  12. Competition between meiotic and apomictic pathways during ovule and seed development results in clonality.

    PubMed

    Hojsgaard, Diego H; Martínez, Eric J; Quarin, Camilo L

    2013-01-01

    Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring. A high variation in the frequencies of sexual and apomictic pathways occurred at the first two stages. A trend of radical decline in realized sexuality was then observed. Sexual and apomictic seeds were produced, but the efficiency of the sexual pathway dropped drastically, and exclusively clonal offspring remained. Both reproductive pathways are unstable at the beginning of development, and only the apomictic one remains functional. Key factors reducing sexuality are the faster growth and parthenogenetic development in the aposporous pathway, and an (epi)genetically negative background related to the extensive gene de-regulation pattern responsible for apomixis. The effects of inbreeding depression during post-fertilization development may further decrease the frequency of effective sexuality.

  13. Interaction of microwaves and germinating seeds

    SciTech Connect

    Shafer, F.L.

    1987-01-01

    The preliminary investigation measured the internal metabolic process by ATP production. Leakage of ions and organic material from germinating seeds indicated that membranes are a target of microwaves and heat. Electron photo-micrographs showed an increase in damage to membranes as heat and microwave treatments were increased. The second phase of this investigation was concerned with determining some of the biological activity at the initiation of germination of wheat seed, Triticum aestivum L., using a resonating microwave cavity oscillating at 9.3 GHz as a probe. Direct current conductivity measurements were also made on the seeds as a means of confirming the observations made with the microwave cavity.

  14. Nutrient Value of Leaf vs. Seed

    PubMed Central

    Edelman, Marvin; Colt, Monica

    2016-01-01

    Major differences stand out between edible leaves and seeds in protein quality, vitamin, and mineral concentrations and omega 6/omega 3 fatty acid ratios. Data for seeds (wheat, rice, corn, soy, lentil, chick pea) are compared with corresponding data for edible green leaves (kale, spinach, broccoli, duckweed). An x/y representation of data for lysine and methionine content highlights the group differences between grains, pulses, leafy vegetables, and animal foods. Leaves come out with flying colors in all these comparisons. The perspective ends with a discussion on “So why do we eat mainly seeds?” PMID:27493937

  15. Seed gum of Stryphnodendron barbatiman (Barbatimao)

    SciTech Connect

    Reicher, F.; Leitner, S.C.S.; Fontana, J.D.; Correa, J.B.C.; Sierakowski, M.R.

    1991-12-31

    Stryphnodendron barbatiman (barbatimao) is a native tree that is found throughout the {open_quotes}Cerrados,{close_quotes} a region of Central Brazil. Plant seeds, on water extraction, furnished 28 g% galactomannan (dry-weight basis), the monosaccharide composition of which (galactose to mannose ratio, 1.0:1.5) fits in the legume heteromannan group. This seed gum, after Sevag deproteinization, still retained 6 g% of associated protein and had a molecular weight of about 1.8 MD on gel filtration. A high intrinsic viscosity (1300 cP) was observed for the polysaccharide sample obtained after reflux of the crushed seeds in 80% aqueous methanol.

  16. Nutrient Value of Leaf vs. Seed.

    PubMed

    Edelman, Marvin; Colt, Monica

    2016-01-01

    Major differences stand out between edible leaves and seeds in protein quality, vitamin, and mineral concentrations and omega 6/omega 3 fatty acid ratios. Data for seeds (wheat, rice, corn, soy, lentil, chick pea) are compared with corresponding data for edible green leaves (kale, spinach, broccoli, duckweed). An x/y representation of data for lysine and methionine content highlights the group differences between grains, pulses, leafy vegetables, and animal foods. Leaves come out with flying colors in all these comparisons. The perspective ends with a discussion on "So why do we eat mainly seeds?" PMID:27493937

  17. Nutrient value of leaf versus seed

    NASA Astrophysics Data System (ADS)

    Edelman, Marvin; Holt, Monica

    2016-07-01

    Major differences stand out between edible leaves and seeds in protein quality, vitamin and mineral concentrations and omega 6 / omega 3 fatty acid ratios. Data for seeds (wheat, rice, corn, soy, lentil, chick pea) are compared with corresponding data for edible green leaves (kale, spinach, broccoli, duckweed). An x/y representation of data for lysine and methionine content highlights the group differences between grains, pulses, leafy vegetables and animal foods. Leaves come out with flying colors in all these comparisons. The perspective ends with a discussion on “So why do we eat mainly seeds?”

  18. Influence of Rice Seeding Rate on Efficacies of Neonicotinoid and Anthranilic Diamide Seed Treatments against Rice Water Weevil

    PubMed Central

    Hamm, Jason; Lanka, Srinivas; Stout, Michael

    2014-01-01

    Rice in the U.S. is frequently seeded at low rates and treated before sowing with neonicotinoid or anthranilic diamide insecticides to target the rice water weevil. A previous study of the influence of seeding rate on rice water weevil densities showed an inverse relationship between seeding rates and immature weevil densities. This study investigated interactive effects of seeding rate and seed treatment on weevil densities and rice yields; in particular, experiments were designed to determine whether seed treatments were less effective at low seeding rates. Four experiments were conducted over three years by varying seeding rates of rice treated at constant per seed rates of insecticide. Larval suppression by chlorantraniliprole was superior to thiamethoxam or clothianidin, and infestations at low seeding rates were up to 47% higher than at high seeding rates. Little evidence was found for the hypothesis that seed treatments are less effective at low seeding rates; in only one of four experiments was the reduction in weevil densities by thiamethoxam greater at high than at low seeding rates. However, suppression of larvae by neonicotinoid seed treatments in plots seeded at low rates was generally poor, and caution must be exercised when using the neonicotioids at low seeding rates. PMID:26462952

  19. Seed size variation in the palm Euterpe edulis and the effects of seed predators on germination and seedling survival

    NASA Astrophysics Data System (ADS)

    Pizo, Marco A.; Von Allmen, Christiane; Morellato, L. Patricia C.

    2006-05-01

    Intraspecific variation in seed size is common in wild plant populations and has important consequences for the reproductive success of individual plants. Multiple, often conflicting evolutionary forces mediated by biotic as well as abiotic agents may maintain such a variation. In this paper we assessed seed size variation in a population of the threatened, commercially important palm Euterpe edulis in southeast Brazil. We investigated (i) how this variation affects the probability of attack by vertebrate and invertebrate post-dispersal seed predators, and (ii) if seed size influences the outcome of seeds damaged by beetles in terms of seed germination and early survival of seedlings. Euterpe edulis seeds varied in diameter from 8.3 to 14.1 mm. Neither insects nor rodents selected the seeds they preyed upon based on seed size. Seed germination and total, shoot and root biomasses of one-year seedlings were significantly and positively affected by seed size. Root biomass and seedling survival were negatively affected by seed damage caused by a scolytid beetle ( Coccotrypes palmarum) whose adults bore into seeds to consume part of the endosperm, but do not oviposit on them. Seed size had a marginally significant effect on seedling survival. Therefore, if any advantage is accrued by E. edulis individuals producing large seeds, this is because of greater seed germination success and seedling vigor. If this is so, even a relatively narrow range of variation in seed size as observed in the E. edulis population studied may translate into differential success of individual plants.

  20. Tracking Seed Fates of Tropical Tree Species: Evidence for Seed Caching in a Tropical Forest in North-East India

    PubMed Central

    Sidhu, Swati; Datta, Aparajita

    2015-01-01

    Rodents affect the post-dispersal fate of seeds by acting either as on-site seed predators or as secondary dispersers when they scatter-hoard seeds. The tropical forests of north-east India harbour a high diversity of little-studied terrestrial murid and hystricid rodents. We examined the role played by these rodents in determining the seed fates of tropical evergreen tree species in a forest site in north-east India. We selected ten tree species (3 mammal-dispersed and 7 bird-dispersed) that varied in seed size and followed the fates of 10,777 tagged seeds. We used camera traps to determine the identity of rodent visitors, visitation rates and their seed-handling behavior. Seeds of all tree species were handled by at least one rodent taxon. Overall rates of seed removal (44.5%) were much higher than direct on-site seed predation (9.9%), but seed-handling behavior differed between the terrestrial rodent groups: two species of murid rodents removed and cached seeds, and two species of porcupines were on-site seed predators. In addition, a true cricket, Brachytrupes sp., cached seeds of three species underground. We found 309 caches formed by the rodents and the cricket; most were single-seeded (79%) and seeds were moved up to 19 m. Over 40% of seeds were re-cached from primary cache locations, while about 12% germinated in the primary caches. Seed removal rates varied widely amongst tree species, from 3% in Beilschmiedia assamica to 97% in Actinodaphne obovata. Seed predation was observed in nine species. Chisocheton cumingianus (57%) and Prunus ceylanica (25%) had moderate levels of seed predation while the remaining species had less than 10% seed predation. We hypothesized that seed traits that provide information on resource quantity would influence rodent choice of a seed, while traits that determine resource accessibility would influence whether seeds are removed or eaten. Removal rates significantly decreased (p < 0.001) while predation rates increased (p = 0

  1. Tracking Seed Fates of Tropical Tree Species: Evidence for Seed Caching in a Tropical Forest in North-East India.

    PubMed

    Sidhu, Swati; Datta, Aparajita

    2015-01-01

    Rodents affect the post-dispersal fate of seeds by acting either as on-site seed predators or as secondary dispersers when they scatter-hoard seeds. The tropical forests of north-east India harbour a high diversity of little-studied terrestrial murid and hystricid rodents. We examined the role played by these rodents in determining the seed fates of tropical evergreen tree species in a forest site in north-east India. We selected ten tree species (3 mammal-dispersed and 7 bird-dispersed) that varied in seed size and followed the fates of 10,777 tagged seeds. We used camera traps to determine the identity of rodent visitors, visitation rates and their seed-handling behavior. Seeds of all tree species were handled by at least one rodent taxon. Overall rates of seed removal (44.5%) were much higher than direct on-site seed predation (9.9%), but seed-handling behavior differed between the terrestrial rodent groups: two species of murid rodents removed and cached seeds, and two species of porcupines were on-site seed predators. In addition, a true cricket, Brachytrupes sp., cached seeds of three species underground. We found 309 caches formed by the rodents and the cricket; most were single-seeded (79%) and seeds were moved up to 19 m. Over 40% of seeds were re-cached from primary cache locations, while about 12% germinated in the primary caches. Seed removal rates varied widely amongst tree species, from 3% in Beilschmiedia assamica to 97% in Actinodaphne obovata. Seed predation was observed in nine species. Chisocheton cumingianus (57%) and Prunus ceylanica (25%) had moderate levels of seed predation while the remaining species had less than 10% seed predation. We hypothesized that seed traits that provide information on resource quantity would influence rodent choice of a seed, while traits that determine resource accessibility would influence whether seeds are removed or eaten. Removal rates significantly decreased (p < 0.001) while predation rates increased (p = 0

  2. Tracking Seed Fates of Tropical Tree Species: Evidence for Seed Caching in a Tropical Forest in North-East India.

    PubMed

    Sidhu, Swati; Datta, Aparajita

    2015-01-01

    Rodents affect the post-dispersal fate of seeds by acting either as on-site seed predators or as secondary dispersers when they scatter-hoard seeds. The tropical forests of north-east India harbour a high diversity of little-studied terrestrial murid and hystricid rodents. We examined the role played by these rodents in determining the seed fates of tropical evergreen tree species in a forest site in north-east India. We selected ten tree species (3 mammal-dispersed and 7 bird-dispersed) that varied in seed size and followed the fates of 10,777 tagged seeds. We used camera traps to determine the identity of rodent visitors, visitation rates and their seed-handling behavior. Seeds of all tree species were handled by at least one rodent taxon. Overall rates of seed removal (44.5%) were much higher than direct on-site seed predation (9.9%), but seed-handling behavior differed between the terrestrial rodent groups: two species of murid rodents removed and cached seeds, and two species of porcupines were on-site seed predators. In addition, a true cricket, Brachytrupes sp., cached seeds of three species underground. We found 309 caches formed by the rodents and the cricket; most were single-seeded (79%) and seeds were moved up to 19 m. Over 40% of seeds were re-cached from primary cache locations, while about 12% germinated in the primary caches. Seed removal rates varied widely amongst tree species, from 3% in Beilschmiedia assamica to 97% in Actinodaphne obovata. Seed predation was observed in nine species. Chisocheton cumingianus (57%) and Prunus ceylanica (25%) had moderate levels of seed predation while the remaining species had less than 10% seed predation. We hypothesized that seed traits that provide information on resource quantity would influence rodent choice of a seed, while traits that determine resource accessibility would influence whether seeds are removed or eaten. Removal rates significantly decreased (p < 0.001) while predation rates increased (p = 0

  3. Seed dimorphism, nutrients and salinity differentially affect seed traits of the desert halophyte Suaeda aralocaspica via multiple maternal effects

    PubMed Central

    2012-01-01

    Background Maternal effects may influence a range of seed traits simultaneously and are likely to be context-dependent. Disentangling the interactions of plant phenotype and growth environment on various seed traits is important for understanding regeneration and establishment of species in natural environments. Here, we used the seed-dimorphic plant Suaeda aralocaspica to test the hypothesis that seed traits are regulated by multiple maternal effects. Results Plants grown from brown seeds had a higher brown:black seed ratio than plants from black seeds, and germination percentage of brown seeds was higher than that of black seeds under all conditions tested. However, the coefficient of variation (CV) for size of black seeds was higher than that of brown seeds. Seeds had the smallest CV at low nutrient and high salinity for plants from brown seeds and at low nutrient and low salinity for plants from black seeds. Low levels of nutrients increased size and germinability of black seeds but did not change the seed morph ratio or size and germinability of brown seeds. High levels of salinity decreased seed size but did not change the seed morph ratio. Seeds from high-salinity maternal plants had a higher germination percentage regardless of level of germination salinity. Conclusions Our study supports the multiple maternal effects hypothesis. Seed dimorphism, nutrient and salinity interacted in determining a range of seed traits of S. aralocaspica via bet-hedging and anticipatory maternal effects. This study highlights the importance of examining different maternal factors and various offspring traits in studies that estimate maternal effects on regeneration. PMID:23006315

  4. Frequency modulated oscillator

    NASA Technical Reports Server (NTRS)

    Honnell, M. A. (Inventor)

    1977-01-01

    A frequency modulated push-pull oscillator in which the non-linear characteristic of varactors producing frequency modulation is compensated for by an opposite non-linear characteristic of a field effect transistor providing modulating bias to the varactors is described.

  5. Frequencies for radio astronomy.

    PubMed

    Smith, F G

    1970-10-31

    At present the scope of research in radio astronomy is limited by the allocation of frequencies, some of which have to be shared with other radio services. When the International Telecommunications Union reconsiders all frequency allocations next year, astronomers are hoping for an improvement.

  6. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1984-12-25

    Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.

  7. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, Henry D.; Fugitt, Jock A.; Howard, Donald R.

    1984-01-01

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  8. Digital frequency discriminator

    NASA Technical Reports Server (NTRS)

    Reid, W. J.

    1970-01-01

    Frequency discriminator has five integrated circuit chips interconnected to provide a divide function, exclusive OR function, phase shifting, and holding so that a single binary output signal results. The state of the binary signal indicates which one of the two input signals has a lower frequency than the other.

  9. [Isothiocyanate and vinyl thio-oxazolidone contents of rape seeds and rape seed oil].

    PubMed

    Franzke, C; Göbel, R; Noack, G; Seiffert, I

    1975-01-01

    Comparative studies on the isothiocyanate content of rape-seeds and rape-seed oil show that, apart from nearly 300 mg/100 g of vinyl thio-oxazolidone, rape-seeds contain almost 200--300 mg/100 g of isothiocyanates of which 3-butenyl isothiocyanate and 4-pentenyl isothiocyanate (ratio of 4:1) are the main components as evidenced thin-layer and gaschromatographically. Only about 1 mg/100 g of isothiocyanates are found in pressed rape-seed oil; and but circa 10 mg/100 g, in extracted rape-seed oil. 3-Butenyl isothiocyanate and 4-pentenyl isothiocyanate (ratio of 4:1) are once more the main components. Thioglycerides are not detected in the oil. Vinyl thio-oxazolidone is found only in extracted rape-seed oil (about 2 mg/100 g). PMID:1152977

  10. Do seed mass and family affect germination and juvenile performance in Knautia arvensis? A study using failure-time methods

    NASA Astrophysics Data System (ADS)

    Vange, Vibekke; Heuch, Ivar; Vandvik, Vigdis

    2004-05-01

    Germination and seedling establishment are vulnerable stages in the plant life cycle. We investigated how seed mass and family (progeny origin) affect germination and juvenile performance in the grassland herb Knautia arvensis. Seeds were produced by cross-pollination by hand. The fate of 15 individually weighed seeds from each of 15 plants was followed during a 3-month growth chamber experiment. Progeny origin affected germination, both through seed mass and as an independent factor. Two groups of progenies could be distinguished by having rapid or delayed germination. The two groups had similar mean seed masses, but a positive relationship between seed mass and germination rate could be established only among the rapidly germinating progenies. These biologically relevant patterns were revealed because timing of germination was taken into account in the analyses, not only frequencies. Time-to-event data were analysed with failure-time methods, which gave more stable estimates for the relation between germination and seed mass than the commonly applied logistic regression. Progeny origin and seed mass exerted less impact on later characters like juvenile survival, juvenile biomass, and rosette number. These characters were not affected by the timing of germination under the competition-free study conditions. The decrease in the effect of progeny origin from the seed and germination to the juvenile stages suggests that parental effects other than those contributing to the offspring genotype strongly influenced the offspring phenotype at the earliest life stages. Further, the division of progeny germination patterns into two fairly distinct groups indicates that there was a genetic basis for the variation in stratification requirements among parental plants. Field studies are needed to elucidate effects of different timing of germination in the seasonal grasslands that K. arvensis inhabits.

  11. Laser Frequency Stabilization

    NASA Technical Reports Server (NTRS)

    Donelan, Darsa; Mueller, Guido; Thorpe, James; Livas, Jeffrey

    2011-01-01

    Laser ranging and interferometry are essential technologies allowing for many astounding new spacebased missions such as the Laser Interferometer Space Antenna (LISA) to measure gravitational radiation emitted from distant super massive black hole mergers or distributed aperture telescopes with unprecedented angular resolution in the NIR or visible regime. The requirements on laser frequency noise depend on the residual motion and the distances between the spacecraft forming the interferometer. The intrinsic frequency stability of commercial lasers is several orders of magnitude above these requirements. Therefore, it is necessary for lasers to be stabilized to an ultrastable frequency reference so that they can be used to sense and control distances between spacecraft. Various optical frequency references and frequency stabilization schemes are considered and investigated for the applicability and usefulness for space-based interferometry missions.

  12. Microfabricated ion frequency standard

    DOEpatents

    Schwindt, Peter; Biedermann, Grant; Blain, Matthew G.; Stick, Daniel L.; Serkland, Darwin K.; Olsson, III, Roy H.

    2010-12-28

    A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

  13. External laser frequency stabilizer

    SciTech Connect

    Hall, J.L.; Hansch, T.W.

    1987-10-13

    A frequency transducer for controlling or modulating the frequency of a light radiation system is described comprising: a source of radiation having a predetermined frequency; an electro-optic phase modulator for receiving the radiation and for changing the phase of the radiation in proportion to an applied error voltage; an acousto-optic modulator coupled to the electro-optic modulator for shifting the frequency of the output signal of the electro-optic modulator; a signal source for providing an error voltage representing undesirable fluctuations in the frequency of the light radiation; a first channel including a fast integrator coupled between the signal source and the input circuit of the electro-optic modulator; a second channel including a voltage controlled oscillator coupled between the signal source and the acousto-optic modulator; and a network including an electronic delay circuit coupled between the first and second channels for matching the delay of the acousto-optic modulator.

  14. 7 CFR 201.54 - Number of seeds for germination.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Number of seeds for germination. 201.54 Section 201.54... REGULATIONS Germination Tests in the Administration of the Act § 201.54 Number of seeds for germination. At least 400 seeds shall be tested for germination; except that in mixtures, 200 seeds of each of...

  15. 7 CFR 201.54 - Number of seeds for germination.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Number of seeds for germination. 201.54 Section 201.54... REGULATIONS Germination Tests in the Administration of the Act § 201.54 Number of seeds for germination. At least 400 seeds shall be tested for germination; except that in mixtures, 200 seeds of each of...

  16. 7 CFR 201.54 - Number of seeds for germination.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Number of seeds for germination. 201.54 Section 201.54... REGULATIONS Germination Tests in the Administration of the Act § 201.54 Number of seeds for germination. At least 400 seeds shall be tested for germination; except that in mixtures, 200 seeds of each of...

  17. 7 CFR 201.54 - Number of seeds for germination.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Number of seeds for germination. 201.54 Section 201.54... REGULATIONS Germination Tests in the Administration of the Act § 201.54 Number of seeds for germination. At least 400 seeds shall be tested for germination; except that in mixtures, 200 seeds of each of...

  18. 7 CFR 201.54 - Number of seeds for germination.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Number of seeds for germination. 201.54 Section 201.54... REGULATIONS Germination Tests in the Administration of the Act § 201.54 Number of seeds for germination. At least 400 seeds shall be tested for germination; except that in mixtures, 200 seeds of each of...

  19. Phytotoxicity of mustard seed meals alone and in combinations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mustard seed meal is produced when oil is extracted from brassicaceous seeds. The high glucosinolate content of these seed meals makes them of interest as management agents for weeds and soilborne pathogens. Previous studies indicated that seed meals from Brassica juncea and Sinapis alba are nemat...

  20. Thieving rodents as substitute dispersers of megafaunal seeds

    PubMed Central

    Jansen, Patrick A.; Hirsch, Ben T.; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, Roland

    2012-01-01

    The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other’s buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees. PMID:22802644