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1

[Sciatica due to unusual causes: Tarlov cysts and nerve roots anomalies].  

PubMed

Tarlov cysts and nerve roots anomalies usually involve lumbosacral roots and are often asymptomatic. MRI has enabled recognition of many conditions that used to be missed by CT or myelography investigations performed for back and leg pain. However, even without additional compressive impingement (disc hernia, spondylolisthesis or lumbar canal stenosis) these anomalies can be responsible for sciatica, motor deficit and bladder sphincter dysfunction. Tarlov cysts are perinervous dilatations of the dorsal root ganglion. CT and especially MRI can reveal these cysts and their precise relations with the neighboring structures. Delayed filling of the cysts can be visualized on the myelogram. MRI is more sensitive than CT myelography for a positive diagnosis of nerve root anomalies, a differential diagnosis with disc hernia and classification of these anomalies. Surgical treatment is indicated for symptomatic Tarlov cysts and nerve root anomalies resistant to conservative treatment. Better outcome is observed in patients with an additional compressive impingement component. We report two cases of sciatica: one caused by Tarlov cysts diagnosed by MRI and the other by nerve root anomalies diagnosed by CT myelography. In both cases, conservative treatment was undertaken. The clinical, radiological and therapeutic aspects of these disorders are discussed. PMID:18809189

Younes, M; Korbaa, W; Zrour, S; Bejia, I; Touzi, M; Bergaoui, N

2009-03-01

2

Anti-inflammatory activity of roots of Cichorium intybus due to its inhibitory effect on various cytokines and antioxidant activity  

PubMed Central

Background: Cichorium intybus L. commonly known as chicory is one of the important medicinal plants commonly used in Ayurvedic system of medicine. It is commonly used for the treatment of diseases involving a khapa and pitta doshas. Traditionally, C. intybus is used for the treatment of inflammatory conditions, but there are only few in vitro studies reporting the anti-inflammatory activity of roots of chicory. Objective: Evaluation of anti-inflammatory activity of roots of chicory and mechanisms involved in it using in vivo models of inflammation. Materials and Methods: Albino Wistar rats of either sex weighing 150–200 g were used. Ethanolic and aqueous extracts of roots of chicory were prepared with the help of Soxhlet's apparatus. The anti-inflammatory activity was studied using carrageenan-induced paw edema method and cotton pellet granuloma method. Levels of cytokines such as tumor necrosis factor alpha (TNF-?), interleukin 6 (IL-6), and IL-1 and activity of antioxidant enzymes such as catalase (CAT) and glutathione peroxidase (GPx) were estimated. Results: Chicory roots demonstrated significant dose-dependent decrease in paw edema in carrageenan-induced paw edema method. Chicory roots diminished the serum TNF-?, IL-6, and IL-1 levels. They also significantly attenuated the malonylaldehyde levels and increased the activities of CAT and GPx in paw tissue. Similarly, chicory roots demonstrated a significant decrease in granuloma formation in cotton pellet induced granuloma method. Conclusion: Chicory roots possess anti-inflammatory activity, and this might be due to the inhibition of various cytokines, antioxidant effects, and their free radical scavenging activity. PMID:25737610

Rizvi, Waseem; Fayazuddin, Mohd.; Shariq, Syed; Singh, Ompal; Moin, Shagufta; Akhtar, Kafil; Kumar, Anil

2014-01-01

3

Muscle hypertrophy due to scarring of the S1 nerve root.  

PubMed

Segmental muscle enlargement occurs in a variety of neurogenic conditions. We present a patient with calf hypertrophy, likely produced by continuous neuromuscular irritability and compensatory type 1 and type 2 muscle fiber hypertrophy. The underlying lesion of the S1 nerve root was caused by scarring, which could be demonstrated by Gadolinum enhanced, fat saturated magnetic resonance imaging. Thus, the application of this technique is recommended in otherwise etiologically unclear cases of neurogenic muscular lesions in order to detect chronic nerve root pathology. PMID:10935218

Heuss, D; Schober, S; Eberhardt, K; Probst-Cousin, S; Kayser, C; Hecht, M; Huk, W; Neundörfer, B

2000-07-01

4

Low back pain due to hypertrophic roots as presenting symptom of CIDP.  

PubMed

Attention has recently been drawn to chronic inflammatory demyelinating polyneuropathy (CIDP) with symptomatic nerve root hypertrophy. A 31-year-old woman had fluctuating and worsening low back pain. Absent tendon jerks and a slight weakness of the hand interossei muscles suggested a diffuse neuropathy. The electrophysiological and histological findings were diagnostic for CIDP. Lumbar spine MRI showed marked nerve root enlargement with gadolinium enhancement. This case widens the range of the clinical presentations of CIDP. Further studies are warranted to ascertain whether cauda equina gadolinium enhancement may be a useful tool in the diagnosis of CIDP and a marker of disease activity for monitoring response to therapy. PMID:9412855

Di Guglielmo, G; Di Muzio, A; Torrieri, F; Repaci, M; De Angelis, M V; Uncini, A

1997-10-01

5

Root zone salinity and sodicity under seasonal rainfall due to feedback of decreasing hydraulic conductivity  

NASA Astrophysics Data System (ADS)

Soil sodicity, where the soil cation exchange complex is occupied for a significant fraction by Na+, may lead to vulnerability to soil structure deterioration. With a root zone flow and salt transport model, we modeled the feedback effects of salt concentration (C) and exchangeable sodium percentage (ESP) on saturated hydraulic conductivity Ks(C, ESP) for different groundwater depths and climates, using the functional approach of McNeal (1968). We assume that a decrease of Ks is practically irreversible at a time scale of decades. Representing climate with a Poisson rainfall process, the feedback hardly affects salt and sodium accumulation compared with the case that feedback is ignored. However, if salinity decreases, the much more buffered ESP stays at elevated values, while Ks decreases. This situation may develop if rainfall has a seasonal pattern where drought periods with accumulation of salts in the root zone alternate with wet rainfall periods in which salts are leached. Feedback that affects both drainage/leaching and capillary upward flow from groundwater, or only drainage, leads to opposing effects. If both fluxes are affected by sodicity-induced degradation, this leads to reduced salinity (C) and sodicity (ESP), which suggests that the system dynamics and feedback oppose further degradation. Experiences in the field point in the same direction.

van der Zee, S. E. A. T. M.; Shah, S. H. H.; Vervoort, R. W.

2014-12-01

6

Atomic structure of As(2)S(3)-Ag chalcogenide glasses.  

PubMed

(As(0.4)S(0.6))(100-x)Ag(x) glasses (x = 0, 4, 8, 12 at.%) have been studied with high-energy x-ray diffraction, neutron diffraction and extended x-ray absorption spectroscopy at As and Ag K-edges. The experimental data were modelled simultaneously with the reverse Monte Carlo simulation method. Analysis of the partial pair correlation functions and coordination numbers extracted from the model atomic configurations revealed that silver preferentially bonds to sulfur in the As(2)S(3)-Ag ternary glasses, which results in the formation of homoatomic As-As bonds. Upon the addition of Ag, a small proportion of Ag-As bonds (N(AgAs)?0.3) are formed in all three ternary compositions, while the direct Ag-Ag bonds (N(AgAg)? 0.4) appear only in the glass with the highest Ag content (12 at.%). Similar to the g- As(2)S(3) binary, the mean coordination number of arsenic is close to three, and that of sulfur is close to two, in the As(2)S(3)-Ag ternary glasses. The first sharp diffraction peak on the total structure factors of As(2)S(3) binary and (As(0.4)S(0.6))(100-x)Ag(x) ternary glasses is related to the As-As and As-S correlations. PMID:21832397

Kaban, I; Jóvári, P; Wagner, T; Frumar, M; Stehlik, S; Bartos, M; Hoyer, W; Beuneu, B; Webb, M A

2009-09-30

7

Sm3+:Ag NPs assisted modification in absorption features of magnesium tellurite glass  

NASA Astrophysics Data System (ADS)

Metallic nanoparticles (NPs) assisted enhancements in absorption and emission cross-section of tellurite glass is the present challenge. The influences of samarium (Sm3+) ions and silver (Ag) NPs ratio on physical and optical absorption properties of melt quench synthesized magnesium tellurite glasses are reported. XRD patterns verify the amorphous nature of glasses. Glass density, molar volume and ionic packing fraction are discerned to be in the range of 4.92-5.0 g cm-3, 29.82-30.26 cm3 mol-1 and 0.452-0.446, respectively. Moderate reduction potential of tellurite glass converted Ag1+ to Ag0 via single step process and NPs are formed. TEM image manifest the existence of NPs of average diameter ?16.94 nm having Gaussian size distribution. The significant changes in structural properties in the presence of Ag NPs are discussed in terms of TeO4 tetrahedra distortion and network depolymerization process. The Sm3+:Ag NPs dependent variation in physical properties are ascribed to the alteration in the number of bridging oxygen to non bridging (NB) one. Enhancement in absorption intensity due to the local field effects of Ag NPs is attributed to the changes in Sm-O bond strength. Optical energy band gap (2.81-3.18 eV) and Urbach energy (0.18-0.24 eV) are found increase and decrease, respectively with the increase of Sm3+:Ag NPs up to 1.33 then quenches and enhances, respectively thereafter which are related to the changes in cross-link and NBO numbers. The FTIR spectra reveal modification in network structures evidenced from vibrational wave-number shifts of TeO4 and TeO3 structural units. The observed notable increase in HOH vibration mode suggests its helpfulness in promoting the absorption of water and light. It is asserted that the physical, optical and structural properties of magnesium tellurite glass can be tuned by controlling Sm3+:Ag NPs.

Yusoff, N. M.; Sahar, M. R.; Ghoshal, S. K.

2015-01-01

8

Highly luminescent material based on Alq3:Ag nanoparticles.  

PubMed

Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices. PMID:23653126

Salah, Numan; Habib, Sami S; Khan, Zishan H

2013-09-01

9

Spectra of surface plasmon polariton enhanced electroluminescence from electroformed Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Narrow band-pass filters have been used to measure the spectral distribution of electroluminescent photons with energies between 1.8 eV and 3.0 eV from electroformed Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 nm and 18 nm. Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown that results in a conducting channel in the insulator and changes the initial high resistance of the MIM diode to a low resistance state. It is a critical step in the development of resistive-switching memories that utilize MIM diodes as the active element. Electroforming of Al-Al2O3-Ag diodes in vacuum results in voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics. Electroluminescence (EL) and electron emission into vacuum (EM) develop simultaneously with the current increase that results in VCNR in the I-V characteristics. EL is due to recombination of electrons injected at the Al-Al2O3 interface with radiative defect centers in Al2O3. Measurements of EL photons between 1.8 eV and 3.0 eV using a wide band-pass filter showed that EL intensity is exponentially dependent on Al2O3 thickness for Al-Al2O3-Ag diodes between 12 nm and 20 nm thick. Enhanced El intensity in the thinnest diodes is attributed to an increase in the spontaneous emission rate of recombination centers due to high electromagnetic fields generated in Al2O3 when EL photons interact with electrons in Ag or Al to form surface plasmon polaritons at the Al2O3-Ag or Al2O3-Al interface. El intensity is a maximum at 2.0-2.2 eV for Al-Al2O3-Ag diodes with Al2O3 thicknesses between 12 nm and 18 nm. EL in diodes with 12 nm or 14 nm of Al2O3 is enhanced by factors of 8-10 over EL from a diode with 18 nm of Al2O3. The extent of EL enhancement in the thinnest diodes can vary significantly between samples. A narrow band of recombination centers was found in one Al-Al2O3-Ag diode with 12 nm of Al2O3; it had EL intensity 100 times greater at 2.15 eV than the diode with 18 nm of Al2O3. EL intensity for photons with energies greater than 2.6 eV is nearly the same for all diodes.

Hickmott, T. W.

2015-03-01

10

Postharvest jasmonic acid treatment of sugarbeet roots reduces rot due to Botrytis cinerea, Penicillium claviforme, and Phoma betae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Although jasmonic acid (JA) and JA derivatives are known to activate plant defense mechanisms and provide protection against postharvest fungal diseases for several horticultural crops, JA’s ability to protect sugarbeet (Beta vulgaris L.) roots against common causal organisms of storage rot is unkno...

11

Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning  

NASA Astrophysics Data System (ADS)

An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

2013-10-01

12

Novel Cs2CO3:Ag\\/Ag Cathode for High-Efficiency Organic Light-Emitting Diodes  

Microsoft Academic Search

We report a novel composite electron injection layer (EIL), Cs2CO3:Ag, for fabricating efficient organic light-emitting diodes (OLEDs). When the composition ratio and thickness of the Cs2CO3:Ag layer were 1:10 and 5 nm, respectively, a maximum current efficiency of 4.4 cd\\/A was achieved, which was 16% higher than that of the control device with a double-layer structure of Cs2CO3\\/Ag. The effect

Qian Liu; Lian Duan; Deqiang Zhang; Guifang Dong; Juan Qiao; Liduo Wang; Yong Qiu

2009-01-01

13

Mitigation of antagonistic effects on plant growth due to root co-colonization by dark septate endophytes and ectomycorrhiza.  

PubMed

Dark septate endophytes (DSE) are very common root colonizers of woody plant species. Ascomycetes of the Phialocephala fortinii s.l.-Acephala applanata species complex (PAC) are the main representatives of DSE fungi in forest ecosystems. PAC and mycorrhizal fungi share the same habitat, but interactions among PAC, mycorrhizal fungi and plants are poorly understood. We compared the effects of single and dual inoculation of Norway spruce seedlings with PAC and the ectomycorrhizal (ECM) fungus Hebeloma crustuliniforme on host growth, degree of mycorrhization and density of endophytic PAC biomass. Single colonization by H.?crustuliniforme or PAC significantly reduced plant biomass. Dual colonization reduced or neutralized plant growth depression caused by single fungal colonization. The degree of mycorrhization was independent on PAC colonization, and mycorrhization significantly reduced endophytic PAC biomass. Plant biomass of dually colonized plants positively correlated with PAC biomass. These results demonstrate the ability of dual inoculation of PAC and H.?crustuliniforme to neutralize plant growth depression caused by single fungal inoculation. Our explanations of enhanced plant growth in dually inoculated plants are the inhibition of PAC during root colonization by the ECM mantle and ECM-mediated access to plant growth-promoting nutrients resulting from the mineralization of the potting medium by PAC. PMID:24249297

Reininger, Vanessa; Sieber, Thomas N

2013-12-01

14

AN ALKALINE HYDROLYSIS TISSUE DIGESTION SYSTEM FOR A BSL-3-AG CONTAINMENT FACILITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

An alkaline hydrolysis tissue digestion system was installed at the Arthropod-borne Animal Diseases Research Laboratory (ABADRL) Biosafety Level (BSL) 3-AG containment facility in 2000 to replace the antiquated pathologic waste incinerator because of significant costs for upgrading this incinerator ...

15

First-principles study of Ag adatoms on the Si(111)-3×3Ag surface  

Microsoft Academic Search

We have performed first-principles calculations for a model system with the 3×3 periodicity in which a Ag adatom per unit cell is adsorbed upon the Si(111)-3×3-Ag surface, whereby discussing the atomic and electronic structures of the Si(111)-21×21-(Ag+Ag) and -(Ag+Au) surfaces. It has been found that the adatom prefers to be located upon Ag triangles rather than upon Si trimers of

Hideaki Aizawa; Masaru Tsukada

1999-01-01

16

A First Principles Study on Dissociation and Adsorption Processes of H2 on Pd3Ag(111) Surface  

Microsoft Academic Search

We investigated dissociative adsorption of H2 molecule on Pd3Ag(111) surface based on the constructed potential energy surfaces (PESs) from the results of first principles calculations. This study is performed to understand H2 dissociative adsorption mechanism on Pd3Ag(111) surface which acts as permeable film for H2 which is a product of biomass gasification. The PES results indicate that when the H2

Hermawan Kresno Dipojono; Allan Abraham B. Padama; Nobuki Ozawa; Hiroshi Nakanishi; Hideaki Kasai

2010-01-01

17

Transparent and transferrable organic optoelectronic devices based on WO3/Ag/WO3 electrodes  

NASA Astrophysics Data System (ADS)

With a thin metal film inserted between two oxide layers, the WO3/Ag/WO3 (WAW) multilayer structure owns both high transmittance and high conductivity. By carefully optimizing Ag film thickness, WAW shows high average transmittance of 82.5% in 400-750 nm range and low sheet resistance of 20 ?/sq. Employing such WAW electrodes, transparent organic photodetectors are fabricated, and with help of a polyacrylonitrile protective layer, the devices can be smartly separated and transferred onto other substrates while maintaining their performances well. Moreover, transferrable organic solar cells are also realized with such transparent WAW electrodes.

Qi, Zhe; Cao, Jiamin; Ding, Liming; Wang, Jizheng

2015-02-01

18

Optical microcavities and enhanced electroluminescence from electroformed Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al2O3-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 nm and 30 nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0 eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0 eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, VLP, is ˜1.5 V. VLP is nearly independent of Al2O3 thickness and of temperature and is 0.3-0.6 V less than the threshold voltage for EL for the SP filter, VSP. EL intensity is primarily between 1.8 and 3.0 eV when the bias voltage, VS ? 7 V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing VS, for diodes with the smallest Al2O3 thicknesses, there is a maximum EL intensity, LMX, at a voltage, VLMX, followed by a decrease to a plateau. LMX and EL intensity at 4.0 V in the plateau region depend exponentially on Al2O3 thickness. The ratio of LMX at 295 K for a diode with 12 nm of Al2O3 to LMX for a diode with 25 nm of Al2O3 is ˜140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ˜3 and ˜35; it depends on Al2O3 thickness and VS. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al2O3 interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed Al-Al2O3-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed Al-Al2O3-Ag diodes.

Hickmott, T. W.

2013-12-01

19

Electromigration of Sn37Pb and Sn3Ag1.5Cu\\/Sn3Ag0.5Cu composite flip-chip solder bumps with Ti\\/Ni(V)\\/Cu under bump metallurgy  

Microsoft Academic Search

We examine electromigration fatigue reliability and morphological patterns of Sn–37Pb and Sn–3Ag–1.5Cu\\/Sn–3Ag–0.5Cu composite solder bumps in a flip–chip package assembly with Ti\\/Ni(V)\\/Cu UBM. The flip–chip test vehicle was subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4A\\/150°C, 0.5A\\/150°C, 0.6A\\/125°C, 0.6A\\/135°C, and 0.6A\\/150°C. The electrothermal coupling analysis was employed to investigate the current crowding

Yi-Shao Lai; Kuo-Ming Chen; Chin-Li Kao; Chiu-Wen Lee; Ying-Ta Chiu

2007-01-01

20

[Aortic root replacement with free-style stentless valve for aorto-left and right ventricular communication due to infective endocarditis; report of a case].  

PubMed

Aortic root abscess remains a major determinant of both early and late results of surgical treatment of endocarditis. This complication rarely progresses to intracardiac shunt followed by cardiac failure. We report a surgical case of a 40-year-old man, who had been diagnosed as prosthetic valve endocarditis with aortic root abscess ruptured into left and right ventricle creating aorto-left and right ventricular communication. Because of complete debridment of infective and/or dead tissue, aortic root replacement was required. We used free-style stentless valve, xenograft, since homograft was not available at the time of operation. We believe that this prosthesis has easier handling and is more resistant to infection, therefore, it might be an option for infective endocarditis with aortic root abscess. PMID:15071869

Kamikubo, Y; Murashita, T; Kunishige, H; Shiiya, N; Matsui, Y; Yasuda, K

2004-04-01

21

Surface-induced magnetism in ?-Fe 2O 3/Ag multilayers  

NASA Astrophysics Data System (ADS)

Anomalous ferromagnetic-like behavior, with significant magnetization and very large coercivities at low temperatures was observed in ?-Fe 2O 3/Ag multilayers. Mössbauer studies showed the presence of two magnetic components, bulk-like and surface-like with substantially lower hyperfine field. It was found that the observed magnetic moment per particle can be accounted for by the contribution of only about 5% of the total number of surface Fe 3+ ions. This result can be explained if the magnetic moments on the surface are predominantly randomly oriented resembling a spin glass state. The negligible quadrupole interaction, observed in the Mössbauer spectra at low temperature, strongly supports the last interpretation. Large shifts in the hysteresis loops of field-cooled samples indicate strong exchange coupling between the antiferromagnetic core and the net magnetic moments on the surface.

Dimitrov, D. V.; Hadjipanayis, G. C.; Papaefthymiou, V.; Simopoulos, A.

1998-09-01

22

Surface-induced magnetism in ?-Fe2O3/Ag multilayers  

NASA Astrophysics Data System (ADS)

Anomalous ferromagnetic-like behavior, with significant magnetization and very large coercivities at low temperatures was observed in ?-Fe2O3/Ag multilayers. Mössbauer studies showed the presence of two magnetic components, bulk-like and surface-like with substantially lower hyperfine field. It was found that the observed magnetic moment per particle can be accounted for by the contribution of only about 5% of the total number of surface Fe3+ ions. This result can be explained if the magnetic moments on the surface are predominantly randomly oriented resembling a spin glass state. The negligible quadrupole interaction, observed in the Mössbauer spectra at low temperature, strongly supports the last interpretation. Large shifts in the hysteresis loops of field-cooled samples indicate strong exchange coupling between the antiferromagnetic core and the net magnetic moments on the surface.

Dimitrov, D. V.; Hadjipanayis, G. C.; Papaefthymiou, V.; Simopoulos, A.

1998-09-01

23

Effects of Bi and Ni addition on wettability and melting point of Sn0.3Ag0.7Cu Low-Ag Pb-free solder  

Microsoft Academic Search

Bi and Ni were added to Sn-0.3Ag-0.7Cu low-Ag solder, to fabricate new low-Ag solders, Sn-0.3Ag-0.7Cu-XBi (X= 1.0, 3.0, 4.5) and Sn-0.3Ag-0.7Cu-XNi (X=0.05, 0.10, 0.15). Melting point tests were carried out with DSC (differential scanning calorimetry) instrument. Wettability tests were conducted on a wetting balance instrument. Test results of the two new solders were compared with that of Sn-0.3Ag-0.7Cu respectively to

Y. Liu; F. L. Sun; T. L. Yan; W. G. Hu

2008-01-01

24

Electron standing waves on the Si,,111...-3 3-Ag surface Norio Sato and Sakura Takeda  

E-print Network

Electron standing waves on the Si,,111...- 3 3-Ag surface Norio Sato and Sakura Takeda Department-0012, Japan Received 2 July 1998 Electron standing waves have been observed near step edges and out as a potential barrier for the surface-state electrons to make the standing waves, while the other type does not

Hasegawa, Shuji

25

MRI in soils: determination of water concent changes due to root water uptake by means of a multi-slice-multi-echo sequence (MSME)  

Microsoft Academic Search

Root water uptake by ricinus communis (castor bean) in fine sand was investigated using MRI with multiecho sampling. Before starting the experiments the plants germinated and grew for 3 weeks in a cylindrical container with a diameter of 9 cm. Immediately before the MRI experiments started, the containers were water-saturated and sealed, so water content changes were only caused by

A. Pohlmeier; F. Vergeldt; E. Gerkema; As van H; Dusschoten van D; H. Vereecken

2010-01-01

26

Changes in root growth and relationships between plant organs and root hydraulic traits in American elm ( Ulmus americana L.) and red oak ( Quercus rubra L.) seedlings due to elevated CO 2 level  

Microsoft Academic Search

The relationships between plant organs and root hydrological traits are not well known and the question arises whether elevated\\u000a CO2 changes these relationships. This study attempted to answer this question. A pseudo-replicated experiment was conducted with\\u000a two times 24 American elm (Ulmus americana L.) and 23 and 24 red oak (Quercus rubra L.) seedlings growing in ambient CO2 (around 360

Song Cheng

2009-01-01

27

Trans. Nonferrous Met. Soc. China 23(2013) 1356-1366 Effects of ball milling time on porous Ti-3Ag alloy and  

E-print Network

-10], composite materials [11-13], porous materials [14-16] have been investigated. Among them, porous titanium to modify the physical and chemical properties of material surface was conducted on porous Ti-3Ag alloys [20 simulated body fluid (SBF) were studied [27-29]. 2 Experimental 2.1 Materials preparation Porous Ti-3Ag

Zheng, Yufeng

28

Defective chemokine signal integration in leukocytes lacking activator of G protein signaling 3 (AGS3).  

PubMed

Activator of G-protein signaling 3 (AGS3, gene name G-protein signaling modulator-1, Gpsm1), an accessory protein for G-protein signaling, has functional roles in the kidney and CNS. Here we show that AGS3 is expressed in spleen, thymus, and bone marrow-derived dendritic cells, and is up-regulated upon leukocyte activation. We explored the role of AGS3 in immune cell function by characterizing chemokine receptor signaling in leukocytes from mice lacking AGS3. No obvious differences in lymphocyte subsets were observed. Interestingly, however, AGS3-null B and T lymphocytes and bone marrow-derived dendritic cells exhibited significant chemotactic defects as well as reductions in chemokine-stimulated calcium mobilization and altered ERK and Akt activation. These studies indicate a role for AGS3 in the regulation of G-protein signaling in the immune system, providing unexpected venues for the potential development of therapeutic agents that modulate immune function by targeting these regulatory mechanisms. PMID:24573680

Branham-O'Connor, Melissa; Robichaux, William G; Zhang, Xian-Kui; Cho, Hyeseon; Kehrl, John H; Lanier, Stephen M; Blumer, Joe B

2014-04-11

29

Polarity Effect in a Sn3Ag0.5Cu/Bismuth Telluride Thermoelectric System  

NASA Astrophysics Data System (ADS)

This study investigates electromigration in Bi2Te3 thermoelectric (TE) material systems and the effectiveness of the diffusion barrier under current. The Peltier effect on the interfacial reaction was decoupled from the effect of electromigration. After connecting p- and n-type Bi2Te3 to Sn3Ag0.5Cu (SAC305) solders, different current densities were applied at varying temperatures. The Bi2Te3 samples were fabricated by the spark plasma sintering technique, and an electroless nickel-phosphorous (Ni-P) layer was deposited at the solder/TE interfaces. The experimental results confirm the importance of the Ni diffusion barrier in joint reliability. Intermetallic compound layers (Cu,Ni)6Sn5 and NiTe formed at the solder/Ni-P and Ni-P/substrate interfaces, respectively. The experimental results indicate that the mechanism of NiTe and (Cu,Ni)6Sn5 compound growth was dominated by the Peltier effect at high current density. When the current density was low, the growth of NiTe was affected by electromigration but the changes of thickness for (Cu,Ni)6Sn5 were not obvious.

Chien, P. Y.; Yeh, C. H.; Hsu, H. H.; Wu, Albert T.

2014-01-01

30

Root systems  

NSDL National Science Digital Library

One purpose that roots serve is that of anchoring the plant in the ground. Roots also take up water and nutrients for the plant. Plants all have different root system types to fit their individual needs and locations.

N/A N/A (U.S. Government; )

2004-10-30

31

Transmission of the M2 double-stranded RNA in Rhizoctonia solani anastomosis group 3 (AG3)  

Microsoft Academic Search

Horizontal transmission of the 3.57 kb M2 double-stranded RNA (dsRNA) between mycelia of somatically incompatible isolates of Rhizoctonia solani anastomosis group 3 (AG-3), an economically impor- tant pathogen of cultivated plants in the family Solanaceae, was investigated. Nine donor isolates of R. solani AG-3 containing the M2 dsRNA were paired on potato-dextrose agar with each of three different recipient isolates

Nikki D. Charlton; Marc A. Cubeta

2007-01-01

32

Nqrs Data for Ag3AsS3 [Ag3(AsS3)] (Subst. No. 0013)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for Ag3AsS3 [Ag3(AsS3)] (Subst. No. 0013)

Chihara, H.; Nakamura, N.

33

Syntheses, structures, and electronic properties of Ba3FeUS6 and Ba3AgUS6.  

PubMed

The compounds Ba3FeUS6 and Ba3AgUS6 have been synthesized by the reactions of BaS, U, S, and M (= Fe or Ag) at 1223 K. These two isostructural compounds crystallize in the K4CdCl6 structure type in the trigonal system in space group D3d(6)–R3c. Both structures feature infinite ?(1)[MUS6(6–)] chains along c that are separated by Ba atoms. The ?(1)[FeUS6(6–)] chains are formed by the face-sharing of US6 trigonal prisms with FeS6 octahedra; in contrast, the ?(1)[AgUS6(6–)] chains are formed by the face-sharing of US6 octahedra with AgS6 trigonal prisms. The Ba3FeUS6 compound charge balances with 3 Ba(2+), 1 Fe(2+), 1 U4+, and 6 S(2–), whereas Ba3AgUS6 charge balances with 3 Ba(2+), 1 Ag(1+), 1 U(5+), and 6 S(2–). This structure offers a remarkable flexibility in terms of the oxidation state of the incorporated uranium depending on the oxidation state of the d-block metal. DFT calculations performed with the HSE functional have led to band gaps of 2.3 and 2.2 eV for Ba3FeUS6 and Ba3AgUS6, respectively. From resistivity measurements, the Arrhenius activation energies are 0.12(1) and 0.43(1) eV for Ba3FeUS6 and Ba3AgUS6, respectively. PMID:24564267

Mesbah, Adel; Malliakas, Christos D; Lebègue, Sébastien; Sarjeant, Amy A; Stojko, Wojciech; Koscielski, Lukasz A; Ibers, James A

2014-03-17

34

Interfacial microstructure between Sn-3Ag-xBi alloy and Cu substrate with or without electrolytic Ni plating  

NASA Astrophysics Data System (ADS)

The microstructure of the interfacial phase of Sn-3Ag-xBi alloy on a Cu substrate with or without electrolytic Ni plating was evaluated. Bismuth additions into Sn-Ag alloys do not affect interfacial phase formations. Without plating, ?-Cu6Sn5/?-Cu3Sn interfacial phases developed as reaction products in the as-soldered condition. The ?-phase Cu6Sn5 with a hexagonal close-packed structure grows about 1-µm scallops. The ?-phase Cu3Sn with an orthorhombic structure forms with small 100-nm grains between ?-Cu6Sn5 and Cu. For Ni plating, a Ni3Sn4 layer of monoclinic structure formed as the primary reaction product, and a thin ?-Ni3Sn2 layer of hexagonal close-packed structure forms between the Ni3Sn4 and Ni layer. In the Ni layer, Ni-Sn compound particles of nanosize distribute by Sn diffusion into Ni. On the total thickness of interfacial reaction layers, Sn-3Ag-6Bi joints are thicker by about 0.9 µm for the joint without Ni plating and 0.18 µm for the joint with Ni plating than Sn-3Ag joints, respectively. The thickening of interfacial reaction layers can affect the mechanical properties of strength and fatigue resistance.

Hwang, Chi-Won; Lee, Jung-Goo; Suganuma, Katsuaki; Mori, Hirotaro

2003-02-01

35

Tooth Eruption without Roots  

PubMed Central

Root development and tooth eruption are very important topics in dentistry. However, they remain among the less-studied and -understood subjects. Root development accompanies rapid tooth eruption, but roots are required for the movement of teeth into the oral cavity. It has been shown that the dental follicle and bone remodeling are essential for tooth eruption. So far, only limited genes have been associated with root formation and tooth eruption. This may be due to the difficulties in studying late stages of tooth development and tooth movement and the lack of good model systems. Transgenic mice with eruption problems and short or no roots can be used as a powerful model for further deciphering of the cellular, molecular, and genetic mechanisms underlying root formation and tooth eruption. Better understanding of these processes can provide hints on delivering more efficient dental therapies in the future. PMID:23345536

2013-01-01

36

Potential for post-closure radionuclide redistribution due to biotic intrusion: aboveground biomass, litter production rates, and the distribution of root mass with depth at material disposal area G, Los Alamos National Laboratory  

SciTech Connect

Low-level radioactive waste (LLW) generated at the Los Alamos National Laboratories (LANL) is disposed of at LANL's Technical Area (T A) 54, Material Disposal Area (MDA) G. The ability of MDA G to safely contain radioactive waste during current and post-closure operations is evaluated as part of the facility's ongoing performance assessment (PA) and composite analysis (CA). Due to the potential for uptake and incorporation of radio nuclides into aboveground plant material, the PA and CA project that plant roots penetrating into buried waste may lead to releases of radionuclides into the accessible environment. The potential amount ofcontamination deposited on the ground surface due to plant intrusion into buried waste is a function of the quantity of litter generated by plants, as well as radionuclide concentrations within the litter. Radionuclide concentrations in plant litter is dependent on the distribution of root mass with depth and the efficiency with which radionuclides are extracted from contaminated soils by the plant's roots. In order to reduce uncertainties associated with the PA and CA for MDA G, surveys are being conducted to assess aboveground biomass, plant litter production rates, and root mass with depth for the four prominent vegetation types (grasses, forbs, shrubs and trees). The collection of aboveground biomass for grasses and forbs began in 2007. Additional sampling was conducted in October 2008 to measure root mass with depth and to collect additional aboveground biomass data for the types of grasses, forbs, shrubs, and trees that may become established at MDA G after the facility undergoes final closure, Biomass data will be used to estimate the future potential mass of contaminated plant litter fall, which could act as a latent conduit for radionuclide transport from the closed disposal area. Data collected are expected to reduce uncertainties associated with the PA and CA for MDA G and ultimately aid in the assessment and subsequent prevention of radionuclide transport within the environment from the closed disposal area and potential exposure to site workers and the public.

French, Sean B [Los Alamos National Laboratory; Christensen, Candace [Los Alamos National Laboratory; Jennings, Terry L [Los Alamos National Laboratory; Jaros, Christopher L [Los Alamos National Laboratory; Wykoff, David S [Los Alamos National Laboratory; Crowell, Kelly J [Los Alamos National Laboratory; Shuman, Rob [URS

2008-01-01

37

[Mn(en)3]CdSnTe4 and [Mn(en)3]Ag6Sn2Te8: New Intermetallic Tellurides Synthesized in Superheated  

E-print Network

this route, we have recently begun to investigate intermetallic compounds that contain more than one type[Mn(en)3]CdSnTe4 and [Mn(en)3]Ag6Sn2Te8: New Intermetallic Tellurides Synthesized in Superheated intermetallic tellurides, Mn(en)3]CdSnTe4 (I) and [Mn(en)3]Ag6Sn2Te8 (II), have been synthesized in superheated

Li, Jing

38

ROOT WEEVILS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Numerous species of root weevil, Otiorhynchus spp. (Coleoptera: Curculionidae), infest hop. The black vine weevil, O. sulcatus (F.), is the dominant species infesting hop followed by the strawberry root weevil, O. ovatus (L.), rough strawberry root weevil, O. rugosostriatus Goeze, and O. meridional...

39

Root Hairs  

PubMed Central

Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair specification in Arabidopsis is determined by position-dependent signaling and molecular feedback loops causing differential accumulation of a WD-bHLH-Myb transcriptional complex. The initiation of root hairs is dependent on the RHD6 bHLH gene family and auxin to define the site of outgrowth. Root hair elongation relies on polarized cell expansion at the growing tip, which involves multiple integrated processes including cell secretion, endomembrane trafficking, cytoskeletal organization, and cell wall modifications. The study of root hair biology in Arabidopsis has provided a model cell type for insights into many aspects of plant development and cell biology. PMID:24982600

Grierson, Claire; Nielsen, Erik; Ketelaarc, Tijs; Schiefelbein, John

2014-01-01

40

Normal Autophagic Activity in Macrophages from Mice Lacking G?i3, AGS3, or RGS19  

PubMed Central

In macrophages autophagy assists antigen presentation, affects cytokine release, and promotes intracellular pathogen elimination. In some cells autophagy is modulated by a signaling pathway that employs G?i3, Activator of G-protein Signaling-3 (AGS3/GPSM1), and Regulator of G-protein Signaling 19 (RGS19). As macrophages express each of these proteins, we tested their importance in regulating macrophage autophagy. We assessed LC3 processing and the formation of LC3 puncta in bone marrow derived macrophages prepared from wild type, Gnai3-/-, Gpsm1-/-, or Rgs19-/- mice following amino acid starvation or Nigericin treatment. In addition, we evaluated rapamycin-induced autophagic proteolysis rates by long-lived protein degradation assays and anti-autophagic action after rapamycin induction in wild type, Gnai3-/-, and Gpsm1-/- macrophages. In similar assays we compared macrophages treated or not with pertussis toxin, an inhibitor of GPCR (G-protein couple receptor) triggered G?i nucleotide exchange. Despite previous findings, the level of basal autophagy, autophagic induction, autophagic flux, autophagic degradation and the anti-autophagic action in macrophages that lacked G?i3, AGS3, or RGS19; or had been treated with pertussis toxin, were similar to controls. These results indicate that while G?i signaling may impact autophagy in some cell types it does not in macrophages. PMID:24312373

Vural, Ali; McQuiston, Travis J.; Blumer, Joe B.; Park, Chung; Hwang, Il-Young; Williams-Bey, Yolanda; Shi, Chong-Shan; Ma, Dzwokai Zach; Kehrl, John H.

2013-01-01

41

Optical microcavities and enhanced electroluminescence from electroformed Al-Al{sub 2}O{sub 3}-Ag diodes  

SciTech Connect

Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al{sub 2}O{sub 3}-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al{sub 2}O{sub 3}-Ag diodes with anodic Al{sub 2}O{sub 3} thicknesses between 12?nm and 30?nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0?eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0?eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, V{sub LP}, is ?1.5?V. V{sub LP} is nearly independent of Al{sub 2}O{sub 3} thickness and of temperature and is 0.3–0.6?V less than the threshold voltage for EL for the SP filter, V{sub SP}. EL intensity is primarily between 1.8 and 3.0?eV when the bias voltage, V{sub S} ? 7?V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing V{sub S}, for diodes with the smallest Al{sub 2}O{sub 3} thicknesses, there is a maximum EL intensity, L{sub MX}, at a voltage, V{sub LMX}, followed by a decrease to a plateau. L{sub MX} and EL intensity at 4.0?V in the plateau region depend exponentially on Al{sub 2}O{sub 3} thickness. The ratio of L{sub MX} at 295?K for a diode with 12?nm of Al{sub 2}O{sub 3} to L{sub MX} for a diode with 25?nm of Al{sub 2}O{sub 3} is ?140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ?3 and ?35; it depends on Al{sub 2}O{sub 3} thickness and V{sub S}. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al{sub 2}O{sub 3} interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed Al-Al{sub 2}O{sub 3}-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed Al-Al{sub 2}O{sub 3}-Ag diodes.

Hickmott, T. W. [Department of Physics, State University of New York at Albany, Albany, New York 12222 (United States)

2013-12-21

42

Spin and orbital magnetism of coinage metal trimers (Cu3, Ag3, Au3): A relativistic density functional theory study  

NASA Astrophysics Data System (ADS)

We have demonstrated electronic structure and magnetic properties of Cu3, Ag3 and Au3 trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21?B was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.

Afshar, Mahdi; Sargolzaei, Mohsen

2013-11-01

43

[Application of minirhizotron in fine root studies].  

PubMed

Due to the production, death, and decomposition of fine root, its turnover plays an important role in carbon allocation and nutrient cycling in terrestrial ecosystems. Some methods such as sequential root coring, compartmental flow model, and ingrowth core have been widely used in collecting root biomass data and estimating fine root turnover, but failed in monitoring the dynamics of fine root due to its simultaneous production and death. Minirhizotron is a nondestructive in situ method for studying the dynamics of fine root, which allows the simultaneous measurement of fine root growth and mortality. This paper reviewed the application of minirhizotron in fine root studies, with the focus on minirhizotron tube installation, image collection, data extraction, and calculation parameters. In a case study, the total fine root length, fine root length density per unit volume, fine root length density per unit area, fine root biomass density, and fine root production and mortality of Fraxinus mandshurica and Larix gmelini were calculated, and the results showed that minirhizotron method was feasible in studying the processes of fine root development, eclipse, death, and decomposition. The factors affecting fine root measurement and its precision mainly included the quality and quantity of tube installation, sampling interval and quantity, and analysis technique of images, etc. Soil texture, tube material, and disturbance of light on root were also the factors affecting the precision of the method. How to improve the measurement precision of minirhizotron would be the critical problem in future study. PMID:16836108

Shi, Jianwei; Yu, Lizhong; Yu, Shuiqiang; Han, Youzhi; Wang, Zhengquan; Guo, Dali

2006-04-01

44

Roots and Root Function: Introduction  

Technology Transfer Automated Retrieval System (TEKTRAN)

A number of current issues related to water management, ecohydrology, and climate change are giving impetus to new research aimed at understanding roots and their functioning. Current areas of research include: use of advanced imaging technologies such as Magnetic Resonance Imaging to observe roots...

45

Root canal  

MedlinePLUS

A root canal is a dental procedure to remove dead or dying nerve tissue and bacteria from inside a tooth. ... is removed with special tools called files. The canals (tiny pathways inside the tooth) are cleaned. Medicines ...

46

How Roots Perceive and Respond to Gravity.  

ERIC Educational Resources Information Center

Discusses graviperception and gravitropism by plant roots. Indicates that graviperception occurs via sedimentation of amyloplasts in columella cells of the root cap and that the minimal graviresponsiveness of lateral roots may be due to the intensity of their caps to establish a concentration gradient of inhibitor(s) sufficient to affect…

Moore, Randy

1984-01-01

47

TPCP: Armillaria Root Rot ARMILLARIA ROOT ROT  

E-print Network

TPCP: Armillaria Root Rot ARMILLARIA ROOT ROT INTRODUCTION A sometimes devastating root rot fungus. Armillaria root rot usually becomes apparent when indigenous forests are cleared for afforestation large indigenous trees In forestry situations, Armillaria root rot has been recorded on both pines

48

Descendant root volume varies as a function of root type: estimation of root biomass lost during uprooting in Pinus pinaster  

PubMed Central

Root systems of woody plants generally display a strong relationship between the cross-sectional area or cross-sectional diameter (CSD) of a root and the dry weight of biomass (DWd) or root volume (Vd) that has grown (i.e., is descendent) from a point. Specification of this relationship allows one to quantify root architectural patterns and estimate the amount of material lost when root systems are extracted from the soil. However, specifications of this relationship generally do not account for the fact that root systems are comprised of multiple types of roots. We assessed whether the relationship between CSD and Vd varies as a function of root type. Additionally, we sought to identify a more accurate and time-efficient method for estimating missing root volume than is currently available. We used a database that described the 3D root architecture of Pinus pinaster root systems (5, 12, or 19 years) from a stand in southwest France. We determined the relationship between CSD and Vd for 10,000 root segments from intact root branches. Models were specified that did and did not account for root type. The relationships were then applied to the diameters of 11,000 broken root ends to estimate the volume of missing roots. CSD was nearly linearly related to the square root of Vd, but the slope of the curve varied greatly as a function of root type. Sinkers and deep roots tapered rapidly, as they were limited by available soil depth. Distal shallow roots tapered gradually, as they were less limited spatially. We estimated that younger trees lost an average of 17% of root volume when excavated, while older trees lost 4%. Missing volumes were smallest in the central parts of root systems and largest in distal shallow roots. The slopes of the curves for each root type are synthetic parameters that account for differentiation due to genetics, soil properties, or mechanical stimuli. Accounting for this differentiation is critical to estimating root loss accurately. PMID:24167506

Danjon, Frédéric; Caplan, Joshua S.; Fortin, Mathieu; Meredieu, Céline

2013-01-01

49

Modeling root reinforcement using a root-failure Weibull survival function  

NASA Astrophysics Data System (ADS)

Root networks contribute to slope stability through complex interactions with soil that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamics of root turnover, the quantification of root reinforcement on steep slopes is challenging and consequently the calculation of slope stability also. Although considerable progress has been made, some important aspects of root mechanics remain neglected. In this study we address specifically the role of root-strength variability on the mechanical behavior of a root bundle. Many factors contribute to the variability of root mechanical properties even within a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field data sets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the equations of the tensile force, the elasticity of the roots, and the root distribution are the most important steps. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for tensile, shear and compression behavior allows for the consideration of the stabilization effects of root networks on steep slopes and the influence that this has on the triggering of shallow landslides.

Schwarz, M.; Giadrossich, F.; Cohen, D.

2013-11-01

50

Pythium Root Rot (and Feeder Root Necrosis)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pythium species cause a number of diseases on corn. Among the Pythium diseases, root rot presents the least conspicuous aboveground symptoms. Broadly defined, root rot also includes feeder root necrosis. At least 16 species of Pythium are known to cause root rot of corn. These include P. acanthicu...

51

Image analysis from root system pictures  

NASA Astrophysics Data System (ADS)

Root research has been hampered by a lack of good methods and by the amount of time involved in making measurements. In general the studies from root system are made with either monolith or minirhizotron method which is used as a quantitative tool but requires comparison with conventional destructive methods. This work aimed to analyze roots systems images, obtained from a root atlas book, to different crops in order to find the root length and root length density and correlate them with the literature. Five crops images from Zea mays, Secale cereale, Triticum aestivum, Medicago sativa and Panicum miliaceum were divided in horizontal and vertical layers. Root length distribution was analyzed for horizontal as well as vertical layers. In order to obtain the root length density, a cuboidal volume was supposed to correspond to each part of the image. The results from regression analyses showed root length distributions according to horizontal or vertical layers. It was possible to find the root length distribution for single horizontal layers as a function of vertical layers, and also for single vertical layers as a function of horizontal layers. Regression analysis showed good fits when the root length distributions were grouped in horizontal layers according to the distance from the root center. When root length distributions were grouped according to soil horizons the fits worsened. The resulting root length density estimates were lower than those commonly found in literature, possibly due to (1) the fact that the crop images resulted from single plant situations, while the analyzed field experiments had more than one plant; (2) root overlapping may occur in the field; (3) root experiments, both in the field and image analyses as performed here, are subject to sampling errors; (4) the (hand drawn) images used in this study may have omitted some of the smallest roots.

Casaroli, D.; Jong van Lier, Q.; Metselaar, K.

2009-04-01

52

Root Canal Treatment of a Two-Rooted C-Shaped Maxillary First Molar: A Case Report  

PubMed Central

The most difficult maxillary teeth for endodontic treatment are the maxillary first molars (MFM) due to their complex root canal anatomy. The presence of two roots and C-shaped canals in MFMs has been reported in rare cases. The present case reports root canal treatment of MFM with two roots, where the palatal and buccal roots were joined together in a C-shaped configuration. PMID:25386214

Paksefat, Sara; Rahimi, Saeed

2014-01-01

53

Effectiveness Review Analysis (Insert Effectiveness Review Name) Root Cause  

E-print Network

Effectiveness Review Analysis ­ (Insert Effectiveness Review Name) 1 of 1 Root Cause: Corrective action address the root cause? 2. Does the corrective action prevent recurrence of similar conditions due

54

Roots and Shoots  

NSDL National Science Digital Library

In this outdoor activity, learners discover that plants aren't just shoots (stem, branches, leaves, and flowers) growing above ground, but contain plenty of roots growing underground—more than half the mass of a plant can be its roots. Learners dig up "mystery" plants to investigate their root structures, and match them to different types of root systems. Learners also learn about animals found near plant roots and how humans use roots.

Lawrence Hall of Science

2008-01-01

55

Study of thermal and optical properties of GeS{sub 2}-Ga{sub 2}S{sub 3}-Ag{sub 2}S chalcogenide glasses  

SciTech Connect

Chalcogenide glasses in the GeS{sub 2}-Ga{sub 2}S{sub 3}-Ag{sub 2}S pseudo-ternary system were prepared by melt-quenching technique. The structural evolvement of the glasses was studied by Raman spectroscopy. The Raman results show that the addition of Ag{sub 2}S involves the breaking of [S{sub 3}Ge-GeS{sub 3}] ethane-like units and the formation of Ag-S ionic bonds. The results of differential scanning calorimetry (DSC) show that the glasses have relatively high-glass transition temperatures and good thermal stabilities. These GeS{sub 2}-Ga{sub 2}S{sub 3}-Ag{sub 2}S glasses have a wide range of transmission approximately from 0.50 to 12.5 {mu}m. In addition, with the method of Maker fringe, SHG was observed in the 0.9GeS{sub 2}-0.05Ga{sub 2}S{sub 3}-0.05Ag{sub 2}S glass irradiated by an electron beam. The value of second-order nonlinear optical susceptibility d is as large as 6.6 pm/V, and the poling mechanism of electron beam irradiation was also discussed in this work.

Dong Guoping [Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Luoshi Road 122, Hongshan District, Wuhan, Hubei 430070 (China)], E-mail: guoping_dong@163.com; Tao Haizheng [Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Luoshi Road 122, Hongshan District, Wuhan, Hubei 430070 (China)], E-mail: thz@mail.whut.edu.cn; Xiao Xiudi; Lin Changgui [Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Luoshi Road 122, Hongshan District, Wuhan, Hubei 430070 (China); Zhao Xiujian [Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Luoshi Road 122, Hongshan District, Wuhan, Hubei 430070 (China)], E-mail: opluse@mail.whut.edu.cn; Gu Shaoxuan [Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Luoshi Road 122, Hongshan District, Wuhan, Hubei 430070 (China)

2007-10-02

56

How the soil-root interface affects water availability to plants  

Microsoft Academic Search

Water supply to roots is essential for plant life. To sustain the root water uptake, a continuous liquid phase has to be maintained at the interface between soil and roots. Gaps between soil and roots may interrupt the liquid-phase continuity across the soil-root interface, acting as capillary barriers for the water flow. Additionally, due to the radial geometry of the

Andrea Carminati; Ahmad Moradi

2010-01-01

57

Root-Gel Interactions and the Root Waving Behavior of Arabidopsis1[w  

PubMed Central

Arabidopsis roots grown on inclined agarose gels exhibit a sinusoidal growth pattern known as root waving. While root waving has been attributed to both intrinsic factors (e.g. circumnutation) and growth responses to external signals such as gravity, the potential for physical interactions between the root and its substrate to influence the development of this complex phenotype has been generally ignored. Using a rotating stage microscope and time-lapse digital imaging, we show that (1) root tip mobility is impeded by the gel surface, (2) this impedance causes root tip deflections by amplifying curvature in the elongation zone in a way that is distinctly nontropic, and (3) root tip impedance is augmented by normal gravitropic pressure applied by the root tip against the gel surface. Thus, both lateral corrective bending near the root apex and root tip impedance could be due to different vector components of the same graviresponse. Furthermore, we speculate that coupling between root twisting and bending is a mechanical effect resulting from root tip impedance. PMID:15247406

Thompson, Matthew V.; Holbrook, N. Michele

2004-01-01

58

Spin and orbital magnetism of coinage metal trimers (Cu{sub 3}, Ag{sub 3}, Au{sub 3}): A relativistic density functional theory study  

SciTech Connect

We have demonstrated electronic structure and magnetic properties of Cu{sub 3}, Ag{sub 3} and Au{sub 3} trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21?{sub B} was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.

Afshar, Mahdi [Department of Physics, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)] [Department of Physics, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Sargolzaei, Mohsen [Department of Chemistry, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)] [Department of Chemistry, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)

2013-11-15

59

Detection of tree roots and determination of root diameters by ground penetrating radar under optimal conditions.  

PubMed

A tree's root system accounts for between 10 and 65% of its total biomass, yet our understanding of the factors that cause this proportion to vary is limited because of the difficulty encountered when studying tree root systems. There is a need to develop new sampling and measuring techniques for tree root systems. Ground penetrating radar (GPR) offers the potential for direct nondestructive measurements of tree root biomass and root distributions to be made. We tested the ability of GPR, with 500 MHz, 800 MHz and 1 GHz antennas, to detect tree roots and determine root size by burying roots in a 32 m3 pit containing damp sand. Within this test bed, tree roots were buried in two configurations: (1) roots of various diameters (1-10 cm) were buried at a single depth (50 cm); and (2) roots of similar diameter (about 5 cm) were buried at various depths (15-155 cm). Radar antennas were drawn along transects perpendicular to the buried roots. Radar profile normalization, filtration and migration were undertaken based on standard algorithms. All antennas produced characteristic reflection hyperbolas on the radar profiles allowing visual identification of most root locations. The 800 MHz antenna resulted in the clearest radar profiles. An unsupervised, maximum-convexity migration algorithm was used to focus information contained in the hyperbolas back to a point. This resulted in a significant gain in clarity with roots appearing as discrete shapes, thereby reducing confusion due to overlapping of hyperbolas when many roots are detected. More importantly, parameters extracted from the resultant waveform through the center of a root correlated well with root diameter for the 500 MHz antenna, but not for the other two antennas. A multiple regression model based on the extracted parameters was calibrated on half of the data (R2 = 0.89) and produced good predictions when tested on the remaining data. Root diameters were predicted with a root mean squared error of 0.6 cm, allowing detection and quantification of roots as small as 1 cm in diameter. An advantage of this processing technique is that it produces results independently of signal strength. These waveform parameters represent a major advance in the processing of GPR profiles for estimating root diameters. We conclude that enhanced data analysis routines combined with improvements in GPR hardware design could make GPR a valuable tool for studying tree root systems. PMID:15465695

Barton, Craig V M; Montagu, Kelvin D

2004-12-01

60

Self-assembly of Sn-3Ag-0.5Cu Solder in Thermoplastic Resin Containing Carboxyl Group and its Interconnection  

NASA Astrophysics Data System (ADS)

The self-assembly of solder powder on pads is attractive as a novel interconnection method between chips and substrates. However, the solder used in this method is limited to Sn-58Bi and Sn-52In. In contrast, Sn-3Ag-0.5Cu has been relatively less studied despite its wide use as a lead-free solder in assembling semiconductor packages. Hence, here, polymeric materials incorporating Sn-3Ag-0.5Cu solder powder were investigated for the self-assembly of the solder on pads at temperatures up to 260°C in a lead-free reflow process. The self-assembly of the solder was observed with an optical microscope through transparent glass chips placed on substrates covered with the polymeric materials incorporating the solder powder. Differential scanning calorimetry measurements were performed to confirm the behaviors of the reaction of the resins and the melting of the solder. When epoxy resin with a fluxing additive was used as a matrix, self-assembly of the solder was prevented by the cross-linking reaction. Conversely, when thermoplastic resin containing carboxyl groups was used as a matrix, the self-assembly of solder was successfully achieved in the absence of fluxing additives. The shear strength of interconnection using reflowfilm with lamination was sufficient and significantly increased during the reflow process. However, the shear strength of the reflowfilm showed cohesive failure, possibly because of the brittle intermetallic compounds (Ag3Sn, Au4Sn) network in bulk was lower than that of conventional solder paste that showed interfacial failure after the reflow process with a rapid cooling rate.

Miyauchi, Kazuhiro; Yamashita, Yukihiko; Suzuki, Naoya; Takano, Nozomu

2014-09-01

61

A statistical approach to root system classification  

PubMed Central

Plant root systems have a key role in ecology and agronomy. In spite of fast increase in root studies, still there is no classification that allows distinguishing among distinctive characteristics within the diversity of rooting strategies. Our hypothesis is that a multivariate approach for “plant functional type” identification in ecology can be applied to the classification of root systems. The classification method presented is based on a data-defined statistical procedure without a priori decision on the classifiers. The study demonstrates that principal component based rooting types provide efficient and meaningful multi-trait classifiers. The classification method is exemplified with simulated root architectures and morphological field data. Simulated root architectures showed that morphological attributes with spatial distribution parameters capture most distinctive features within root system diversity. While developmental type (tap vs. shoot-borne systems) is a strong, but coarse classifier, topological traits provide the most detailed differentiation among distinctive groups. Adequacy of commonly available morphologic traits for classification is supported by field data. Rooting types emerging from measured data, mainly distinguished by diameter/weight and density dominated types. Similarity of root systems within distinctive groups was the joint result of phylogenetic relation and environmental as well as human selection pressure. We concluded that the data-define classification is appropriate for integration of knowledge obtained with different root measurement methods and at various scales. Currently root morphology is the most promising basis for classification due to widely used common measurement protocols. To capture details of root diversity efforts in architectural measurement techniques are essential. PMID:23914200

Bodner, Gernot; Leitner, Daniel; Nakhforoosh, Alireza; Sobotik, Monika; Moder, Karl; Kaul, Hans-Peter

2013-01-01

62

Soil Bacterial Diversity Responses to Root Colonization by an Ectomycorrhizal Fungus are not Root-Growth-Dependent  

E-print Network

Fungus are not Root-Growth-Dependent Komi Assigbetse1 , Mariama Gueye1 , Jean Thioulouse2 and Robin addition of the ectomycorrhizal fungus or N/P/K fertilization (to reproduce the fungal effect on root effect is not root- growth-dependent but is mainly due to the presence of the ectomycorrhizal fungus

Thioulouse, Jean

63

PHIV-RootCell: a supervised image analysis tool for rice root anatomical parameter quantification  

PubMed Central

We developed the PHIV-RootCell software to quantify anatomical traits of rice roots transverse section images. Combined with an efficient root sample processing method for image acquisition, this program permits supervised measurements of areas (those of whole root section, stele, cortex, and central metaxylem vessels), number of cell layers and number of cells per cell layer. The PHIV-RootCell toolset runs under ImageJ, an independent operating system that has a license-free status. To demonstrate the usefulness of PHIV-RootCell, we conducted a genetic diversity study and an analysis of salt stress responses of root anatomical parameters in rice (Oryza sativa L.). Using 16 cultivars, we showed that we could discriminate between some of the varieties even at the 6 day-olds stage, and that tropical japonica varieties had larger root sections due to an increase in cell number. We observed, as described previously, that root sections become enlarged under salt stress. However, our results show an increase in cell number in ground tissues (endodermis and cortex) but a decrease in external (peripheral) tissues (sclerenchyma, exodermis, and epidermis). Thus, the PHIV-RootCell program is a user-friendly tool that will be helpful for future genetic and physiological studies that investigate root anatomical trait variations. PMID:25646121

Lartaud, Marc; Perin, Christophe; Courtois, Brigitte; Thomas, Emilie; Henry, Sophia; Bettembourg, Mathilde; Divol, Fanchon; Lanau, Nadege; Artus, Florence; Bureau, Charlotte; Verdeil, Jean-Luc; Sarah, Gautier; Guiderdoni, Emmanuel; Dievart, Anne

2015-01-01

64

The Root Pressure Phenomenon  

ERIC Educational Resources Information Center

Describes experiments demonstrating that root pressure in plants is probably controlled by a circadian rhythm (biological clock). Root pressure phenomenon plays significant part in water transport in contradiction with prevalent belief. (PS)

Marsh, A. R.

1972-01-01

65

Using Square Roots  

ERIC Educational Resources Information Center

This article describes techniques which enable the user of a comparatively simple calculator to perform calculations of cube roots, nth roots, trigonometric, and inverse trigonometric functions, logarithms, and exponentials. (DT)

Wilson, William Wynne

1976-01-01

66

Root Biomass of Individual Species, and Root Size Characteristics After Five Years of CO 2 Enrichment on Native Shortgrass Steppe  

Microsoft Academic Search

Information from field studies investigating the responses of roots to increasing atmospheric CO2 is limited and somewhat inconsistent, due partly to the difficulty in studying root systems in situ. In this report, we present standing root biomass of species and root length and diameter after five years of CO2 enrichment (?720 ?mol mol?1) in large (16 m2 ground area) open-top chambers placed over

D. R. LeCain; J. A. Morgan; D. G. Milchunas; A. R. Mosier; J. A. Nelson; D. P. Smith

2006-01-01

67

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode  

PubMed Central

We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693

2014-01-01

68

WHY ROOTING FAILS.  

SciTech Connect

I explore the origins of the unphysical predictions from rooted staggered fermion algorithms. Before rooting, the exact chiral symmetry of staggered fermions is a flavored symmetry among the four 'tastes.' The rooting procedure averages over tastes of different chiralities. This averaging forbids the appearance of the correct 't Hooft vertex for the target theory.

CREUTZ,M.

2007-07-30

69

Corky root rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

Corky root rot (corchosis) was first reported in Argentina in 1985, but the disease was presumably present long before that. The disease occurs in most alfalfa-growing areas of Argentina but is more common in older stands. In space-planted alfalfa trials scored for root problems, corky root rot was ...

70

BLACK ROOT ROT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Black Root Rot Prepared by G. S. Abawi, Revised by L.E. Hanson Black root rot is caused by Thielaviopsis basicola (syn. Chalara elegans). The pathogen is widely distributed, can infect more than 130 plant species in 15 families, and causes severe black root rot diseases in ornamentals and crops suc...

71

Reciprocation, Square Root, Inverse Square Root, and Some Elementary Functions  

E-print Network

Reciprocation, Square Root, Inverse Square Root, and Some Elementary Functions Using Small with the computation of reciprocals, square roots, inverse square roots, and some elementary functions using small/number of multipliers and compare with other related methods. Index TermsÐReciprocal, square root, inverse square root

Muller, Jean-Michel

72

Investigation of VEGGIE Root Mat  

NASA Technical Reports Server (NTRS)

VEGGIE is a plant growth facility that utilizes the phenomenon of capillary action as its primary watering system. A cloth made of Meta Aramid fiber, known as Nomex is used to wick water up from a reservoir to the bottom of the plants roots. This root mat system is intended to be low maintenance with no moving parts and requires minimal crew interface time. Unfortunately, the water wicking rates are inconsistent throughout the plant life cycle, thus causing plants to die. Over-wicking of water occurs toward the beginning of the cycle, while under-wicking occurs toward the middle. This inconsistency of wicking has become a major issue, drastically inhibiting plant growth. The primary objective is to determine the root cause of the inconsistent wicking through experimental testing. Suspect causes for the capillary water column to break include: a vacuum effect due to a negative pressure gradient in the water reservoir, contamination of material due to minerals in water and back wash from plant fertilizer, induced air bubbles while using syringe refill method, and material limitations of Nomex's ability to absorb and retain water. Experimental testing will be conducted to systematically determine the cause of under and over-wicking. Pressure gages will be used to determine pressure drop during the course of the plant life cycle and during the water refill process. A debubbler device will be connected to a root mat in order to equalize pressure inside the reservoir. Moisture and evaporation tests will simultaneously be implemented to observe moisture content and wicking rates over the course of a plant cycle. Water retention tests will be performed using strips of Nomex to determine materials wicking rates, porosity, and absorptivity. Through these experimental tests, we will have a better understanding of material properties of Nomex, as well as determine the root cause of water column breakage. With consistent test results, a forward plan can be achieved to resolve the issue and give valuable insight for the next generation of VEGGIE.

Subbiah, Arun M.

2013-01-01

73

Why fine tree roots are stronger than thicker roots: The role of cellulose and lignin in relation to slope stability  

NASA Astrophysics Data System (ADS)

Plant roots help to reinforce the soil, increase slope stability and decrease water erosion. Root tensile strength plays an important role in soil reinforcement and slope stabilization. The relationship between tensile strength and internal chemical composition of roots is unknown due to limited studies. Thus, it is difficult to determine why root tensile strength tends to decrease with increasing root diameter. In this study, biomechanical and biochemical tests were performed on the roots of Chinese pine (Pinus tabulaeformis) to determine the relationships among tensile strength and the contents of the main chemical composition: cellulose, alpha-cellulose and lignin in the roots with different diameters. Our results confirmed that the tensile strength of Chinese pine roots decreased with increasing root diameter, and this relationship might be a power function. The chemical contents of the roots and root diameter were also related to each other with significant power regression. With increasing root diameter, the cellulose content and alpha-cellulose content increased, but the lignin content decreased. In addition, the lignin content exhibited a significantly positive relationship with tensile strength. Furthermore, the ratios of lignin/cellulose and lignin/alpha-cellulose decreased with increasing root diameter following significant power regressions, and they also demonstrated a positive relationship with tensile strength. Taken together, these results may be useful for studies on root tensile strength, soil reinforcement and slope stability.

Zhang, Chao-Bo; Chen, Li-Hua; Jiang, Jing

2014-02-01

74

Charge carrier mobility and concentration as a function of composition in AgPO3-AgI glasses  

NASA Astrophysics Data System (ADS)

Conductivity data of the xAgI(1 - x)AgPO3 system (0 ? x ? 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (Tg) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below Tg and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at ?0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (?10-4 cm2 V-1 s-1) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO3.

Rodrigues, Ana Candida Martins; Nascimento, Marcio Luis Ferreira; Bragatto, Caio Barca; Souquet, Jean-Louis

2011-12-01

75

Natural variation of root traits: from development to nutrient uptake.  

PubMed

The root system has a crucial role for plant growth and productivity. Due to the challenges of heterogeneous soil environments, diverse environmental signals are integrated into root developmental decisions. While root growth and growth responses are genetically determined, there is substantial natural variation for these traits. Studying the genetic basis of the natural variation of root growth traits can not only shed light on their evolution and ecological relevance but also can be used to map the genes and their alleles responsible for the regulation of these traits. Analysis of root phenotypes has revealed growth strategies and root growth responses to a variety of environmental stimuli, as well as the extent of natural variation of a variety of root traits including ion content, cellular properties, and root system architectures. Linkage and association mapping approaches have uncovered causal genes underlying the variation of these traits. PMID:25104725

Ristova, Daniela; Busch, Wolfgang

2014-10-01

76

High resolution modeling of water and nutrient uptake by plant roots: at a scale from single root to root system  

NASA Astrophysics Data System (ADS)

The uptake of nutrients by plant roots is a multiscale problem. At the small scale, nutrient fluxes towards single roots lead to strong gradients in nutrient concentrations around single roots. At the scale of the root system and soil profile, nutrient fluxes are generated by water fluxes and variations in nutrient uptake due to spatially varying root density, nutrient concentrations and water contents. In this contribution, we present a numerical simulation model that describes the processes at the scale of a single root and the scale of the entire root system simultaneously. Water flow and nutrient transport in the soil are described by the 3-D Richards and advection-dispersion equations, respectively. Water uptake by a root segment is simulated based on the difference between the soil water potential at the soil root interface and in the xylem tissue. The xylem water potential is derived from solving a set of flow equations that describe flow in the root network (Javaux et al., 2008). Nutrient uptake by a segment is simulated as a function of the nutrient concentration at the soil-root interface using a nonlinear Michaelis-Menten equation. An accurate description of the nutrient concentrations gradients around single roots requires a spatial resolution in the sub mm scale and is therefore not feasible for simulations of the entire root system or soil profile. In order to address this problem, a 1-D axisymmetric model (Barber and Cushman, 1981) was used to describe nutrient transport towards a single root segment. The network of connected cylindrical models was coupled to a 3-D regular grid that was used to solve the flow and transport equations at the root system scale. The coupling was done by matching the fluxes across the interfaces of the voxels of the 3-D grid that contain root segments with the fluxes at the outer boundaries of the cylindrical domains and by matching the sink terms in these voxels with uptake by the root segments. To demonstrate the feasibility of this method, we compared cumulative nutrient uptake by the coupled (3D-1D) with results obtained at the single root scale using a high resolution model and the approximate analytical solution of Roose et al., (2001). The good agreement between the fine mesh 3-D and a coupled (3D-1D) model makes this coupling approach capable to simulate a root system scale models without a high computational cost. Furthermore, the coupling allows to account for the effect of water uptake and soil drying on nutrient uptake and to account for spatial variations in root density and nutrient concentrations. These effects cannot be represented by a simple upscaling of single root scale models since they require the description of water and nutrient fluxes within the entire root zone.

Abesha, Betiglu; Vanderborght, Jan; Javaux, Mathieu; Schnepf, Andrea; Vereecken, Harry

2014-05-01

77

Omnidirectional and broadband optical absorption enhancement in small molecule organic solar cells by a patterned MoO3/Ag/MoO3 transparent anode  

NASA Astrophysics Data System (ADS)

We designed and calculated a novel organic solar cell (OSC) with MoO3/Ag/MoO3 (MAM) grating as transparent anode and the patterned copper phthalocyanine (CuPc)/fullerence (C60) as active layer. The numerical results indicate that a broadband, omnidirectional light absorption enhancement is realized by utilizing such a one-dimensional (1D) grating with core-shell structure. The total absorption efficiency of the active layer over the wavelength range from 400 to 900 nm is enhanced by 178.88%, 19.44% and 99.16% relative to the equivalent planar cell considering the weight of air-mass 1.5 global (AM 1.5G) solar spectrum at normally incident transverse magnetic (TM), transverse electric (TE) and TM/TE hybrid polarized light, respectively. The improved light trapping is attributed to the multiple modes hybridization of propagating surface plasmon polaritons (SPPs), localized surface plasmons (LSPs) and the strong coupling of SPP waves at TM polarization along with the Floquet modes at TE polarization. Furthermore, the proposed optimized architecture also exhibits an expected short-circuit current density (Jsc) with the value of 11.11 mA/cm2 in theory, which is increased by 116.6% compared with that of the planar control device.

Tian, Ximin; Hao, Yuying; Zhang, Ye; Cui, Yanxia; Ji, Ting; Wang, Hua; Wei, Bin; Huang, Wei

2015-03-01

78

Cell wall properties play an important role in the emergence of lateral root primordia from the parent root  

PubMed Central

Plants adapt to their unique soil environments by altering the number and placement of lateral roots post-embryonic. Mutants were identified in Arabidopsis thaliana that exhibit increased lateral root formation. Eight mutants were characterized in detail and were found to have increased lateral root formation due to at least three distinct mechanisms. The causal mutation in one of these mutants was found in the XEG113 gene, recently shown to be involved in plant cell wall biosynthesis. Lateral root primordia initiation is unaltered in this mutant. In contrast, synchronization of lateral root initiation demonstrated that mutation of XEG113 increases the rate at which lateral root primordia develop and emerge to form lateral roots. The effect of the XEG113 mutation was specific to the root system and had no apparent effect on shoot growth. Screening of 17 additional cell wall mutants, altering a myriad of cell wall components, revealed that many (but not all) types of cell wall defects promote lateral root formation. These results suggest that proper cell wall biosynthesis is necessary to constrain lateral root primordia emergence. While previous reports have shown that lateral root emergence is accompanied by active remodelling of cell walls overlying the primordia, this study is the first to demonstrate that alteration of the cell wall is sufficient to promote lateral root formation. Therefore, inherent cell wall properties may play a previously unappreciated role in regulation of root system architecture. PMID:24619997

Malamy, Jocelyn E.

2014-01-01

79

Root canal irrigants  

PubMed Central

Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are discussed. We performed a Medline search for English-language papers published untill July 2010. The keywords used were ‘root canal irrigants’ and ‘endodontic irrigants.’ The reference lists of each article were manually checked for additional articles of relevance. PMID:21217955

Kandaswamy, Deivanayagam; Venkateshbabu, Nagendrababu

2010-01-01

80

Plant root exudates  

Microsoft Academic Search

Conclusions  Although the quantities of organic compounds exuding from roots is not large, seldom exceeding 0.4% of the carbon photosynthesized,\\u000a they do exert a very strong influence on the soil microorganisms and may be significant in affecting plant nutrient availability.\\u000a There is evidence that exudates from the roots of some plants are toxic to roots of neighboring plants and to the

Albert D. Rovira

1969-01-01

81

Where do roots take up water? A method to quantify local root water uptake  

NASA Astrophysics Data System (ADS)

During the past decades, considerable advances have been made in the conceptual understanding and mathematical description of root water uptake process. A large number of models of root water uptake with different degrees of complexity are now available. However, effective application of these models to practical situations for mechanistic description of root water uptake requires proper experimental data. The aim of this study is to introduce and test a non-destructive method for quantifying local water flow from soil to roots. We grew lupin in 30-25-1 cm containers. Each container was filled with a sandy soil which was partitioned into different compartments using 1cm-thick layers of coarse sand. Deuterium (D2O) was locally injected in soil near the root surface of 18-day old plans. The flow of D2O into transpiring plants (day) and non-transpiring plants (night) was traced using time-series neutron radiography. The results showed that: 1) D2O entered the roots faster during the day than night; 2) D2O quickly transported inside the roots towards the shoots during the day, while at night this flow was negligible. Differences between day and night were explained by convective flow of water into the root due to transpiration. To quantify the transport of D2O into roots, we developed a simple convection-diffusion model. The root water uptake predicted by the model was compared with the direct measurements of axial water flow in the roots. This new method allows for quantifying local water uptake in different parts of the root system.

Zarebanadkouki, M.; Kim, Y.; Carminati, A.

2012-04-01

82

“Internal root resorption: An endodontic challenge”: A case series  

PubMed Central

Management of internal root resorption is a challenge to the endodontists. It may occur in cases with chronic pulpal inflammation, following caries or due to trauma in the form of an accidental blow. Most cases of internal root resorption are seen in anterior teeth, due to their susceptibility to trauma. However, it may be seen in posterior teeth, most likely because of carious involvement of the pulp. Early diagnosis, removal of the cause, proper treatment of the resorbed root is mandatory for successful treatment outcome. This paper is an attempt to summarize the knowledge on internal root resorption and present various cases, which were successfully managed with different treatment modalities. PMID:25506152

Mittal, Sunandan; Kumar, Tarun; Mittal, Shifali; Sharma, Jyotika

2014-01-01

83

Pressure induced silver ion displacement in La{sub 3}Ag{sub 0.82}SnS{sub 7}  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer The silver ion shifts with increasing pressure in the direction of the central-point of sulphur trigonal antiprism. Black-Right-Pointing-Pointer Coordination number changes from CN = 3 to CN = 6 at {approx}3 GPa. Black-Right-Pointing-Pointer Zero-pressure bulk modulus is B{sub 0} = 61.74 GPa and the pressure derivative is B{sup Prime }{sub 0}=4.02. Black-Right-Pointing-Pointer No phase transition up to 4.5 GPa was detected. -- Abstract: The compounds with the general formula Ln{sub 3}MTX{sub 7} (space group P6{sub 3}) (Ln - rare-earth element, M - monovalent element (Cu, Ag), T - Si, Ge, Sn and X - S, Se) are interesting owing to the possible application in the field of ionic conductivity. In the crystal structure the face-sharing [Ag(S){sub 6}] triangular antiprisms form the channels where the Ag{sup +} ion can migrate along the crystallographic c axis. High-pressure X-ray diffraction shows that Ag{sup +} ion moves towards the central-point of [Ag(S){sub 6}] when pressure is risen. As a consequence, the coordination number of Ag{sup +} changes from CN = 3 to CN = 6 at {approx}3 GPa. The La{sub 3}Ag{sub 0.82}SnS{sub 7} has stiff structure; zero-pressure bulk modulus is B{sub 0} = 61.74 GPa and the pressure derivative is B{sup Prime }{sub 0}=4.02.

Daszkiewicz, Marek, E-mail: m.daszkiewicz@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P. O. Box 1410, 50-950 Wroclaw (Poland)] [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P. O. Box 1410, 50-950 Wroclaw (Poland); Gulay, Lubomir D. [Department of Ecology and Protection of Environment, Volyn National University, Voli Ave 13, 43009 Lutsk (Ukraine)] [Department of Ecology and Protection of Environment, Volyn National University, Voli Ave 13, 43009 Lutsk (Ukraine)

2012-02-15

84

How to bond to root canal dentin  

NASA Astrophysics Data System (ADS)

Bonding to root canal dentin may be difficult due to various factors: the structural characteristic of the root canal dentin, which is different from that of the coronal dentin; the presence of the organic tissue of the dental pulp inside the root canal, which has to be removed during the cleaning-shaping of the root canal system; the smear-layer resulted after mechanical instrumentation, which may interfere with the adhesion of the filling materials; the type of the irrigants used in the cleaning protocol; the type of the sealer and core material used in the obturation of the endodontic space; the type of the materials used for the restoration of the endodontically treated teeth. The influence of the cleaning protocol, of the root canal filling material, of the type of the adhesive system used in the restoration of the treated teeth and of the region of the root canal, on the adhesion of several filling and restorative materials to root canal dentin was evaluated in the push-out bond strength test on 1-mm thick slices of endodontically treated human teeth. The results showed that all these factors have a statistically significant influence on the push-out bond strength. Formation of resin tags between radicular dentin and the investigated materials was observed in some of the samples at SEM analysis.

Nica, Luminita; Todea, Carmen; Furtos, Gabriel; Baldea, Bogdan

2014-01-01

85

Excited-State Dynamics of Overlapped Optically-Allowed 1Bu+ and Optically-Forbidden 1Bu? or 3Ag? Vibronic Levels of Carotenoids: Possible Roles in the Light-Harvesting Function  

PubMed Central

The unique excited-state properties of the overlapped (diabatic) optically-allowed 1Bu+ and the optically-forbidden 1Bu? or 3Ag? vibronic levels close to conical intersection (‘the diabatic pair’) are summarized: Pump-probe spectroscopy after selective excitation with ?100 fs pulses of all-trans carotenoids (Cars) in nonpolar solvent identified a symmetry selection rule in the diabatic electronic mixing and diabatic internal conversion, i.e., ‘1Bu+-to-1Bu? is allowed but 1Bu+-to-3Ag? is forbidden’. On the other hand, pump-probe spectroscopy after coherent excitation with ?30 fs of all-trans Cars in THF generated stimulated emission with quantum beat, consisting of the long-lived coherent diabatic cross term and a pair of short-lived incoherent terms. PMID:20480049

Koyama, Yasushi; Kakitani, Yoshinori; Miki, Takeshi; Christiana, Rebecca; Nagae, Hiroyoshi

2010-01-01

86

ROOT Statistical Software  

E-print Network

Advanced mathematical and statistical computational methods are required by the LHC experiments for analyzing their data. Some of these methods are provided by the ROOT project, a C++ Object Oriented framework for large scale data handling applications. We review the current mathematical and statistical classes present in ROOT, emphasizing the recent developments.

Moneta, Lorenzo; Brun, R; Kreshuk, Anna

2008-01-01

87

Irrational Square Roots  

ERIC Educational Resources Information Center

If students are presented the standard proof of irrationality of [square root]2, can they generalize it to a proof of the irrationality of "[square root]p", "p" a prime if, instead of considering divisibility by "p", they cling to the notions of even and odd used in the standard proof?

Misiurewicz, Michal

2013-01-01

88

Seeds: Roots and Shoots  

NSDL National Science Digital Library

In this indepth hands-on activity, learners build a structure that allows them to observe the growth of roots and the correlation between root growth and stem extension. Because no dirt is used in this arrangement, a guiding question can be posed: What does the plant need to grow? The PDF includes activity rationale, procedure, background and follow-up discussion suggestions.

Education Development Center, Inc.

2010-01-01

89

ROOTING GUATEMALAN AVOCADO CUTTINGS  

Microsoft Academic Search

SUMMARY A method is described which, although not considered commercially practical, proved to be very successful in rooting cuttings of Guatemalan avocado varieties. Essentially it consists of obtaining cuttings from stems, the bases of which have at no time been exposed to light or low humidity. In certain experimental work with the avocado, own rooted trees, that is trees propagated

E. F. Frolich

90

DMA thermal analysis of yacon tuberous roots  

NASA Astrophysics Data System (ADS)

Specimens prepared from yacon roots in first two weeks after harvest were tested by dynamic mechanical analysis thermal analysis at temperatures between 30 and 90°C. No differences between different parts of roots were proved. There were indicated some differences in the test parameters that were caused by short time storage of the roots. One source of the differences was loss of water during the roots storage. The measured modulus increased during short time storage. Detailed study of changes of the modulus during the specimen dynamic mechanical analysis test provided information about different development of the storage and loss moduli during the specimen heating. The observed results can be caused by changes in cellular membranes observed earlier during vegetable heating, and by composition changes due to less stable components of yacon like inulin.

Blahovec, J.; Lahodová, M.; Kindl, M.; Fernández, E. C.

2013-12-01

91

Gravitropic response of adventitious roots cultivated in light and darkness on sucrose-free medium.  

PubMed

Elongation of adventitious roots of Dracaena fragrans was investigated under photoautotrophic conditions. Root elongation decreased and stopped when cultures were transferred to darkness. Upon return to light roots renewed growth after a 5 day lag period. During the first two days of intensive new growth roots were agravitropic elongating in random directions. Investigation showed that transient absence of geotropic response was connected with disappearance of starch grains in root tip which occurred due to sucrose starvation of cultures in continuous darkness. PMID:11543427

Vinterhalter, D V; Vinterhalter, B S

1999-11-30

92

Size Effect of Rare-Earth Intermetallics in Sn-9Zn-0.5Ce and Sn-3Ag-0.5Cu-0.5Ce Solders on the Growth of Tin Whiskers  

NASA Astrophysics Data System (ADS)

In contrast to the large cluster-shaped CeSn3 peritectic phase formed in Sn-3Ag-0.5Cu-0.5Ce solder, Sn-9Zn-0.5Ce possesses very fine (Ce0.8Zn0.2)Sn3 intermetallics. Image analyses indicate that the total exposed area of fine peritectic intermetallics in Sn-9Zn-0.5Ce solder is near that of coarse clusters in Sn-3Ag-0.5Cu-0.5Ce. However, long fiber-type and coarse hillock-type whiskers have been observed on the surface of Sn-3Ag-0.5Cu-0.5Ce after air storage at room temperature and 150 °C, respectively. On the contrary, only tin sprouts appear on the oxide layer of peritectic (Ce0.8Zn0.2)Sn3 intermetallics of Sn-9Zn-0.5Ce solder. The prevention of the lengthening and coarsening of these tin sprouts in Sn-9Zn-0.5Ce solder is attributed to the small size of its rare-earth (RE) containing peritectic clusters. The results imply that Zn atoms have an inhibition effect for the whisker growth of RE-doped solders.

Chuang, T. H.; Lin, H. J.

2008-12-01

93

A new Approach for Quantifying Root-Reinforcement of Streambanks: the RipRoot Model  

NASA Astrophysics Data System (ADS)

Riparian vegetation plays an important role in controlling geotechnical and fluvial processes acting along and within streambanks through the binding effects of roots. Quantification of this mechanical effect is therefore essential to accurately model streambank stability. Until now, most attempts to include the effects of root reinforcement by riparian vegetation have used root-cohesion values estimated using the Wu et al. (1979) equation, requiring the tensile strengths and diameters of the roots crossing the potential shear-plane. However, the Wu et al. equation is a static model that assumes that all roots break, and that they all break simultaneously. Field observations and laboratory experiments have shown that in reality the roots do not all break simultaneously, and that the breaking of roots during mass failure is in fact a dynamic process. Static models such as the Wu et al. equation are therefore likely to produce overestimations of cohesion due to roots. As a response to this concern, a dynamic root reinforcement model (RipRoot) was developed, based on the concepts of fiber bundle models (FBM's) used in materials science. Within the model the root-soil system is loaded incrementally resulting in progressive root breaking and redistribution of stresses from the broken roots to the remaining intact roots in the soil matrix. The redistribution and loading process continues until either all of the roots have broken, or equilibrium is reached where the root network supports the driving force imposed on the bank. The increase in bank cohesion using the static Wu et al. equation are 18% to 38% higher than RipRoot for riparian tree species, including Black Willow, Sandbar Willow, Cottonwood, River Birch and Eastern Sycamore, and 49% higher for Switch Grass. These variations in cohesion values can have a significant impact on streambank Factor of Safety (Fs) values calculated using the Simon et al. (2000) bank-stability model. For example, a 3m high silt streambank had a Fs of 0.98 without vegetation, indicating instability. With the addition of cohesion from 200 River Birch roots this value increased to 1.22 using the RipRoot value (Conditionally Stable) and 1.37 using the Wu et al. equation (Stable). In this example both of the root models produced cohesion values that were large enough to make the bank more stable, but the more conservative value from RipRoot suggests the bank may only be conditionally stable. Results to date indicate that the dynamic nature of RipRoot removes some of the overestimation from the static equation of Wu et al. (1979), therefore producing more realistic values for root reinforcement, which are particularly useful and important in the context of river management and restoration.

Pollen, N. L.; Simon, A.

2003-12-01

94

ECOLOGY: How Do Roots Interact?  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Roots actively forage for nutrient hot spots and avoid patches where root densities of competing neighbors are high. Several studies have shown that roots respond to neighboring roots in a very specific manner that depends on the identity of the neighbor. Root extension tends to be greater when roots grow into substrate containing "nonself " roots of a genetically different individual or a detached plant with the same genotype than when "self " roots of the same (physiological and genetic) individual are encountered.

Hans de Kroon (Radboud University; Department of Experimental Plant Ecology, Institute for Water and Wetland Research)

2007-12-07

95

Neighbor influences on root morphology and mycorrhizal fungus colonization in tallgrass prairie plants  

SciTech Connect

A field study was conducted across a chronosequence of tallgrass prairie restorations to investigate the influence a plant's neighbor may have on its gross root morphology and association with mycorrhizal fungi. The root systems of a warm-season grass, Andropogon gerardii, and two perennial forbs, Coreopsis tripteris and Solidago altissima, were sampled by excavating soil blocks representing all pairwise inter- and intra-specific combinations of these species. With forb neighbors, Andropogon had higher percentages of its firbrous roots colonized by mycorrhizal fungi than with conspecific neighbors. Andropogon root morphology (as measured by average root radius, specific root length, and root branching) did not vary with neighbor growth form; however, Andropogon roots did become finer as restoration age and root densities increased. For Coreopsis and Solidago, colonization of fibrous roots did not vary with neighbor species, but both forbs had coarser roots with interspecific neighbors than with conspecifics. With interspecific neighbors, Coreopsis almost doubled the number of branches per centimetre of root observed in conspecific pairs. Although some of the variations in colonization and root morphology may be attributable specifically to neighbor root mass, others were related to the overall root mass of the target-neighbor pair. The observed variations in mycorrhizal colonization may be related to increased opportunities for colonization by the fungus that are due not only to higher root densities but also to some sort of interaction between the root systems of Andropogon and the forbs. 44 refs., 2 figs., 2 tabs.

Jastrow, J.D. (Argonne National Lab., IL (United States) Univ. of Illinois, Chicago (United States)); Miller, R.M. (Argonne National Lab., IL (United States))

1993-03-01

96

Topics In Primitive Roots  

E-print Network

This monograph considers a few topics in the theory of primitive roots g(p) modulo a prime p>=2. A few estimates of the least primitive roots g(p) and the least prime primitive roots g^*(p) modulo p, a large prime, are determined. One of the estimate here seems to sharpen the Burgess estimate g(p) number 3 > 0, to the smaller estimate g(p) 2. The expected order of magnitude is g(p) 1 constant. The corresponding estimates for least prime primitive roots g^*(p) are slightly higher. Anotrher topic deals with an effective lower bound #{p > x/log x for the number of primes p number x >1. The current results in the literature claim the lower bound #{p > x/(log x)^2, and have restrictions on the minimal number of fixed integers to three or more.

N. A. Carella

2015-03-12

97

Corn root gravitropism  

NSDL National Science Digital Library

Gravitropism is the turning or growing in a different direction of a plant in response to gravity. This corn plant's root grows downward and exhibits positive gravitropism because it is growing toward gravity's pull.

Roger P. Hangarter (Indiana University; Department of Biology)

2000-01-01

98

Experimentally reduced root–microbe interactions reveal limited plasticity in functional root traits in Acer and Quercus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Abstract. Background and Aims Interactions between roots and soil microbes are critical components of below-ground ecology. It is essential to quantify the magnitude of root trait variation both among and within species, including variation due to plasticity. In addition to contextualizing the mag...

99

[Surgical treatment for prosthetic valve endocarditis after aortic root replacement].  

PubMed

Aorto-left ventricular continuity destruction due to prosthetic valve endocarditis is rare, but it is one of the fatal complications after aortic root operation. We report a case of surgical treatment for prosthetic valve endocarditis after aortic root replacement. A 47-year-old man, who had undergone aortic root replacement with a composite graft was transferred to our hospital with sudden chest pain and high fever. Enhanced computed tomography showed a large space with contrast enhancement suggesting perivalvular leakage around the artificial composite graft. Emergency operation including aortic root re-replacement and reconstruction of the left ventricular outflow tract was performed successfully. We focused on its technical aspect. PMID:24917287

Kanamori, Taro; Ichihara, Tetsuya; Sakaguchi, Hidehito; Inoue, Takehiko

2014-05-01

100

Identification of soil-borne pathogens in a common bean root rot nursery in Isabela, Puerto Rico  

Technology Transfer Automated Retrieval System (TEKTRAN)

Limited research has been completed on the root rot complex of the common bean (Phaseolus vulgaris L.) in the Caribbean, while yield losses of over 50% due to root rot disease have been reported worldwide. In this study, the predominant root rot pathogens in a 40-year old common bean root rot nurser...

101

The "Green" Root Beer Laboratory  

ERIC Educational Resources Information Center

No, your students will not be drinking green root beer for St. Patrick's Day--this "green" root beer laboratory promotes environmental awareness in the science classroom, and provides a venue for some very sound science content! While many science classrooms incorporate root beer-brewing activities, the root beer lab presented in this article has…

Clary, Renee; Wandersee, James

2010-01-01

102

Developmental Changes in Peanut Root Structure during Root Growth and Root-structure Modification by Nodulation  

PubMed Central

Background and Aims Basic information about the root and root nodule structure of leguminous crop plants is incomplete, with many aspects remaining unresolved. Peanut (Arachis hypogaea) forms root nodules in a unique process. Structures of various peanut root types were studied with emphasis on insufficiently characterized lateral roots, changes in roots during their ontogenesis and root modification by nodule formation. Methods Peanut plants were grown in the field, in vermiculite or in filter paper. The taproot, first-order and second-order lateral roots and root nodules were analysed using bright-field and fluorescence microscopy with hand sections and resin sections. Key Results Three root categories were recognized. The primary seminal root was thick, exhibiting early and intensive secondary thickening mainly on its base. It was tetrarch and contained broad pith. First-order lateral roots were long and thin, with limited secondary thickening; they contained no pith. Particularly different were second- and higher-order lateral roots, which were anatomically simple and thin, with little or no secondary growth. Unusual wall ingrowths were visible in the cells of the central part of the cortex in the first-order and second-order lateral roots. The nodule body was formed at the junction of the primary and lateral roots by the activity of proliferating cells derived originally from the pericycle. Conclusions Two morphologically and anatomically distinct types of lateral roots were recognized: long, first-order lateral roots, forming the skeleton of the root system, and thin and short second- and higher-order lateral roots, with an incomplete second state of endodermal development, which might be classified as peanut ‘feeder roots’. Formation of root nodules at the base of the lateral roots was the result of proliferating cell divisions derived originally from the pericycle. PMID:18256023

Tajima, Ryosuke; Abe, Jun; Lee, O. New; Morita, Shigenori; Lux, Alexander

2008-01-01

103

Arabidopsis alcohol dehydrogenase expression in both shoots and roots is conditioned by root growth environment  

NASA Technical Reports Server (NTRS)

It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. beta-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.

Chung, H. J.; Ferl, R. J.

1999-01-01

104

Simulating root-induced rhizosphere deformation and its effect on water flow  

NASA Astrophysics Data System (ADS)

Soil structure in the rhizosphere is influenced by root activities, such as mucilage production, microbial activity and root growth. Root growth alters soil structure by moving and deforming soil aggregates, affecting water and nutrient flow from the bulk soil to the root surface. In this study, we utilized synchrotron X-ray micro-tomography (XMT) and finite element analysis to quantify the effect of root-induced compaction on water flow through the rhizosphere to the root surface. In a first step, finite element meshes of structured soil around the root were created by processing rhizosphere XMT images. Then, soil deformation by root expansion was simulated using COMSOL Multiphysics° (Version 4.2) considering the soil an elasto-plastic porous material. Finally, fluid flow simulations were carried out on the deformed mesh to quantify the effect of root-induced compaction on water flow to the root surface. We found a 31% increase in water flow from the bulk soil to the root due to a 56% increase in root diameter. Simulations also show that the increase of root-soil contact area was the dominating factor with respect to the calculated increase in water flow. Increase of inter-aggregate contacts in size and number were observed within a couple of root diameters away from the root surface. But their influence on water flow was, in this case, rather limited compared to the immediate soil-root contact.

Aravena, J. E.; Ruiz, S.; Mandava, A.; Regentova, E. E.; Ghezzehei, T.; Berli, M.; Tyler, S. W.

2011-12-01

105

Improving predictions of root biomechanical properties, is age a better determinant than diameter?  

NASA Astrophysics Data System (ADS)

Roots mechanically reinforce many soils. Root tensile strength and stiffness is critical for soil stabilisation with plants potentially providing civil engineers a 'green' alternative for soil stabilisation. Relatively little is known on factors influencing root tensile strength. Through a better understanding of these factors the adoption of 'green engineering' techniques by civil engineers will improve. Existing models are limited in their accuracy due to simplistic assumptions to derive root contributions to the resistance of soil to failure. Current models typically use relationships between strength and diameter, however, there are a number of other factors potentially influencing root biomechanical properties. The effects of root age on biomechanical properties have largely been overlooked. Barley (Hordeum vulgare) was grown under differing soil conditions, waterlogged, moderate mechanical impedance and in unimpeded, control, conditions. The root system was excavated and tensile tests performed on root sections along the length of each root axis. Root tensile strength increased with increasing distance along the root axes in control soil from 0.5 MPa to 7.0 MPa at a distance of 800mm from the root tip and from 1.0 Mpa to 8.0 MPa, 500mm from the root tip when under moderate mechanical impedance. Increases in strength were also observed when plants were subjected to waterlogging with tensile strength increasing from 1.0 MPa to 3.0 MPa, 200mm from the root tip. Young's modulus increased from ~10 MPa at the root tip to ~60 MPa 400mm and 800mm from the root tip in mechanically impeded and control treatments respectively. Distance from root tip explained over 47% of the variance in root tensile strength and 34% of root stiffness. Including root diameter in the model led to further improvements in predicting root properties, explaining ~54% of root strength variance and ~49% of root stiffness. Root age has been shown to improve predictions of root tensile strength and modulus with the inclusion of root diameter improving predictions further. Laser sectioning of maize (Zea mays) roots demonstrate the damage caused during biomechanical testing and help explain potential reasons for poor relationships between diameter and strength due to stress localisation within the stele. Furthermore, changes in biomechanical root properties associated with age maybe as a result of lignin deposition but this remains to be established.

Loades, Kenneth; Hallett, Paul; Lynch, Jonathan; Chimungu, Joseph; Bengough, Anthony

2014-05-01

106

Geoperception in primary and lateral roots of Phaseolus vulgaris (Fabaceae). III. A model to explain the differential georesponsiveness of primary and lateral roots  

NASA Technical Reports Server (NTRS)

Half-tipped primary and lateral roots of Phaseolus vulgaris bend toward the side of the root on which the intact half tip remains. Therefore, tips of lateral and primary roots produce growth effectors capable of inducing gravicurvature. The asymmetrical placement of a tip of a lateral root onto a detipped primary root results in the root bending toward the side of the root onto which the tip was placed. That is, the lesser graviresponsiveness of lateral roots as compared with primary roots is not due to the inability of their caps to produce growth inhibitors. The more pronounced graviresponsiveness of primary roots is positively correlated with the presence of columella tissues that are 3.8 times longer, 1.7 times wider, and 10.5 times more voluminous than the columellas of lateral roots. We propose that the lack of graviresponsiveness exhibited by lateral roots is due to the fact that they (i) produce smaller amounts of the inhibitor than primary (i.e., strongly graviresponsive) roots and (ii) are unable to redistribute the inhibitor so as to be able to create a concentration gradient sufficient to induce a pronounced gravitropic response.

Ransom, J. S.; Moore, R.

1985-01-01

107

Glutamate signalling in roots.  

PubMed

As a signalling molecule, glutamate is best known for its role as a fast excitatory neurotransmitter in the mammalian nervous system, a role that requires the activity of a family of ionotropic glutamate receptors (iGluRs). The unexpected discovery in 1998 that Arabidopsis thaliana L. possesses a family of iGluR-related (GLR) genes laid the foundations for an assessment of glutamate's potential role as a signalling molecule in plants that is still in progress. Recent advances in elucidating the function of Arabidopsis GLR receptors has revealed similarities with iGluRs in their channel properties, but marked differences in their ligand specificities. The ability of plant GLR receptors to act as amino-acid-gated Ca(2+) channels with a broad agonist profile, combined with their expression throughout the plant, makes them strong candidates for a multiplicity of amino acid signalling roles. Although root growth is inhibited in the presence of a number of amino acids, only glutamate elicits a specific sequence of changes in growth, root tip morphology, and root branching. The recent finding that the MEKK1 gene is a positive regulator of glutamate sensitivity at the root tip has provided genetic evidence for the existence in plants of a glutamate signalling pathway analogous to those found in animals. This short review will discuss the most recent advances in understanding glutamate signalling in roots, considering them in the context of previous work in plants and animals. PMID:24151303

Forde, Brian G

2014-03-01

108

Side-Branching Statistics of Plant Root Networks  

NASA Astrophysics Data System (ADS)

Many studies exist that characterise plant root architecture by calculating the fractal dimension of the root network, but few studies quantify the branching characteristics of the root network. This paper examines the Tokunaga side-branching statistics for the root systems of four plants--Sugar Beet (Beta vulgaris), Lucern (Medicago sativa), Common Wheat (Triticum aestivum) and White Clover (Trifolium michelianum)--and compares the resulting statistics to those calculated by similar means (by other authors) for the Kentucky and Powder River drainage basins and several Diffusion Limited Aggregation (DLA) models. The plant root networks studied all contained similar numbers of different order roots, but the side-branching statistics differed, offering one explanation for the differing visual appearance of the branching root networks. The White Clover plant had similar Tokunaga branching statistics to the drainage networks and DLA models. This may be due to the dichotomous root structure of the White Clover plant, which produces a network that is much more similar in appearance to the two drainage networks and DLA models than the other three plants, which had herringbone root. All of the root networks, drainage basins, and DLA models had branching networks that could be quantified well to very well by Tokunaga side-branching statistics. For many years, engineers have avoided implementation of stabilisation schemes involving vegetation, due to the inherent problems involved in the quantification of their dynamic and complex root structures. The use of Tokunaga statistics as a simplifying measure of root branching characteristics, may aid in this aspect, as well as others, such as the modelling of nutrient or water uptake.

Pollen, N.; Malamud, B.

2001-12-01

109

Root architecture and root and tuber crop productivity.  

PubMed

It is becoming increasingly evident that optimization of root architecture for resource capture is vital for enabling the next green revolution. Although cereals provide half of the calories consumed by humans, root and tuber crops are the second major source of carbohydrates globally. Yet, knowledge of root architecture in root and tuber species is limited. In this opinion article, we highlight what is known about the root system in root and tuber crops, and mark new research directions towards a better understanding of the relation between root architecture and yield. We believe that unraveling the role of root architecture in root and tuber crop productivity will improve global food security, especially in regions with marginal soil fertility and low-input agricultural systems. PMID:24630073

Villordon, Arthur Q; Ginzberg, Idit; Firon, Nurit

2014-07-01

110

Neutron tomography of the root-soil interface: water distribution around different parts of the root structure  

NASA Astrophysics Data System (ADS)

Although the importance of the root-soil interface in water uptake by plant roots has been acknowledged in many studies, there is a gap of knowledge on how water enters the roots. The main reason for this gap is the technical difficulties in resolving soil moisture dynamics in the vicinity of roots. Spatially and temporally resolved data on water flow across soil-root interface is needed to improve our understanding of mechanisms controlling water uptake by roots. We used neutron tomography to image soil water distribution around roots in-situ. We grew chick peas and lupines in sand-filled cylinders for 10 days at a water potential of -20 hPa. The samples were tomographed for 4 days over day and night and during a drying period and after rewetting. We observed that water content near the root surface was higher than in the bulk soil during the whole course of measurement for all the samples. Our hypothesis is that this increase of water content next to roots was due to the distinct water retention curve of the soil next to roots, the rhizosphere. Our hypothesis is that the rhizosphere water retention curve is caused by mucilage exuded by roots. Mucilage contains more than 90% water even at low water potentials, consequently increasing the water holding capacity of the rhizosphere. In another words, the roots modify the physical and chemical properties of their rhizosphere. The thickness of the area of increasing water, rhizosphere, varied along the root length. It ranged from slightly less than 1.5 mm in the distal part of the roots to more than 3 mm around the root tip. Also, it was slightly thicker around the main root compared to the lateral roots. As the soil water was being consumed by the roots, the extent of the rhizosphere decreased slightly, and then increased again after rewetting. We expect that the high water-holding capacity of the rhizosphere favors root water uptake, especially in dry soils. Most of the present modeling approaches neglect this effect.

Moradi, A. B.; Carminati, A.

2009-12-01

111

Wired to the roots  

PubMed Central

Often, plant-pathogenic microbe interactions are discussed in a host-microbe two-component system, however very little is known about how the diversity of rhizospheric microbes that associate with plants affect host performance against pathogens. There are various studies, which specially direct the importance of induced systemic defense (ISR) response in plants interacting with beneficial rhizobacteria, yet we don’t know how rhizobacterial associations modulate plant physiology. In here, we highlight the many dimensions within which plant roots associate with beneficial microbes by regulating aboveground physiology. We review approaches to study the causes and consequences of plant root association with beneficial microbes on aboveground plant-pathogen interactions. The review provides the foundations for future investigations into the impact of the root beneficial microbial associations on plant performance and innate defense responses. PMID:23073006

Kumar, Amutha Sampath; Bais, Harsh P.

2012-01-01

112

"GALVANOTROPISM" OF ROOTS  

PubMed Central

1. New experiments, made in such a way to eliminate as completely as possible products of polarization and the migration of such products when formed, have shown that the exhibition of galvanotropic curvature in roots is mainly dependent upon such products, since no curvature appears when they are excluded. 2. The polarization products injure the external layer of cells of the root; this allows these cells to act as electrodes directly applied on the internal tissues. The inner electrolysis produces such changes in the interior cells that they may be considered as becoming ionically different. This differential state is responsible for curvature. 3. "Galvanotropism" of roots, therefore, cannot be regarded as exactly comparable to the galvanotropic orientations of certain animals, but is essentially dependent upon injury. PMID:19872344

Navez, A. E.

1927-01-01

113

Vertical root fracture: prevalence, etiology, and diagnosis.  

PubMed

A vertical root fracture (VRF) is a frustrating complication that may occur following root canal treatment, and in almost every case leads to the extraction of the affected tooth. This type of fracture is usually diagnosed by secondary symptoms that develop some time after primary treatment, often when prosthodontic restoration has already been completed. The fracture line itself is often not directly visible, and therefore clinical and radiographic signs and symptoms indicate the diagnosis indirectly. Knowledge of the condition and pathogenesis of VRF is required in order to avoid hopeless trials of periodontal and/or endodontic therapy. Several etiologic factors are discussed that make teeth susceptible to VRF, such as the loss of substance due to restorative and endodontic therapy and stress factors associated with root canal debridement, and filling. PMID:23757466

Haueisen, Helga; Gärtner, Kathrin; Kaiser, Lea; Trohorsch, Dominik; Heidemann, Detlef

2013-07-01

114

Cytosolic pH regulates root water transport during anoxic stress through gating of aquaporins  

Microsoft Academic Search

Flooding of soils results in acute oxygen deprivation (anoxia) of plant roots during winter in temperate latitudes, or after irrigation, and is a major problem for agriculture. One early response of plants to anoxia and other environmental stresses is downregulation of water uptake due to inhibition of the water permeability (hydraulic conductivity) of roots (Lpr). Root water uptake is mediated

Colette Tournaire-Roux; Moira Sutka; Hélène Javot; Elisabeth Gout; Patricia Gerbeau; Doan-Trung Luu; Richard Bligny; Christophe Maurel

2003-01-01

115

The distribution and strength of riparian tree roots in relation to riverbank reinforcement  

Microsoft Academic Search

The main influences of plants on the mass stability of riverbanks are those that affect the strength of bank sediments. Plants enhance bank strength by reducing pore-water pressures and by directly reinforcing bank material with their roots. In this paper we do not consider bank hydrology but focus on quantifying increases in sediment strength due to root reinforcement. Root reinforcement

Bruce Abernethy; Ian D. Rutherfurd

2001-01-01

116

Root-Surface Caries in Rats and Humans: Inhibition by a Non-Antimicrobial Property of Tetracyclines  

Microsoft Academic Search

The incidence of root caries has been found to increase as the population ages and as edentulism becomes less prevalent due to improved dental awareness and care, and as exposure of roots due to gingival recession has also increased in the elderly. The mechanism of root caries is thought to be mediated by both bacterial and mammalian proteases produced by

N. S. Ramamurthy; K. L. Schroeder; T. F. McNamara; A. J. Gwinnett; R. T. Evans; C. Bosko; L. M. Golub

1998-01-01

117

Violet root rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fungus causing violet root rot, Helicobasidium brebissonii (anamorph Rhizoctonia crocorum), is widely distributed in Europe and North America but is rarely of much economic importance on alfalfa. The disease has also been reported in Australia, Argentina, and Iran. The disease is characterized b...

118

The Roots of Reading.  

ERIC Educational Resources Information Center

This newsletter covers educational issues affecting schools in the Western Regional Educational Laboratory's 4-state region (Arizona, California, Nevada, and Utah) and nationwide. The following articles appear in the Volume 4, Number 1 issue: (1) "The Roots of Reading"; (2) "Breaking the Code: Reading Literacy in K-3"; (3) "Improving Secondary…

Montoya, Colleen, Ed.

2002-01-01

119

Root Canal Irrigants  

Microsoft Academic Search

Local wound debridement in the diseased pulp space is the main step in root canal treatment to prevent the tooth from being a source of infection. In this review article, the specifics of the pulpal microenvironment and the resulting requirements for irrigating solutions are spelled out. Sodium hypochlorite solutions are recommended as the main irrigants. This is because of their

Matthias Zehnder

2006-01-01

120

Root Beer Float  

NSDL National Science Digital Library

In this quick activity/demonstration about density, learners examine what happens when two cans of root beer--one diet and one regular--are placed in a large container of water. Do they sink or float? Use this activity to introduce learners to the importance of density as well as the nutritional content of soft drinks.

Colorado State University

2009-01-01

121

Great Plains Roots.  

ERIC Educational Resources Information Center

Sandy White Hawk, Sicangu Lakota, was adopted by white missionaries as an infant and suffered child abuse. After 33 years, she found her birth family and formed First Nations Orphans Association, which uses songs and ceremonies to help adoptees return to their roots. Until the 1970s, federal agencies and welfare organizations facilitated removal…

Frey, Jennifer

2001-01-01

122

PESTICIDE ROOT ZONE MODEL  

EPA Science Inventory

PRZM3 is a modeling system that links two subordinate models - PRZM and VADOFT to predict pesticide transport and transformation down through the crop root and unsaturated zone. PRZM3 includes modeling capabilities for such phenomena as soil temperature simulation, vo...

123

Stachbotrys Root Rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

Stachybotrys root rot is caused by Stachybotrys chartarum, a cellulytic saprophytic hyphomycete fungus. The pathogen produces mycotoxins including a host of immunosupressant compounds for human and is one of the causes of the "sick building syndrome." Although S. chartarum is rarely known as a plan...

124

Evaluating Ecohydrological Theories of Woody Root Distribution in the Kalahari  

PubMed Central

The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1) the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis), and (2) the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis). Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity. PMID:22470506

Bhattachan, Abinash; Tatlhego, Mokganedi; Dintwe, Kebonye; O'Donnell, Frances; Caylor, Kelly K.; Okin, Gregory S.; Perrot, Danielle O.; Ringrose, Susan; D'Odorico, Paolo

2012-01-01

125

Invertase Activity in Root Growth  

NSDL National Science Digital Library

This resource is a manual for instructing a laboratory exercise in plant biology and enzyme kinetics. Students microscopically observe corn root sections and determine by enzymatic assays, the intergrase enzyme activity in selected regions of the root.

Chris J. Perumalla (University of Toronto; )

1994-01-01

126

Square Root SAM Frank Dellaert  

E-print Network

Square Root SAM Frank Dellaert College of Computing Georgia Institute of Technology Abstract information matrix or the measurement matrix into square root form. Such techniques have several significant that square root information smoothing (SRIS) is a fundamentally better approach to the problem of SLAM than

Dellaert, Frank

127

Strigolactones Effects on Root Growth  

NASA Astrophysics Data System (ADS)

Strigolactones (SLs) were defined as a new group of plant hormones that suppress lateral shoot branching. Our previous studies suggested SLs to be regulators of root development. SLs were shown to alter root architecture by regulating lateral root formation and to affect root hair elongation in Arabidopsis. Another important effect of SLs on root growth was shown to be associated with root directional growth. Supplementation of SLs to roots led to alterations in root directional growth, whereas associated mutants showed asymmetrical root growth, which was influenced by environmental factors. The regulation by SLs of root development was shown to be conducted via a cross talk of SLs with other plant hormones, including auxin. SLs were shown to regulate auxin transport, and to interfere with the activity of auxin-efflux carriers. Therefore, it might be that SLs are regulators of root directional growth as a result of their ability to regulated auxin transport. However, other evidences suggest a localized effect of SLs on cell division, which may not necessarily be associated with auxin efflux. These and other, recent hypothesis as to the SLs mode of action and the associated root perception and response to environmental factors will be discussed.

Koltai, Hinanit

2012-07-01

128

Lesson 24: Roots and Radicals  

NSDL National Science Digital Library

Exponential notation for Nth roots and radicals is introduced. A short discussion about Nth roots and irrational numbers follows before symbolic manipulation of fractional exponents and solving equations is presented. Power functions and solving radical equations are presented before the lesson concludes with roots of negative numbers.

2011-01-01

129

Defective secretion of mucilage is the cellular basis for agravitropism in primary roots of Zea mays cv. Ageotropic  

NASA Technical Reports Server (NTRS)

Root caps of primary, secondary, and seminal roots of Z. mays cv. Kys secrete large amounts of mucilage and are in close contact with the root all along the root apex. These roots are strongly graviresponsive. Secondary and seminal roots of Z. mays cv. Ageotropic are also strongly graviresponsive. Similarly, their caps secrete mucilage and closely appress the root all along the root apex. However, primary roots of Z. mays cv. Ageotropic are non-responsive to gravity. Their caps secrete negligible amounts of mucilage and contact the root only at the extreme apex of the root along the calyptrogen. These roots become graviresponsive when their tips are coated with mucilage or mucilage-like materials. Peripheral cells of root caps of roots of Z. mays cv. Kys contain many dictyosomes associated with vesicles that migrate to and fuse with the plasmalemma. Root-cap cells of secondary and seminal (i.e. graviresponsive) roots of Z. mays cv. Ageotropic are similar to those of primary roots of Z. mays cv. Kys. However, root-cap cells of primary (i.e. non-graviresponsive) roots of Z. mays cv. Ageotropic have distended dictyosomal cisternae filled with an electron-dense, granular material. Large vesicles full of this material populate the cells and apparently do not fuse with the plasmalemma. Taken together, these results suggest that non-graviresponsiveness of primary roots of Z. mays cv. Ageotropic results from the lack of apoplastic continuity between the root and the periphery of the root cap. This is a result of negligible secretion of mucilage by cells along the edge of the root cap which, in turn, appears to be due to the malfunctioning of dictyosomes in these cells.

Miller, I.; Moore, R.

1990-01-01

130

Springback in root gravitropism.  

PubMed

Conditions under which a gravistimulus of Merit corn roots (Zea mays L.) is withdrawn result in a subsequent loss of gravitropic curvature, an effect which we refer to as springback.' This loss of curvature begins within 1 to 10 minutes after removal of the gravistimulus. It occurs regardless of the presence or absence of the root cap. It is insensitive to inhibitors of auxin transport (2,3,5-triiodobenzoic acid, naphthylphthalamic [correction of naphthylphthalmaic] acid) or to added auxin (2,4-dichlorophenoxyacetic acid). Springback is prevented if a clinostat treatment is interjected to neutralize gravistimulation during germination, which suggests that the change in curvature is a response to a memory' effect carried over from a prior gravistimulation. PMID:11537456

Leopold, A C; Wettlaufer, S H

1989-01-01

131

Springback in root gravitropism  

NASA Technical Reports Server (NTRS)

Conditions under which a gravistimulus of Merit corn roots (Zea mays L.) is withdrawn result in a subsequent loss of gravitropic curvature, an effect which we refer to as springback.' This loss of curvature begins within 1 to 10 minutes after removal of the gravistimulus. It occurs regardless of the presence or absence of the root cap. It is insensitive to inhibitors of auxin transport (2,3,5-triiodobenzoic acid, naphthylphthalamic [correction of naphthylphthalmaic] acid) or to added auxin (2,4-dichlorophenoxyacetic acid). Springback is prevented if a clinostat treatment is interjected to neutralize gravistimulation during germination, which suggests that the change in curvature is a response to a memory' effect carried over from a prior gravistimulation.

Leopold, A. C.; Wettlaufer, S. H.

1989-01-01

132

Mathematica with ROOT  

E-print Network

We present an open-source Mathematica importer for CERN ROOT files. Taking advantage of Mathematica's import/export plug-in mechanism, the importer offers a simple, unified interface that cleanly wraps around its MathLink-based core that links the ROOT libraries with Mathematica. Among other tests for accuracy and efficiency, the importer has also been tested on a large (~5 Gbyte) file structure, D3PD, used by the ATLAS experiment for offline analysis without problems. In addition to describing the installation and usage of the importer, we discuss how the importer may be further improved and customized. A link to the package can be found at: http://library.wolfram.com/infocenter/Articles/7793/ and a related presentation is at: http://cd-docdb.fnal.gov/cgi-bin/DisplayMeeting?conferenceid=522

Ken Hsieh; Thomas G. Throwe; Sebastian White

2011-03-07

133

Diagravitropism in corn roots  

NASA Technical Reports Server (NTRS)

The diagravitropic behavior of Merit corn (Zea mays L.) roots grown in darkness provides an opportunity for comparison of two qualitatively different gravitropic systems. As with positive gravitropism, diagravitropism is shown to require the presence of the root cap, have a similar time course for the onset of curvature, and a similar presentation time. In contrast with positive gravitropism, diagravitropism appears to have a more limited requirement for calcium, for it is insensitive to the elution of calcium by EGTA and insensitive to the subsequent addition of a calcium/EGTA complex. These results are interpreted as indicating that whereas the same sensing system is shared by the two types of gravitropism, separate transductive systems are involved, one for diagravitropism, which is relatively independent of calcium, and one for positive gravitropism, which is markedly dependent on calcium.

Leopold, A. C.; Wettlaufer, S. H.

1988-01-01

134

Helical Root Buckling: A Transient Mechanism for Stiff Interface Penetration  

NASA Astrophysics Data System (ADS)

Tilling in agriculture is commonly used to loosen the topmost layer of soil and promote healthy plant growth. As roots navigate this mechanically heterogeneous environment, they encounter interfaces between the compliant soil and the underlying compacted soil. Inspired by this problem, we used 3D time-lapse imaging of Medicago Truncatula plants to study root growth in two-layered transparent hydrogels. The layers are mechanically distinct; the top layer is more compliant than the bottom. We observe that the roots form a transient helical structure as they attempt to penetrate the bi-layer interface. Interpreting this phenotype as a form of buckling due to root elongation, we measured the helix size as a function of the surrounding gel modulus. Our measurements show that by twisting the root tip during growth, the helical structure recruits the surrounding medium for an enhanced penetration force allowing the plants access to the lower layer of gel.

Silverberg, Jesse; Noar, Roslyn; Packer, Michael; Harrison, Maria; Cohen, Itai; Henley, Chris; Gerbode, Sharon

2011-03-01

135

Root growth and development in response to CO2 enrichment  

NASA Technical Reports Server (NTRS)

A non-destructive technique (minirhizotron observation tubes) was used to assess the effects of CO2 enrichment on root growth and development in experimental plots in a scrub oak-palmetto community at the Kennedy Space Center. Potential effects of CO2 enrichment on plants have a global significance in light of concerns over increasing CO2 concentrations in the Earth's atmosphere. The study at Kennedy Space Center focused on aboveground physiological responses (photosynthetic efficiency and water use efficiency), effects on process rates (litter decomposition and nutrient turnover), and belowground responses of the plants. Belowground dynamics are an exceptionally important component of total plant response but are frequently ignored due to methodological difficulties. Most methods used to examine root growth and development are destructive and, therefore, severely compromise results. Minirhizotrons allow nondestructive observation and quantification of the same soil volume and roots through time. Root length density and root phenology were evaluated for CO2 effects with this nondestructive technique.

Day, Frank P., Jr.

1994-01-01

136

Graviresponsiveness of surgically altered primary roots of Zea mays  

NASA Technical Reports Server (NTRS)

We examined the gravitropic responses of surgically altered primary roots of Zea mays to determine the route by which gravitropic inhibitors move from the root tip to the elongating zone. Horizontally oriented roots, from which a 1-mm-wide girdle of epidermis plus 2-10 layers of cortex were removed from the apex of the elongating zone, curve downward. However, curvature occurred only apical to the girdle. Filling the girdle with mucilage-like material transmits curvature beyond the girdle. Vertically oriented roots with a half-girdle' (i.e. the epidermis and 2-10 layers of the cortex removed from half of the circumference of the apex of the elongating zone) curve away from the girdle. Inserting the half-girdle at the base of the elongating zone induces curvature towards the girdle. Filling the half-circumference girdles with mucilage-like material reduced curvature significantly. Stripping the epidermis and outer 2-5 layers of cortex from the terminal 1.5 cm of one side of a primary root induces curvature towards the cut, irrespective of the root's orientation to gravity. This effect is not due to desiccation since treated roots submerged in water also curved towards their cut surface. Coating a root's cut surface with a mucilage-like substance minimizes curvature. These results suggest that the outer cell-layers of the root, especially the epidermis, play an important role in root gravicurvature, and the gravitropic signals emanating from the root tip can move apoplastically through mucilage.

Maimon, E.; Moore, R.

1991-01-01

137

Hydraulic conductivity of rice roots.  

PubMed

A pressure chamber and a root pressure probe technique have been used to measure hydraulic conductivities of rice roots (root Lp(r) per m(2) of root surface area). Young plants of two rice (Oryza sativa L.) varieties (an upland variety, cv. Azucena and a lowland variety, cv. IR64) were grown for 31-40 d in 12 h days with 500 micromol m(-2) s(-1) PAR and day/night temperatures of 27 degrees C and 22 degrees C. Root Lp(r) was measured under conditions of steady-state and transient water flow. Different growth conditions (hydroponic and aeroponic culture) did not cause visible differences in root anatomy in either variety. Values of root Lp(r) obtained from hydraulic (hydrostatic) and osmotic water flow were of the order of 10(-8) m s(-1) MPa(-1) and were similar when using the different techniques. In comparison with other herbaceous species, rice roots tended to have a higher hydraulic resistance of the roots per unit root surface area. The data suggest that the low overall hydraulic conductivity of rice roots is caused by the existence of apoplastic barriers in the outer root parts (exodermis and sclerenchymatous (fibre) tissue) and by a strongly developed endodermis rather than by the existence of aerenchyma. According to the composite transport model of the root, the ability to adapt to higher transpirational demands from the shoot should be limited for rice because there were minimal changes in root Lp(r) depending on whether hydrostatic or osmotic forces were acting. It is concluded that this may be one of the reasons why rice suffers from water shortage in the shoot even in flooded fields. PMID:11520872

Miyamoto, N; Steudle, E; Hirasawa, T; Lafitte, R

2001-09-01

138

Arabidopsis thaliana root growth kinetics and lunisolar tidal acceleration.  

PubMed

• All living organisms on Earth are continually exposed to diurnal variations in the gravitational tidal force due to the Sun and Moon. • Elongation of primary roots of Arabidopsis thaliana seedlings maintained at a constant temperature was monitored for periods of up to 14 d using high temporal- and spatial-resolution video imaging. The time-course of the half-hourly elongation rates exhibited an oscillation which was maintained when the roots were placed in the free-running condition of continuous illumination. • Correlation between the root growth kinetics collected from seedlings initially raised under several light protocols but whose roots were subsequently in the free-running condition and the lunisolar tidal profiles enabled us to identify that the latter is the probable exogenous determinant of the rhythmic variation in root elongation rate. Similar observations and correlations using roots of Arabidopsis starch mutants suggest a central function of starch metabolism in the response to the lunisolar tide. The periodicity of the lunisolar tidal signal and the concomitant adjustments in root growth rate indicate that an exogenous timer exists for the modulation of root growth and development. • We propose that, in addition to the sensitivity to Earthly 1G gravity, which is inherent to all animals and plants, there is another type of responsiveness which is attuned to the natural diurnal variations of the lunisolar tidal force. PMID:22583121

Fisahn, Joachim; Yazdanbakhsh, Nima; Klingele, Emile; Barlow, Peter

2012-07-01

139

Impact of Brassicaceae Cover Crops on Pea Root Rot (Aphanomyces  

E-print Network

.3.1 Soil moisture 15 3.3.2 Soil temperature 15 3.3.3 Soil types 15 3.4 Control of pea root rot 15 3 crop on pea root rot (Aphanomyces euteiches) in subsequent peas Abstract The soil-borne pathogen persist in soil for many years without a host plant and is very difficult to control due to its long

140

Matching roots to their environment  

PubMed Central

Background Plants form the base of the terrestrial food chain and provide medicines, fuel, fibre and industrial materials to humans. Vascular land plants rely on their roots to acquire the water and mineral elements necessary for their survival in nature or their yield and nutritional quality in agriculture. Major biogeochemical fluxes of all elements occur through plant roots, and the roots of agricultural crops have a significant role to play in soil sustainability, carbon sequestration, reducing emissions of greenhouse gasses, and in preventing the eutrophication of water bodies associated with the application of mineral fertilizers. Scope This article provides the context for a Special Issue of Annals of Botany on ‘Matching Roots to Their Environment’. It first examines how land plants and their roots evolved, describes how the ecology of roots and their rhizospheres contributes to the acquisition of soil resources, and discusses the influence of plant roots on biogeochemical cycles. It then describes the role of roots in overcoming the constraints to crop production imposed by hostile or infertile soils, illustrates root phenotypes that improve the acquisition of mineral elements and water, and discusses high-throughput methods to screen for these traits in the laboratory, glasshouse and field. Finally, it considers whether knowledge of adaptations improving the acquisition of resources in natural environments can be used to develop root systems for sustainable agriculture in the future. PMID:23821619

White, Philip J.; George, Timothy S.; Gregory, Peter J.; Bengough, A. Glyn; Hallett, Paul D.; McKenzie, Blair M.

2013-01-01

141

The Roots of Beowulf  

NASA Technical Reports Server (NTRS)

The first Beowulf Linux commodity cluster was constructed at NASA's Goddard Space Flight Center in 1994 and its origins are a part of the folklore of high-end computing. In fact, the conditions within Goddard that brought the idea into being were shaped by rich historical roots, strategic pressures brought on by the ramp up of the Federal High-Performance Computing and Communications Program, growth of the open software movement, microprocessor performance trends, and the vision of key technologists. This multifaceted story is told here for the first time from the point of view of NASA project management.

Fischer, James R.

2014-01-01

142

Microtubules in root hairs.  

PubMed

The microtubules of root hairs of Raphanus sativus, Lepidium sativum, Equisetum hyemale, Limnobium stoloniferum, Ceratopteris thalictroides, Allium sativum and Urtica dioica were investigated using immunofluorescence and electron microscopy. Arrays of cortical microtubules were observed in all hairs. The microtubules in the hairs show net axial orientations, but in Allium and Urtica helical microtubule patterns are also present. Numerical parameters of microtubules in Raphanus, Equisetum and Limnobium were determined from dry-cleave preparations. The results are discussed with respect to cell wall deposition and cell morphogenesis. PMID:4066793

Traas, J A; Braat, P; Emons, A M; Meekes, H; Derksen, J

1985-06-01

143

How the soil-root interface affects water availability to plants  

NASA Astrophysics Data System (ADS)

Water supply to roots is essential for plant life. To sustain the root water uptake, a continuous liquid phase has to be maintained at the interface between soil and roots. Gaps between soil and roots may interrupt the liquid-phase continuity across the soil-root interface, acting as capillary barriers for the water flow. Additionally, due to the radial geometry of the flow to roots and the non-linearity of the soil hydraulic conductivity, a drop in water potential and consequently of water content is expected to occur next to the roots, in particular when soil dries and transpiration demand is high. Such a drop in water content may limit water and nutrient uptake by roots. How plants can overcome these mechanical and hydraulic flow resistances at the root-soil interface? Recent experiments with neutron radiography showed that during transpiration the water content next to roots was larger than in the bulk soil. Immediately after rewetting, the picture reversed and the soil next to roots remained markedly dry. During the following days the water content next to roots increased, exceeding that of the bulk soil. These water dynamics cannot be described by models assuming homogeneous soil around roots. Our hypothesis is that the observed moisture dynamics at the soil-root interface were caused by mucilage exuded by roots. Mucilage is mainly composed of polymeric substances and has a high water holding capacity. Mucilage is known to be exuded by roots but its effect on water uptake is not known. By calculating the water flux to roots we demonstrate that mucilage weakens the drop in water potential at the root-soil interface, increasing the conductivity of the flow path across soil and roots and reducing the energy needed to take up water. Additionally, mucilage improves the mechanical contact between soil and roots, avoiding formation of gaps as roots shrink in response to high transpiration demand or drought stress. In conclusion, mucilage works as hydraulic and mechanical connector between soil and roots, favoring water availability to plants. However, under severe drought conditions, mucilage becomes dehydrated and reduces the wettability of the soil next to roots. Such a temporary low wettability may have harmful consequences for the water storage in the root zone and should be taken into account in irrigation policy.

Carminati, Andrea; Moradi, Ahmad

2010-05-01

144

Disentangling root responses to climate change in a semiarid grassland.  

PubMed

Future ecosystem properties of grasslands will be driven largely by belowground biomass responses to climate change, which are challenging to understand due to experimental and technical constraints. We used a multi-faceted approach to explore single and combined impacts of elevated CO2 and warming on root carbon (C) and nitrogen (N) dynamics in a temperate, semiarid, native grassland at the Prairie Heating and CO2 Enrichment experiment. To investigate the indirect, moisture mediated effects of elevated CO2, we included an irrigation treatment. We assessed root standing mass, morphology, residence time and seasonal appearance/disappearance of community-aggregated roots, as well as mass and N losses during decomposition of two dominant grass species (a C3 and a C4). In contrast to what is common in mesic grasslands, greater root standing mass under elevated CO2 resulted from increased production, unmatched by disappearance. Elevated CO2 plus warming produced roots that were longer, thinner and had greater surface area, which, together with greater standing biomass, could potentially alter root function and dynamics. Decomposition increased under environmental conditions generated by elevated CO2, but not those generated by warming, likely due to soil desiccation with warming. Elevated CO2, particularly under warming, slowed N release from C4-but not C3-roots, and consequently could indirectly affect N availability through treatment effects on species composition. Elevated CO2 and warming effects on root morphology and decomposition could offset increased C inputs from greater root biomass, thereby limiting future net C accrual in this semiarid grassland. PMID:24643718

Carrillo, Yolima; Dijkstra, Feike A; LeCain, Dan; Morgan, Jack A; Blumenthal, Dana; Waldron, Sarah; Pendall, Elise

2014-06-01

145

A novel bioassay using root re-growth in Lemna.  

PubMed

A new phytotoxicity test method based on root elongation of three Lemna species (Lemna gibba, L. minor, and L. paucicostata) has been developed. Tests with aquatic plants have, typically, favored measurements on fronds (e.g. frond number, area, biomass) rather than on roots, due, in part, to issues associated with handling fragile roots and the time-consuming procedures of selecting roots with identical root lengths. The present method differs in that roots were excised prior to exposure with subsequent measurements on newly developed roots. Results show that there were species-specific difference in sensitivity to the five metals tested (Ag, Cd, Cr, Cu and Hg), with Ag being the most toxic (EC50=5.3-37.6 ?gL(-1)) to all three species, and Cr the least toxic for L. gibba and L. minor (1148.3 and 341.8 ?gL(-1), respectively) and Cu for L. paucicostata (470.4 ?gL(-1)). Direct comparisons were made with measurements of frond area, which were found to be less sensitive. More generally, root re-growth was shown to reflect the toxic responses of all three Lemna species to these five important metals. The root growth bioassay differs from three internationally standardized methods (ISO, OCED and US EPA) in that it is completed in 48 h, the required volume of test solutions is only 3 ml and non-axenic plants are used. Our results show that the Lemna root method is a simple, rapid, cost-effective, sensitive and precise bioassay to assess the toxic risks of metals and has practical application for monitoring municipal and industrial waste waters where metals are common constituents. PMID:23917640

Park, Areum; Kim, Youn-Jung; Choi, Eun-Mi; Brown, Murray T; Han, Taejun

2013-09-15

146

Root–root interactions: extending our perspective to be more inclusive of the range of theories in ecology and agriculture using in-vivo analyses  

PubMed Central

Background There is a large body of literature on competitive interactions among plants, but many studies have only focused on above-ground interactions and little is known about root–root dynamics between interacting plants. The perspective on possible mechanisms that explain the outcome of root–root interactions has recently been extended to include non-resource-driven mechanisms (as well as resource-driven mechanisms) of root competition and positive interactions such as facilitation. These approaches have often suffered from being static, partly due to the lack of appropriate methodologies for in-situ non-destructive root characterization. Scope Recent studies show that interactive effects of plant neighbourhood interactions follow non-linear and non-additive paths that are hard to explain. Common outcomes such as accumulation of roots mainly in the topsoil cannot be explained solely by competition theory but require a more inclusive theoretical, as well as an improved methodological framework. This will include the question of whether we can apply the same conceptual framework to crop versus natural species. Conclusions The development of non-invasive methods to dynamically study root–root interactions in vivo will provide the necessary tools to study a more inclusive conceptual framework for root–root interactions. By following the dynamics of root–root interactions through time in a whole range of scenarios and systems, using a wide variety of non-invasive methods, (such as fluorescent protein which now allows us to separately identify the roots of several individuals within soil), we will be much better equipped to answer some of the key questions in root physiology, ecology and agronomy. PMID:23378521

Faget, Marc; Nagel, Kerstin A.; Walter, Achim; Herrera, Juan M.; Jahnke, Siegfried; Schurr, Ulrich; Temperton, Vicky M.

2013-01-01

147

Anti-inflammatory activities of ent-16? H,17-hydroxy-kauran-19-oic acid isolated from the roots of Siegesbeckia pubescens are due to the inhibition of iNOS and COX2 expression in RAW 264.7 macrophages via NF-?B inactivation  

Microsoft Academic Search

To isolate the anti-inflammatory components in Siegesbeckia pubescens root, we performed activity-guided fractionation using a carrageenan-induced edema rat model. Antinociceptive effects were followed using acetic acid-induced abdominal constriction and hot plate tests in mice. Chloroform extract was subjected to silica gel and octadesyl silane (ODS) column chromatography, and a diterpene was isolated which was identified as ent-16?H,17-hydroxy-kauran-19-oic acid (siegeskaurolic acid).

Hee-Juhn Park; In-Tae Kim; Jong-Heon Won; Seoung-Hee Jeong; Eun-Young Park; Jung-Hwan Nam; Jongwon Choi; Kyung-Tae Lee

2007-01-01

148

Density of the continental roots: Compositional and thermal contributions  

USGS Publications Warehouse

The origin and evolution of cratonic roots has been debated for many years. Precambrian cratons are underlain by cold lithospheric roots that are chemically depleted. Thermal and petrologic data indicate that Archean roots are colder and more chemically depleted than Proterozoic roots. This observation has led to the hypothesis that the degree of depletion in a lithospheric root depends mostly on its age. Here we test this hypothesis using gravity, thermal, petrologic, and seismic data to quantify differences in the density of cratonic roots globally. In the first step in our analysis we use a global crustal model to remove the crustal contribution to the observed gravity. The result is the mantle gravity anomaly field, which varies over cratonic areas from -100 to +100 mGal. Positive mantle gravity anomalies are observed for cratons in the northern hemisphere: the Baltic shield, East European Platform, and the Siberian Platform. Negative anomalies are observed over cratons in the southern hemisphere: Western Australia, South America, the Indian shield, and Southern Africa. This indicates that there are significant differences in the density of cratonic roots, even for those of similar age. Root density depends on temperature and chemical depletion. In order to separate these effects we apply a lithospheric temperature correction using thermal estimates from a combination of geothermal modeling and global seismic tomography models. Gravity anomalies induced by temperature variations in the uppermost mantle range from -200 to +300 mGal, with the strongest negative anomalies associated with mid-ocean ridges and the strongest positive anomalies associated with cratons. After correcting for thermal effects, we obtain a map of density variations due to lithospheric compositional variations. These maps indicate that the average density decrease due to the chemical depletion within cratonic roots varies from 1.1% to 1.5%, assuming the chemical boundary layer has the same thickness as the thermal boundary layer. The maximal values of the density drop are in the range 1.7-2.5%, and correspond to the Archean portion of each craton. Temperatures within cratonic roots vary strongly, and our analysis indicates that density variations in the roots due to temperature are larger than the variations due to chemical differences. ?? 2003 Elsevier Science B.V. All rights reserved.

Kaban, M.K.; Schwintzer, P.; Artemieva, I.M.; Mooney, W.D.

2003-01-01

149

Mucilage exudation facilitates root water uptake in dry soils  

NASA Astrophysics Data System (ADS)

As plant roots take up water and the soil dries, water depletion is expected to occur in the rhizosphere. However, recent experiments showed that the rhizosphere of lupines was wetter than the bulk soil during root water uptake. On the other hand, after irrigation the rhizosphere remained markedly dry and it rewetted only after one-two days. We hypothesize that: 1) drying/wetting rates of the rhizosphere are controlled by mucilage exuded by roots; 2) mucilage alters the soil hydraulic conductivity: in particular, wet mucilage increases the soil hydraulic conductivity and dry mucilage makes the soil water repellent; 3) mucilage exudation favors root water uptake in dry soil; and 4) dry mucilage limits water loss from roots to dry soils. We used a root pressure probe to measure the hydraulic conductance of artificial roots sitting in soils. As an artificial root we employed a suction cup with a diameter of 2 mm and a length of 45 mm. The root pressure probe gave the hydraulic conductance of the soil-root continuum during pulse experiments in which water was injected into or sucked from the soil. First, we performed experiments with roots in a relatively dry soil with a volumetric water content of 0.03. Then, we repeated the experiment with artificial roots covered with mucilage and then placed into the soil. As a model for mucilage, we collected mucilage from Chia seeds. The water contents (including that of mucilage) in the experiments with and without mucilage were equal. The pressure curves were fitted with a model of root water that includes rhizosphere dynamics. We found that the artificial roots covered with wet mucilage took up water more easily. In a second experimental set-up we measured the outflow of water from the artificial roots into dry soils. We compared two soils: 1) a sandy soil and 2) the same soil wetted with mucilage from Chia seeds and then let dry. The latter soil became water repellent. Due to the water repellency, the outflow of water from the root in this soil was significantly reduced. The experiments demonstrated that mucilage increased the hydraulic conductance of the root-soil continuum and facilitated the extraction of water from dry soils. The increase in conductivity resulted from the higher water content of the soil near the roots. Mucilage has a lower surface tension than pure water and a higher viscosity, resulting in a slower penetration of mucilage into the soil. After mucilage was placed into the soil, it did not spread into the bulk soil, but it remained near the roots, maintaining the rhizosphere wetter and more conductive than the bulk soil. However, as mucilage dried, it turned water repellent and reduced the back flow of water from the root to soil. We hypothesize that mucilage exudation is a plant strategy to locally and temporally facilitate water uptake from dry soils. After drying, mucilage becomes water repellent and may limit the local uptake of water after irrigation. On the other hand, mucilage water repellency may as well be a strategy to reduce water loss from roots to dry soils.

Ahmed, Mutez; Kroener, Eva; Holz, Maire; Zarebanadkouki, Mohsen; Carminati, Andrea

2014-05-01

150

Effects of root anatomy and Fe plaque on arsenic uptake by rice seedlings grown in solution culture  

Microsoft Academic Search

Hydroponic experiments were carried out to investigate the effects of root anatomy, induced by aeration and stagnation, and Fe plaque on arsenic (III&V) uptake and translocation by rice plants. The results showed that As uptake in rice plants (Gui Chao-2) treated by aeration was decreased due to lower root specific surface area. Rice roots with larger specific surface area tended

Dan Deng; Sheng-Chun Wu; Fu-Yong Wu; Hong Deng; Ming-Hung Wong

2010-01-01

151

Controlled Field and Laboratory Experiments to Investigate soil-root Interactions and Streambank Stability.  

NASA Astrophysics Data System (ADS)

Riparian vegetation has a number of mechanical and hydrologic effects on streambank stability, some of which are positive and some of which are negative. The mechanical reinforcement provided by root networks is one of the most important stabilizing factors, as roots are strong in tension but weak in compression and conversely soil is strong in compression but weak in tension. A soil that contains roots therefore has increased shear strength due to the production of a reinforced matrix, which is stronger than the soil or roots separately (Thorne, 1990). Quantification and understanding of the way the soil and roots interact individually and as a complete matrix is important if we are to predict the reinforcing effects of different types of riparian vegetation in streambank stabilizing schemes. Previous estimates of the contribution of root networks to soil strength have been attained either by using equations that sum root tensile and the soil shear strengths (eg. Wu et al., 1979), or by carrying out shear tests of root-permeated soils. However, neither of these methods alone allows a full investigation and understanding of the interactions that take place between the soil and the roots as a soil is sheared. These interactions are complex, and the simple addition of root tensile and soil shear strengths may therefore lead to overestimation of the increased strength provided to the soil by the roots, as the rate of mobilization of stress in the roots may not be the same as that of the soil (Waldron and Dakessian, 1981; Pollen et al., 2002). This paper describes a series of experiments that were carried out to test the material properties of roots, and soil samples from a streambank along Goodwin Creek, N. Mississippi. Results from field experiments carried out to measure root-tensile strengths, and stress-displacement characteristics of roots, were compared with laboratory shear tests of soil samples from Goodwin Creek. It was shown that the roots of different species took up strain at different rates, and that these rates differed considerably from that of the Goodwin Creek soil sample. For example, the mean displacement of Eastern Sycamore roots before breaking was 3.57cm, whereas the displacement of the soil sample at peak strength was just 0.68cm, suggesting that the critical factor in root reinforcement of soil matrices may in fact be the rate of mobilization of tension in the roots, rather than their ultimate tensile strength. Isolation and testing of the roots and soil separately, in the field and the laboratory, allowed the formulation of two hypotheses to explain the way in which roots and soil interact during shearing: As the soil shears, either the roots reinforce the soil after the peak soil strength has been overcome, until the ultimate tensile strength of the roots is reached, or the roots only reinforce the soil until the peak soil strength has been reached, beyond which point the entire root-soil matrix fails. These hypotheses were then tested by running a series of laboratory-shear tests of root-permeated and non-root-permeated soils. The results of these studies were used in the ARS-Bank Stability Model (ver. 2.0) to simulate the increase in factor of safety of streambanks due to root reinforcement. The calculations suggest that overestimation of increased soil shear strength from the root network using the sum of root tensile and soil shear strengths, may be as high as 78% for Eastern Sycamore roots which uptake strain slowly, but only 10% for Sandbar Willow roots, which take up tension more quickly.

Pollen, N. L.; Simon, A.

2002-12-01

152

Root Development in Aluminous Hawaiian Soils  

Microsoft Academic Search

Roots of Rhodomyrtus tomentosa and Melastoma malabathricum were excavated in three soil series from the bauxitic area of Kauai . Root systems of R. tomentosa and M. malabathricum in Kapaa and Halii soils were very shal­ low, with tap roots turning laterally at shallow depth and with long lateral roots very close to the soil surface. Deeper tap-root penetration of

J. C. MOOMAW; C. H. LAMOUREUX

153

Exogenous polyamines improve rooting of hazel microshoots  

Microsoft Academic Search

A strong positive effect of polyamines on rooting of microshoots of adult hazel (Corylus avellana L., cv. Gironell) is described. The effect of polyamines, both in the root induction solution and in the actual rooting medium, was assessed in order to study the effect on the successive rooting phases. Polyamines improved rooting of indole-3-butyric acid-treated microshoots in a synergistic fashion,

Manuel Rey; Carmen Díaz-Sala; Roberto Rodríguez

1994-01-01

154

Theon's Ladder for Any Root  

ERIC Educational Resources Information Center

Theon's ladder is an ancient algorithm for calculating rational approximations for the square root of 2. It features two columns of integers (called a ladder), in which the ratio of the two numbers in each row is an approximation to the square root of 2. It is remarkable for its simplicity. This algorithm can easily be generalized to find rational…

Osler, Thomas J.; Wright, Marcus; Orchard, Michael

2005-01-01

155

Gut and Root Microbiota Commonalities  

PubMed Central

Animal guts and plant roots have absorption roles for nutrient uptake and converge in harboring large, complex, and dynamic groups of microbes that participate in degradation or modification of nutrients and other substances. Gut and root bacteria regulate host gene expression, provide metabolic capabilities, essential nutrients, and protection against pathogens, and seem to share evolutionary trends. PMID:23104406

Ramírez-Puebla, Shamayim T.; Servín-Garcidueñas, Luis E.; Jiménez-Marín, Berenice; Bolaños, Luis M.; Rosenblueth, Mónica; Martínez, Julio; Rogel, Marco Antonio; Ormeño-Orrillo, Ernesto

2013-01-01

156

The "Green" Root Beer Laboratory  

NSDL National Science Digital Library

No, your students will not be drinking green root beer for St. Patrick's Day--this "green" root beer laboratory promotes environmental awareness in the science classroom, and provides a venue for some very sound science content! While many science classroo

James Wandersee

2010-02-01

157

Determinants and Polynomial Root Structure  

ERIC Educational Resources Information Center

A little known property of determinants is developed in a manner accessible to beginning undergraduates in linear algebra. Using the language of matrix theory, a classical result by Sylvester that describes when two polynomials have a common root is recaptured. Among results concerning the structure of polynomial roots, polynomials with pairs of…

De Pillis, L. G.

2005-01-01

158

The root as a drill  

PubMed Central

Plant roots forage the soil for water and nutrients and overcome the soil’s physical compactness. Roots are endowed with a mechanism that allows them to penetrate and grow in dense media such as soil. However, the molecular mechanisms underlying this process are still poorly understood. The nature of the media in which roots grow adds to the difficulty to in situ analyze the mechanisms underlying root penetration. Inhibition of ethylene perception by application of 1-methyl cyclopropene (1-MCP) to tomato seedlings nearly abolished the root penetration in Soilrite. The reversal of this process by auxin indicated operation of an auxin-ethylene signaling pathway in the regulation of root penetration. The tomato pct1–2 mutant that exhibits an enhanced polar transport of auxin required higher doses of 1-MCP to inhibit root penetration, indicating a pivotal role of auxin transport in this process. In this update we provide a brief review of our current understanding of molecular processes underlying root penetration in higher plants. PMID:22415043

Santisree, Parankusam; Nongmaithem, Sapana; Sreelakshmi, Yellamaraju; Ivanchenko, Maria; Sharma, Rameshwar

2012-01-01

159

Parameterizing complex root water uptake models - the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake  

NASA Astrophysics Data System (ADS)

Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However they suffer from a lack of information in important parameters, especially distribution of root hydraulic properties. In this paper we explore the role that arrangement of root hydraulic properties and root system topology play for modelled uptake dynamics. We apply microscopic models of single root structures to investigate the mechanisms shaping uptake dynamics and demonstrate the effects in a complex three dimensional root water uptake model. We introduce two efficiency indices, for (a) overall plant resistance and (b) water stress and show that an appropriate arrangement of root hydraulic properties can increase modelled efficiency of root water uptake in single roots, branched roots and entire root systems. The average uptake depth of the complete root system was not influenced by parameterization. However, other factors such as evolution of collar potential, which is related to the plant resistance, root bleeding and redistribution patterns were strongly affected by the parameterization. Root systems are more efficient when they are assembled of different root types, allowing for separation of root function in uptake (short young) roots and transport (longer mature) roots. Results become similar, as soon as this composition is accounted for to some degree (between 40 and 80% of young uptake roots). Overall resistance to root water uptake was decreased up to 40% and total transpiration was increased up to 25% in these composed root systems, compared to homogenous root systems. Also, one parameterization (homogenous young root system) was characterized by excessive bleeding (hydraulic lift), which was accompanied by lowest efficiency. We conclude that heterogeneity of root hydraulic properties is a critical component of complex three dimensional uptake models. Efficiency measures together with information on critical xylem potentials may be useful in parameterizing root property distribution.

Bechmann, M.; Schneider, C.; Carminati, A.; Vetterlein, D.; Attinger, S.; Hildebrandt, A.

2014-01-01

160

Multiple idiopathic apical root resorption.  

PubMed

Idiopathic external root resorption is a rarely reported condition which has been observed in single or multiple teeth. This is a rare case of multiple idiopathic apical root resorption (MIARR) in a 16-year-old boy. External root resorption of the permanent teeth is a multifactorial process. Well-recognised causes of apical root resorption in permanent teeth include orthodontic therapy, trauma, periapical or periodontal inflammation, tumours, cysts, occlusal stresses, impacted teeth, systemic conditions, endocrine imbalances and dietary habits. When none of these causes are present, it is termed idiopathic root resorption which may be either cervical or apical. MIARR is a rare condition which is usually detected as an incidental radiographic finding. However, it may cause pain and mobility in severe cases. PMID:23616336

Kanungo, Manish; Khandelwal, Vishal; Nayak, Ullal Anand; Nayak, Prathibha Anand

2013-01-01

161

Extensive Idiopathic External Root Resorption in First Maxillary Molar: A Case Report  

PubMed Central

External root resorption of permanent teeth is a multifactorial process. Several etiologic and predisposing factors have been related to external root resorption. Idiopathic external root resorption is defined as cases of external root resorption without a distinct etiologic factor. This article presents an extensive idiopathic external root resorption of maxillary first molar with irreversible pulpitis in an 18-year-old patient. The resorption was diagnosed in conventional radiographs and confirmed with Cone Beam Computed Tomography (CBCT) images. Unlike other reports in this field, and despite the severe resorption of all roots, there was no abnormal tooth mobility. Cold and electric pulp tests confirmed tooth vitality and revealed irreversible pulpitis. Therefore the exact etiology of the resorption remained unclear. Considering the poor prognosis due to severe root resorption, extraction and implant replacement was indicated. PMID:23717334

Bolhari, Behnam; Meraji, Naghmeh; Nosrat, Ali

2013-01-01

162

Evaluation of root fungicides as root dips for the control of root rot in storage, 2009  

Technology Transfer Automated Retrieval System (TEKTRAN)

Root rot in storage can lead to considerable sucrose losses in storage and adversely affect factory processing as well. The use of fungicide treatments applied to the root surface prior to storage were investigated to determine if they could reduce storage rots caused by Botrytis sp., Penicillium s...

163

A root hairless barley mutant for elucidating genetic of root hairs and phosphorus uptake  

Microsoft Academic Search

This paper reports a new barley mutant missing root hairs. The mutant was spontaneously discovered among the population of wild type (Pallas, a spring barley cultivar), producing normal, 0.8 mm long root hairs. We have called the mutant bald root barley (brb). Root anatomical studies confirmed the lack of root hairs on mutant roots. Amplified Fragment Length Polymorphism (AFLP) analyses

Tara S. Gahoonia; Niels Erik Nielsen; Priyavadan A. Joshi; Ahmed Jahoor

2001-01-01

164

Root and Root Collar Disease of Eucalyptus grandis Caused by Pythium splendens  

E-print Network

Root and Root Collar Disease of Eucalyptus grandis Caused by Pythium splendens 125 C. LINDE, M. J. H. J. 1994. Root and root collar disease of Eucalyptus gramlis caused by Pythium spJendens. Plant Dis. 78:1006-1009. A serious root and root collar disease of Eucal}ptus grandis occurred

165

Plant root distributions and nitrogen uptake predicted by a hypothesis of optimal root foraging  

E-print Network

Plant root distributions and nitrogen uptake predicted by a hypothesis of optimal root foraging-uptake fraction, nitrogen-uptake model, nitrogen-use efficiency, optimal foraging by roots, optimal rooting depth, root distributions, root strategies. Correspondence Ross E. McMurtrie, School of Biological, Earth

166

Root Rot of Cotton or "Cotton Blight"  

E-print Network

and whether the fungus precedes or follows the damage to tl nutrition and pi-ogress of the root is hard to Ray, but its appearant is certainly connected in a very large number of cases with a reac ing of an undrained and impervious subsoil." Numerous... Entomological Department, writes me that the de- partment entomologists had always supposed the disease to be due to a fungus and not to insects. I have frequently found nematodes ancl mites, such as are co in putrefactive substances. I never found...

Pammel, L. H. (Louis Herman)

1888-01-01

167

Random root movements in weightlessness  

NASA Technical Reports Server (NTRS)

The dynamics of root growth was studied in weightlessness. In the absence of the gravitropic reference direction during weightlessness, root movements could be controlled by spontaneous growth processes, without any corrective growth induced by the gravitropic system. If truly random of nature, the bending behavior should follow so-called 'random walk' mathematics during weightlessness. Predictions from this hypothesis were critically tested. In a Spacelab ESA-experiment, denoted RANDOM and carried out during the IML-2 Shuttle flight in July 1994, the growth of garden cress (Lepidium sativum) roots was followed by time lapse photography at 1-h intervals. The growth pattern was recorded for about 20 h. Root growth was significantly smaller in weightlessness as compared to gravity (control) conditions. It was found that the roots performed spontaneous movements in weightlessness. The average direction of deviation of the plants consistently stayed equal to zero, despite these spontaneous movements. The average squared deviation increased linearly with time as predicted theoretically (but only for 8-10 h). Autocorrelation calculations showed that bendings of the roots, as determined from the 1-h photographs, were uncorrelated after about a 2-h interval. It is concluded that random processes play an important role in root growth. Predictions from a random walk hypothesis as to the growth dynamics could explain parts of the growth patterns recorded. This test of the hypothesis required microgravity conditions as provided for in a space experiment.

Johnsson, A.; Karlsson, C.; Iversen, T. H.; Chapman, D. K.

1996-01-01

168

Root cooperation in a clonal plant: connected strawberries segregate roots.  

PubMed

The ability to selectively avoid competition with members of the same clone should be highly advantageous but has not been demonstrated in plants. We found that physical connection between plants in a clone of the wild strawberry Fragaria chiloensis induced them to segregate their roots, significantly increasing clonal performance. Such increase in performance was not found when plants were grown in containers that artificially divided their rooting zones. There was no effect of connection in a different clone of F. chiloensis with a lower degree of carbon transport between connected plants, suggesting that the mechanism for root segregation depended upon transport of a signal through the strawberry runners. We suggest that clonal integration allows some clones to coordinate below-ground resource foraging with other clone members, thus exhibiting a type of root cooperation. PMID:12647182

Holzapfel, Claus; Alpert, Peter

2003-01-01

169

Breakage of transgenic tobacco roots for monoclonal antibody release in an ultra-scale down shearing device  

PubMed Central

Transgenic tobacco roots offer a potential alternative to leaves for monoclonal antibody (MAb) production. A possible method for extraction of MAbs from roots is by homogenization, breaking the roots into fragments to release the antibody. This process was assessed by shearing 10?mm root sections (“roots”) in a 24?mL ultra-scale down shearing device, including an impeller with serrated blade edges, intended to mimic the action of a large-scale homogenizer. Size distributions of the remaining intact roots and root fragments were obtained as a function of shearing time. The data suggest that about 36% of the roots could not be broken under the prevailing conditions and, beyond these unbreakable roots, the fragmentation was approximately first order with respect to intact root number. It was postulated that root breakage in such a high shearing device was due to root-impeller collisions and the particle size data suggest that roots colliding with the impeller were completely fragmented into debris particles of the order of 0.1?mm in length. IgG release normalized to release by grinding appeared to lag behind the number of roots that had fragmented, suggesting that a process of leakage followed fragmentation in the ultra-scale down shearing device. PMID:23860965

Hassan, Sally; Keshavarz-Moore, Eli; Ma, Julian; Thomas, Colin

2014-01-01

170

Breakage of transgenic tobacco roots for monoclonal antibody release in an ultra-scale down shearing device.  

PubMed

Transgenic tobacco roots offer a potential alternative to leaves for monoclonal antibody (MAb) production. A possible method for extraction of MAbs from roots is by homogenization, breaking the roots into fragments to release the antibody. This process was assessed by shearing 10?mm root sections ("roots") in a 24?mL ultra-scale down shearing device, including an impeller with serrated blade edges, intended to mimic the action of a large-scale homogenizer. Size distributions of the remaining intact roots and root fragments were obtained as a function of shearing time. The data suggest that about 36% of the roots could not be broken under the prevailing conditions and, beyond these unbreakable roots, the fragmentation was approximately first order with respect to intact root number. It was postulated that root breakage in such a high shearing device was due to root-impeller collisions and the particle size data suggest that roots colliding with the impeller were completely fragmented into debris particles of the order of 0.1?mm in length. IgG release normalized to release by grinding appeared to lag behind the number of roots that had fragmented, suggesting that a process of leakage followed fragmentation in the ultra-scale down shearing device. PMID:23860965

Hassan, Sally; Keshavarz-Moore, Eli; Ma, Julian; Thomas, Colin

2014-01-01

171

Root Words- Greek and Latin  

NSDL National Science Digital Library

Greek and Latin are parts of many of the words you use every day. Using the links provided create 10 new words. Also figure out what the 5 words below mean. Check out these links for help in creating your new words. Sometimes you will need to scroll down to find the information. Latin and Greek Word Elements Greek and Latin Root Words List Latin Greek Roots Index Take Our Word For It Word Translation 1. Chromophobe 2. Loqumal 3. Rogospath 4. Hypnoliver 5. Aquaport Root Words Quiz Select one of the sections one-six and see how well you do now that you have become better acquainted with Greek and ...

Miss B

2007-06-21

172

Hypocotyl adventitious root organogenesis differs from lateral root development  

PubMed Central

Wound-induced adventitious root (AR) formation is a requirement for plant survival upon root damage inflicted by pathogen attack, but also during the regeneration of plant stem cuttings for clonal propagation of elite plant varieties. Yet, adventitious rooting also takes place without wounding. This happens for example in etiolated Arabidopsis thaliana hypocotyls, in which AR initiate upon de-etiolation or in tomato seedlings, in which AR initiate upon flooding or high water availability. In the hypocotyl AR originate from a cell layer reminiscent to the pericycle in the primary root (PR) and the initiated AR share histological and developmental characteristics with lateral roots (LRs). In contrast to the PR however, the hypocotyl is a determinate structure with an established final number of cells. This points to differences between the induction of hypocotyl AR and LR on the PR, as the latter grows indeterminately. The induction of AR on the hypocotyl takes place in environmental conditions that differ from those that control LR formation. Hence, AR formation depends on differentially regulated gene products. Similarly to AR induction in stem cuttings, the capacity to induce hypocotyl AR is genotype-dependent and the plant growth regulator auxin is a key regulator controlling the rooting response. The hormones cytokinins, ethylene, jasmonic acid, and strigolactones in general reduce the root-inducing capacity. The involvement of this many regulators indicates that a tight control and fine-tuning of the initiation and emergence of AR exists. Recently, several genetic factors, specific to hypocotyl adventitious rooting in A. thaliana, have been uncovered. These factors reveal a dedicated signaling network that drives AR formation in the Arabidopsis hypocotyl. Here we provide an overview of the environmental and genetic factors controlling hypocotyl-born AR and we summarize how AR formation and the regulating factors of this organogenesis are distinct from LR induction. PMID:25324849

Verstraeten, Inge; Schotte, Sébastien; Geelen, Danny

2014-01-01

173

Rootin, a compound that inhibits root development through modulating PIN-mediated auxin distribution.  

PubMed

Plant roots anchor the plant to the soil and absorb water and nutrients for growth. Understanding the molecular mechanisms regulating root development is essential for improving plant survival and agricultural productivity. Extensive molecular genetic studies have provided important information on crucial components for the root development control over the last few decades. However, it is becoming difficult to identify new regulatory components in root development due to the functional redundancy and lethality of genes involved in root development. In this study, we performed a chemical genetic screen to identify novel synthetic compounds that regulate root development in Arabidopsis seedlings. The screen yielded a root growth inhibitor designated as 'rootin', which inhibited Arabidopsis root development by modulating cell division and elongation, but did not significantly affect shoot development. Transcript analysis of phytohormone marker genes revealed that rootin preferentially altered the expression of auxin-regulated genes. Furthermore, rootin reduced the accumulation of PIN1, PIN3, and PIN7 proteins, and affected the auxin distribution in roots, which consequently may lead to the observed defects in root development. Our results suggest that rootin could be utilized to unravel the mechanisms underlying root development and to investigate dynamic changes in PIN-mediated auxin distribution. PMID:25711819

Jeong, Suyeong; Kim, Jun-Young; Choi, Hyunmo; Kim, Hyunmin; Lee, Ilhwan; Soh, Moon-Soo; Nam, Hong Gil; Chang, Young-Tae; Lim, Pyung Ok; Woo, Hye Ryun

2015-04-01

174

Genetic analysis of the gravitropic set-point angle in lateral roots of Arabidopsis  

NASA Technical Reports Server (NTRS)

Research on gravity responses in plants has mostly focused on primary roots and shoots, which typically orient to a vertical orientation. However, the distribution of lateral organs and their characteristically non-vertical growth orientation are critical for the determination of plant form. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting overall root system architecture. We found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of new lateral roots appears to be determined by what is called the gravitropic set-point angle (GSA). This developmental control of the GSA of lateral roots in Arabidopsis provides a useful system for investigating the components involved in regulating gravitropic responses. Using this system, we have identified several Arabidopsis mutants that have altered lateral root orientations but maintain normal primary root orientation. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Mullen, J. L.; Hangarter, R. P.; Kiss, J. Z. (Principal Investigator)

2003-01-01

175

Root hairs improve root penetration, root-soil contact, and phosphorus acquisition in soils of different strength.  

PubMed

Root hairs are a key trait for improving the acquisition of phosphorus (P) by plants. However, it is not known whether root hairs provide significant advantage for plant growth under combined soil stresses, particularly under conditions that are known to restrict root hair initiation or elongation (e.g. compacted or high-strength soils). To investigate this, the root growth and P uptake of root hair genotypes of barley, Hordeum vulgare L. (i.e. genotypes with and without root hairs), were assessed under combinations of P deficiency and high soil strength. Genotypes with root hairs were found to have an advantage for root penetration into high-strength layers relative to root hairless genotypes. In P-deficient soils, despite a 20% reduction in root hair length under high-strength conditions, genotypes with root hairs were also found to have an advantage for P uptake. However, in fertilized soils, root hairs conferred an advantage for P uptake in low-strength soil but not in high-strength soil. Improved root-soil contact, coupled with an increased supply of P to the root, may decrease the value of root hairs for P acquisition in high-strength, high-P soils. Nevertheless, this work demonstrates that root hairs are a valuable trait for plant growth and nutrient acquisition under combined soil stresses. Selecting plants with superior root hair traits is important for improving P uptake efficiency and hence the sustainability of agricultural systems. PMID:23861547

Haling, Rebecca E; Brown, Lawrie K; Bengough, A Glyn; Young, Iain M; Hallett, Paul D; White, Philip J; George, Timothy S

2013-09-01

176

IAA transport in corn roots includes the root cap  

SciTech Connect

In earlier reports we concluded that auxin is the growth regulator that controls gravicurvature in roots and that the redistribution of auxin occurs within the root cap. Since other reports did not detect auxin in the root cap, we attempted to confirm the IAA does move through the cap. Agar blocks containing {sup 3}H-IAA were applied to the cut surface of 5 mm long apical segments of primary roots of corn (mo17xB73). After 30 to 120 min radioactivity (RA) of the cap and root tissue was determined. While segments suspended in water-saturated air accumulated very little RA in the cap, application of 0.5 {mu}1 of dist. water to the cap (=controls) increased RA of the cap dramatically. Application to the cap of 0.5 {mu}1 of sorbitol or the Ca{sup 2+} chelator EGTA reduced cap RA to 46% and 70% respectively compared to water, without affecting uptake. Control root segments gravireacted faster than non-treated or osmoticum or EGTA treated segments. The data indicate that both the degree of hydration and calcium control the amount of auxin moving through the cap.

Hasenstein, K.H. (Univ. of SW Louisiana, Lafayette (USA))

1989-04-01

177

Root Foraging Influences Plant Growth Responses to Earthworm Foraging  

PubMed Central

Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503

Cameron, Erin K.; Cahill, James F.; Bayne, Erin M.

2014-01-01

178

Root foraging influences plant growth responses to earthworm foraging.  

PubMed

Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503

Cameron, Erin K; Cahill, James F; Bayne, Erin M

2014-01-01

179

Systemic ozone effects on root hydraulic properties in pima cotton  

SciTech Connect

Ambient ozone concentrations have become problematic even in rural, agricultural areas such as the San Joaquin Valley of California. Pima cotton (cv. S6) has been shown to be relatively sensitive to ozone air pollution, at levels occurring in this production area. In this semi-arid area acquisition of water and nutrients may limit yield and biological productivity. Therefore maximal proliferation, exploration, and efficiency of root systems is desirable. Hydraulic conductance provides a parameter to characterize the efficiency of roots and shoots and their interaction. The authors have used a variety of transpiration and pressure vessel techniques to document ozone-induced reduction of root hydraulic conductance in cotton. They hypothesized that these effects are caused by reduced carbohydrate supply due to reduction of photosynthetic capacity of the shoot associated with direct oxidant damage to foliage. However, the authors simulated this reduced photosynthetic capacity by continuously removing leaf area to match that of ozone treated plants. This resulted in a reduction of whole plant biomass similar to ozone-treated plants, but a root/shoot biomass ratio and root hydraulic properties similar to control plants and contrasting with ozone-treated plants. Thus leaf removal did not simulate effects of ozone on root hydraulic properties. A systematic effect of ozone on whole plant function is indicated, perhaps mediated by direct effects on carbohydrate translocation throughout the plant.

Grantz, D.A.; Yang, S. [Univ. of California, Riverside, CA (United States); [Kearney Agricultural Center, Parlier, CA (United States)

1995-12-31

180

Loss of tooth substance during root planing with various periodontal instruments: an in vitro study  

Microsoft Academic Search

Ultrasonic and power-driven instrumentation is gaining in significance as an acceptable alternative to manual periodontal root treatment. Some question whether they do not remove too much tooth substance. Various ultrasonic scalers, hand instruments and two power-driven systems were compared by assessing the loss of tooth substance due to root instrumentation. Quantitative analysis of this effect of the instruments used was

Patrick Obeid; Pierre Bercy

2005-01-01

181

Endodontic Treatment of a Mandibular Second Premolar with Three Roots and Three Canals  

PubMed Central

Complex root canal system with atypical variations is a common finding among mandibular premolars. Endodontic treatment in these teeth may not be successful due to the failure to recognise and treat multiple canals. This paper presents endodontic treatment of a mandibular second premolar with three roots and three canals. PMID:25431692

Paul, Bonny; Dube, Kavita

2014-01-01

182

Nitrate Control of Root Hydraulic Properties in Plants: Translating Local Information to  

E-print Network

between nitrate availability and water acquisition results from changes in cell membrane hydraulic that the increase in root hydraulic conductance in one part causes a decline of water uptake in the other part dueNitrate Control of Root Hydraulic Properties in Plants: Translating Local Information to Whole

Holbrook, N. Michele

183

Passive transport of microconidia of Fusarium oxysporum f. sp. dianthi in carnation after root inoculation  

Microsoft Academic Search

Root inoculation of susceptible carnations withFusarium oxysporum f. sp.dianthi induced characteristic unilateral wilt only if root woundings and use of a microconidial suspension had not been combined at the time of inoculation. The combination, however, induced atypical and sudden stem breaking soon followed by death. In all cases wilt was due to destruction of the xylem. Unilateral wilt appeared to

R. P. Baayen; A. L. De Maat

1987-01-01

184

ROOT GROWTH AND TURNOVER IN DIFFERENT AGED PONDEROSA PINE STANDS IN OREGON, USA  

EPA Science Inventory

The impacts of pollution and climate change on soil carbon dynamics are poorly understood, in part due to a lack of information regarding root production and turnover in natural ecosystems. In order to examine how root dynamics change with stand age in ponderosa pine forests (...

185

Proteome changes induced by aluminum stress in tomato roots  

Technology Transfer Automated Retrieval System (TEKTRAN)

Growth inhibition in acid soils due to Al stress affects crop production worldwide. To understand mechanisms in sensitive crops that are affected by Al stress, a proteomic analysis of primary tomato root tissue, grown in Alamended and non-amended liquid cultures, was performed. DIGE-SDS-MALDI-TOF-TO...

186

The root apices of the premolars and molars  

E-print Network

of the mandibular molar region does not show all of the specific region on the film. The third molar has been "cutFig. 8-1 The root apices of the premolars and molars are "cut off" because the film was placed too. Fig. A Illusion of a closed contact point between the second premolar and first molar due to incorrect

187

MOLECULAR APPROACHES FOR CONTROL OF THE SUGAR BEET ROOT MAGGOT  

Technology Transfer Automated Retrieval System (TEKTRAN)

The sugar beet root maggot (Tetanops myopaeformis Roder) is a major insect pest of sugar beet in the United States and Canada accounting for yield losses in the range of 10 to 100%. Currently no biological control measures exist and crop rotation has been ineffective due to the mobility of the adul...

188

On the re-rooting invariance property of Levy trees  

E-print Network

On the re-rooting invariance property of L´evy trees Thomas Duquesne and Jean-Fran¸cois Le Gall of the continuous random trees called L´evy trees. This extends previous results due to several authors. 1 Introduction Continuous random trees have been studied extensively in the last fifteen years and have found

Le Gall, Jean-François

189

Aphanomyces root rot of alfalfa: widespread distribution of race 2  

Technology Transfer Automated Retrieval System (TEKTRAN)

The early spring of 2012 with prolonged wet soil conditions in many parts of the country resulted in reports of poor performance of alfalfa due to Aphanomyces root rot (ARR). Varieties with resistance to ARR are available, although fewer varieties have resistance to both race 1 and race 2 of the pat...

190

Triacontagonal coordinates for the E(8) root system  

E-print Network

This note gives an explicit formula for the elements of the E(8) root system. The formula is triacontagonally symmetric in that one may clearly see an action by the cyclic group with 30 elements. The existence of such a formula is due to the fact that the Coxeter number of E(8) is 30.

David A. Richter

2007-04-24

191

Piriformospora indica, a Cultivable Plant-Growth-Promoting Root Endophyte  

PubMed Central

Piriformospora indica (Hymenomycetes, Basidiomycota) is a newly described cultivable endophyte that colonizes roots. Inoculation with the fungus and application of fungal culture filtrate promotes plant growth and biomass production. Due to its ease of culture, this fungus provides a model organism for the study of beneficial plant-microbe interactions and a new tool for improving plant production systems. PMID:10347070

Varma, Ajit; Savita Verma; Sudha; Sahay, Nirmal; Bütehorn, Britta; Franken, Philipp

1999-01-01

192

Root systems and generalized associahedra  

Microsoft Academic Search

These lecture notes for the IAS\\/Park City Graduate Summer School in Geometric Combinatorics (July 2004) provide an overview of root systems, generalized associahedra, and the combinatorics of clusters. Lectures 1-2 cover classical material: root systems, finite reflection groups, and the Cartan-Killing classification. Lectures 3-4 provide an introduction to cluster algebras from a combinatorial perspective. Lecture 5 is devoted to related

Sergey Fomin; Nathan Reading

2005-01-01

193

Drying of Echinacea angustifolia Roots  

Microsoft Academic Search

Echinacea angustifolia roots were dried at 23, 30, 40, 50, and 60°C to determine the effect of drying on chemical constituency. During drying, the concentrations of the alkamides, cis or trans undeca-2-en 8, 10-diyonic acid isobutylamide and cis or trans dodeca-2E, 4E, 8Z, 10-tetraenoic acid isobutylamide, did not decrease at any of the drying temperatures as compared with roots dried

R. Kabganian; D. J. Carrier; S. Sokansanj

2003-01-01

194

Nerve and Nerve Root Biomechanics  

Microsoft Academic Search

\\u000a Together, the relationship between the mechanical response of neural tissues and the related mechanisms of injury provide\\u000a a foundation for defining relevant thresholds for injury. The nerves and nerve roots are biologic structures with specific\\u000a and important functions, and whose response to mechanical loading can have immediate, long-lasting and widespread consequences.\\u000a In particular, when nerves or nerve roots are mechanically

Kristen J. Nicholson; Beth A. Winkelstein

195

Effect of parameter choice in root water uptake models - the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake  

NASA Astrophysics Data System (ADS)

Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However, they suffer from a lack of information on important parameters, particularly on the spatial distribution of root axial and radial conductivities, which vary greatly along a root system. In this paper we explore how the arrangement of those root hydraulic properties and branching within the root system affects modelled uptake dynamics, xylem water potential and the efficiency of root water uptake. We first apply a simple model to illustrate the mechanisms at the scale of single roots. By using two efficiency indices based on (i) the collar xylem potential ("effort") and (ii) the integral amount of unstressed root water uptake ("water yield"), we show that an optimal root length emerges, depending on the ratio between roots axial and radial conductivity. Young roots with high capacity for radial uptake are only efficient when they are short. Branching, in combination with mature transport roots, enables soil exploration and substantially increases active young root length at low collar potentials. Second, we investigate how this shapes uptake dynamics at the plant scale using a comprehensive three-dimensional root water uptake model. Plant-scale dynamics, such as the average uptake depth of entire root systems, were only minimally influenced by the hydraulic parameterization. However, other factors such as hydraulic redistribution, collar potential, internal redistribution patterns and instantaneous uptake depth depended strongly on the arrangement on the arrangement of root hydraulic properties. Root systems were most efficient when assembled of different root types, allowing for separation of root function in uptake (numerous short apical young roots) and transport (longer mature roots). Modelling results became similar when this heterogeneity was accounted for to some degree (i.e. if the root systems contained between 40 and 80% of young uptake roots). The average collar potential was cut to half and unstressed transpiration increased by up to 25% in composed root systems, compared to homogenous ones. Also, the least efficient root system (homogenous young root system) was characterized by excessive bleeding (hydraulic lift), which seemed to be an artifact of the parameterization. We conclude that heterogeneity of root hydraulic properties is a critical component for efficient root systems that needs to be accounted for in complex three-dimensional root water uptake models.

Bechmann, M.; Schneider, C.; Carminati, A.; Vetterlein, D.; Attinger, S.; Hildebrandt, A.

2014-10-01

196

Root Canal Morphology of Permanent Three-rooted Mandibular First Molars: Part II—Measurement of Root Canal Curvatures  

Microsoft Academic Search

IntroductionThe distolingual (DL) roots of three-rooted mandibular molars often challenge clinicians during root canal therapy. This study investigated canal curvatures in permanent three-rooted mandibular first molars by using micro–computed tomography (micro-CT) scans.

Yongchun Gu; Qun Lu; Ping Wang; Longxing Ni

2010-01-01

197

Root waving and skewing: unexpectedly in micro-g.  

PubMed

Gravity has major effects on both the form and overall length of root growth. Numerous papers have documented these effects (over 300 publications in the last 5 years), the most well-studied being gravitropism, which is a growth re-orientation directed by gravity toward the earth's center. Less studied effects of gravity are undulations due to the regular periodic change in the direction root tips grow, called waving, and the slanted angle of growth roots exhibit when they are growing along a nearly-vertical surface, called skewing. Although diverse studies have led to the conclusion that a gravity stimulus is needed for plant roots to show waving and skewing, the novel results just published by Paul et al. (2012) reveal that this conclusion is not correct. In studies carried out in microgravity on the International Space Station, the authors used a new imaging system to collect digital photographs of plants every six hours during 15 days of spaceflight. The imaging system allowed them to observe how roots grew when their orientation was directed not by gravity but by overhead LED lights, which roots grew away from because they are negatively phototropic. Surprisingly, the authors observed both skewing and waving in spaceflight plants, thus demonstrating that both growth phenomena were gravity independent. Touch responses and differential auxin transport would be common features of root waving and skewing at 1-g and micro-g, and the novel results of Paul et al. will focus the attention of cell and molecular biologists more on these features as they try to decipher the signaling pathways that regulate root skewing and waving. PMID:23217095

Roux, Stanley J

2012-01-01

198

Root dynamics in native grassland exposed to elevated CO2 and warming  

NASA Astrophysics Data System (ADS)

Responses of belowground processes to global change play a major role in terrestrial ecosystem carbon (C) storage and feedbacks to climate, but remain understudied in comparison to aboveground processes. In grasslands, roots comprise about 75 percent of the biomass, and are responsible for increased inputs of C to soil pools under elevated CO2. Root exudation may also be responsible for increased rates of soil organic matter decomposition, or priming, potentially offsetting inputs of new C. Understanding the fate of belowground C allocation requires a better understanding of root processes including growth, rhizodeposition, turnover and decomposition. We studied root dynamics in mixed C3/C4 grassland at the Prairie Heating and CO2 Enrichment experiment near Cheyenne, WY, where Free-Air CO2 Enrichment is applied at 600 ppm during daytime in the growing season, and temperature is elevated by 1.5/3 deg C day/night all year. We applied several belowground techniques, including direct biomass measurements coupled with C isotope labeling, root litter decomposition measured in litter bags and in plots with herbicide applied, and image analysis of intact and harvested root systems . Direct measurements indicated that elevated CO2 increased root biomass, a trend that became increasingly significant over the first four years of treatments. Warming by itself tended to decrease root biomass in the first two years, and this effect declined in the next two years of the experiment, suggesting a transient negative response of root growth to warming. Continuous 13C labeling in elevated CO2 plots allowed detection of a greater proportion of new C in warmed than ambient temperature plots, demonstrating greater allocation of C to roots exposed to both elevated CO2 and warming. A root litter bag decomposition experiment showed that C3 grass roots decomposed more rapidly with elevated CO2 alone, but more slowly when elevated CO2 was combined with warming, possibly due to soil drying. C4 grass roots decomposed more slowly than C3 roots, probably due to higher C/N values, and were less responsive to global change treatments. Recent research has shown that C4 grasses become more competitive with elevated CO2 and warming, which together with their lower decomposition rates and higher root growth under these conditions, suggests that roots are likely to play an increasingly important role in belowground C storage in grasslands in the coming century. Changes in root system structure detected in minirhizotron and harvested root images, including lengths, diameters, and demography, will contribute further understanding of how belowground ecosystems will respond to global change.

Pendall, E.; Carrillo, Y.; Morgan, J. A.; Newcomb, J.

2011-12-01

199

Aortic root dilation after the Ross procedure  

Microsoft Academic Search

This study evaluated changes in neoaortic root geometry in patients who underwent the Ross procedure. Serial postoperative echocardiographic measurements of the neoaortic root indexed to the square root of body surface area (centimeters divided by meters) were obtained from 30 patients (age range 3.1 to 31.4 years) and compared with paired preoperative and immediate postoperative values. Normal aortic root diameter

M. Victoria T Tantengco; Richard A Humes; Sandra K Clapp; Kevin W Lobdell; Henry L Walters; Mehdi Hakimi; Michael L Epstein

1999-01-01

200

A root Cheat Sheet A. Stephen Beach  

E-print Network

A root Cheat Sheet A. Stephen Beach June 9, 1998 Abstract This is a quick guide to root programming, but has no experience with root or C++. Its goal is to get the user up and running quickly? . . . . . . . . . . . . . . . . . . . . . . . 4 2 Basic Questions 4 2.1 What is root

Gilfoyle, Jerry

201

Evidence of Differences between the Communities of Arbuscular Mycorrhizal Fungi Colonizing Galls and Roots of Prunus persica Infected by the Root-Knot Nematode Meloidogyne incognita?  

PubMed Central

Arbuscular mycorrhizal fungi (AMF) play important roles as plant protection agents, reducing or suppressing nematode colonization. However, it has never been investigated whether the galls produced in roots by nematode infection are colonized by AMF. This study tested whether galls produced by Meloidogyne incognita infection in Prunus persica roots are colonized by AMF. We also determined the changes in AMF composition and biodiversity mediated by infection with this root-knot nematode. DNA from galls and roots of plants infected by M. incognita and from roots of noninfected plants was extracted, amplified, cloned, and sequenced using AMF-specific primers. Phylogenetic analysis using the small-subunit (SSU) ribosomal DNA (rDNA) data set revealed 22 different AMF sequence types (17 Glomus sequence types, 3 Paraglomus sequence types, 1 Scutellospora sequence type, and 1 Acaulospora sequence type). The highest AMF diversity was found in uninfected roots, followed by infected roots and galls. This study indicates that the galls produced in P. persica roots due to infection with M. incognita were colonized extensively by a community of AMF, belonging to the families Paraglomeraceae and Glomeraceae, that was different from the community detected in roots. Although the function of the AMF in the galls is still unknown, we hypothesize that they act as protection agents against opportunistic pathogens. PMID:21984233

Alguacil, Maria del Mar; Torrecillas, Emma; Lozano, Zenaida; Roldán, Antonio

2011-01-01

202

Community composition of root-associated fungi in a Quercus-dominated temperate forest: “codominance” of mycorrhizal and root-endophytic fungi  

PubMed Central

In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak-dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic units (OTUs) of fungi were found from 159 terminal-root samples from 12 plant species occurring in the forest. Due to the dominance of an oak species (Quercus serrata), diverse ectomycorrhizal clades such as Russula, Lactarius, Cortinarius, Tomentella, Amanita, Boletus, and Cenococcum were observed. Unexpectedly, the root-associated fungal community was dominated by root-endophytic ascomycetes in Helotiales, Chaetothyriales, and Rhytismatales. Overall, 55.3% of root samples were colonized by both the commonly observed ascomycetes and ectomycorrhizal fungi; 75.0% of the root samples of the dominant Q. serrata were so cocolonized. Overall, this study revealed that root-associated fungal communities of oak-dominated temperate forests were dominated not only by ectomycorrhizal fungi but also by diverse root endophytes and that potential ecological interactions between the two ecotypes may be important to understand the complex assembly processes of belowground fungal communities. PMID:23762515

Toju, Hirokazu; Yamamoto, Satoshi; Sato, Hirotoshi; Tanabe, Akifumi S; Gilbert, Gregory S; Kadowaki, Kohmei

2013-01-01

203

Root penetration through sealing layers at mine deposit sites.  

PubMed

To prevent acid mine drainage arising from oxygen and water penetration of sulphide-rich mine tailings, the tailings are covered with layers of dry sealing material. Plant roots have a great ability to penetrate dense materials, and if the roots are able to penetrate the sealing layer of a tailings deposit, its oxygen-shielding properties could be reduced. The objective of this study was to evaluate whether plant roots are able to penetrate sealing layers covering mine tailings deposits. Root penetration into layers of various sealing materials, such as clayey moraine (clay, 8-10%; silt, 22-37%; sand, 37-55%; gravel, 15-18%), moraine (unspecified), 6-mm bentonite (kaolin clay) fabric, lime and clay, Cefyll (mixture of pulverized coal fly ash, cement and water) and a mixture containing biosludge (30-35%) and bioashes (65-70%), was investigated. In the field, roots were studied by digging trenches alongside vegetation growing in 3- and 10-year-old mine sites. In the greenhouse root growth of Betula pendula, Pinus sylvestris, Poa pratensis and Salix viminalis were studied in compartments where the plants had been growing for 22 months. The results from the field experiment indicated that roots are able to penetrate both deep down in the cover layer (1.7 m) and also into the sealing layers of various materials, and even to penetrate hard Cefyll. The addition of nutrients in the top cover reduced deep root growth and thereby also penetration through the sealing layer. Low hydraulic conductivity of the sealing layer or a thick cover layer had less effect on root penetration. In the greenhouse experiment roots did not penetrate the thin bentonite fabric, due to low pH (2.1-2.7) that was created from the underlying weathered mine tailings. The clayey moraine was penetrated by all species used in the greenhouse experiment; Pinus sylvestris had the greatest ability to penetrate. To prevent root penetration of the other sealing layer, a suitable condition for the plants should be created in the upper part of the cover layer, namely a sufficient amount of plant nutrients. However, to define such a condition is difficult since different plant species have different requirements. PMID:17253002

Stoltz, Eva; Greger, Maria

2006-12-01

204

Orthodontic treatment in patient with idiopathic root resorption: A case report  

PubMed Central

Multiple idiopathic external root resorption is a rare pathological condition usually detected as an incidental radiographic finding. External root resorption of permanent teeth is a multifactorial process related to several local and systemic factors. If an etiological factor cannot be identified for root resorption, the term "idiopathic" is applied. This report presents a case of multiple idiopathic apical root resorption. The condition was found in a young female patient seeking orthodontic treatment due to malocclusion. This kind of resorption starts apically and progresses coronally, causing a gradual shortening and rounding of the remaining root. Patients with this condition are not the ideal candidates for orthodontic treatment; however, the aim of this report is to describe an unusual case of idiopathic root resorption involving the entire dentition, and to present the orthodontic treatment of this patient. It describes the progress and completion of orthodontic therapy with satisfactory end results. PMID:25741832

Rey, Diego; Smit, Rosana Martínez; Gamboa, Liliana

2015-01-01

205

Alpine climate alters the relationships between leaf and root morphological traits but not chemical traits.  

PubMed

Leaves and fine roots are among the most important and dynamic components of terrestrial ecosystems. To what extent plants synchronize their resource capture strategies above- and belowground remains uncertain. Existing results of trait relationships between leaf and root showed great inconsistency, which may be partly due to the differences in abiotic environmental conditions such as climate and soil. Moreover, there is currently little evidence on whether and how the stringent environments of high-altitude alpine ecosystems alter the coordination between above- and belowground. Here we measured six sets of analogous traits for both leaves and fine roots of 139 species collected from Tibetan alpine grassland and Mongolian temperate grassland. N, P and N:P ratio of leaves and fine roots were positively correlated, independent of biogeographic regions, phylogenetic affiliation or climate. In contrast, leaves and fine roots seem to regulate morphological traits more independently. The specific leaf area (SLA)-specific root length (SRL) correlation shifted from negative at sites under low temperature to positive at warmer sites. The cold climate of alpine regions may impose different constraints on shoots and roots, selecting simultaneously for high SLA leaves for rapid C assimilation during the short growing season, but low SRL roots with high physical robustness to withstand soil freezing. In addition, there might be more community heterogeneity in cold soils, resulting in multidirectional strategies of root in resource acquisition. Thus our results demonstrated that alpine climate alters the relationships between leaf and root morphological but not chemical traits. PMID:24633995

Geng, Yan; Wang, Liang; Jin, Dongmei; Liu, Huiying; He, Jin-Sheng

2014-06-01

206

TIME FOR COFFEE controls root meristem size by changes in auxin accumulation in Arabidopsis  

PubMed Central

Roots play important roles in plant survival and productivity as they not only anchor the plants in the soil but are also the primary organ for the uptake of nutrients from the outside. The growth and development of roots depend on the specification and maintenance of the root meristem. Here, we report a previously unknown role of TIME FOR COFFEE (TIC) in controlling root meristem size in Arabidopsis. The results showed that loss of function of TIC reduced root meristem length and cell number by decreasing the competence of meristematic cells to divide. This was due to the repressed expression of PIN genes for decreased acropetal auxin transport in tic-2, leading to low auxin accumulation in the roots responsible for reduced root meristem, which was verified by exogenous application of indole-3-acetic acid. Downregulated expression of PLETHORA1 (PLT1) and PLT2, key transcription factors in mediating the patterning of the root stem cell niche, was also assayed in tic-2. Similar results were obtained with tic-2 and wild-type plants at either dawn or dusk. We also suggested that the MYC2-mediated jasmonic acid signalling pathway may not be involved in the regulation of TIC in controlling the root meristem. Taken together, these results suggest that TIC functions in an auxin–PLTs loop for maintenance of post-embryonic root meristem. PMID:24277277

Lu, Ying-Tang

2014-01-01

207

Root traits for infertile soils  

PubMed Central

Crop production is often restricted by the availability of essential mineral elements. For example, the availability of N, P, K, and S limits low-input agriculture, the phytoavailability of Fe, Zn, and Cu limits crop production on alkaline and calcareous soils, and P, Mo, Mg, Ca, and K deficiencies, together with proton, Al and Mn toxicities, limit crop production on acid soils. Since essential mineral elements are acquired by the root system, the development of crop genotypes with root traits increasing their acquisition should increase yields on infertile soils. This paper examines root traits likely to improve the acquisition of these elements and observes that, although the efficient acquisition of a particular element requires a specific set of root traits, suites of traits can be identified that benefit the acquisition of a group of mineral elements. Elements can be divided into three Groups based on common trait requirements. Group 1 comprises N, S, K, B, and P. Group 2 comprises Fe, Zn, Cu, Mn, and Ni. Group 3 contains mineral elements that rarely affect crop production. It is argued that breeding for a limited number of distinct root ideotypes, addressing particular combinations of mineral imbalances, should be pursued. PMID:23781228

White, Philip J.; George, Timothy S.; Dupuy, Lionel X.; Karley, Alison J.; Valentine, Tracy A.; Wiesel, Lea; Wishart, Jane

2013-01-01

208

Magnetophoretic Induction of Root Curvature  

NASA Technical Reports Server (NTRS)

The last year of the grant period concerned the consolidation of previous experiments to ascertain that the theoretical premise apply not just to root but also to shoots. In addition, we verified that high gradient magnetic fields do not interfere with regular cellular activities. Previous results have established that: (1) intracellular magnetophoresis is possible; and (2) HGMF lead to root curvature. In order to investigate whether HGMF affect the assembly and/or organization of structural proteins, we examined the arrangement of microtubules in roots exposed to HGMF. The cytoskeletal investigations were performed with fomaldehyde-fixed, nonembedded tissue segments that were cut with a vibratome. Microtubules (MTs) were stained with rat anti-yeast tubulin (YOL 1/34) and DTAF-labeled antibody against rat IgG. Microfilaments (MFs) were visualized by incubation in rhodamine-labeled phalloidin. The distribution and arrangement of both components of the cytoskeleton were examined with a confocal microscope. Measurements of growth rates and graviresponse were done using a video-digitizer. Since HGMF repel diamagnetic substances including starch-filled amyloplasts and most The second aspect of the work includes studies of the effect of cytoskeletal inhibitors on MTs and MFs. The analysis of the effect of micotubular inhibitors on the auxin transport in roots showed that there is very little effect of MT-depolymerizing or stabilizing drugs on auxin transport. This is in line with observations that application of such drugs is not immediately affecting the graviresponsiveness of roots.

Hasenstein, Karl H.

1997-01-01

209

Efficient hydraulic properties of root systems  

NASA Astrophysics Data System (ADS)

Understanding the mechanisms of ecosystem root water uptake (RWU) is paramount for parameterizing hydrological models. With the increase in computational power it is possible to calculate RWU explicitly up to the single plant scale using physical models. However, application of these models for increasing our understanding of ecosystem root water uptake is hindered by the deficit in knowledge about the detailed hydraulic parameter distribution within root systems. However, those physical models may help us to identify efficient parameterizations and to describe the influence of these hydraulic parameters on RWU profiles. In this research, we investigated the combined influence of root hydraulic parameters and different root topologies on shaping efficient root water uptake. First, we use a conceptual model of simple branching structures to understand the influence of branching location and transitions in root hydraulic properties on the RWU patterns in typical sub root structures. Second, we apply a physical model called "aRoot" to test our conclusions on complex root system architectures of single plants. aRoot calculates the distribution of xylem potential within arbitrary root geometries to satisfy a given water demand depending on the available water in the soil. Redistribution of water within the bulk soil is calculated using the Richards equation. We analyzed results using a measure of uptake efficiency, which describes the effort necessary for transpiration. Simulations with the conceptual model showed that total transpiration in sub root structures is independent of root hydraulic properties over a wide range of hydraulic parameters. On the other hand efficiency of root water uptake depends crucially on distribution hydraulic parameters in line with root topology. At the same time, these parameters shape strongly the distribution of RWU along the roots, and its evolution in time, thus leading to variable individual root water uptake profiles. Calculating RWU of three dimensional root architectures unveiled that the same effects can be observed at the single plant scale. Total transpiration is almost independent of root hydraulic properties. On the other hand, the arrangement of hydraulic properties significantly influences RWU efficiency. Furthermore the vertical root water uptake profiles are governed by the different root properties. They result from two combined re-distribution patterns over time: One within a rooting branch similar to the results mentioned above, and a second one between the different rooting branches within the root system. This leads to complex vertical uptake profiles, which cannot be predicted from a combination of root abundance and soil moisture, and depend strongly on the individual morphology.

Bechmann, Marcel; Schneider, Christoph; Carminati, Andrea; Hildebrandt, Anke

2013-04-01

210

Logarithms and Square Roots of Real Matrices  

E-print Network

In these notes, we consider the problem of finding the logarithm or the square root of a real matrix. It is known that for every real n x n matrix, A, if no real eigenvalue of A is negative or zero, then A has a real logarithm, that is, there is a real matrix, X, such that e^X = A. Furthermore, if the eigenvalues, xi, of X satisfy the property -pi < Im(xi) < pi, then X is unique. It is also known that under the same condition every real n x n matrix, A, has a real square root, that is, there is a real matrix, X, such that X^2 = A. Moreover, if the eigenvalues, rho e^{i theta}, of X satisfy the condition -pi/2 < theta < pi/2, then X is unique. These theorems are the theoretical basis for various numerical methods for exponentiating a matrix or for computing its logarithm using a method known as scaling and squaring (resp. inverse scaling and squaring). Such methods play an important role in the log-Euclidean framework due to Arsigny, Fillard, Pennec and Ayache and its applications to medical imaging. Actually, there is a necessary and sufficient condition for a real matrix to have a real logarithm (or a real square root) but it is fairly subtle as it involves the parity of the number of Jordan blocks associated with negative eigenvalues. As far as I know, with the exception of Higham's recent book, proofs of these results are scattered in the literature and it is not easy to locate them. Moreover, Higham's excellent book assumes a certain level of background in linear algebra that readers interested in the topics of this paper may not possess so we feel that a more elementary presentation might be a valuable supplement to Higham. In these notes, I present a unified exposition of these results and give more direct proofs of some of them using the Real Jordan Form.

Jean Gallier

2013-11-09

211

Metabolic changes associated with cluster root development in white lupin ( Lupinus albus L.): relationship between organic acid excretion, sucrose metabolism and energy status  

Microsoft Academic Search

Under phosphorous deficiency, plants of white lupin (Lupinus albus L.) develop root clusters, which are also called proteoid roots due to their preferential presence in the Proteaceae. In their mature stage, these roots acidify the soil and excrete high amounts of carboxylates [up to 1.5 and 7 µmol (g FW)-1 h-1 of malate and citrate, respectively] enabling lupins to utilise

Agnès Massonneau; Nicolas Langlade; Sébastien Léon; Jana Smutny; Esther Vogt; Günter Neumann; Enrico Martinoia

2001-01-01

212

A weak combined magnetic field changes root gravitropism  

NASA Astrophysics Data System (ADS)

Immobile higher plants are oriented in the gravitational field due to gravitropim that is a physiological growth reaction and consists of three phases: reception of a gravitational signal by statocytes, its transduction to the elongation zone, and finally the organ bending. According to the starch-statolith hypothesis, amyloplasts in the specialized graviperceptive cells - statocytes sediment in the direction of a gravitational vector in the distal part of a cell. The polar arrangement of organelles is maintained by means of the cytoskeleton. On the Kholodny-Went's, theory the root bending is provided by the polar movement of auxin from a root cap to the elongation zone. It is also known that gravistimulation initiates a rapid Ca2+ redistribution in a root apex. Calcium ions modify an activity of many cytoskeletal proteins and clustering of calcium channels may be directed by actin microfilaments. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence with regard to the participation of cytoskeletal elements and calcium ions in these processes is therefore substantial but still circumstantial and requires new experimental data. Roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector. It was first shown by us that roots change the direction of a gravitropic reaction under gravistimulation in the weak combined magnetic field with a frequency of 32 Hz. 2-3-day old cress seedlings were gravistimulated in moist chambers, which are placed in ?-metal shields. Inside ? -metal shields, combined magnetic fields have been created. Experiments were performed in darkness at temperature 20±10C. Measurements of the magnitude of magnetic fields were carried out with a flux-gate magnetometer. Cress roots reveal negative gravitropism, i. e. they grow in the opposite direction to a gravitational vector, during 2 h of gravistimulation and then roots begin to grow more or less parallel to the Earth's surface, i.e. they reveal plagiotropism. Since such combined magnetic field is adjusted to the cyclotron frequency of Ca2+ ions, these observations demonstrate the participation of calcium ions in root gravitropism. Cyclotron frequency of Ca2+ ions is the formal frequency of ion rotation in the static magnetic field. Simultaneous applying the altering magnetic field with the same frequency can provoke auto-oscillation in the system and consequently change the rate and/or the direction of Ca2+ ion flow in a root under gravistimulation. The data of light, electron, and confocal laser microscopy and kinetics of a gravitropic reaction, which have been obtained on such the new original model, are discussed in the light of current concepts of root gravitropism.

Kordyum, E. L.; Bogatina, N. I.; Kalinina, Ja. M.; Sheykina, N. V.

213

Root reinforcement and its contribution to slope stability in the Western Ghats of Kerala, India  

NASA Astrophysics Data System (ADS)

The Western Ghats of Kerala, India is prone to shallow landslides and consequent debris flows. An earlier study (Kuriakose et al., DOI:10.1002/esp.1794) with limited data had already demonstrated the possible effects of vegetation on slope hydrology and stability. Spatially distributed root cohesion is one of the most important data necessary to assess the effects of anthropogenic disturbances on the probability of shallow landslide initiation, results of which are reported in sessions GM6.1 and HS13.13/NH3.16. Thus it is necessary to the know the upper limits of reinforcement that the roots are able to provide and its spatial and vertical distribution in such an anthropogenically intervened terrain. Root tensile strength and root pull out tests were conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) Gambooge (Garcinia gummi-gutta), 8) Coffee (Coffea Arabica) and 9) Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested had a length of 15 cm. Root pull out tests were conducted in the field. Root tensile strength vs root diameter, root pull out strength vs diameter, root diameter vs root depth and root count vs root depth relationships were derived. Root cohesion was computed for nine most dominant plants in the region using the perpendicular root model of Wu et al. (1979) modified by Schimidt et al. (2001). A soil depth map was derived using regression kriging as suggested by Kuriakose et al., (doi:10.1016/j.catena.2009.05.005) and used along with the land use map of 2008 to distribute the computed root tensile strength both vertically and spatially. Root cohesion varies significantly with the type of land use and the depth of soil. The computation showed that a maximum root reinforcement of 40 kPa was available in the first 30 cm of soil while exponentially decreased with depth to just about 3 kPa at 3 m depth. Mixed crops land use unit had the maximum root cohesion while fallow land, degraded forest and young rubber plantation had the lowest root reinforcement. These are the upper limits of root reinforcement that the vegetation can provide. When the soil is saturated, the bond between soil and roots reduces and thus the applicable root reinforcement is limited by the root pullout strength. Root reinforcement estimated from pullout strength vs diameter relationships was significantly lower than those estimated from tensile strength vs diameter relationships.

Lukose Kuriakose, Sekhar; van Beek, L. P. H.

2010-05-01

214

Root cooperation in a clonal plant: connected strawberries segregate roots  

Microsoft Academic Search

The ability to selectively avoid competition with members of the same clone should be highly advantageous but has not been demonstrated in plants. We found that physical connection between plants in a clone of the wild strawberry Fragaria chiloensis induced them to segregate their roots, significantly increasing clonal performance. Such increase in performance was not found when plants were grown

Claus Holzapfel; Peter Alpert

2003-01-01

215

Rhizobial infection in Adesmia bicolor (Fabaceae) roots.  

PubMed

The native legume Adesmia bicolor shows nitrogen fixation efficiency via symbiosis with soil rhizobia. The infection mechanism by means of which rhizobia infect their roots has not been fully elucidated to date. Therefore, the purpose of the present study was to identify the infection mechanism in Adesmia bicolor roots. To this end, inoculated roots were processed following conventional methods as part of our root anatomy study, and the shape and distribution of root nodules were analyzed as well. Neither root hairs nor infection threads were observed in the root system, whereas infection sites-later forming nodules-were observed in the longitudinal sections. Nodules were found to form between the main root and the lateral roots. It can be concluded that in Adesmia bicolor, a bacterial crack entry infection mechanism prevails and that such mechanism could be an adaptive strategy of this species which is typical of arid environments. PMID:24938768

Bianco, Luciana

2014-09-01

216

Colonization of lettuce rhizosphere and roots by tagged Streptomyces  

PubMed Central

Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots, and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic. PMID:25705206

Bonaldi, Maria; Chen, Xiaoyulong; Kunova, Andrea; Pizzatti, Cristina; Saracchi, Marco; Cortesi, Paolo

2015-01-01

217

Competition for water between deep- and shallow-rooted grasses  

SciTech Connect

Competition between root systems of neighboring plants may be altered by seasonal variation in precipitation and soil moisture. Competitive effects of a deep-rooted, perennial grass, Pseudoroegneria spicata, on a shallow-rooted, perennial grass, Poa sandbergii, were monitored over two growing seasons by isolating the root system of P. sandbergii individuals within PVC tubes and comparing plant and soil characteristics to controls. When isolated for the entire growing season, P. sandbergii continued vegetative growth three weeks longer and later season soil water content was significantly greater than controls. Differences in soil water content were greatest between 30 and 50cm, below P. sandbergii's typical rooting depth. Flowering phenology was unchanged. When plants were isolated late in the season, treated plants showed more negative predown xylem pressure potential the morning after isolatron. Compared to controls, soil water content was reduced the day after tube insertion. These immediate effects on plant and soil water status may be due to removal of water supplied nightly by hydraulic lift.

Healy, J.L.; Black, R.A. (Washington State Univ., Pullman, WA (United States)); Link, S.O. (Pacific Northwest Laboratory, Richland, WA (United States))

1994-06-01

218

Colonization of lettuce rhizosphere and roots by tagged Streptomyces.  

PubMed

Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots, and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic. PMID:25705206

Bonaldi, Maria; Chen, Xiaoyulong; Kunova, Andrea; Pizzatti, Cristina; Saracchi, Marco; Cortesi, Paolo

2015-01-01

219

Soil bacteria hold the key to root cluster formation.  

PubMed

Root clusters are bunches of hairy rootlets that enhance nutrient uptake among many plants. Since first being reported in 1974, the involvement of rhizobacteria in their formation has received conflicting support. Attempts to identify specific causative organisms have failed and their role has remained speculative. We set up a gnotobiotic experiment using two root-clustered species, Viminaria juncea (Fabaceae) and Hakea laurina (Proteaceae), and inoculated them with two plant-growth-promoting rhizobacteria (PGPR), Bradyrhizobium elkanii and Bacillus mageratium, that produce indole-3-acetic-acid (IAA). Plants were suspended in water culture with four combinations of nitrogen and phosphorus. Clusters only developed in the presence of PGPR in two treatments, were greatly enhanced in another four, suppressed in five, and unaffected in five. Nitrogen amendment was associated with a higher density of clusters. Bradyrhizobium promoted cluster formation in Hakea, whereas Bacillus promoted cluster formation in Viminaria and suppressed it in Hakea. Greater root cluster numbers were due either to a larger root system induced by PGPR (indirect resource effect) and/or to more clusters per unit length of parent root (direct morphogenetic effect). The results are interpreted in terms of greater IAA production by Bradyrhizobium than Bacillus and greater sensitivity of Viminaria to IAA than Hakea. PMID:25534068

Lamont, Byron B; Pérez-Fernández, Maria; Rodríguez-Sánchez, Jesús

2015-05-01

220

Logarithms and Square Roots of Real Matrices  

E-print Network

In these notes, we consider the problem of finding the logarithm or the square root of a real matrix. It is known that for every real n x n matrix, A, if no real eigenvalue of A is negative or zero, then A has a real logarithm, that is, there is a real matrix, X, such that e^X = A. Furthermore, if the eigenvalues, xi, of X satisfy the property -pi < Im(xi) < pi, then X is unique. It is also known that under the same condition every real n x n matrix, A, has a real square root, that is, there is a real matrix, X, such that X^2 = A. Moreover, if the eigenvalues, rho e^{i theta}, of X satisfy the condition -pi/2 < theta < pi/2, then X is unique. These theorems are the theoretical basis for various numerical methods for exponentiating a matrix or for computing its logarithm using a method known as scaling and squaring (resp. inverse scaling and squaring). Such methods play an important role in the log-Euclidean framework due to Arsigny, Fillard, Pennec and Ayache and its applications to medical imagin...

Gallier, Jean

2008-01-01

221

Root growth, secondary root formation and root gravitropism in carotenoid-deficient seedlings of Zea mays L  

NASA Technical Reports Server (NTRS)

The effect of ABA on root growth, secondary-root formation and root gravitropism in seedlings of Zea mays was investigated by using Fluridone-treated seedlings and a viviparous mutant, both of which lack carotenoids and ABA. Primary roots of seedlings grown in the presence of Fluridone grew significantly slower than those of control (i.e. untreated) roots. Elongation of Fluridone-treated roots was inhibited significantly by the exogenous application of 1 mM ABA. Exogenous application of 1 micromole and 1 nmole ABA had either no effect or only a slight stimulatory effect on root elongation, depending on the method of application. The absence of ABA in Fluridone-treated plants was not an important factor in secondary-root formation in seedlings less than 9-10 d old. However, ABA may suppress secondary-root formation in older seedlings, since 11-d-old control seedlings had significantly fewer secondary roots than Fluridone-treated seedlings. Roots of Fluridone-treated and control seedlings were graviresponsive. Similar data were obtained for vp-9 mutants of Z. mays, which are phenotypically identical to Fluridone-treated seedlings. These results indicate that ABA is necessary for neither secondary-root formation nor for positive gravitropism by primary roots.

Ng, Y. K.; Moore, R.

1985-01-01

222

Control of Root Meristem Size by DA1-RELATED PROTEIN2 in Arabidopsis1[C][W  

PubMed Central

The control of organ growth by coordinating cell proliferation and differentiation is a fundamental developmental process. In plants, postembryonic root growth is sustained by the root meristem. For maintenance of root meristem size, the rate of cell differentiation must equal the rate of cell division. Cytokinin and auxin interact to affect the cell proliferation and differentiation balance and thus control root meristem size. However, the genetic and molecular mechanisms that determine root meristem size still remain largely unknown. Here, we report that da1-related protein2 (dar2) mutants produce small root meristems due to decreased cell division and early cell differentiation in the root meristem of Arabidopsis (Arabidopsis thaliana). dar2 mutants also exhibit reduced stem cell niche activity in the root meristem. DAR2 encodes a Lin-11, Isl-1, and Mec-3 domain-containing protein and shows an expression peak in the border between the transition zone and the elongation zone. Genetic analyses show that DAR2 functions downstream of cytokinin and SHORT HYPOCOTYL2 to maintain normal auxin distribution by influencing auxin transport. Further results indicate that DAR2 acts through the PLETHORA pathway to influence root stem cell niche activity and therefore control root meristem size. Collectively, our findings identify the role of DAR2 in root meristem size control and provide a novel link between several key regulators influencing root meristem size. PMID:23296689

Peng, Yuancheng; Ma, Wenying; Chen, Liangliang; Yang, Lei; Li, Shengjun; Zhao, Hongtao; Zhao, Yankun; Jin, Weihuan; Li, Na; Bevan, Michael W.; Li, Xia; Tong, Yiping; Li, Yunhai

2013-01-01

223

Characterizing pathways by which gravitropic effectors could move from the root cap to the root of primary roots of Zea mays  

NASA Technical Reports Server (NTRS)

Plasmodesmata linking the root cap and root in primary roots Zea mays are restricted to approx. 400 protodermal cells bordering approx. 110000 microns2 of the calyptrogen of the root cap. This area is less than 10% of the cross-sectional area of the root-tip at the cap junction. Therefore, gravitropic effectors moving from the root cap to the root can move symplastically only through a relatively small area in the centre of the root. Decapped roots are non-responsive to gravity. However, decapped roots whose caps are replaced immediately after decapping are strongly graviresponsive. Thus, gravicurvature occurs only when the root cap contacts the root, and symplastic continuity between the cap and root is not required for gravicurvature. Completely removing mucilage from the root tip renders the root non-responsive to gravity. Taken together, these data suggest that gravitropic effectors move apoplastically through mucilage from the cap to the root.

Moore, R.; McClelen, C. E.

1989-01-01

224

Cotton Root-Rot and Its Control.  

E-print Network

-rot is caused by a fungus, Phynztctotrichum omnivorum, which attacks the roots of susceptible plants and causes them, to decay. The vegetative strands of the fungus are found on the diseased roots, and the spore-mat stage is formed on the surface of the soil... above the affected roots. Resting bodies, or sclerotia, are formed in the soil near the diseased roots, and aid in the survival of the fungus. Root-rot spreads from plant to plant chiefly along the roots rather than by independent growth for long...

Taubenhaus, J. J. (Jacob Joseph); Ezekiel, (Walter Naphtali) Walter N.

1931-01-01

225

Deep Phenotyping of Coarse Root Architecture in R. pseudoacacia Reveals That Tree Root System Plasticity Is Confined within Its Architectural Model  

PubMed Central

This study aims at assessing the influence of slope angle and multi-directional flexing and their interaction on the root architecture of Robinia pseudoacacia seedlings, with a particular focus on architectural model and trait plasticity. 36 trees were grown from seed in containers inclined at 0° (control) or 45° (slope) in a glasshouse. The shoots of half the plants were gently flexed for 5 minutes a day. After 6 months, root systems were excavated and digitized in 3D, and biomass measured. Over 100 root architectural traits were determined. Both slope and flexing increased significantly plant size. Non-flexed trees on 45° slopes developed shallow roots which were largely aligned perpendicular to the slope. Compared to the controls, flexed trees on 0° slopes possessed a shorter and thicker taproot held in place by regularly distributed long and thin lateral roots. Flexed trees on the 45° slope also developed a thick vertically aligned taproot, with more volume allocated to upslope surface lateral roots, due to the greater soil volume uphill. We show that there is an inherent root system architectural model, but that a certain number of traits are highly plastic. This plasticity will permit root architectural design to be modified depending on external mechanical signals perceived by young trees. PMID:24386227

Danjon, Frédéric; Khuder, Hayfa; Stokes, Alexia

2013-01-01

226

Deep phenotyping of coarse root architecture in R. pseudoacacia reveals that tree root system plasticity is confined within its architectural model.  

PubMed

This study aims at assessing the influence of slope angle and multi-directional flexing and their interaction on the root architecture of Robinia pseudoacacia seedlings, with a particular focus on architectural model and trait plasticity. 36 trees were grown from seed in containers inclined at 0° (control) or 45° (slope) in a glasshouse. The shoots of half the plants were gently flexed for 5 minutes a day. After 6 months, root systems were excavated and digitized in 3D, and biomass measured. Over 100 root architectural traits were determined. Both slope and flexing increased significantly plant size. Non-flexed trees on 45° slopes developed shallow roots which were largely aligned perpendicular to the slope. Compared to the controls, flexed trees on 0° slopes possessed a shorter and thicker taproot held in place by regularly distributed long and thin lateral roots. Flexed trees on the 45° slope also developed a thick vertically aligned taproot, with more volume allocated to upslope surface lateral roots, due to the greater soil volume uphill. We show that there is an inherent root system architectural model, but that a certain number of traits are highly plastic. This plasticity will permit root architectural design to be modified depending on external mechanical signals perceived by young trees. PMID:24386227

Danjon, Frédéric; Khuder, Hayfa; Stokes, Alexia

2013-01-01

227

Root system stabilization of sugarcane fertigated by subsurface drip using a minirhizotron  

NASA Astrophysics Data System (ADS)

To improve the efficiency of water use in irrigation practices and to provide information for modeling the knowledge of plants root system becomes necessary. The use of subsurface drip irrigation (SDI) in sugarcane cultivation is an interesting cultural practice to improve production and allow cultivation in marginal lands due to water deficits conditions. The SDI provides better water use efficiency, due to the water and nutrients application in root zone plants. However, despite of the agronomic importance, few studies about the root system of sugarcane were performed. The use of root scanner is an alternative to the evaluation of the root system, which enables the continuous study of the roots throughout the cycle and for many years, but data about the use of this method for sugarcane are still scarce. The aim of this study was to determine the time required for stabilization of the root system growth of sugarcane cultivar IACSP-5000 around the access tube in which images were captured. The field experiment was carried out in Campinas, São Paulo State, Brazil. The fertigation was applied by a subsurface drip system.. The soil moisture was monitored by capacitance probes. The pH and electrical conductivity of the soil solution were monitored through solution extractor. Two access tubes with 1.05 m length were used, with 7 days difference between installations. The images were captured at 110, 128, 136, 143 and 151 days after harvest cane-plant, in the second cycle (1st cane ratoon), with the Root Scanner CI-600 ™ and were analyzed the number of roots and root length in each layer in different depths in the soil profile by software RootSnap! ™. The results show that the highest rates of increase in the number and length of roots were observed in the first 27 days. Absolute growth rates of up to 81 mm day-1 and 38 mm day-1 were presented in 0-20 and 20-40 cm layer respectively. The number of roots stabilized from 27 days after installation of the tube, while the length of the root system stabilized between 30 and 40 days. Root growth was more intense in the first two layers (0 to 0.4 m depth) of soil profile, which presented more than 80% of the total root length after the stabilization.

Yukitaka Pessinatti Ohashi, Augusto; Célia de Matos Pires, Regina; Barros de Oliveira Silva, Andre Luiz; Vasconcelos Ribeiro, Rafael

2013-04-01

228

Disease notes - Bacterial root rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bacterial root rot initiated by lactic acid bacteria, particularly Leuconostoc, occurs every year in Idaho sugarbeet fields. Hot fall weather seems to make the problem worse. Although Leuconostoc initiates the rot, other bacteria and yeast frequently invade the tissue as well. The acetic acid bac...

229

The Roots of Organized Crime  

Microsoft Academic Search

The hierarchy of organized crime is a new economically powerful and politically influential class in American society. Once the servant of politics, business, and labor in social struggles, organized crime now reaches out to become the master: an economy behind the economy, a government behind govern ment. Its roots lie deep within the American culture, drawing nourishment from the traditional

Gus Tyler

1962-01-01

230

Diseases with rooted staggered quarks  

E-print Network

Calculations using staggered quarks augmented with a root of the fermion determinant to reduce doubling give a qualitatively incorrect behavior in the small quark mass region. Attempts to circumvent this problem for the continuum limit involve an unproven combination of unphysical states, a loss of unitarity, and a rather peculiar non-commutation of limits.

Michael Creutz

2006-08-28

231

Assessing and analyzing 3D architecture of woody root systems, a review of methods and applications in tree and soil stability, resource acquisition and allocation  

Microsoft Academic Search

In numerous studies dealing with roots of woody plants, a description of the root system architecture is needed. During the\\u000a twentieth century, several manual measurement methods were used, depending on the objectives of study. Due to the difficulties\\u000a in accessing the roots and the duration of measurements, the studies generally involved a low number of root systems, were\\u000a often qualitative

Frédéric Danjon; Bert Reubens

2008-01-01

232

Root resistance to cavitation is accurately measured using a centrifuge technique.  

PubMed

Plants transport water under negative pressure and this makes their xylem vulnerable to cavitation. Among plant organs, root xylem is often highly vulnerable to cavitation due to water stress. The use of centrifuge methods to study organs, such as roots, that have long vessels are hypothesized to produce erroneous estimates of cavitation resistance due to the presence of open vessels through measured samples. The assumption that roots have long vessels may be premature since data for root vessel length are sparse; moreover, recent studies have not supported the existence of a long-vessel artifact for stems when a standard centrifuge technique was used. We examined resistance to cavitation estimated using a standard centrifuge technique and compared these values with native embolism measurements for roots of seven woody species grown in a common garden. For one species we also measured vulnerability using single-vessel air injection. We found excellent agreement between root native embolism and the levels of embolism measured using a centrifuge technique, and with air-seeding estimates from single-vessel injection. Estimates of cavitation resistance measured from centrifuge curves were biologically meaningful and were correlated with field minimum water potentials, vessel diameter (VD), maximum xylem-specific conductivity (Ksmax) and vessel length. Roots did not have unusually long vessels compared with stems; moreover, root vessel length was not correlated to VD or to the vessel length of stems. These results suggest that root cavitation resistance can be accurately and efficiently measured using a standard centrifuge method and that roots are highly vulnerable to cavitation. The role of root cavitation resistance in determining drought tolerance of woody species deserves further study, particularly in the context of climate change. PMID:25716876

Pratt, R B; MacKinnon, E D; Venturas, M D; Crous, C J; Jacobsen, A L

2015-02-01

233

Internal hydraulic redistribution prevents the loss of root conductivity during drought.  

PubMed

Shrubs of the Great Basin desert in Utah are subjected to a prolonged summer drought with the potential consequence of reduced water transport capability of the xylem due to drought-induced cavitation. Hydraulic redistribution (HR) is the passive movement of water from deep to shallow soil through plant roots. Hydraulic redistribution can increase water availability in shallow soil and ameliorate drought stress, providing better soil and root water status, which could affect shallow root conductivity (Ks) and native root embolism. We tested this hypothesis in an Artemisia tridentata Nutt. mono-specific stand grown in a common garden in Utah. We enhanced HR artificially by applying a once a week deep-irrigation treatment increasing the water potential gradient between deep and shallow soil layers. Plants that were deep-watered had less negative water potentials and greater stomatal conductance and transpiration rates than non-watered control plants. After irrigation with labeled water (?D), xylem water in stems and shallow roots of watered shrubs was enriched with respect to control shrubs, a clear indication of deep water uptake and HR. Shallow root conductivity was threefold greater and shrubs experienced lower native embolism when deep-watered. We found clear evidence of water transfer between deep and shallow roots through internal HR that delayed depletion of shallow soil water content, maintained Ks and prevented root embolism. Overall, our results show a positive effect of HR on root water transport capacity in otherwise dry soil, with important implications for plant water status. PMID:24436338

Prieto, Iván; Ryel, Ronald J

2014-01-01

234

Classifying stages of third molar development: crown length as a predictor for the mature root length.  

PubMed

Multiple tooth development staging techniques were reported based on arbitrarily set borderlines between succeeding stages. Anatomic tooth features or predictions of future tooth part dimensions were described to identify the thresholds between the established stages. The need to predict mature tooth dimensions, while the tooth considered is still in development, is a drawback to use this staging technique for dental age estimations. Using the fully mature crown length as a predictor for the future root length could provide a tool for undisputable staging. The aim of this study was first to measure the crown and root length of fully mature third molars and second to investigate whether the crown length could be used as a predictor of the root length, in order to classify the observed root length as a proportion of the future mature root. The crown and root lengths of all present third molars were digitally measured on dental panoramic radiographs of 1,000 subjects. The included subjects were equally distributed in gender, and their age ranged between 22 and 40 years. Two occlusal borders, the cement enamel junction and the root apices, were defined as landmarks for standardized measurements. Regression models with root length as response and crown length as predictor were established and revealed low R (2) and high RMSE values. Due to the small explained variance by the prediction models and the high variation in prediction errors, the observed crown length cannot be used to predict the final root length of a developing third molar. PMID:24801360

Altalie, Salem; Thevissen, Patrick; Willems, Guy

2015-01-01

235

Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution  

USGS Publications Warehouse

This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A.

2000-01-01

236

Assessment of Ustilago maydis as a fungal model for root infection studies.  

PubMed

Ustilago maydis is a fungus infecting aerial parts of maize to form smutted galls. Due to its interest as a genetic tool in plant pathology, we evaluated its ability to penetrate into plant roots. The fungus can penetrate between epidermic root cells, forming inter and intracellular pseudohyphae. Root infection didn't provoke gall formation on the maize lines tested, and targeted PCR detection showed that U. maydis, unlike the other maize smut fungus Sporisorium reilianum, has a weak aptitude to grow from the roots up to the aerial part of maize. We also observed that U. maydis can infect Medicago truncatula hairy roots as an alternative host. This plant species is a model host to study root symbiosis, and this pathosystem can provide new insights on root-microbe interactions. Considering that U. maydis could be a soil fungus, we tested its responsiveness to GR24, a strigolactone analogue. Strigolactones are root exuded molecules which activate mitochondrial metabolism of arbuscular mycorrhizal (AM) fungi. Physiologic and molecular analysis revealed that GR24 also increases cell respiration of U. maydis. This result points out that strigolactones could have an incidence on several rhizospheric microbes. These data provide evidences that the biotrophic pathogen U. maydis has to be considered for studying root infection. PMID:25749366

Mazaheri-Naeini, Mahta; Sabbagh, Seyed Kazem; Martinez, Yves; Séjalon-Delmas, Nathalie; Roux, Christophe

2015-03-01

237

Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake.  

PubMed

*Deep root water uptake in tropical Amazonian forests has been a major discovery during the last 15 yr. However, the effects of extended droughts, which may increase with climate change, on deep soil moisture utilization remain uncertain. *The current study utilized a 1999-2005 record of volumetric water content (VWC) under a throughfall exclusion experiment to calibrate a one-dimensional model of the hydrologic system to estimate VWC, and to quantify the rate of root uptake through 11.5 m of soil. *Simulations with root uptake compensation had a relative root mean square error (RRMSE) of 11% at 0-40 cm and < 5% at 350-1150 cm. The simulated contribution of deep root uptake under the control was c. 20% of water demand from 250 to 550 cm and c. 10% from 550 to 1150 cm. Furthermore, in years 2 (2001) and 3 (2002) of throughfall exclusion, deep root uptake increased as soil moisture was available but then declined to near zero in deep layers in 2003 and 2004. *Deep root uptake was limited despite high VWC (i.e. > 0.30 cm(3) cm(-3)). This limitation may partly be attributable to high residual water contents (theta(r)) in these high-clay (70-90%) soils or due to high soil-to-root resistance. The ability of deep roots and soils to contribute increasing amounts of water with extended drought will be limited. PMID:20659251

Markewitz, Daniel; Devine, Scott; Davidson, Eric A; Brando, Paulo; Nepstad, Daniel C

2010-08-01

238

A global analysis of fine root production as affected by soil nitrogen and phosphorus.  

PubMed

Fine root production is the largest component of belowground production and plays substantial roles in the biogeochemical cycles of terrestrial ecosystems. The increasing availability of nitrogen (N) and phosphorus (P) due to human activities is expected to increase aboveground net primary production (ANNP), but the response of fine root production to N and P remains unclear. If roots respond to nutrients as ANNP, fine root production is anticipated to increase with increasing soil N and P. Here, by synthesizing data along the nutrient gradient from 410 natural habitats and from 469 N and/or P addition experiments, we showed that fine root production increased in terrestrial ecosystems with an average increase along the natural N gradient of up to 0.5 per cent with increasing soil N. Fine root production also increased with soil P in natural conditions, particularly at P < 300 mg kg(-1). With N, P and combined N + P addition, fine root production increased by a global average of 27, 21 and 40 per cent, respectively. However, its responses differed among ecosystems and soil types. The global average increases in fine root production are lower than those of ANNP, indicating that above- and belowground counterparts are coupled, but production allocation shifts more to aboveground with higher soil nutrients. Our results suggest that the increasing fertilizer use and combined N deposition at present and in the future will stimulate fine root production, together with ANPP, probably providing a significant influence on atmospheric CO(2) emissions. PMID:22764168

Yuan, Z Y; Chen, Han Y H

2012-09-22

239

An L-system model for root system mycorrhization  

NASA Astrophysics Data System (ADS)

Mineral phosphate fertilisers are a non-renewable resource; rock phosphate reserves are estimated to be depleted in 50 to 100 years. In order to prevent a severe phosphate crisis in the 21st century, there is a need to decrease agricultural inputs such as P fertilisers by making use of plant mechanisms that increase P acquisition efficiency. Most plants establish mycorrhizal symbiosis as an adaptation to increase/economize their P acquisition from the soil. However, there is a great functional diversity in P acquisition mechanisms among different fungal species that colonize the roots (Thonar et al. 2011), and the composition of mycorrhizal community is known to depend strongly on agricultural management practices. Thus, the agroecosystem management may substantially affect the mycorrhizal functioning and also the use of P fertilizers. To date, it is still difficult to quantify the potential input savings for the agricultural crops through manipulation of their symbiotic microbiome, mainly due to lack of mechanistic understanding of P uptake dynamics by the fungal hyphae. In a first attempt, Schnepf et al. (2008b) have used mathematical modelling to show on the single root scale how different fungal growth pattern influence root P uptake. However, their approach was limited by the fact that it was restricted to the scale of a single root. The goal of this work is to advance the dynamic, three-dimensional root architecture model of Leitner et al. (2010) to include root system infection with arbuscular mycorrhizal fungi and growth of external mycelium. The root system infection model assumes that there is an average probability of infection (primary infection), that the probability of infection of a new root segment immediately adjacent to an existing infection is much higher than the average (secondary infection), that infected root segments have entry points that are the link between internal and external mycelium, that only uninfected root segments are susceptible (since new infection can only be detected in previously uninfected root) and that there is a maximum percentage of overall root system infection. Growth of external mycelium is based on the model of Schnepf et al. (2008a) but translated into L-system form. Different hypotheses about the effect of inoculum position (dispersed vs. localized) and about root system infection mechanisms can be tested with this model. This will help to quantify the role of the complex geometric structure of external mycelia in plant P acquisition and to gain mechanistic insights into whole-plant processes affected by mycorrhizal symbiosis. Literature Leitner, D., Klepsch, S., Bodner, G., Schnepf, A., 2010a. A dynamic root system growth model based on L-Systems. Plant Soil 332, 177-192. Schnepf, A., Roose, T., Schweiger, P., 2008a. Growth model for arbuscular mycorrhizal fungi. J R Soc Interface 5, 773-784. Schnepf, A., Roose, T., Schweiger, P., 2008b. Impact of growth and uptake patterns of arbuscular mycorrhizal fungi on plant phosphorus uptake - a modelling study. Plant Soil 312, 85-99. Thonar C, Schnepf A, Frossard E, Roose T, Jansa J (2011) Traits related to differences in function among three arbuscular mycorrhizal fungi. Plant and Soil 339: 231-245. Acknowledgements This research was partly supported by the Austrian Science Fund FWF (Grant No.: V220-N13) and by an APART fellowship of the Austrian Academy of Sciences at the Computational Science Center, University of Vienna (to D.L.).

Schnepf, Andrea; Schweiger, Peter; Jansa, Jan; Leitner, Daniel

2014-05-01

240

Tracking soil structural changes during root growth with sequential X-Ray CT scanning  

NASA Astrophysics Data System (ADS)

Crop productivity is highly dependent on a good supply of water and nutrients. With increasing demand for food and variable water regimes due to climate change, it is important to get a better understanding on the processes involved in water and nutrient uptake by roots. Changes in soil structure affect water and nutrient availabilities for plants. It is known that roots change their environment during growth but little is known on how soil structural properties change as roots penetrate soils. More detailed information on root growth induced changes in the rhizosphere will help us to model water and nutrient uptake by plants. The objective of this study was to measure directly how soil structure changes in close proximity to the root as a seedling root penetrates through the soil. 3D volumetric images of maize root growth during six hours were obtained using X-ray microtomography at a resolution of 21 ?m. Roots were grown in soils of two different compaction levels (50 kPa and 200 kPa uniaxial load) and matric potentials (10 kPa and 100 kPa). Changes in porosity, pore connectivity and root-soil contact were determined from 2D cross sections for each time step. The 2D cross sections were chosen at 4 different positions in the sample, and each section was divided into sections of 64 voxels (1.3 mm2) to determine changes in porosity and connectivity with distance from the root. Soil movement caused by root growth was quantified from 2D cross sections at different positions along the sample using Particle image velocimetry (PIV). Changes in soil structure during root growth were observed. Porosity in close proximity to the root decreased whereas root-soil contact increased with time. The PIV showed a radial deformation of the soil. Greatest deformation was found close to the root. Some aggregates fractured during root growth whereas others were pushed into the pore space. These data on the changes in soil structure will help us to predict water and nutrient availability for plants. They are also a useful first step in a better understanding of root growth mechanisms and how they overcome physical constraints imposed by soils.

Schmidt, Sonja; Bengough, Glyn; Hallett, Paul

2014-05-01

241

Coarse root distribution of a semi-arid oak savanna estimated with ground penetrating radar  

NASA Astrophysics Data System (ADS)

North California enjoys wet and mild winters, but experiences extreme hot, dry summer conditions, with occasional drought years. Despite the severity of summer conditions, blue oaks are winter-deciduous. We hypothesized that the binary nature of water availability would be reflected in blue oak root architecture. Our objective was to understand how the form of the root system facilitates ecosystem functioning. To do this, we sought to characterize the structure of the root system, and survey coarse root distribution with ground penetrating radar (GPR), due to its advantages in covering large areas rapidly and non-destructively. Because GPR remains a relatively new technology for examining root distribution, an ancillary objective was to test this methodology, and help facilitate its application more broadly. A third objective was to test the potential for upscaling coarse root biomass by developing allometric relations based on LIDAR measurements of above ground canopy structure. We surveyed six 8x8 m locations with trees varying in size, age and clumping (i.e. isolated trees vs. tree clusters). GPR signals were transformed to root biomass by calibrating them against excavated roots. Toward this goal, we positioned two rectangles of size 60x100 cm in each of the grids, excavated and sieved soil to harvest roots. Our results indicate that coarse roots occupy the full soil profile, and that root biomass of old large trees peaks just above the bedrock. As opposed to other semi-arid regions, where trees often develop extensive shallow coarse lateral roots, in order to exploit the entire wet-soil medium, we found that coarse root density decreased with distance from the bole, and dropped sharply at a distance of 2 m. We upscaled root biomass to stand-scale (2.8±0.4 kg m-2) based on LiDAR analysis of the relative abundance of each tree configuration. We argue that the deep and narrow root structure we observed reflects the ecohydrology of oaks in this ecosystem, because extensive lateral roots would not be beneficial during the growing season (water is sufficiently abundant), nor during the summer season (soil water is highly limited). Our research has shown that the combination of resource availability, which is primarily water in this ecosystem, and plant demand, are portrayed in the form of the root system.

Raz-Yaseef, N.; Koteen, L. E.; Baldocchi, D. D.

2012-12-01

242

Root strength of tropical plants - An investigation in the Western Ghats of Kerala, India  

NASA Astrophysics Data System (ADS)

Earlier research on debris flows in the Tikovil River basin of the Western Ghats concluded that root cohesion is significant in maintaining the overall stability of the region. In this paper we present the most recent results (December 2008) of root tensile strength tests conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) A variety of Tamarind (Garcinia gummigutta), 8) Coffee (Coffea Arabica) and Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested has a length of 15 cm. Results indicate that the roots of Coffee, Tamarind, Lemon grass and Jackfruit are the strongest of the nine plant types tested whereas Tea and Teak plants had the most fragile roots. Coconut roots behaved atypical to the others, as the bark of the roots was crushed and slipped from the clamp when tested whereas its internal fiber was the strongest of all tested. Root tensile strength decreases with increasing diameters, Rubber showing more ductile behaviour than Coffee and Tamarind that behaved more brittle, root tensile strength increasing exponentially for finer roots. Teak and Tea showed almost a constant root tensile strength over the range of diameters tested and little variability. Jack fruit and mango trees showed the largest variability, which may be explained by the presence of root nodules, preventing the derivation of an unequivocal relationship between root diameters and tensile strength. This results in uncertainty of root strength estimates that are applicable. These results provide important information to quantify the upper limit of the root cohesion at the stand level in combination with land use maps. This is an indispensable component in the evaluation of slope stability in the region.

Lukose Kuriakose, S.; van Beek, L. P. H.; van Westen, C. J.

2009-04-01

243

Numerical analysis of the effect of root reinforcement on the triggering of shallow landslides  

NASA Astrophysics Data System (ADS)

Triggering mechanisms of shallow landslides in vegetated slopes are strongly influenced by roots and their distribution. The mechanical properties of rooted soils are reported in numerous studies but are yet to be widely used for slope stability calculations. Quantifying root reinforcement in slope stability calculation, is difficult due to the complexity of soil-root interactions and the lack of knowledge of spatial root distribution. Moreover, the compressibility of rooted soil contributes both to the stiffness of the body of the slope and to the foot of the slope. Thus, they plays a fundamental role in landslide activation. Next to the well-documented contribution of roots to shear and tensile strength of soils, there are no studies that discuss the effects of roots on the compressibility of soils and how this mechanical property influences the triggering and size of shallow landslides. In this study we present the results of the sensitivity analysis of the SOSlope model based on the implementation of recent field and laboratory investigation results on the effects of root reinforcement and water content on the tensile-compressive behavior of rooted soil. The model simulates the effects of the spatial and temporal variability of root reinforcement on the stability of a slope as a function of position, dimension, and tree species. Including the compressive behavior or rooted soils is particularly important to estimate how vegetation stabilizes slopes of protection forests and bioengineered slopes. Results of the model are compared to field observations and discussed in the context of future validations. This study represents an important improvement for strategies within the scope of bioengineering measures and for the management of protection forests against shallow landslides.

Schwarz, Massimiliano; Cohen, Denis; Giadrossich, Filippo

2014-05-01

244

Micropropagation Splitting of Malus microcuttings enhances rooting  

E-print Network

Micropropagation Splitting of Malus microcuttings enhances rooting J Puente, JA Marín* CSIC shoots. Malus x domestica / splitting / rooting / in vitro / micropropagation Résumé — La fente des microbouture. Malus x domestica / fente / enracinement/ in vitro / micropropagation INTRODUCTION Jork 9 (J9

Paris-Sud XI, Université de

245

Root Canal Treatment from Start to Finish  

MedlinePLUS

Illustrations: Root Canal Treatment From Start to Finish 1. A Deep Infection Root canal treatment is needed when an injury or ... the canals and remove debris. 4. Filling the Canals The canals are filled with a permanent material. ...

246

Splints of root systems on Lie Superalgebras  

E-print Network

This paper classifies the splints of the root system of classical Lie superalgebras as a superalgebraic conversion of the splints of classical root systems. It can be used to derive branching rules, which have potential physical application in theoretical physics.

B. Ransingh; K. C. Pati

2014-04-29

247

Inhibition of strigolactones promotes adventitious root formation  

PubMed Central

Roots that form from non-root tissues (adventitious roots) are crucial for cutting propagation in the forestry and horticulture industries. Strigolactone has been demonstrated to be an important regulator of these roots in both Arabidopsis and pea using strigolactone deficient mutants and exogenous hormone applications. Strigolactones are produced from a carotenoid precursor which can be blocked using the widely available but broad terpenoid biosynthesis blocker, fluridone. We demonstrate here that fluridone can be used to promote adventitious rooting in the model species Pisum sativum (pea). In addition, in the garden species Plumbago auriculata and Jasminium polyanthum fluridone was equally as successful at promoting roots as a commercial rooting compound containing NAA and IBA. Our findings demonstrate that inhibition of strigolactone signaling has the potential to be used to improve adventitious rooting in commercially relevant species. PMID:22580687

Beveridge, Christine A.; Geelen, Danny

2012-01-01

248

Development and function of Azospirillum -inoculated roots  

Microsoft Academic Search

Summary  The surface distribution ofAzospirillum on inoculated roots of maize and wheat is generally similar to that of other members of the rhizoplane microflora. During the first three days, colonization takes place mainly on the root elongation zone, on the base of root hairs and, to a lesser extent, on the surface of young root hairs.Azospirillum has been found in cortical

Y. Okon; Y. Kapulnik

1986-01-01

249

Root canal filling using Resilon: a review  

Microsoft Academic Search

Root canal treatment is achieved by chemo-mechanical debridement of the root canal system followed by filling. The filling material 'entombs' residual bacteria and acts as a barrier which prevents the entrance of oral microorganisms and reinfection of the root canal system through microleakage. However, filling with contemporary root filling materials such as gutta-percha offers limited long-term resistance to microorganisms; as

D. J. Shanahan; H. F. Duncan

2011-01-01

250

Root proliferation in decaying roots and old root channels: A nutrient conservation mechanism in oligotrophic mangrove forests?  

USGS Publications Warehouse

1. In oligotrophic habitats, proliferation of roots in nutrient-rich microsites may contribute to overall nutrient conservation by plants. Peat-based soils on mangrove islands in Belize are characterized by the presence of decaying roots and numerous old root channels (0.1-3.5 cm diameter) that become filled with living and highly branched roots of Rhizophora mangle and Avicennia germinans. The objectives of this study were to quantify the proliferation of roots in these microsites and to determine what causes this response. 2. Channels formed by the refractory remains of mangrove roots accounted for only 1-2% of total soil volume, but the proportion of roots found within channels varied from 9 to 24% of total live mass. Successive generations of roots growing inside increasingly smaller root channels were also found. 3. When artificial channels constructed of PVC pipe were buried in the peat for 2 years, those filled with nutrient-rich organic matter had six times more roots than empty or sand-filled channels, indicating a response to greater nutrient availability rather than to greater space or less impedance to root growth. 4. Root proliferation inside decaying roots may improve recovery of nutrients released from decomposing tissues before they can be leached or immobilized in this intertidal environment. Greatest root proliferation in channels occurred in interior forest zones characterized by greater soil waterlogging, which suggests that this may be a strategy for nutrient capture that minimizes oxygen losses from the whole root system. 5. Improved efficiency of nutrient acquisition at the individual plant level has implications for nutrient economy at the ecosystem level and may explain, in part, how mangroves persist and grow in nutrient-poor environments.

McKee, K.L.

2001-01-01

251

Anaphylaxis due to caffeine.  

PubMed

We report a rare case of anaphylaxis due to caffeine intake. A 27-year-old woman suffered her first episode of anaphylaxis and a positive skin prick test suggested that the anaphylaxis was due to an IgE-mediated hypersensitivity reaction to caffeine. She was diagnosed with caffeine allergy and has not had an allergic reaction after avoiding foods and drinks containing caffeine. Although caffeine is known to have antiallergic effects, this case shows that caffeine can be an allergen and cause anaphylaxis. PMID:25653922

Sugiyama, Kumiya; Cho, Tatsurai; Tatewaki, Masamitsu; Onishi, Shogo; Yokoyama, Tatsuya; Yoshida, Naruo; Fujimatsu, Takayoshi; Hirata, Hirokuni; Fukuda, Takeshi; Fukushima, Yasutsugu

2015-01-01

252

Anaphylaxis due to caffeine  

PubMed Central

We report a rare case of anaphylaxis due to caffeine intake. A 27-year-old woman suffered her first episode of anaphylaxis and a positive skin prick test suggested that the anaphylaxis was due to an IgE-mediated hypersensitivity reaction to caffeine. She was diagnosed with caffeine allergy and has not had an allergic reaction after avoiding foods and drinks containing caffeine. Although caffeine is known to have antiallergic effects, this case shows that caffeine can be an allergen and cause anaphylaxis. PMID:25653922

Cho, Tatsurai; Tatewaki, Masamitsu; Onishi, Shogo; Yokoyama, Tatsuya; Yoshida, Naruo; Fujimatsu, Takayoshi; Hirata, Hirokuni; Fukuda, Takeshi; Fukushima, Yasutsugu

2015-01-01

253

The Compact Root Architecture1 Gene Regulates Lignification, Flavonoid Production, and Polar Auxin Transport in Medicago truncatula1[W  

PubMed Central

The root system architecture is crucial to adapt plant growth to changing soil environmental conditions and consequently to maintain crop yield. In addition to root branching through lateral roots, legumes can develop another organ, the nitrogen-fixing nodule, upon a symbiotic bacterial interaction. A mutant, cra1, showing compact root architecture was identified in the model legume Medicago truncatula. cra1 roots were short and thick due to defects in cell elongation, whereas densities of lateral roots and symbiotic nodules were similar to the wild type. Grafting experiments showed that a lengthened life cycle in cra1 was due to the smaller root system and not to the pleiotropic shoot phenotypes observed in the mutant. Analysis of the cra1 transcriptome at a similar early developmental stage revealed few significant changes, mainly related to cell wall metabolism. The most down-regulated gene in the cra1 mutant encodes a Caffeic Acid O-Methyl Transferase, an enzyme involved in lignin biosynthesis; accordingly, whole lignin content was decreased in cra1 roots. This correlated with differential accumulation of specific flavonoids and decreased polar auxin transport in cra1 mutants. Exogenous application of the isoflavone formononetin to wild-type plants mimicked the cra1 root phenotype, whereas decreasing flavonoid content through silencing chalcone synthases restored the polar auxin transport capacity of the cra1 mutant. The CRA1 gene, therefore, may control legume root growth through the regulation of lignin and flavonoid profiles, leading to changes in polar auxin transport. PMID:20522723

Laffont, Carole; Blanchet, Sandrine; Lapierre, Catherine; Brocard, Lysiane; Ratet, Pascal; Crespi, Martin; Mathesius, Ulrike; Frugier, Florian

2010-01-01

254

EFFECTS OF OZONE ON ROOT PROCESSES  

EPA Science Inventory

Ozone alters root growth and root processes by first reducing photosynthesis and altering foliar metabolic pathways. The alteration in foliar metabolism is reflected in lowered carbohydrate levels in the roots. This can reduce key metabolic processes such as mineral uptake and sy...

255

Square Root Propagation Andrew G. Howard  

E-print Network

Square Root Propagation Andrew G. Howard Department of Computer Science Columbia University New caused by finite numerical precision. We adapt square root algo- rithms, popular in Kalman filtering that involve the square root of precision matrices. Combining this with the machinery of the junction tree

Jebara, Tony

256

Square Root Propagation Andrew G. Howard  

E-print Network

Square Root Propagation Andrew G. Howard Department of Computer Science Columbia University New caused by finite numerical precision. We adapt square root algo­ rithms, popular in Kalman filtering that involve the square root of precision matrices. Combining this with the machinery of the junction tree

257

Cultivar selection for sugarbeet root rot resistance.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fungal and bacterial root rots in sugar beet caused by Rhizoctonia solani (Rs) and Leuconostoc mesenteroides subsp. dextranicum (Lm) can lead to root yield losses greater than 50%. To reduce the impact of these root rots on sucrose loss in the field, storage, and factories, studies were conducted t...

258

Vascular permeability of spinal nerve roots  

Microsoft Academic Search

The permeability of blood vessels in rat spinal nerve roots was investigated with Evans blue-albumin as an in vivo macromolecular tracer and lanthanum as tracers as an electron microscopic ionic marker added to a fixative. Rats injected intravenously with Evans blue, showed macroscopic distinct staining of dorsal root ganglia, whereas spinal nerve roots remained unstained. Fluorescence microscopy, however, revealed clear

C. Å. V. Pettersson; H. S. Sharma; Y. Olsson

1990-01-01

259

Healthy Roots By: Shelly Van Landingham, Forester  

E-print Network

the absorbing roots to the tree. The large woody transport roots also store water, and store sugar starches: They anchor the tree, absorb water, and wrest vital nutrients from the soil. Tree root systems consist do not "seek out" water with a large taproot (a large taproot only persists in very few species

260

Bell pepper responses to root restriction  

Microsoft Academic Search

Various container sizes were used to induce root restriction on ‘Jupiter’ bell pepper (Capsicum annuum L.). There was little or no effect of container size on plant growth up to 23 days after transplanting (DAT). By 45 DAT, leaf area and plant dry weight was diminished proportional to container volume. Root?to?shoot ratio was constant among the various root restricting conditions

D. S. NeSmith; D. C. Bridges; J. C. Barbour

1992-01-01

261

ROOT — An object oriented data analysis framework  

Microsoft Academic Search

The ROOT system in an Object Oriented framework for large scale data analysis. ROOT written in C++, contains, among others, an efficient hierarchical OO database, a C++ interpreter, advanced statistical analysis (multi-dimensional histogramming, fitting, minimization, cluster finding algorithms) and visualization tools. The user interacts with ROOT via a graphical user interface, the command line or batch scripts. The command and

Rene Brun; Fons Rademakers

1997-01-01

262

Efficient Real Root Approximation Michael Kerber  

E-print Network

Efficient Real Root Approximation Michael Kerber IST (Institute of Science and Technology) Austria real roots of a square- free polynomial f . Given isolating intervals, our algorithm refines each of them to a width at most 2-L, that is, each of the roots is approximated to L bits after the binary

263

Efficient Real Root Approximation Michael Kerber  

E-print Network

Efficient Real Root Approximation Michael Kerber IST (Institute of Science and Technology) Austria real roots of a square- free polynomial f. Given isolating intervals, our algorithm refines each of them to a certain width 2-L, that is, each of the roots is approximated to L bits after the binary

264

FOREST PATHOLOGY Root and Butt Rot Diseases  

E-print Network

FOREST PATHOLOGY Root and Butt Rot Diseases M Garbelotto, University of California ­ Berkeley Diseases caused by root rots figure prominently amongst the most-studied pathologies of forest trees. Indeed, root and butt rots cause more economic damage to commercial forestry in the temperate world than

California at Berkeley, University of

265

Estimation of cadmium availability using transformed roots  

Microsoft Academic Search

We have explored cultures of roots transformed by Agrobacterium rhizogenes to test the availability of cadmium in sewage sludges. The toxic effects of Cd and the kinetics of Cd accumulation were examined for three species of transformed roots, grown for 2 weeks in nutrient media, containing Cd as a salt. Roots of sugar beet (Beta vulgaris L.) were highly sensitive,

Lionel Metzger; Isabelle Fouchault; Christine Glad; René Prost; David Tepfer

1992-01-01

266

Auxin Transport Promotes Arabidopsis Lateral Root Initiation  

Microsoft Academic Search

Lateral root development in Arabidopsis provides a model for the study of hormonal signals that regulate postembry- onic organogenesis in higher plants. Lateral roots originate from pairs of pericycle cells, in several cell files positioned opposite the xylem pole, that initiate a series of asymmetric, transverse divisions. The auxin transport inhibitor N -1-naph- thylphthalamic acid (NPA) arrests lateral root development

Ilda Casimiro; Alan Marchant; Rishikesh P. Bhalerao; Tom Beeckman; Sandra Dhooge; Ranjan Swarup; Neil Graham; Dirk Inzé; Goran Sandberg; Pedro J. Casero; Malcolm Bennett

2001-01-01

267

The ROOTS Constraint Christian Bessiere1  

E-print Network

nature of the Roots constraint as in many situations met in practice, it prunes all possible values primitives: the Range constraint, which computes the range of values used by a sequence of variables, and the Roots constraint, which computes the variables mapping onto a set of values. We focus here on the Roots

Paris-Sud XI, Université de

268

Effect of scapling on root respiration rate  

Technology Transfer Automated Retrieval System (TEKTRAN)

Scalping improves root quality at harvest since impurities such as potassium, sodium, amino nitrogen and invert sugars that hinder sugarbeet processing are concentrated in the upper root crown. The effect of scalping on root storage properties, however, is less clear. A small study was conducted t...

269

Phene Synergism between Root Hair Length and Basal Root Growth Angle for Phosphorus Acquisition1[OPEN  

PubMed Central

Shallow basal root growth angle (BRGA) increases phosphorus acquisition efficiency by enhancing topsoil foraging because in most soils, phosphorus is concentrated in the topsoil. Root hair length and density (RHL/D) increase phosphorus acquisition by expanding the soil volume subject to phosphorus depletion through diffusion. We hypothesized that shallow BRGA and large RHL/D are synergetic for phosphorus acquisition, meaning that their combined effect is greater than the sum of their individual effects. To evaluate this hypothesis, phosphorus acquisition in the field in Mozambique was compared among recombinant inbred lines of common bean (Phaseolus vulgaris) having four distinct root phenotypes: long root hairs and shallow basal roots, long root hairs and deep basal roots, short root hairs and shallow basal roots, and short root hairs and deep basal roots. The results revealed substantial synergism between BRGA and RHL/D. Compared with short-haired, deep-rooted phenotypes, long root hairs increased shoot biomass under phosphorus stress by 89%, while shallow roots increased shoot biomass by 58%. Genotypes with both long root hairs and shallow roots had 298% greater biomass accumulation than short-haired, deep-rooted phenotypes. Therefore, the utility of shallow basal roots and long root hairs for phosphorus acquisition in combination is twice as large as their additive effects. We conclude that the anatomical phene of long, dense root hairs and the architectural phene of shallower basal root growth are synergetic for phosphorus acquisition. Phene synergism may be common in plant biology and can have substantial importance for plant fitness, as shown here. PMID:25699587

Miguel, Magalhaes Amade

2015-01-01

270

Phene Synergism between Root Hair Length and Basal Root Growth Angle for Phosphorus Acquisition.  

PubMed

Shallow basal root growth angle (BRGA) increases phosphorus acquisition efficiency by enhancing topsoil foraging because in most soils, phosphorus is concentrated in the topsoil. Root hair length and density (RHL/D) increase phosphorus acquisition by expanding the soil volume subject to phosphorus depletion through diffusion. We hypothesized that shallow BRGA and large RHL/D are synergetic for phosphorus acquisition, meaning that their combined effect is greater than the sum of their individual effects. To evaluate this hypothesis, phosphorus acquisition in the field in Mozambique was compared among recombinant inbred lines of common bean (Phaseolus vulgaris) having four distinct root phenotypes: long root hairs and shallow basal roots, long root hairs and deep basal roots, short root hairs and shallow basal roots, and short root hairs and deep basal roots. The results revealed substantial synergism between BRGA and RHL/D. Compared with short-haired, deep-rooted phenotypes, long root hairs increased shoot biomass under phosphorus stress by 89%, while shallow roots increased shoot biomass by 58%. Genotypes with both long root hairs and shallow roots had 298% greater biomass accumulation than short-haired, deep-rooted phenotypes. Therefore, the utility of shallow basal roots and long root hairs for phosphorus acquisition in combination is twice as large as their additive effects. We conclude that the anatomical phene of long, dense root hairs and the architectural phene of shallower basal root growth are synergetic for phosphorus acquisition. Phene synergism may be common in plant biology and can have substantial importance for plant fitness, as shown here. PMID:25699587

Miguel, Magalhaes Amade; Postma, Johannes Auke; Lynch, Jonathan Paul

2015-04-01

271

Calcium movement, graviresponsiveness and the structure of columella cells and columella tissues in roots of Allium cepa L  

NASA Technical Reports Server (NTRS)

Roots of Allium cepa L. cv. Yellow are differentially responsive to gravity. Long (e.g. 40 mm) roots are strongly graviresponsive, while short (c.g. 4 mm) roots are minimally responsive to gravity. Although columella cells of graviresponsive roots are larger than those of nongraviresponsive roots, they partition their volumes to cellular organelles similarly. The movement of amyloplasts and nuclei in columella cells of horizontally-oriented roots correlates positively with the onset of gravicurvature. Furthermore, there is no significant difference in the rates of organellar redistribution when graviresponsive and nongraviresponsive roots are oriented horizontally. The more pronounced graviresponsiveness of longer roots correlates positively with (1) their caps being 9-6 times more voluminous, (2) their columella tissues being 42 times more voluminous, (3) their caps having 15 times more columella cells, and (4) their columella tissues having relative volumes 4.4 times larger than those of shorter, nongraviresponsive roots. Graviresponsive roots that are oriented horizontally are characterized by a strongly polar movement of 45Ca2+ across the root tip from the upper to the lower side, while similarly oriented nongraviresponsive roots exhibit only a minimal polar transport of 45Ca2+. These results indicate that the differential graviresponsiveness of roots of A. cepa is probably not due to either (1) ultrastructural differences in their columella cells, (2) differences in the rates of organellar redistribution when roots are oriented horizontally. Rather, these results indicate the graviresponsiveness may require an extensive columella tissue, which, in turn, may be necessary for polar movement of 45Ca2+ across the root tip.

Moore, R.

1985-01-01

272

Root growth response to defoliation in two Agropyron bunchgrasses: field observations with an improved root periscope  

Microsoft Academic Search

Root growth responses to defoliation were observed in the field with an improved root periscope technique, which is described. The grazing tolerant, Eurasian bunchgrass, Agropyron desertorum, was compared with the very similar but grazing sensitive, North American bunchgrass, A. spicatum. Root length growth of clipped A. desertorum was about 50% of that of intact plants, while root elongation of clipped

J. H. Richards

1984-01-01

273

Simulation of Impacts of Annosus Root Disease with the Western Root Disease Model1  

E-print Network

Simulation of Impacts of Annosus Root Disease with the Western Root Disease Model1 Charles G. Shaw, III Donald J. Goheen Bov B. Eav 2 Abstract: The Western Root Disease Model as it currently exists. These simulations indicate that with no action, or with continued improper management, annosus root disease

Standiford, Richard B.

274

Plants: Roots, Stems and Leaves 85 Plants: Roots, Stems and Leaves  

E-print Network

on the same plant. One aspect of understanding plants is to be able to figure out what is root, stem, and leaf of the stem between the nodes (Figure 1). Figure 1. Shoot structure. #12;Plants: Roots, Stems and Leaves 86 meristem, the differentiating cells produce the root cap, a structure that protects the root apical

Koptur, Suzanne

275

Hydraulic lift: water efflux from upper roots improves effectiveness of water uptake by deep roots  

Microsoft Academic Search

Deuterated water absorbed by deep roots of Artemisia tridentata appeared in the stem water of neighboring Agropyron desertorum tussocks. This supports the hypothesis that water absorbed by deep roots in moist soil moves through the roots, is released in the upper soil profile at night, and is stored there until it is resorbed by roots the following day. This phenomenon

M. M. Caldwell; J. H. Richards

1989-01-01

276

Root filtration spaces from Lie algebras and abstract root groups 1  

E-print Network

Root filtration spaces from Lie algebras and abstract root groups 1 Arjeh M. Cohen a, G Academy of Sciences, Kende u. 13-17, 1111 Budapest, Hungary Abstract Both Timmesfeld's abstract root subgroups and simple Lie algebras generated by extremal elements lead to root filtration spaces

Cohen, Arjeh M.

277

Update on Root Chemical Defenses In Defense of Roots: A Research Agenda for Studying  

E-print Network

Update on Root Chemical Defenses In Defense of Roots: A Research Agenda for Studying Plant and Evolutionary Biology, Cornell University, Ithaca, New York 14853­2701 Interest in root biology research (Arabidopsis thaliana) mutants, along with a sequenced genome, has led to valuable insights into root

Agrawal, Anurag

278

Auxin fluxes in the root apex co-regulate gravitropism and lateral root1 initiation2  

E-print Network

1 Auxin fluxes in the root apex co-regulate gravitropism and lateral root1 initiation2 Running title: Co-regulation of root gravitropism and branching by auxin3 transport4 Lucas, M.1,2 , Godin, C.2 and root5 gravitropism, two processes that are regulated by auxin, are co-regulated in6 Arabidopsis. We

Paris-Sud XI, Université de

279

Root Growth and Yield of Differing Alfalfa Rooting Populations under Increasing Salinity and Zero Leaching  

E-print Network

Root Growth and Yield of Differing Alfalfa Rooting Populations under Increasing Salinity and Zero-rootedAccumulation of salinity in the root zone can be detrimental to crops such as alfalfa to exploit the lower average salinitysustained crop production. Irrigation, even with moderately saline water, pushes accumulated salts deeper

Smith, Steven E.

280

Comparative proteomic profiles of the soybean (Glycine max) root apex and differentiated root zone.  

PubMed

The root apical meristem (RAM) is responsible for the growth of the plant root system. Because of the importance of root architecture in the performance of crop plants, we established a proteome reference map of the soybean root apex and compared this with the proteome of the differentiated root zone. The root apex samples contained the apical 1?mm of the root, comprising the RAM, quiescent center and root cap. We identified 342 protein spots from 550 excised proteins (?62%) of root apex samples by MALDI-TOF MS/MS analysis. All these proteins were also present in the differentiated root, but differed in abundance. Functional classification showed that the most numerous protein categories represented in the root were those of stress response, glycolysis, redox homeostasis and protein processing. Using DIGE, we identified 73 differentially accumulated proteins between root apex and differentiated root. Proteins overrepresented in the root apex belonged primarily to the pathways for protein synthesis and processing, cell redox homeostasis and flavonoid biosynthesis. Proteins underrepresented in the root apex were those of glycolysis, tricarboxylic acid metabolism and stress response. Our results highlight the importance of stress and defense response, redox control and flavonoid metabolism in the root apex. PMID:21438152

Mathesius, Ulrike; Djordjevic, Michael A; Oakes, Marie; Goffard, Nicolas; Haerizadeh, Farzad; Weiller, Georg F; Singh, Mohan B; Bhalla, Prem L

2011-05-01

281

Analysis of maize (Zea mays L.) seedling roots with the high-throughput image analysis tool ARIA (Automatic Root Image Analysis).  

PubMed

The maize root system is crucial for plant establishment as well as water and nutrient uptake. There is substantial genetic and phenotypic variation for root architecture, which gives opportunity for selection. Root traits, however, have not been used as selection criterion mainly due to the difficulty in measuring them, as well as their quantitative mode of inheritance. Seedling root traits offer an opportunity to study multiple individuals and to enable repeated measurements per year as compared to adult root phenotyping. We developed a new software framework to capture various traits from a single image of seedling roots. This framework is based on the mathematical notion of converting images of roots into an equivalent graph. This allows automated querying of multiple traits simply as graph operations. This framework is furthermore extendable to 3D tomography image data. In order to evaluate this tool, a subset of the 384 inbred lines from the Ames panel, for which extensive genotype by sequencing data are available, was investigated. A genome wide association study was applied to this panel for two traits, Total Root Length and Total Surface Area, captured from seedling root images from WinRhizo Pro 9.0 and the current framework (called ARIA) for comparison using 135,311 single nucleotide polymorphism markers. The trait Total Root Length was found to have significant SNPs in similar regions of the genome when analyzed by both programs. This high-throughput trait capture software system allows for large phenotyping experiments and can help to establish relationships between developmental stages between seedling and adult traits in the future. PMID:25251072

Pace, Jordon; Lee, Nigel; Naik, Hsiang Sing; Ganapathysubramanian, Baskar; Lübberstedt, Thomas

2014-01-01

282

Analysis of Maize (Zea mays L.) Seedling Roots with the High-Throughput Image Analysis Tool ARIA (Automatic Root Image Analysis)  

PubMed Central

The maize root system is crucial for plant establishment as well as water and nutrient uptake. There is substantial genetic and phenotypic variation for root architecture, which gives opportunity for selection. Root traits, however, have not been used as selection criterion mainly due to the difficulty in measuring them, as well as their quantitative mode of inheritance. Seedling root traits offer an opportunity to study multiple individuals and to enable repeated measurements per year as compared to adult root phenotyping. We developed a new software framework to capture various traits from a single image of seedling roots. This framework is based on the mathematical notion of converting images of roots into an equivalent graph. This allows automated querying of multiple traits simply as graph operations. This framework is furthermore extendable to 3D tomography image data. In order to evaluate this tool, a subset of the 384 inbred lines from the Ames panel, for which extensive genotype by sequencing data are available, was investigated. A genome wide association study was applied to this panel for two traits, Total Root Length and Total Surface Area, captured from seedling root images from WinRhizo Pro 9.0 and the current framework (called ARIA) for comparison using 135,311 single nucleotide polymorphism markers. The trait Total Root Length was found to have significant SNPs in similar regions of the genome when analyzed by both programs. This high-throughput trait capture software system allows for large phenotyping experiments and can help to establish relationships between developmental stages between seedling and adult traits in the future. PMID:25251072

Pace, Jordon; Lee, Nigel; Naik, Hsiang Sing; Ganapathysubramanian, Baskar; Lübberstedt, Thomas

2014-01-01

283

Springback in Root Gravitropism 1  

PubMed Central

Conditions under which a gravistimulus of Merit corn roots (Zea mays L.) is withdrawn result in a subsequent loss of gravitropic curvature, an effect which we refer to as `springback.' This loss of curvature begins within 1 to 10 minutes after removal of the gravistimulus. It occurs regardless of the presence or absence of the root cap. It is insensitive to inhibitors of auxin transport (2,3,5-triiodobenzoic acid, naphthylphthalmaic acid) or to added auxin (2,4-dichlorophenoxyacetic acid). Springback is prevented if a clinostat treatment is interjected to neutralize gravistimulation during germination, which suggests that the change in curvature is a response to a `memory' effect carried over from a prior gravistimulation. PMID:11537456

Leopold, A. Carl; Wettlaufer, Scott H.

1989-01-01

284

Quantum Roots in Geometry: I  

E-print Network

In the present work, it is shown that the geometerization philosophy has not been exhausted. Some quantum roots are already built in non-symmetric geometries. Path equations in such geometries give rise to spin-gravity interaction. Some experimental evidences (the results of the COW-experiment) indicate the existence of this interaction. It is shown that the new quantum path equations could account for the results of the COW-experiment. Large scale applications, of the new path equations, admitted by such geometries, give rise to tests for the existence of this interaction on the astrophysical and cosmological scales. As a byproduct, it is shown that the quantum roots appeared explicitly, in the path equations, can be diffused in the whole geometry using a parameterization scheme.

M. I. Wanas

2005-06-14

285

Root-shoot interaction in the greening of wheat seedlings grown under red light  

NASA Technical Reports Server (NTRS)

Wheat seedlings grown with roots exposed to constant red light (300-500 micromoles m-2 s-1) did not accumulate chlorophyll in the leaves. In contrast, seedlings grown with their roots shielded from light accumulated chlorophylls. Chlorophyll biosynthesis could be induced in red-light-grown chlorophyll-deficient yellow plants by either reducing the red-light intensity at the root surface to 100 micromoles m-1 s-1 or supplementing with 6% blue light. The inhibition of chlorophyll biosynthesis was due to impairment of the Mg-chelatase enzyme working at the origin of the Mg-tetrapyrrole pathway. The root-perceived photomorphogenic inhibition of shoot greening demonstrates root-shoot interaction in the greening process.

Tripathy, B. C.; Brown, C. S.

1995-01-01

286

Indirect Methods Produce Higher Estimates of Fine Root Production and Turnover Rates than Direct Methods  

PubMed Central

The production and turnover of fine roots play substantial roles in the biogeochemical cycles of terrestrial ecosystems. However, the disparity among the estimates of both production and turnover, particularly due to technical limitations, has been debated for several decades. Here, we conducted a meta-analysis to compare published estimates of fine root production and turnover rates derived from different methods at the same sites and at the same sampling time. On average, the estimates of fine root production and turnover rates were 87% and 124% higher, respectively, by indirect methods than by direct methods. The substantially higher fine root production and turnover estimated by indirect methods, on which most global carbon models are based, indicate the necessity of re-assessing the global carbon model predictions for atmospheric carbon sequestration in soils as a result of the production and turnover of fine roots. PMID:23166603

Yuan, Z. Y.; Chen, Han Y. H.

2012-01-01

287

8.NS Estimating Square Roots  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Without using the square root button on your calculator, estimate $\\sqrt{800}$ as accurately as possible to $2$ decimal places. (Hint: It is worth noti...

288

Archimedes' calculations of square roots  

E-print Network

We reconsider Archimedes' evaluations of several square roots in 'Measurement of a Circle'. We show that several methods proposed over the last century or so for his evaluations fail one or more criteria of plausibility. We also provide internal evidence that he probably used an interpolation technique. The conclusions are relevant to the precise calculations by which he obtained upper and lower bounds on pi.

Davies, E B

2011-01-01

289

On the Hopf Algebra of Rooted Trees  

E-print Network

We find a formula to compute the number of the generators, which generate the $n$-filtered space of Hopf algebra of rooted trees, i.e. the number of equivalent classes of rooted trees with weight $n$. Applying Hopf algebra of rooted trees, we show that the analogue of Andruskiewitsch and Schneider's Conjecture is not true. The Hopf algebra of rooted trees and the enveloping algebra of the Lie algebra of rooted trees are two important examples of Hopf algebras. We give their representation and show that they have not any nonzero integrals. We structure their graded Drinfeld doubles and show that they are local quasitriangular Hopf algebras.

Shouchuan Zhang; Jieqiong He; Peng Wang

2007-11-20

290

Root traits and yield in sugar beet: identification of AFLP markers associated with root elongation rate  

Microsoft Academic Search

Morpho-physiological and molecular analysis were conducted to identify useful root indexes of sugar beet nutrient uptake capacity\\u000a and productivity. Root architectural parameters, root elongation rate, sulfate uptake rate and glucose and fructose content\\u000a in the root apex, traits involved in the plant response to sulfate stress, were evaluated in 18 sugar beet genotypes characterized\\u000a by different root yield. Morpho-physiological traits,

Piergiorgio Stevanato; Daniele Trebbi; Massimo Saccomani

2010-01-01

291

Linking root morphology, longevity and function to root branch order: a case study in three shrubs  

Microsoft Academic Search

Root branching order supports a powerful approach to understanding complex root systems; however, how the pattern of root\\u000a morphological characteristics, tissue carbon (C) and nitrogen (N) concentrations, and root lifespan are related to anatomical\\u000a features of variable root orders for mature shrubs (?19 years old) in sandy habitats is still unclear. In this study, these\\u000a relationships were investigated for three typical

Gang Huang; Xue-yong Zhao; Ha-lin Zhao; Ying-xin Huang; Xiao-an Zuo

2010-01-01

292

Induction of branch roots by cutting method in t Hyoscyamus niger root culture  

Microsoft Academic Search

Root tips of Hyoscyamus niger were cultivated on agar or in liquid medium, and patterns of elongation and branching were investigated.\\u000a The elongation of roots compared to branching, particularly tertiary root branching, was more effective in liquid medium than\\u000a on agar medium. The number (0.06 per cm) of tertiary roots which branched out from secondary roots was far less than

Seung Han Woo; Jong Moon Park; Ji-Won Yang

1997-01-01

293

Natural variation of the root morphological response to nitrate supply in Arabidopsis thaliana.  

PubMed

Nitrogen fertilization increases crop yield but excessive nitrate use can be a major environmental problem due to soil leaching or greenhouse gas emission. Root traits have been seldom considered as selection criteria to improve Nitrogen Use Efficiency of crops, due to the difficulty of measuring root traits under field conditions. Nonetheless, learning about mechanisms of lateral root (LR) growth stimulation or repression by nitrate availability could help to redesign root system architecture (RSA), a strategy aimed at developing plants with a dense and profound root system and with higher N uptake efficiency. Here, we explored the genetic diversity provided by natural populations of the model species Arabidopsis thaliana to identify potentially adaptive differences in biomass production and root morphology in response to nitrate availability. A core collection of 24 accessions that maximizes the genetic diversity within the species and Col-0 (the reference accession) were grown vertically on agar medium at moderate (N+) nitrate level for 6 days and then transferred to the same condition or to low (N-) nitrate concentration for 7 days. There was a major nutritional effect on the shoot biomass and root to shoot biomass ratio. The variation of the root biomass and RSA traits (primary root length, LRs number, LR mean length, total LRs length and LR densities) was primarily genetically determined. Differences in RSA traits between accessions were somewhat more pronounced at N-. Some accessions produced almost no visible LRs (Pyl-1, N13) at N-, while other produced up to a dozen (Kn-0). Taken together our data illustrate that natural variation exists within Arabidopsis for the studied traits. The identification of RSA ideotypes in the N response will facilitate further analysis of quantitative traits for root morphology. PMID:22683348

De Pessemier, Jérôme; Chardon, Fabien; Juraniec, Michal; Delaplace, Pierre; Hermans, Christian

2013-01-01

294

Phytotoxic cyanamide affects maize (Zea mays) root growth and root tip function: from structure to gene expression.  

PubMed

Cyanamide (CA) is a phytotoxic compound produced by four Fabaceae species: hairy vetch, bird vetch, purple vetch and black locust. Its toxicity is due to complex activity that involves the modification of both cellular structures and physiological processes. To date, CA has been investigated mainly in dicot plants. The goal of this study was to investigate the effects of CA in the restriction of the root growth of maize (Zea mays), representing the monocot species. CA (3mM) reduced the number of border cells in the root tips of maize seedlings and degraded their protoplasts. However, CA did not induce any significant changes in the organelle structure of other root cells, apart from increased vacuolization. CA toxicity was also demonstrated by its effect on cell cycle activity, endoreduplication intensity, and modifications of cyclins CycA2, CycD2, and histone HisH3 gene expression. In contrast, the arrangement of microtubules was not altered by CA. Treatment of maize seedlings with CA did not completely arrest mitotic activity, although the frequency of dividing cells was reduced. Furthermore, prolonged CA treatment increased the proportion of endopolyploid cells in the root tip. Cytological malformations were accompanied by an induction of oxidative stress in root cells, which manifested as enhanced accumulation of H2O2. Exposure of maize seedlings to CA resulted in an increased concentration of auxin and stimulated ethylene emission. Taken together, these findings suggested that the inhibition of root growth by CA may be a consequence of stress-induced morphogenic responses. PMID:24709147

Soltys, Dorota; Rudzi?ska-Langwald, Anna; Kurek, Wojciech; Szajko, Katarzyna; Sliwinska, Elwira; Bogatek, Renata; Gniazdowska, Agnieszka

2014-05-01

295

Human due diligence.  

PubMed

Most companies do a thorough job of financial due diligence when they acquire other companies. But all too often, deal makers simply ignore or underestimate the significance of people issues in mergers and acquisitions. The consequences are severe. Most obviously, there's a high degree of talent loss after a deal's announcement. To make matters worse, differences in decision-making styles lead to infighting; integration stalls; and productivity declines. The good news is that human due diligence can help companies avoid these problems. Done early enough, it helps acquirers decide whether to embrace or kill a deal and determine the price they are willing to pay. It also lays the groundwork for smooth integration. When acquirers have done their homework, they can uncover capability gaps, points of friction, and differences in decision making. Even more important, they can make the critical "people" decisions-who stays, who goes, who runs the combined business, what to do with the rank and file-at the time the deal is announced or shortly thereafter. Making such decisions within the first 30 days is critical to the success of a deal. Hostile situations clearly make things more difficult, but companies can and must still do a certain amount of human due diligence to reduce the inevitable fallout from the acquisition process and smooth the integration. This article details the steps involved in conducting human due diligence. The approach is structured around answering five basic questions: Who is the cultural acquirer? What kind of organization do you want? Will the two cultures mesh? Who are the people you most want to retain? And how will rank-and-file employees react to the deal? Unless an acquiring company has answered these questions to its satisfaction, the acquisition it is making will be very likely to end badly. PMID:17432159

Harding, David; Rouse, Ted

2007-04-01

296

miR396 affects mycorrhization and root meristem activity in the legume Medicago truncatula.  

PubMed

The root system is crucial for acquisition of resources from the soil. In legumes, the efficiency of mineral and water uptake by the roots may be reinforced due to establishment of symbiotic relationships with mycorrhizal fungi and interactions with soil rhizobia. Here, we investigated the role of miR396 in regulating the architecture of the root system and in symbiotic interactions in the model legume Medicago truncatula. Analyses with promoter-GUS fusions suggested that the mtr-miR396a and miR396b genes are highly expressed in root tips, preferentially in the transition zone, and display distinct expression profiles during lateral root and nodule development. Transgenic roots of composite plants that over-express the miR396b precursor showed lower expression of six growth-regulating factor genes (MtGRF) and two bHLH79-like target genes, as well as reduced growth and mycorrhizal associations. miR396 inactivation by mimicry caused contrasting tendencies, with increased target expression, higher root biomass and more efficient colonization by arbuscular mycorrhizal fungi. In contrast to MtbHLH79, repression of three GRF targets by RNA interference severely impaired root growth. Early activation of mtr-miR396b, concomitant with post-transcriptional repression of MtGRF5 expression, was also observed in response to exogenous brassinosteroids. Growth limitation in miR396 over-expressing roots correlated with a reduction in cell-cycle gene expression and the number of dividing cells in the root apical meristem. These results link the miR396 network to the regulation of root growth and mycorrhizal associations in plants. PMID:23566016

Bazin, Jérémie; Khan, Ghazanfar Abbas; Combier, Jean-Philippe; Bustos-Sanmamed, Pilar; Debernardi, Juan Manuel; Rodriguez, Ramiro; Sorin, Céline; Palatnik, Javier; Hartmann, Caroline; Crespi, Martin; Lelandais-Brière, Christine

2013-06-01

297

Plant responsiveness to root–root communication of stress cues  

PubMed Central

Background and Aims Phenotypic plasticity is based on the organism's ability to perceive, integrate and respond to multiple signals and cues informative of environmental opportunities and perils. A growing body of evidence demonstrates that plants are able to adapt to imminent threats by perceiving cues emitted from their damaged neighbours. Here, the hypothesis was tested that unstressed plants are able to perceive and respond to stress cues emitted from their drought- and osmotically stressed neighbours and to induce stress responses in additional unstressed plants. Methods Split-root Pisum sativum, Cynodon dactylon, Digitaria sanguinalis and Stenotaphrum secundatum plants were subjected to osmotic stress or drought while sharing one of their rooting volumes with an unstressed neighbour, which in turn shared its other rooting volume with additional unstressed neighbours. Following the kinetics of stomatal aperture allowed testing for stress responses in both the stressed plants and their unstressed neighbours. Key Results In both P. sativum plants and the three wild clonal grasses, infliction of osmotic stress or drought caused stomatal closure in both the stressed plants and in their unstressed neighbours. While both continuous osmotic stress and drought induced prolonged stomatal closure and limited acclimation in stressed plants, their unstressed neighbours habituated to the stress cues and opened their stomata 3–24 h after the beginning of stress induction. Conclusions The results demonstrate a novel type of plant communication, by which plants might be able to increase their readiness to probable future osmotic and drought stresses. Further work is underway to decipher the identity and mode of operation of the involved communication vectors and to assess the potential ecological costs and benefits of emitting and perceiving drought and osmotic stress cues under various ecological scenarios. PMID:22408186

Falik, Omer; Mordoch, Yonat; Ben-Natan, Daniel; Vanunu, Miriam; Goldstein, Oron; Novoplansky, Ariel

2012-01-01

298

NAME: Chedella In patients with a nonvital asymptomatic tooth, will a singlevisit root canal therapy, as compared to multiplevisit root  

E-print Network

canal therapy, as compared to multiplevisit root canal therapy provide better healing and longevity) P: nonvital asymptomatic tooth I: singlevisit root canal therapy C: multiplevisit root canal therapy O: healing and longevity QUESTION TYPE: Treatment SEARCH STRATEGY: root canal therapy

Goldman, Steven A.

299

Hydrogenase in actinorhizal root nodules and root nodule homogenates.  

PubMed

Hydrogenases were measured in intact actinorhizal root nodules and from disrupted nodules of Alnus glutinosa, Alnus rhombifolia, Alnus rubra, and Myrica pensylvanica. Whole nodules took up H2 in an O2-dependent reaction. Endophyte preparations oxidized H2 through the oxyhydrogen reaction, but rates were enhanced when hydrogen uptake was coupled to artificial electron acceptors. Oxygen inhibited artifical acceptor-dependent H2 uptake. The hydrogenase system from M. pensylvanica had a different pattern of coupling to various electron acceptors than the hydrogenase systems from the alders; only the bayberry system evolved H2 from reduced viologen dyes. PMID:6989799

Benson, D R; Arp, D J; Burris, R H

1980-04-01

300

Complex Square Root with Operand Prescaling Milos D. Ercegovac  

E-print Network

Complex Square Root with Operand Prescaling Milos D. Ercegovac Computer Science Department, 3732-recurrence algorithm for complex square-root. The operand is prescaled to allow the selection of square-root digits routines for complex square root. 1 Introduction 1.1 Complex square-root Complex square-root appears

Paris-Sud XI, Université de

301

Hydrotropism in pea roots in a porous-tube water delivery system  

NASA Technical Reports Server (NTRS)

Orientation of root growth on earth and under microgravity conditions can possibly be controlled by hydrotropism--growth toward a moisture source in the absence of or reduced gravitropism. A porous-tube water delivery system being used for plant growth studies is appropriate for testing this hypothesis since roots can be grown aeroponically in this system. When the roots of the agravitropic mutant pea ageotropum (Pisum sativum L.) were placed vertically in air of 91% relative humidity and 2 to 3 mm from the water-saturated porous tube placed horizontally, the roots responded hydrotropically and grew in a continuous arch along the circular surface of the tube. By contrast, normal gravitropic roots of Alaska' pea initially showed a slight transient curvature toward the tube and then resumed vertical downward growth due to gravitropism. Thus, in microgravity, normal gravitropic roots could respond to a moisture gradient as strongly as the agravitropic roots used in this study. Hydrotropism should be considered a significant factor responsible for orientation of root growth in microgravity.

Takahashi, H.; Brown, C. S.; Dreschel, T. W.; Scott, T. K.; Knott, W. M. (Principal Investigator)

1992-01-01

302

Stress-induced accumulation of wheat germ agglutinin and abscisic acid in roots of wheat seedlings  

SciTech Connect

Wheat germ agglutinin (WGA) levels in roots of 2-day-old wheat seedlings increased up to three-fold when stressed by air-drying. Similar results were obtained when seedling roots were incubated either in 0.5 molar mannitol or 180 grams per liter polyethylene glycol 6,000, with a peak level of WGA after 5 hours of stress. Longer periods of osmotic treatment resulted in a gradual decline of WGA in the roots. Since excised wheat roots incorporate more ({sup 35}S)cysteine into WGA under stress conditions, the observed increase of lectin levels is due to de novo synthesis. Measurement of abscisic acid (ABA) levels in roots of control and stressed seedlings indicated a 10-fold increase upon air-drying. Similarly, a five- and seven-fold increase of ABA content of seedling roots was found after 2 hours of osmotic stress by polyethylene glycol 6,000 and mannitol, respectively. Finally, the stress-induced increase of WGA in wheat roots could be inhibited by growing seedlings in the presence of fluridone, an inhibitor of ABA synthesis. These results indicate that roots of water-stressed wheat seedlings (a) contain more WGA as a result of an increased de novo synthesis of this lectin, and (b) exhibit higher ABA levels. The stress-induced increase of lectin accumulation seems to be under control of ABA.

Cammue, B.P.A.; Broekaert, W.F.; Kellens, J.T.C.; Peumans, W.J. (Laboratorium voor Plantenbiochemie K. U. Leuven (Belgium)); Raikhel, N.V. (Michigan State Univ., East Lansing (USA))

1989-12-01

303

Ammonium Uptake by Rice Roots (III. Electrophysiology).  

PubMed

The transmembrane electrical potential differences ([delta][psi]) were measured in epidermal and cortical cells of intact roots of 3-week-old rice (Oryza sativa L. cv M202) seedlings grown in 2 or 100 [mu]M NH4+ (G2 or G100 plants, respectively). In modified Johnson's nutrient solution containing no nitrogen, [delta][psi] was in the range of -120 to -140 mV. Introducing NH4+ to the bathing medium caused a rapid depolarization. At the steady state, average [delta][psi] of G2 and G100 plants were -116 and -89 mV, respectively. This depolarization exhibited a biphasic response to external NH4+ concentration similar to that reported for 13NH4+ influx isotherms (M.Y. Wang, M.Y. Siddiqi, T.J. Ruth, A.D.M. Glass [1993] Plant Physiol 103: 1259-1267). Plots of membrane depolarization versus 13NH4+ influx were also biphasic, indicating distinct coupling processes for the two transport systems, with a breakpoint between two concentration ranges around 1 mM NH4+. The extent of depolarization was also influenced by nitrogen status, which was larger for G2 plants than for G100 plants. Depolarization of [delta][psi] due to NH4+ uptake was eliminated by a protonophore (carboxylcyanide-m-chlorophenylhydrazone), inhibitors of ATP synthesis (sodium cyanide plus salicylhydroxamic acid), or an ATPase inhibitor (diethylstilbestrol). The results of these observations are discussed in the context of the mechanisms of NH4+ uptake by high- and low-affinity transport systems operating across the plasma membranes of root cells. PMID:12232135

Wang, M. Y.; Glass, ADM.; Shaff, J. E.; Kochian, L. V.

1994-03-01

304

The effects of certain fungicidal treatments on the rooting of cuttings  

E-print Network

. These observations Included& photographs which appear in the Appendtut counting the number of blackened roots per pltn4 plus observations of callus formation or discoloration of callus tissue, end the relative deterioration o! the stems and foUage. Quantitative... of root development. and for all cuttings following reoting. A difference in the relative degree of callus formation due to treatment was not detectable. Considerable discoloration of the cuttings occurred and symptoms of degeneration increased...

Pate, David Azariah

1961-01-01

305

Constructing the uncertainty of due dates.  

PubMed

By its nature, the date that a baby is predicted to be born, or the due date, is uncertain. How women construct the uncertainty of their due dates may have implications for when and how women give birth. In the United States as many as 15% of births occur before 39 weeks because of elective inductions or cesarean sections, putting these babies at risk for increased medical problems after birth and later in life. This qualitative study employs a grounded theory approach to understand the decisions women make on how and when to give birth. Thirty-three women who were pregnant or had given birth within the past 2 years participated in key informant or small-group interviews. The results suggest that women interpret the uncertainty of their due dates as a reason to wait for birth and as a reason to start the process early; however, information about a baby's brain development in the final weeks of pregnancy may persuade women to remain pregnant longer. The uncertainties of due dates are analyzed using Babrow's problematic integration, which distinguishes between epistemological and ontological uncertainty. The results point to a third type of uncertainty, axiological uncertainty. Axiological uncertainty is rooted in the values and ethics of outcomes. PMID:24266788

Vos, Sarah C; Anthony, Kathryn E; O'Hair, H Dan

2014-01-01

306

Constructing the Uncertainty of Due Dates  

PubMed Central

By its nature, the date that a baby is predicted to be born, or the due date, is uncertain. How women construct the uncertainty of their due dates may have implications for when and how women give birth. In the United States as many as 15% of births occur before 39 weeks because of elective inductions or cesarean sections, putting these babies at risk for increased medical problems after birth and later in life. This qualitative study employs a grounded theory approach to understand the decisions women make of how and when to give birth. Thirty-three women who were pregnant or had given birth within the past two years participated in key informant or small group interviews. The results suggest that women interpret the uncertainty of their due dates as a reason to wait on birth and as a reason to start the process early; however, information about a baby's brain development in the final weeks of pregnancy may persuade women to remain pregnant longer. The uncertainties of due dates are analyzed using Babrow's problematic integration, which distinguishes between epistemological and ontological uncertainty. The results point to a third type uncertainty, axiological uncertainty. Axiological uncertainty is rooted in the values and ethics of outcomes. PMID:24266788

Vos, Sarah C.; Anthony, Kathryn E.; O'Hair, H. Dan

2015-01-01

307

[Onychomycoses due to molds].  

PubMed

Onychomycoses represent about 30% of superficial mycosis that are encountered in Dermatology consults. Fungi such as dermatophytes, which are mainly found on the feet nails, cause nearly 50% of these onychopathies. Yeasts are predominantly present on hands, whereas non-dermatophytic moulds are very seldom involved in both foot and hand nails infections. According to literature, these moulds are responsible for 2 to 17% of onychomycoses. Nevertheless, we have to differentiate between onychomycoses due to pseudodermatophytes such as Neoscytalidium (ex-Scytalidium) and Onychocola canadensis, which present a high affinity for keratin, and onychomycoses due to filamentous fungi such as Aspergillus, Fusarium, Scopulariopsis, Acremonium... These saprophytic moulds are indeed most of the time considered as colonizers rather than real pathogens agents. Mycology and histopathology laboratories play an important role. They allow to identify the species that is involved in nail infection, but also to confirm parasitism by the fungus in the infected nails. Indeed, before attributing any pathogenic role to non-dermatophytic moulds, it is essential to precisely evaluate their pathogenicity through samples and accurate mycological and/or histological analysis. The treatment of onychomycoses due to non-dermatophytic moulds is difficult, as there is today no consensus. The choice of an antifungal agent will first depend on the species that is involved in the infection, but also on the severity of nail lesions and on the patient himself. In most cases, the onychomycosis will be cured with chemical or mechanical removing of the infected tissues, followed by a local antifungal treatment. In some cases, a systemic therapy will be discussed. PMID:25458362

Chabasse, D; Pihet, M

2014-12-01

308

Root Water Uptake and Tracer Transport in a Lupin Root System: Integration of Magnetic Resonance Images and the Numerical Model RSWMS  

NASA Astrophysics Data System (ADS)

Combination of experimental studies with detailed deterministic models help understand root water uptake processes. Recently, Javaux et al. developed the RSWMS model by integration of Doussa?s root model into the well established SWMS code[1], which simulates water and solute transport in unsaturated soil [2, 3]. In order to confront RSWMS modeling results to experimental data, we used Magnetic Resonance Imaging (MRI) technique to monitor root water uptake in situ. Non-invasive 3-D imaging of root system architecture, water content distributions and tracer transport by MR were performed and compared with numerical model calculations. Two MRI experiments were performed and modeled: i) water uptake during drought stress and ii) transport of a locally injected tracer (Gd-DTPA) to the soil-root system driven by root water uptake. Firstly, the high resolution MRI image (0.23x0.23x0.5mm) of the root system was transferred into a continuous root system skeleton by a combination of thresholding, region-growing filtering and final manual 3D redrawing of the root strands. Secondly, the two experimental scenarios were simulated by RSWMS with a resolution of about 3mm. For scenario i) the numerical simulations could reproduce the general trend that is the strong water depletion from the top layer of the soil. However, the creation of depletion zones in the vicinity of the roots could not be simulated, due to a poor initial evaluation of the soil hydraulic properties, which equilibrates instantaneously larger differences in water content. The determination of unsaturated conductivities at low water content was needed to improve the model calculations. For scenario ii) simulations confirmed the solute transport towards the roots by advection. 1. Simunek, J., T. Vogel, and M.T. van Genuchten, The SWMS_2D Code for Simulating Water Flow and Solute Transport in Two-Dimensional Variably Saturated Media. Version 1.21. 1994, U.S. Salinity Laboratory, USDA, ARS: Riverside, California. 2. Javaux, M., et al., Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake. Vadose Zone J., 2008. 7(3): p. 1079-1088. 3. Schröder, T., et al., Effect of Local Soil Hydraulic Conductivity Drop Using a Three Dimensional Root Water Uptake Model. Vadose Zone J., 2008. 7(3): p. 1089-1098.

Pohlmeier, Andreas; Vanderborght, Jan; Haber-Pohlmeier, Sabina; Wienke, Sandra; Vereecken, Harry; Javaux, Mathieu

2010-05-01

309

PATTERNS IN SOIL FERTILITY AND ROOT HERBIVORY INTERACT TO INFLUENCE FINE-ROOT DYNAMICS.  

SciTech Connect

Fine-scale soil nutrient enrichment typically stimulates root growth, but it may also increase root herbivory, resulting in trade-offs for plant species and potentially influencing carbon cycling patterns. We used root ingrowth cores to investigate the effects of microsite fertility and root herbivory on root biomass in an aggrading upland forest in the coastal plain of South Carolina, USA. Treatments were randomly assigned to cores from a factorial combination of fertilizer and insecticide. Soil, soil fauna, and roots were removed from the cores at the end of the experiment (8–9 mo), and roots were separated at harvest into three diameter classes. Each diameter class responded differently to fertilizer and insecticide treatments. The finest roots (,1.0 mm diameter), which comprised well over half of all root biomass, were the only ones to respond significantly to both treatments, increasing when fertilizer and when insecticide were added (each P , 0.0001), with maximum biomass found where the treatments were combined (interaction term significant, P , 0.001). These results suggest that root-feeding insects have a strong influence on root standing crop with stronger herbivore impacts on finer roots and within more fertile microsites. Thus, increased vulnerability to root herbivory is a potentially significant cost of root foraging in nutrient-rich patches.

Stevens, Glen, N.; Jones, Robert, H.

2006-03-01

310

Inhibition of auxin movement from the shoot into the root inhibits lateral root development in Arabidopsis  

NASA Technical Reports Server (NTRS)

In roots two distinct polar movements of auxin have been reported that may control different developmental and growth events. To test the hypothesis that auxin derived from the shoot and transported toward the root controls lateral root development, the two polarities of auxin transport were uncoupled in Arabidopsis. Local application of the auxin-transport inhibitor naphthylphthalamic acid (NPA) at the root-shoot junction decreased the number and density of lateral roots and reduced the free indoleacetic acid (IAA) levels in the root and [3H]IAA transport into the root. Application of NPA to the basal half of or at several positions along the root only reduced lateral root density in regions that were in contact with NPA or in regions apical to the site of application. Lateral root development was restored by application of IAA apical to NPA application. Lateral root development in Arabidopsis roots was also inhibited by excision of the shoot or dark growth and this inhibition was reversible by IAA. Together, these results are consistent with auxin transport from the shoot into the root controlling lateral root development.

Reed, R. C.; Brady, S. R.; Muday, G. K.

1998-01-01

311

Foraging strategies in trees of different root morphology: the role of root lifespan.  

PubMed

Resource exploitation of patches is influenced not simply by the rate of root production in the patches but also by the lifespan of the roots inhabiting the patches. We examined the effect of sustained localized nitrogen (N) fertilization on root lifespan in four tree species that varied widely in root morphology and presumed foraging strategy. The study was conducted in a 12-year-old common garden in central Pennsylvania using a combination of data from minirhizotron and root in-growth cores. The two fine-root tree species, Acer negundo L. and Populus tremuloides Michx., exhibited significant increases in root lifespan with local N fertilization; no significant responses were observed in the two coarse-root tree species, Sassafras albidum Nutt. and Liriodendron tulipifera L. Across species, coarse-root tree species had longer median root lifespan than fine-root tree species. Localized N fertilization did not significantly increase the N concentration or the respiration of the roots growing in the N-rich patch. Our results suggest that some plant species appear to regulate the lifespan of different portions of their root system to improve resource acquisition while other species do not. Our results are discussed in the context of different strategies of foraging of nutrient patches in species of different root morphology. PMID:24128849

Adams, Thomas S; McCormack, M Luke; Eissenstat, David M

2013-09-01

312

The formation of adventitious roots on root axes is a widespread occurrence in field-grown dicotyledonous plants  

Microsoft Academic Search

The formation of adventitious branch roots in the secondary tissues of parental root axes is a widespread and frequent occurrence under field conditions. Anatomical features diagnostic for the recognition of adventitious roots were utilized to confirm the occurrence of adventitious roots on roots of 22 species from 12 families in nine orders of dicotyledonous plants. Adventitious roots may play an

DOMINICK J. PAOLILLO; R. W. Zobel

2002-01-01

313

1-aminocyclopropane-1-carboxylic acid (ACC) concentration and ACC synthase expression in soybean roots and root tips and soybean cyst nematode (Heterodera glycines) colonized root pieces  

Technology Transfer Automated Retrieval System (TEKTRAN)

It's fairly well established that a functional ethylene response path is important to root knot and cyst nematode colonization of plant roots. However, ethylene plays many roles in root development and the role of ethylene in nematode colonization of roots may be indirect, e.g. lateral root initiati...

314

Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton  

PubMed Central

A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100?mM) or non-uniform NaCl concentrations (0/200 and 50/150?mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na+ concentrations in leaves. The [Na+] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na+] in the ‘0’ side roots was possibly due to transportation of foliar Na+ to roots through phloem. Plants under non-uniform salinity extruded more Na+ from the root than those under uniform salinity. Root Na+ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na+ efflux and H+ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na+ extrusion was probably due to active Na+/H+ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na+ concentration, transport of excessive foliar Na+ to the low salinity side, and enhanced Na+ efflux from the low salinity root. PMID:22200663

Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A. Egrinya

2012-01-01

315

Genetic ablation of root cap cells in Arabidopsis  

NASA Technical Reports Server (NTRS)

The root cap is increasingly appreciated as a complex and dynamic plant organ. Root caps sense and transmit environmental signals, synthesize and secrete small molecules and macromolecules, and in some species shed metabolically active cells. However, it is not known whether root caps are essential for normal shoot and root development. We report the identification of a root cap-specific promoter and describe its use to genetically ablate root caps by directing root cap-specific expression of a diphtheria toxin A-chain gene. Transgenic toxin-expressing plants are viable and have normal aerial parts but agravitropic roots, implying loss of root cap function. Several cell layers are missing from the transgenic root caps, and the remaining cells are abnormal. Although the radial organization of the roots is normal in toxin-expressing plants, the root tips have fewer cytoplasmically dense cells than do wild-type root tips, suggesting that root meristematic activity is lower in transgenic than in wild-type plants. The roots of transgenic plants have more lateral roots and these are, in turn, more highly branched than those of wild-type plants. Thus, root cap ablation alters root architecture both by inhibiting root meristematic activity and by stimulating lateral root initiation. These observations imply that the root caps contain essential components of the signaling system that determines root architecture.

Tsugeki, R.; Fedoroff, N. V.

1999-01-01

316

Rhizoslides: paper-based growth system for non-destructive, high throughput phenotyping of root development by means of image analysis  

PubMed Central

Background A quantitative characterization of root system architecture is currently being attempted for various reasons. Non-destructive, rapid analyses of root system architecture are difficult to perform due to the hidden nature of the root. Hence, improved methods to measure root architecture are necessary to support knowledge-based plant breeding and to analyse root growth responses to environmental changes. Here, we report on the development of a novel method to reveal growth and architecture of maize root systems. Results The method is based on the cultivation of different root types within several layers of two-dimensional, large (50 × 60 cm) plates (rhizoslides). A central plexiglass screen stabilizes the system and is covered on both sides with germination paper providing water and nutrients for the developing root, followed by a transparent cover foil to prevent the roots from falling dry and to stabilize the system. The embryonic roots grow hidden between a Plexiglas surface and paper, whereas crown roots grow visible between paper and the transparent cover. Long cultivation with good image quality up to 20 days (four fully developed leaves) was enhanced by suppressing fungi with a fungicide. Based on hyperspectral microscopy imaging, the quality of different germination papers was tested and three provided sufficient contrast to distinguish between roots and background (segmentation). Illumination, image acquisition and segmentation were optimised to facilitate efficient root image analysis. Several software packages were evaluated with regard to their precision and the time investment needed to measure root system architecture. The software 'Smart Root’ allowed precise evaluation of root development but needed substantial user interference. 'GiaRoots’ provided the best segmentation method for batch processing in combination with a good analysis of global root characteristics but overestimated root length due to thinning artefacts. 'WhinRhizo’ offered the most rapid and precise evaluation of root lengths in diameter classes, but had weaknesses with respect to image segmentation and analysis of root system architecture. Conclusion A new technique has been established for non-destructive root growth studies and quantification of architectural traits beyond seedlings stages. However, automation of the scanning process and appropriate software remains the bottleneck for high throughput analysis. PMID:25093035

2014-01-01

317

Simple analytical model of evapotranspiration in the presence of roots  

NASA Astrophysics Data System (ADS)

Evaporation of water out of a soil involves complicated and well-debated mechanisms. When plant roots are added into the soil, water transfer between the soil and the outside environment is even more complicated. Indeed, plants provide an additional process of water transfer. Water is pumped by the roots, channeled to the leaf surface, and released into the surrounding air by a process called transpiration. Prediction of the evapotranspiration of water over time in the presence of roots helps keep track of the amount of water that remains in the soil. Using a controlled visual setup of a two-dimensional model soil consisting of monodisperse glass beads, we perform experiments on actual roots grown under different relative humidity conditions. We record the total water mass loss in the medium and the position of the evaporating front that forms within the medium. We then develop a simple analytical model that predicts the position of the evaporating front as a function of time as well as the total amount of water that is lost from the medium due to the combined effects of evaporation and transpiration. The model is based on fundamental principles of evaporation fluxes and includes empirical assumptions on the quantity of open stomata in the leaves, where water transpiration occurs. Comparison between the model and experimental results shows excellent prediction of the position of the evaporating front as well as the total mass loss from evapotranspiration in the presence of roots. The model also provides a way to predict the lifetime of a plant.

Cejas, Cesare M.; Hough, L. A.; Castaing, Jean-Christophe; Frétigny, Christian; Dreyfus, Rémi

2014-10-01

318

Antioxidant tannins from Rosaceae plant roots  

Microsoft Academic Search

Polyphenols were analyzed by HPLC after thioacidolysis of proanthocyanidins polymers and acid hydrolysis of phenolic acid esters. The predominant constitutive units of the procyanidins of Aruncus Silvester and Potentilla alba roots were (?)epicatechin, and Geum rivale and Waldsteinia geoides roots (+)catechin. The highest proanthocyanidin concentrations were found in Potentilla alba roots (close to 80g\\/kg) and W. geoides (64g\\/kg). Ellagic acid

Jan Oszmianski; Aneta Wojdylo; Eliza Lamer-Zarawska; Katarzyna Swiader

2007-01-01

319

Springback and diagravitropism in Merit corn roots.  

PubMed Central

Dark-treated Merit corn (Zea mays L.) roots are diagravitropic and lose curvature upon withdrawal of the gravity stimulus (springback). Springback was not detected in a variety of corn that is orthogravitropic in the dark, nor in Merit roots in which tropistic response was enhanced either with red light or with abscisic acid. A possible interpretation is that springback may be associated with a weak growth response of diagravitropic roots. PMID:11537884

Kelly, M O; Leopold, A C

1992-01-01

320

Springback and diagravitropism in Merit corn roots.  

PubMed

Dark-treated Merit corn (Zea mays L.) roots are diagravitropic and lose curvature upon withdrawal of the gravity stimulus (springback). Springback was not detected in a variety of corn that is orthogravitropic in the dark, nor in Merit roots in which tropistic response was enhanced either with red light or with abscisic acid. A possible interpretation is that springback may be associated with a weak growth response of diagravitropic roots. PMID:11537884

Kelly, M O; Leopold, A C

1992-06-01

321

Cluster Roots: A Curiosity in Context  

Microsoft Academic Search

Cluster roots are an adaptation for nutrient acquisition from nutrient-poor soils. They develop on root systems of a range\\u000a of species belonging to a number of different families (e.g., Proteaceae, Casuarinaceae, Fabaceae and Myricaceae) and are\\u000a also found on root systems of some crop species (e.g., albus, Macadamia integrifoliaandCucurbita pepo). Their morphology is variable but typically, large numbers of determinate

Michael W. Shane; Hans Lambers

2005-01-01

322

Hairy Root Cultures for Secondary Metabolites Production  

Microsoft Academic Search

\\u000a Hairy roots (HRs) are differentiated cultures of transformed roots generated by the infection of wounded higher plants with\\u000a Agrobacterium rhizogenes. This pathogen causes the HR disease leading to the neoplastic growth of roots that are characterized by high growth rate\\u000a in hormone free media and genetic stability. HRs produce the same phytochemicals pattern of the corresponding wild type organ.\\u000a High

Laura Pistelli; Annalisa Giovannini; Barbara Ruffoni; Alessandra Bertoli; Luisa Pistelli

323

Environmental effects on the maturation of the endodermis and multiseriate exodermis of Iris germanica roots  

PubMed Central

Background and Aims Most studies of exodermal structure and function have involved species with a uniseriate exodermis. To extend this work, the development and apoplastic permeability of Iris germanica roots with a multiseriate exodermis (MEX) were investigated. The effects of different growth conditions on MEX maturation were also tested. In addition, the exodermises of eight Iris species were observed to determine if their mature anatomy correlated with habitat. Methods Plants were grown in soil, hydroponics (with and without a humid air gap) or aeroponics. Roots were sectioned and stained with various dyes to detect MEX development from the root apical meristem, Casparian bands, suberin lamellae and tertiary wall thickenings. Apoplastic permeability was tested using dye (berberine) and ionic (ferric) tracers. Key Results The root apical meristem was open and MEX development non-uniform. In soil-grown roots, the exodermis started maturing (i.e. Casparian bands and suberin lamellae were deposited) 10 mm from the tip, and two layers had matured by 70 mm. In both hydro- and aeroponically grown roots, exodermal maturation was delayed. However, in areas of roots exposed to an air gap in the hydroponic system, MEX maturation was accelerated. In contrast, maturation of the endodermis was not influenced by the growth conditions. The mature MEX had an atypical Casparian band that was continuous around the root circumference. The MEX prevented the influx and efflux of berberine, but had variable resistance to ferric ions due to their toxic effects. Iris species living in well-drained soils developed a MEX, but species in water-saturated substrates had a uniseriate exodermis and aerenchyma. Conclusions MEX maturation was influenced by the roots' growth medium. The MEX matures very close to the root tip in soil, but much further from the tip in hydro- and aeroponic culture. The air gap accelerated maturation of the second exodermal layer. In Iris, the type of exodermis was correlated with natural habitat suggesting that a MEX may be advantageous for drought tolerance. PMID:19151041

Meyer, Chris J.; Seago, James L.; Peterson, Carol A.

2009-01-01

324

Mechanism of Short Term FeIII Reduction by Roots 1  

PubMed Central

The hypothesized role of secreted reducing compounds in FeIII reduction has been examined with Fe-deficient peanuts (Arachis hypogaea L. cv A124B). Experiments involved the exposure of roots to (a) different gas mixtures, (b) carbonyl cyanide m-chlorophenylhydrazone (CCCP), and (c) agents which impair membrane integrity. Removing roots from solution and exposing them to air or N2 for 10 minutes did not result in any accumulation in the free space of compounds capable of increasing rates of FeIII reduction when roots were returned to solutions. On the contrary, exposing roots to N2 decreased rates of FeIII reduction. CCCP also decreased rates of FeIII reduction. Acetic acid and ethylenediaminetetraacetic acid (disodium salt) (EDTA) impaired the integrity and function of the plasma membranes of roots of Fe-deficient peanuts. That is, in the presence of acetic acid or EDTA, there was an efflux of K+ from the roots; K+ (86Rb) uptake was also impaired. Acetic acid increased the efflux from the roots of compounds capable of reducing FeIII. However, both acetic acid and EDTA caused rapid decreases in rates of FeIII reduction by the roots. In addition to peanuts, acetic acid also decreased rates of FeIII reduction by roots of Fe-deficient sunflowers (Helianthus annuus L. cv Sobrid) but not maize (Zea mays L. cv Garbo). These results suggest that, at least in the short term, the enhanced FeIII reduction by roots of Fe-deficient plants is not due to the secretion of reducing compounds. PMID:16663338

Barrett-Lennard, Edward G.; Marschner, Horst; Römheld, Volker

1983-01-01

325

Promotion ofin vitro shoot formation from excised roots of silktree (Albizzia julibrissin) by an oxime ether derivative and other ethylene inhibitors.  

PubMed

This report describes the regeneration response of excised seedling roots of silktree (Albizzia julibrissin) to added ethylene precursors/generators (1-amino-cyclopropane-1-carboxylic acid [ACC], 2-chloroethylphosphonic acid [CEPA]), biosynthesis inhibitors (aminoethoxyvinylglycine [AVG], an oxime ether derivative [OED={[(ispropylidene)-amino]oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester], CoCl(2) [Co(++)]), and an ethylene action inhibitor (AgNO3 [Ag(+)]). When placed on B5 medium, about 50% of the control explants formed shoot buds within 15 days. Addition of ACC or CEPA (1-10 µM) to the culture medium decreased both the percentage of cultures forming shoots and the number of shoots formed per culture. In contrast, AVG and OED (1-10 µM) increased shoot formation to almost 100% and increased the number of shoots formed per culture. Likewise, both Co(++) and Ag(+) (1-10 µM) increased shoot regeneration, but the number of shoots produced after 30 days was less than with AVG or OED. The inhibitors of ethylene biosynthesis were partially effective in counteracting the inhibitory effect of ACC on shoot formation. These results suggest that modulation of ethylene biosynthesis and/or action can strongly influence the formation of adventitious shoots from excised roots of silktree. PMID:24185673

Sankhla, D; Sankhla, N; Davis, T D

1995-01-01

326

Eastern Australian Examples of River Bank Soil Reinforcement by Tree Roots (Invited)  

NASA Astrophysics Data System (ADS)

Riverside vegetation is a significant factor influencing the occurrence and progress of stream-bed and river-bank erosion. Recent riparian management practice in Australia has focussed on re-establishing or maintaining native riparian vegetation in order to control or prevent erosion as well as regenerate or preserve the complex variety of in-stream and riverside habitats. This work presents an integrated review of field and experimental studies conducted in eastern Australia that evaluate native vegetation’s role in reducing riverine erosion. Several results of these studies have general application and include the following. 1) Riparian vegetation reduces the impact of subaerial processes on soils and significantly increases a soil’s resistance to fluvial scour. 2) The presence of riparian forest on river banks significantly reduces the likelihood of erosion by mass failure due to reinforcement of river bank soils by tree roots; 3) Many Australian tree species have evolved roots that seek the permanent, summer water-table in order to survive prolonged dry spells and are particularly effective in mass failure mitigation due to rooting depths that are commonly greater than five metres. 4) The "Root-Area-Ratio Method" of calculating the shear strength of root-reinforced soil using root tensile-strength data and Waldron’s (1977) and Wu et al.’s (1979) simple root model leads to significant overestimation of the actual root reinforcement due to the fact the soil mass fails progressively along the length of potential shear plane rather instantaneously across the entire shear plane.

Hubble, T.; Rutherfurd, I.; Docker, B.

2010-12-01

327

Self-similar continued root approximants  

NASA Astrophysics Data System (ADS)

A novel method of summing asymptotic series is advanced. Such series repeatedly arise when employing perturbation theory in powers of a small parameter for complicated problems of condensed matter physics, statistical physics, and various applied problems. The method is based on the self-similar approximation theory involving self-similar root approximants. The constructed self-similar continued roots extrapolate asymptotic series to finite values of the expansion parameter. The self-similar continued roots contain, as a particular case, continued fractions and Padé approximants. A theorem on the convergence of the self-similar continued roots is proved. The method is illustrated by several examples from condensed-matter physics.

Gluzman, S.; Yukalov, V. I.

2012-12-01

328

Root grooves on sandstone bedrock, Ouachita Mountains  

NASA Astrophysics Data System (ADS)

This study presents findings demonstrating the existence of root grooves on siliceous sandstone. It is clear from biochemical studies that weathering in ecosystems with vigorous plant growth is more rapid than in non-vegetated areas, and previous studies of the interactions between tree roots and bedrock have demonstrated the importance of trees in breaking down bedrock through biophysical and biomechanical processes, including treethrow. However, the development of root grooves has rarely been reported on bedrock other than limestone or calcareous substrate. This poster will show the existence of tree root grooves on siliceous sandstone in the Ouachita Mountains, and will discuss the processes that have led to their genesis and development.

Turkington, A. T.

2010-12-01

329

't Hooft vertices, partial quenching, and rooted staggered QCD  

SciTech Connect

We discuss the properties of 't Hooft vertices in partially quenched and rooted versions of QCD in the continuum. These theories have a physical subspace, equivalent to ordinary QCD, that is contained within a larger space that includes many unphysical correlation functions. We find that the 't Hooft vertices in the physical subspace have the expected form, despite the presence of unphysical 't Hooft vertices appearing in correlation functions that have an excess of valence quarks (or ghost quarks). We also show that, due to the singular behavior of unphysical correlation functions as the massless limit is approached, order parameters for nonanomalous symmetries can be nonvanishing in finite volume if these symmetries act outside of the physical subspace. Using these results, we demonstrate that arguments recently given by Creutz - claiming to disprove the validity of rooted staggered QCD - are incorrect. In particular, the unphysical 't Hooft vertices do not present an obstacle to the recovery of taste symmetry in the continuum limit.

Bernard, Claude [Department of Physics, Washington University, Saint Louis, MI 63130 (United States); Golterman, Maarten [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Shamir, Yigal [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Ramat Aviv, 69978 (Israel); Sharpe, Stephen R. [Physics Department, University of Washington, Seattle, WA 98195 (United States)

2008-06-01

330

Dynamics of air gap formation around roots with changing soil water content.  

NASA Astrophysics Data System (ADS)

Most models regarding uptake of water and nutrients from soil assume intimate contact between roots and soil. However, it is known for a long time that roots may shrink under drought conditions. Due to the opaque nature of soil this process could not be observed in situ until recently. Combining tomography of the entire sample (field of view of 16 x 16 cm, pixel side 0.32 mm) with local tomography of the soil region around roots (field of view of 5 x 5 cm, pixel side 0.09 mm), the high spatial resolution required to image root shrinkage and formation of air-filled gaps around roots could be achieved. Applying this technique and combining it with microtensiometer measurements, measurements of plant gas exchange and microscopic assessment of root anatomy, a more detailed study was conducted to elucidate at which soil matric potential roots start to shrink in a sandy soil and which are the consequences for plant water relations. For Lupinus albus grown in a sandy soil tomography of the entire root system and of the interface between taproot and soil was conducted from day 11 to day 31 covering two drying cycles. Soil matric potential decreased from -36 hPa at day 11 after planting to -72, -251, -429 hPa, on day 17, 19, 20 after planting. On day 20 an air gap started to occur around the tap root and extended further on day 21 with matric potential below -429 hPa (equivalent to 5 v/v % soil moisture). From day 11 to day 21 stomatal conductivity decreased from 467 to 84 mmol m-2 s-1, likewise transpiration rate decreased and plants showed strong wilting symptoms on day 21. Plants were watered by capillary rise on day 21 and recovered completely within a day with stomatal conductivity increasing to 647 mmol m-2 s-1. During a second drying cycle, which was shorter as plants continuously increased in size, air gap formed again at the same matric potential. Plant stomatal conductance and transpiration decreased in a similar fashion with decreasing matric potential and appearance of air gap as during the first cycle. Microscopic assessment of the tap root at day 31 showed that secondary thickening of the taproot occurred all along the region of interest observed during X-ray tomography. A large part of the cross sections consists of lignified tissue; no root hairs could be observed along the tap root. Gaps are expected to reduce water transfers between soil and roots. Opening and closing of gaps may help plants to prevent water loss when the soil dries, and to restore the soil-root continuity when water becomes available.

Vetterlein, D.; Carminati, A.; Weller, U.; Oswald, S.; Vogel, H.-J.

2009-04-01

331

Performance of seminal and nodal roots of wheat in stagnant solution: K+ and P uptake and effects of increasing O2 partial pressures around the shoot on nodal root elongation.  

PubMed

Roots of intact wheat plants were grown for 7-12 d in stagnant nutrient solution, containing 0.1% agar, to mimic the lack of convection in waterlogged soil. Net K+ and P uptakes by seminal and nodal roots were measured separately using a split root system. For seminal roots in stagnant solution, net uptakes as a percentage of aerated roots were between 0% and 16% for P, while K+ ranged between 15% uptake and 54% loss. For the more waterlogging-tolerant nodal roots, net uptakes in stagnant nutrient solution, as a percentage of aerated roots, were 31-73% for P and 69-115% for K+. Elongation rates of nodal roots in stagnant nutrient were about 35-43% of those for roots in aerated solution. This partial inhibition occurred in these nodal roots despite their 15% porosity (v/v). Elevation of O2 partial pressures around the shoots to 40 kPa and then to 80 kPa substantially accelerated nodal root elongation in stagnant solution, demonstrating that most of the inhibition seen with ambient O2 around the shoots was associated with a restricted O2 supply to these nodal roots. Thus, in wheat nodal roots, with a partial pressure of 20 kPa O2 around the shoots, O2 diffusion from the shoots did not completely relieve the restrictions on elongation resulting from stagnancy in the nutrient solution. These results contrast with those in the literature for rice, in which roots function efficiently in stagnant solutions (0.1% agar). So, when wheat roots are aerenchymatous there are still restrictions to O2 diffusion in the gas space continuum between the atmosphere and the functional tissues of the roots. This poor acclimation must have been due to inefficiency of the aerenchymatous axes, which may include persistence of anoxic steles, and/or restricted O2 diffusion in other parts of the gas space continuum, in either the shoots and shoot-root junction or in the root tip. PMID:15310817

Wiengweera, Amara; Greenway, Hank

2004-09-01

332

Increased symplasmic permeability in barley root epidermal cells correlates with defects in root hair development  

PubMed Central

It is well known that the process of plant cell differentiation depends on the symplasmic isolation of cells. Before starting the differentiation programme, the individual cell or group of cells should restrict symplasmic communication with neighbouring cells. We tested the symplasmic communication between epidermal cells in the different root zones of parental barley plants Hordeum vulgare L., cv. ‘Karat’ with normal root hair development, and two root hairless mutants (rhl1.a and rhl1.b). The results clearly show that symplasmic communication was limited during root hair differentiation in the parental variety, whereas in both root hairless mutants epidermal cells were still symplasmically connected in the corresponding root zone. This paper is the first report on the role of symplasmic isolation in barley root cell differentiation, and additionally shows that a disturbance in the restriction of symplasmic communication is present in root hairless mutants. PMID:23927737

Marzec, M; Muszynska, A; Melzer, M; Sas-Nowosielska, H; Kurczynska, E U; Wick, S

2014-01-01

333

Increased symplasmic permeability in barley root epidermal cells correlates with defects in root hair development.  

PubMed

It is well known that the process of plant cell differentiation depends on the symplasmic isolation of cells. Before starting the differentiation programme, the individual cell or group of cells should restrict symplasmic communication with neighbouring cells. We tested the symplasmic communication between epidermal cells in the different root zones of parental barley plants Hordeum vulgare L., cv. 'Karat' with normal root hair development, and two root hairless mutants (rhl1.a and rhl1.b). The results clearly show that symplasmic communication was limited during root hair differentiation in the parental variety, whereas in both root hairless mutants epidermal cells were still symplasmically connected in the corresponding root zone. This paper is the first report on the role of symplasmic isolation in barley root cell differentiation, and additionally shows that a disturbance in the restriction of symplasmic communication is present in root hairless mutants. PMID:23927737

Marzec, M; Muszynska, A; Melzer, M; Sas-Nowosielska, H; Kurczynska, E U

2014-03-01

334

OZONE DECREASES SPRING ROOT GROWTH AND ROOT CARBOHYDRATE CONTENT IN PONDEROSA PINE THE YEAR FOLLOWING EXPOSURE  

EPA Science Inventory

Storage carbohydrates are extremely important for new shoot and root development following dormancy or during periods of high stress. he hypothesis that ozone decreases carbohydrate storage and decreases new root growth during the year following exposure was investigated. eedling...

335

Essential oils from hairy root cultures and from plant roots of Achillea millefolium  

Microsoft Academic Search

The essential oils isolated from roots of two Achillea millefolium populations (BGL and CGA) and from two hairy root cultures (A4 and LBA) derived from one of these were analysed by GC and GC–mass spectrometry. The essential oils from the plant roots were obtained in a yield of 0.10% (BGL) and 0.05% (CGA) (v\\/w), whereas that of both hairy root

P. M. L Lourenço; A. C Figueiredo; J. G Barroso; L. G Pedro; M. M Oliveira; S. G Deans; J. J. C Scheffer

1999-01-01

336

ROOT LOCUS TECHNIQUE 325 7.6.2 DiscreteTime Root Locus Experiment  

E-print Network

ROOT LOCUS TECHNIQUE 325 7.6.2 Discrete­Time Root Locus Experiment Part 1. Give interpretation of the root locus rules from Table 7.1 in the context of discrete­time systems. Note that the imaginary axis(A,B,C,D,K) to draw the root locus for a fifth­order discrete­time model of a steam power control system considered

Gajic, Zoran

337

Root tip-dependent, active riboflavin secretion by Hyoscyamus albus hairy roots under iron deficiency  

Microsoft Academic Search

Hyoscyamus albus hairy roots with\\/without an exogenous gene (11 clones) were established by inoculation of Agrobacterium rhizogenes. All clones cultured under iron-deficient condition secreted riboflavin from the root tips into the culture medium and the productivity depended on the number and size of root tips among the clones. A decline of pH was observed before riboflavin production and root development.

Ataru Higa; Erika Miyamoto; Laiq ur Rahman; Yoshie Kitamura

2008-01-01

338

Root water uptake model based on water potential gradient with water redistribution via roots: application to coniferous forest site  

NASA Astrophysics Data System (ADS)

A simple macroscopic vertically distributed plant root water uptake (RWU) model based on traditional water-potential-gradient formulation (Vogel et al., 2013), in which the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow, was tested. This RWU modeling approach was implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation and used to simulate soil water distribution changes during a vegetation season at a forest site located in a temperate humid climate of central Europe. The main objectives were to test the ability of the presented RWU model to simulate the observed soil-plant-atmosphere interactions, and to examine the differences between empirical and more physically-based RWU modeling approaches (accommodated in the same soil water flow model). The tested RWU model was capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers was compensated for by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. Comparison of the model results with the sap flow observed reveals some limitations related to the quasi-steady-state assumption for the plant xylem and zero transpiration rates prescribed during nights and precipitation. This stated, the model seems to simulate adequately both the regular nightly hydraulic redistribution, due to reduced night transpiration, and the episodic daytime hydraulic redistribution during wet canopy events. The model results were compared to simulations produced using the semi-empirical RWU model of Feddes. Based on both an improved agreement between the observed and simulated soil water pressure responses to daily variations of transpiration, and a more realistic seasonal distribution of the transpiration rate reduction, we concluded that the physically based root water uptake model with negative RWU rates enabled substantially better approximation of the soil water extraction by spruce trees under moderate water scarcity. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, accepted.

Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir; Tesar, Miroslav

2013-04-01

339

Shoot-root defense signaling and activation of root defense by leaf damage in poplar  

Microsoft Academic Search

Shoot-root systemic defense signaling of hybrid poplar (Populus trichocarpa Torr. & A. Gray Populus del- toides Bartr. ex Marsh.) was investigated with molecular techniques to extend existing knowledge of poplar defense. Treat- ment of roots with methyl jasmonate demonstrated that transcripts of PtdTI3, a poplar trypsin inhibitor and marker of poplar defense responses, can be induced in poplar roots as

Ian T. Major; C. Peter Constabel

2007-01-01

340

Root diversity in alpine plants: root length, tensile strength and plant age  

NASA Astrophysics Data System (ADS)

A high diversity of plant species and functional groups is hypothesised to increase the diversity of root types and their subsequent effects for soil stability. However, even basic data on root characteristics of alpine plants are very scarce. Therefore, we determined important root characteristics of 13 plant species from different functional groups, i.e. grasses, herbs and shrubs. We excavated the whole root systems of 62 plants from a machine-graded ski slope at 2625 m a.s.l. and analysed the rooting depth, the horizontal root extension, root length and diameter. Single roots of plant species were tested for tensile strength. The age of herbs and shrubs was determined by growth-ring analysis. Root characteristics varied considerably between both plant species and functional groups. The rooting depth of different species ranged from 7.2 ± 0.97 cm to 20.5 ± 2.33 cm, but was significantly larger in the herb Geum reptans (70.8 ± 10.75 cm). The woody species Salix breviserrata reached the highest horizontal root extensions (96.8 ± 25.5 cm). Most plants had their longest roots in fine diameter classes (0.5

Pohl, M.; Stroude, R.; Körner, C.; Buttler, A.; Rixen, C.

2009-04-01

341

RootScan: Software for high-throughput analysis of root anatomical traits  

Technology Transfer Automated Retrieval System (TEKTRAN)

RootScan is a program for semi-automated image analysis of anatomical phenes in root cross-sections. RootScan uses pixel value thresholds to separate the cross-section from its background and to visually dissect it into tissue regions. Area measurements and object counts are performed within various...

342

Relations between Roots and Coefficients of Cubic Equations with One Root Negative the Reciprocal of Another  

ERIC Educational Resources Information Center

Under predetermined conditions on the roots and coefficients, necessary and sufficient conditions relating the coefficients of a given cubic equation x[cubed] + ax[squared] + bx + c = 0 can be established so that the roots possess desired properties. In this note, the condition for one root of a cubic equation to be "the negative reciprocal of…

Asiru, M. A.

2007-01-01

343

Inhibition of Auxin Movement from the Shoot into the Root Inhibits Lateral Root Development in Arabidopsis  

Microsoft Academic Search

In roots two distinct polar movements of auxin have been re- ported that may control different developmental and growth events. To test the hypothesis that auxin derived from the shoot and trans- ported toward the root controls lateral root development, the two polarities of auxin transport were uncoupled in Arabidopsis. Local application of the auxin-transport inhibitor naphthylphthalamic acid (NPA) at

Robyn C. Reed; Shari R. Brady; Gloria K. Muda

1998-01-01

344

Kinetics of short-term root-carbon mineralization in roots of biofuel crops in soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

To better understand and document the rates of root decomposition in biofuel cropping systems, we compared the evolution of CO2 from roots incubated with samples of two Iowa Mollisols. Root samples were collected from experimental plots for four cropping systems: a multispecies reconstructed prairie...

345

Human Root Caries: Microbiota in Plaque Covering Sound, Carious and Arrested Carious Root Surfaces  

Microsoft Academic Search

The plaque microbiota covering sound or carious root surfaces were studied and compared with that covering arrested root caries lesions. From each of these categories five extracted teeth were examined. The experimental design of the study allowed us to relate the qualitative and quantitative microbial composition to the degree of integrity of the root surface. Plaque was sampled by a

P. Schüpbach; V. Osterwalder; B. Guggenheim

1995-01-01

346

Regulation of shoot\\/root ratio by cytokinins from roots in Urtica dioica : Opinion  

Microsoft Academic Search

According to current knowledge, cytokinins are predominantly root-born phytohormones which are transported into the shoot by the transpiration stream. In the “hormone message concept” they are considered the root signals, which mediate the flux of the photosynthates to the various sinks of the plant. In this review, experiments are assessed, in which changes of the shoot to root ratio of

Erwin H. Beck

1996-01-01

347

Simulating root carbon storage with a coupled carbon — Water cycle root model  

Microsoft Academic Search

Is it possible to estimate carbon allocation to fine roots from the water demands of the vegetation? We assess this question by applying a root model which is based on optimisation principles. The model uses a new formulation of water uptake by fine roots, which is necessary to explicitly take into account the highly dynamic and non-steady process of water

A. Kleidon; M. Heimann

1996-01-01

348

ROOT CAUSE ANALYSIS PROGRAM MANUAL  

SciTech Connect

Root Cause Analysis (RCA) identifies the cause of an adverse condition that, if corrected, will preclude recurrence or greatly reduce the probability of recurrence of the same or similar adverse conditions and thereby protect the health and safety of the public, the workers, and the environment. This procedure sets forth the requirements for management determination and the selection of RCA methods and implementation of RCAs that are a result of significant findings from Price-Anderson Amendments Act (PAAA) violations, occurrences/events, Significant Adverse Conditions, and external oversight Corrective Action Requests (CARs) generated by the Office of Enforcement (PAAA headquarters), the U.S. Environmental Protection Agency, and other oversight entities against Lawrence Berkeley National Laboratory (LBNL). Performance of an RCA may result in the identification of issues that should be reported in accordance with the Issues Management Program Manual.

Gravois, Melanie C.

2007-05-02

349

Root-growth-inhibiting sheet  

DOEpatents

In accordance with this invention, a porous sheet material is provided at intervals with bodies of a polymer which contain a 2,6-dinitroaniline. The sheet material is made porous to permit free passage of water. It may be either a perforated sheet or a woven or non-woven textile material. A particularly desirable embodiment is a non-woven fabric of non-biodegradable material. This type of material is known as a geotextile'' and is used for weed control, prevention of erosion on slopes, and other landscaping purposes. In order to obtain a root repelling property, a dinitroaniline is blended with a polymer which is attached to the geotextile or other porous material.

Burton, F.G.; Cataldo, D.A.; Cline, J.F.; Skiens, W.E.; Van Voris, P.

1993-01-26

350

Image-Based High-Throughput Field Phenotyping of Crop Roots1[W][OPEN  

PubMed Central

Current plant phenotyping technologies to characterize agriculturally relevant traits have been primarily developed for use in laboratory and/or greenhouse conditions. In the case of root architectural traits, this limits phenotyping efforts, largely, to young plants grown in specialized containers and growth media. Hence, novel approaches are required to characterize mature root systems of older plants grown under actual soil conditions in the field. Imaging methods able to address the challenges associated with characterizing mature root systems are rare due, in part, to the greater complexity of mature root systems, including the larger size, overlap, and diversity of root components. Our imaging solution combines a field-imaging protocol and algorithmic approach to analyze mature root systems grown in the field. Via two case studies, we demonstrate how image analysis can be utilized to estimate localized root traits that reliably capture heritable architectural diversity as well as environmentally induced architectural variation of both monocot and dicot plants. In the first study, we show that our algorithms and traits (including 13 novel traits inaccessible to manual estimation) can differentiate nine maize (Zea mays) genotypes 8 weeks after planting. The second study focuses on a diversity panel of 188 cowpea (Vigna unguiculata) genotypes to identify which traits are sufficient to differentiate genotypes even when comparing plants whose harvesting date differs up to 14 d. Overall, we find that automatically derived traits can increase both the speed and reproducibility of the trait estimation pipeline under field conditions. PMID:25187526

Bucksch, Alexander; Burridge, James; York, Larry M.; Das, Abhiram; Nord, Eric; Weitz, Joshua S.; Lynch, Jonathan P.

2014-01-01

351

Iron- and ferritin-dependent reactive oxygen species distribution: impact on Arabidopsis root system architecture.  

PubMed

Iron (Fe) homeostasis is integrated with the production of reactive oxygen species (ROS), and distribution at the root tip participates in the control of root growth. Excess Fe increases ferritin abundance, enabling the storage of Fe, which contributes to protection of plants against Fe-induced oxidative stress. AtFer1 and AtFer3 are the two ferritin genes expressed in the meristematic zone, pericycle and endodermis of the Arabidopsis thaliana root, and it is in these regions that we observe Fe stained dots. This staining disappears in the triple fer1-3-4 ferritin mutant. Fe excess decreases primary root length in the same way in wild-type and in fer1-3-4 mutant. In contrast, the Fe-mediated decrease of lateral root (LR) length and density is enhanced in fer1-3-4 plants due to a defect in LR emergence. We observe that this interaction between excess Fe, ferritin, and root system architecture (RSA) is in part mediated by the H2O2/O2·(-) balance between the root cell proliferation and differentiation zones regulated by the UPB1 transcription factor. Meristem size is also decreased in response to Fe excess in ferritin mutant plants, implicating cell cycle arrest mediated by the ROS-activated SMR5/SMR7 cyclin-dependent kinase inhibitors pathway in the interaction between Fe and RSA. PMID:25624148

Reyt, Guilhem; Boudouf, Soukaina; Boucherez, Jossia; Gaymard, Frédéric; Briat, Jean-Francois

2015-03-01

352

Spatial separation of light perception and growth response in maize root phototropism  

NASA Technical Reports Server (NTRS)

Although the effects of gravity on root growth are well known and interactions between light and gravity have been reported, details of root phototropic responses are less documented. We used high-resolution image analysis to study phototropism in primary roots of Zea mays L. Similar to the location of perception in gravitropism, the perception of light was localized in the root cap. Phototropic curvature away from the light, on the other hand, developed in the central elongation zone, more basal than the site of initiation of gravitropic curvature. The phototropic curvature saturated at approximately 10 micromoles m-2 s-1 blue light with a peak curvature of 29 +/- 4 degrees, in part due to induction of positive gravitropism following displacement of the root tip from vertical during negative phototropism. However, at higher fluence rates, development of phototropic curvature is arrested even if gravitropism is avoided by maintaining the root cap vertically using a rotating feedback system. Thus continuous illumination can cause adaptation in the signalling pathway of the phototropic response in roots.

Mullen, J. L.; Wolverton, C.; Ishikawa, H.; Hangarter, R. P.; Evans, M. L.

2002-01-01

353

Copper regulates primary root elongation through PIN1-mediated auxin redistribution.  

PubMed

The heavy metal copper (Cu) is an essential microelement required for normal plant growth and development, but it inhibits primary root growth when in excess. The mechanism underlying how excess Cu functions in this process remains to be further elucidated. Here, we report that a higher concentration of CuSO4 inhibited primary root elongation of Arabidopsis seedlings by affecting both the elongation and meristem zones. In the meristem zone, meristematic cell division potential was reduced by excess Cu. Further experiments showed that Cu can modulate auxin distribution, resulting in higher auxin activities in both the elongation and meristem zones of Cu-treated roots based on DR5::GUS expression patterns. This Cu-mediated auxin redistribution was shown to be responsible for Cu-mediated inhibition of primary root elongation. Additional genetic and physiological data demonstrated that it was PINFORMED1 (PIN1), but not PIN2 or AUXIN1 (AUX1), that regulated this process. However, Cu-induced hydrogen peroxide accumulation did not contribute to Cu-induced auxin redistribution for inhibition of root elongation. When the possible role of ethylene in this process was analyzed, Cu had a similar impact on the root elongation of both the wild type and the ein2-1 mutant, implying that Cu-mediated inhibition of primary root elongation was not due to the ethylene signaling pathway. PMID:23396597

Yuan, Hong-Mei; Xu, Heng-Hao; Liu, Wen-Cheng; Lu, Ying-Tang

2013-05-01

354

Image-based high-throughput field phenotyping of crop roots.  

PubMed

Current plant phenotyping technologies to characterize agriculturally relevant traits have been primarily developed for use in laboratory and/or greenhouse conditions. In the case of root architectural traits, this limits phenotyping efforts, largely, to young plants grown in specialized containers and growth media. Hence, novel approaches are required to characterize mature root systems of older plants grown under actual soil conditions in the field. Imaging methods able to address the challenges associated with characterizing mature root systems are rare due, in part, to the greater complexity of mature root systems, including the larger size, overlap, and diversity of root components. Our imaging solution combines a field-imaging protocol and algorithmic approach to analyze mature root systems grown in the field. Via two case studies, we demonstrate how image analysis can be utilized to estimate localized root traits that reliably capture heritable architectural diversity as well as environmentally induced architectural variation of both monocot and dicot plants. In the first study, we show that our algorithms and traits (including 13 novel traits inaccessible to manual estimation) can differentiate nine maize (Zea mays) genotypes 8 weeks after planting. The second study focuses on a diversity panel of 188 cowpea (Vigna unguiculata) genotypes to identify which traits are sufficient to differentiate genotypes even when comparing plants whose harvesting date differs up to 14 d. Overall, we find that automatically derived traits can increase both the speed and reproducibility of the trait estimation pipeline under field conditions. PMID:25187526

Bucksch, Alexander; Burridge, James; York, Larry M; Das, Abhiram; Nord, Eric; Weitz, Joshua S; Lynch, Jonathan P

2014-10-01

355

Reconcilable differences: a joint calibration of fine-root turnover times with radiocarbon and minirhizotrons.  

PubMed

We used bomb-radiocarbon and raw minirhizotron lifetimes of fine roots (< 0.5 mm in diameter) in the organic layer of Norway spruce (Picea abies) forests in southern Sweden to test if different models are able to reconcile the apparently contradicting turnover time estimates from both techniques. We present a framework based on survival functions that is able to jointly model bomb-radiocarbon and minirhizotron data. At the same time we integrate prior knowledge about biases of both techniques--the classification of dead roots in minirhizotrons and the use of carbon reserves to grow new roots. Two-pool models, either in parallel or in serial setting, were able to reconcile the bomb-radiocarbon and minirhizotron data. These models yielded a mean residence time of 3.80 ± 0.16 yr (mean ± SD). On average 60 ± 2% of fine roots turned over within 0.75 ± 0.10 yr, while the rest was turning over within 8.4 ± 0.2 yr. Bomb-radiocarbon and minirhizotron data alone give a biased estimate of fine-root turnover. The two-pool models allow a mechanistic interpretation for the coexistence of fast- and slow-cycling roots--suberization and branching for the serial-two-pool model and branching due to ectomycorrhizal fungi-root interactions for the parallel-two-pool model. PMID:25196967

Ahrens, Bernhard; Hansson, Karna; Solly, Emily F; Schrumpf, Marion

2014-12-01

356

Pruning effects on root length density, root biomass, and arbuscular mycorrhizal colonization in two shrubs in a simulated xeric landscaped yard  

E-print Network

planted with six Leucophyllum frutescens I. M. Johnst. `Green CloudTM' (Texas sage) plants and six Nerium sample and three Nerium samples were discarded due to irrigation problems. Roots were washed free planted with six Leucophyllum frutescens I. M. Johnst. `Green CloudTM' (Texas sage) plants and six Nerium

Hall, Sharon J.

357

Effect of Root System Morphology on Root-sprouting and Shoot-rooting Abilities in 123 Plant Species from Eroded Lands in North-east Spain  

PubMed Central

• Background and Aims The objective of this study was to test whether the mean values of several root morphological variables were related to the ability to develop root-borne shoots and/or shoot-borne roots in a wide range of vascular plants. • Methods A comparative study was carried out on the 123 most common plant species from eroded lands in north-east Spain. After careful excavations in the field, measurements were taken of the maximum root depth, absolute and relative basal root diameter, specific root length (SRL), and the root depth/root lateral spread ratio on at least three individuals per species. Shoot-rooting and root-sprouting were observed in a large number of individuals in many eroded and sedimentary environments. The effect of life history and phylogeny on shoot-rooting and root-sprouting abilities was also analysed. • Key Results The species with coarse and deep tap-roots tended to be root-sprouting and those with fine, fasciculate and long main roots (which generally spread laterally), tended to be shoot-rooting. Phylogeny had an important influence on root system morphology and shoot-rooting and root-sprouting capacities. However, the above relations stood after applying analyses based on phylogenetically independent contrasts (PICs). • Conclusions The main morphological features of the root system of the study species are related to their ability to sprout from their roots and form roots from their shoots. According to the results, such abilities might only be functionally viable in restricted root system morphologies and ecological strategies. PMID:16790468

GUERRERO-CAMPO, JOAQUÍN; PALACIO, SARA; PÉREZ-RONTOMÉ, CARMEN; MONTSERRAT-MARTÍ, GABRIEL

2006-01-01

358

Plant root research: the past, the present and the future  

PubMed Central

This special issue is dedicated to root biologists past and present who have been exploring all aspects of root structure and function with an extensive publication record going over 100 years. The content of the Special Issue on Root Biology covers a wide scale of contributions, spanning interactions of roots with microorganisms in the rhizosphere, the anatomy of root cells and tissues, the subcellular components of root cells, and aspects of metal accumulation and stresses on root function and structure. We have organized the papers into three topic categories: (1) root ecology, interactions with microbes, root architecture and the rhizosphere; (2) experimental root biology, root structure and physiology; and (3) applications of new technology to study root biology. Finally, we will speculate on root research for the future. PMID:22966495

Lux, Alexander; Rost, Thomas L.

2012-01-01

359

Gene for a protein capable of enhancing lateral root formation.  

PubMed

Analysis of genes preferentially expressed in hairy roots caused by infection with Agrobacterium rhizogenes has provided insights into the regulation of lateral root formation. A hairy root preferential cDNA, HR7, has been cloned from hairy roots of Hyoscyamus niger. HR7 encodes a novel protein partially homologous to a metallocarboxypeptidase inhibitor and is expressed exclusively in the primordium and base of lateral roots in hairy roots. Overexpression of HR7 in transgenic roots of H. niger dramatically enhances the frequency of lateral root formation. The results of this study indicate that expression of HR7 plays a critical role in initiating lateral root formation. PMID:10356981

Mikami, Y; Horiike, G; Kuroyanagi, M; Noguchi, H; Shimizu, M; Niwa, Y; Kobayashi, H

1999-05-14

360

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones.  

PubMed

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite-granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of ?(18)O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil ?(18)O isotopic signature declined with depth, providing conditions for plant-soil ?(18)O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10-20 cm depth but broader under phyllite-granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

Isaac, Marney E; Anglaaere, Luke C N

2013-05-01

361

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones  

PubMed Central

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of ?18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil ?18O isotopic signature declined with depth, providing conditions for plant–soil ?18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

Isaac, Marney E; Anglaaere, Luke C N

2013-01-01

362

Simulation of root development based on the dielectric breakdown model  

Microsoft Academic Search

Knowing the root distribution in soil is essential for estimating water uptake by plant roots. It is difficult, however, to characterize and model undisturbed root systems. Root development in a two-dimensional potential field is simulated with the dielectric breakdown model (DBM), which implies a similarity between electric discharge and root distribution. A weighted potential gradient with an exponent rj was

O. HIROTA

1999-01-01

363

Simulation of root development based on the dielectric breakdown model  

Microsoft Academic Search

Knowing the root distribution in soil is essential for estimating water uptake by plant roots. It is difficult, however, to characterize and model undisturbed root systems. Root development in a two-dimensional potential field is simulated with the dielectric breakdown model (DBM), which implies a similarity between electric discharge and root distribution. A weighted potential gradient with an exponent ? was

J. CHIKUSHI; O. HIROTA

1998-01-01

364

PHYSICAL CHARACTERISTICS AND DRYING RATE OF ECHINACEA ROOT  

Microsoft Academic Search

Echinacea angustifolia or the purple coneflower is an important medicinal plant that boosts the immune system. It is believed that the active ingredients are predominantly located in the root. Physical characteristics and drying rates of the root of E. angustifolia from a farm in Saskatchewan, Canada were studied. Root consisted of a main (central) root and secondary root branches. Cleaned

Reza Kabganian; Danielle Julie Carrier; Shahab Sokhansanj

2002-01-01

365

Direct analysis of root zone data in a microculture system  

Microsoft Academic Search

The feasibility of using a whole plant microculture system coupled with image analysis to observe and quantify elusive root growth phenomena was demonstrated. Subtle differences in root initiation and growth rate for maple microcuttings inserted into three distinct rooting media were recurrently registered over the span of the rooting phase in terms of root length, number, and weighted density (equivalent

M. A. L. Smith; L. A. Spomer; M. T. McClelland

1990-01-01

366

Pitfalls and Opportunities: What Macroeconomists Should Know About Unit Roots  

Microsoft Academic Search

This paper is an introduction to unit root econometrics as applied in macroeconomics. The paper first discusses univariate time series analysis, emphasizing the following topics: alternative representations of unit root processes, unit root testing procedures, the power of unit root tests, and the interpretation of unit root econometrics in finite samples. A second part of the paper tackles similar issues

John Y. Campbell; Pierre Perron

1991-01-01

367

Correlation between cortical plate proximity and apical root resorption  

Microsoft Academic Search

Root resorption is one of the most common iatrogenic sequelae of orthodontic treatment. Recently, root contact with the labial or palatal cortical plate at root apex level during orthodontic tooth movement was reported to be related to root resorption, and dentofacial morphology was suggested to predispose certain persons to root contact with the cortical plate. In this study, we constructed

Akira Horiuchi; Hitoshi Hotokezaka; Kazuhide Kobayashi

1998-01-01

368

Management of Six Root Canals in Mandibular First Molar  

PubMed Central

Success in root canal treatment is achieved after thorough cleaning, shaping, and obturation of the root canal system. This clinical case describes conventional root canal treatment of an unusual mandibular first molar with six root canals. The prognosis for endodontic treatment in teeth with abnormal morphology is unfavorable if the clinician fails to recognize extra root canals. PMID:25685156

Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

2015-01-01

369

Metabolic Profiling of Root Exudates of Arabidopsis thaliana  

Microsoft Academic Search

In addition to accumulating biologically active chemicals, plant roots continuously produce and secrete compounds into their immediate rhizosphere. However, the mechanisms that drive and regulate root secretion of secondary metabolites are not fully understood. To enlighten two neglected areas of root biology, root secretion and secondary metabolism, an in vitro system implementing root-specific elicitation over a 48-day time course was

Travis S. Walker; Harsh Pal Bais; Kathleen M. Halligan; Frank R. Stermitz; Jorge M. Vivanco

2003-01-01

370

Cytological and ultrastructural studies on root tissues  

NASA Technical Reports Server (NTRS)

The anatomy and fine structure of roots from oat and mung bean seedlings, grown under microgravity conditions for 8 days aboard the Space Shuttle, was examined and compared to that of roots from ground control plants grown under similar conditions. Roots from both sets of oat seedlings exhibited characteristic monocotyledonous tissue organization and normal ultrastructural features, except for cortex cell mitochondria, which exhibited a 'swollen' morphology. Various stages of cell division were observed in the meristematic tissues of oat roots. Ground control and flight-grown mung bean roots also showed normal tissue organization, but root cap cells in the flight-grown roots were collapsed and degraded in appearance, especially at the cap periphery. At the ultrastructural level, these cells exhibited a loss of organelle integrity and a highly-condensed cytoplasm. This latter observation perhaps suggests a differing tissue sensitivity for the two species to growth conditions employed in space flight. The basis for abnormal root cap cell development is not understood, but the loss of these putative gravity-sensing cells holds potential significance for long term plant growth orientation during space flight.

Slocum, R. D.; Gaynor, J. J.; Galston, A. W.

1984-01-01

371

Large-scale production of hairy root.  

PubMed

Many products of interest are synthesized in organized tissues, but not formed in suspension or callus culture. Therefore, most attention has been focused on root cultures. The transgenic plant,"hairy root", has brought us to dramatic improvements in growth rate and high content of desirable products. Since the roots are quite different from callus in morphology, the culture manner should be explored independently. By providing a growth environment, an elite hairy root can be a more attractive plant. Both of strain selection to generate more competent plants in breeding and engineering development are necessary to overcome various limitations. In this chapter the engineering issues involved in using hairy root culture are discussed, as follows. 1. Measurement of cell concentration on line, and a designing bioreactors for hairy root in liquid culture. 2. High cell density culture and its kinetic parameters. 3. Secretion of target products. 4. The micropropagation of the regenerated hairy root by means of artificial seed system. In some cases where callus and suspension culture show negligible productivity, organ culture will be necessary to achieve good formation. This study on hairy root culture indicates one of the best attempts to the recovery of products from the organ culture in plant biotechnology. PMID:15453193

Uozumi, Nobuyuki

2004-01-01

372

Compounds from the roots of Jasminum sambac.  

PubMed

Four new compounds (+)-jasminoids A, B, C, and D, together with seven known compounds, were isolated from the roots of Jasminum sambac. Their structures were identified using spectroscopic methods. This study provides a better understanding to the chemical composition of J. sambac roots that have been thought to be one ingredient of an ancient prescription 'Ma-Fei-San'. PMID:23134371

Zeng, Lin-Hong; Hu, Min; Yan, Yong-Ming; Lu, Qing; Cheng, Yong-Xian

2012-01-01

373

MOLECULAR BASES OF ROOT DEFENSE RESPONSES.  

Technology Transfer Automated Retrieval System (TEKTRAN)

This review will focus on the molecular and genetic mechanisms underlying defense responses of roots to fungal pathogens. Soil-borne pathogens, including Phytophthora, Pythium, Fusarium, and Bipolaris, represent major sources of biotic stress in the rhizosphere and roots of plants. Molecular recog...

374

Nitric Oxide Is Required for Root Organogenesis  

Microsoft Academic Search

In this report, we demonstrate that nitric oxide (NO) mediates the auxin response leading the adven- titious root formation. A transient increase in NO concentration was shown to be required and to be part of the molecular events involved in adventitious root development induced by indole acetic acid (IAA). The discovery of signal molecules involved in the intricate network that

Gabriela Carolina Pagnussat; Marcela Simontacchi; Susana Puntarulo; Lorenzo Lamattina

2002-01-01

375

Root-L Geneaology Discussion List  

NSDL National Science Digital Library

ROOTS-L is a mailing list for genealogical researchers. Topics include surname queries, discussions of methodology and interesting genealogical web sites, etc. send email to: LISTSERV@MAIL.EWORLD.COM in the body of the message type: SUBSCRIBE ROOTS-L yourfirstname yourlastname

1987-01-01

376

Original article Micropropagation and ex vitro rooting  

E-print Network

Original article Micropropagation and ex vitro rooting of several clones of late-flushing Quercus-flushing Quercus robur trees were used as initial explants for micropropagation. From 60 acorns, 45 clones which / micropropagation / in vitro propagation / Ouercus/ ex vitro rooting Résumé — Micropropagation et enracinement

Paris-Sud XI, Université de

377

Micropropagation Factors affecting adventitious root formation  

E-print Network

Micropropagation Factors affecting adventitious root formation in microcuttings of Malus GJ De, la vitrification, la durée du cycle final de micropropagation et la concentration en acide indolebuty or by micropropagation. In the vegetative propagation of many crops, rooting of (micro)cuttings is the most crucial step

Boyer, Edmond

378

Method for Constructing Standardized Simulated Root Canals.  

ERIC Educational Resources Information Center

The construction of visual and manipulative aids, clear resin blocks with root-canal-like spaces, for simulation of root canals is explained. Time, materials, and techniques are discussed. The method allows for comparison of canals, creation of any configuration of canals, and easy presentation during instruction. (MSE)

Schulz-Bongert, Udo; Weine, Franklin S.

1990-01-01

379

Promotion of root elongation by phosphorus deficiency  

Microsoft Academic Search

Decrease of culture solution pH and increase in cation\\/anion ratio in the plant were observed when horsegram (Macrotyloma uniflorum (Lam.) Verdc.) was grown in solution culture deficient in phosphorus. The effux of H+ from the roots of ?P plants was observed in bromocresol purple agar. The length of root cells was considerably increased by ?P treatment. Thus a close correlation

M. Anuradha; A. Narayanan

1991-01-01

380

ADVANCING FINE ROOT RESEARCH WITH MINIRHIZOTRONS  

EPA Science Inventory

Minirhizotrons provide a nondestructive, in situ method for directly viewing and studying fine roots. Although many insights into fine roots have been gained using minirhizotrons, it is clear from the literature that there is still wide variation in how minirhizotrons and minirhi...

381

33 CFR 117.1095 - Root River.  

Code of Federal Regulations, 2013 CFR

...Navigable Waters 1 2013-07-01 2013-07-01 false Root River. 117.1095 Section 117.1095 Navigation and Navigable...REGULATIONS Specific Requirements Wisconsin § 117.1095 Root River. (a) The draw of the Main Street...

2013-07-01

382

33 CFR 117.1095 - Root River.  

Code of Federal Regulations, 2014 CFR

...Navigable Waters 1 2014-07-01 2014-07-01 false Root River. 117.1095 Section 117.1095 Navigation and Navigable...REGULATIONS Specific Requirements Wisconsin § 117.1095 Root River. (a) The draw of the Main Street...

2014-07-01

383

33 CFR 117.1095 - Root River.  

Code of Federal Regulations, 2011 CFR

...Navigable Waters 1 2011-07-01 2011-07-01 false Root River. 117.1095 Section 117.1095 Navigation and Navigable...REGULATIONS Specific Requirements Wisconsin § 117.1095 Root River. (a) The draw of the Main Street...

2011-07-01

384

Testing for unit roots in heterogeneous panels  

Microsoft Academic Search

This paper proposes unit root tests for dynamic heterogeneous panels based on the mean of individual unit root statistics. In particular it proposes a standardized t-bar test statistic based on the (augmented) Dickey–Fuller statistics averaged across the groups. Under a general setting this statistic is shown to converge in probability to a standard normal variate sequentially with T (the time

Kyung So Im; M. Hashem Pesaran; Yongcheol Shin

2003-01-01

385

Testing for Unit Roots in Heterogeneous Panels  

Microsoft Academic Search

This paper proposes unit root tests for dynamic heterogeneous panels based on the mean of individual unit root statistics. In particular it proposes a standardized t-bar test statistic based on the (augmented) Dickey-Fuller statistics averaged across the groups. Under a general setting this statistic is shown to converge in probability to a standard normal variate sequentially with T (the time

Kyung So Im; M. Hashem Pesaran; Yongcheol Shin

1997-01-01

386

Iron deficiency responses in roots of kiwi  

Microsoft Academic Search

Many dicotyledonous species respond to iron (Fe) deficiency by morphological and physiological changes at root level, which are usually defined as Strategy I. Particularly, these latter modifications include a higher acidification of the external medium and the induction of a high root Fe reductase activity. The aim of this work was to investigate the response of kiwi (Actinidia deliciosa cv.

Giannina Vizzotto; Ivica Matosevic; Roberto Pinton; Zeno Varanini; Guglielmo Costa

1997-01-01

387

ACETOGENIC BACTERIA ASSOCIATED WITH SEAGRASS ROOTS  

EPA Science Inventory

Seagrasses are adapted to being rooted in reduced, anoxic sediments with high rates of sulfate reduction. During the day, an oxygen gradient is generated around the roots, becoming anoxic at night. Thus, obligate anaerobic bacteria in the rhizosphere have to tolerate elevated oxy...

388

Thermal measurement of root surface temperatures during application of intracanal laser energy in vitro  

NASA Astrophysics Data System (ADS)

The use of laser energy to clean, shape, and sterilize a root canal system space involves the generation of heat due to the thermal effect of the laser on the organic tissue contents and dentin walls of that space. If heat generation is above physiologic levels, irreparable damage may occur to the periodontal ligament and surrounding bone. This study measured temperature rise on the outer root surfaces of extracted teeth during intracanal laser exposure. Thirty single rooted, recently extracted teeth free of caries and restorations were accessed pulps extirpated and divided into three groups. Each root canal system was treated with a 1.06 micrometers pulsed Nd:YAG laser with quartz contact probes. Temperatures were recorded for all surfaces (mesial distal, buccal, lingual, apical) with infrared thermography utilizing a detector response time of 1 (mu) sec, sensitivity range (infrared) of 8 to 12 micrometers and a scan rate of 30 frames/sec.

Goodis, Harold E.; White, Joel M.; Neev, Joseph

1993-07-01

389

Tissue engineering in endodontics: root canal revascularization.  

PubMed

Root canal revascularization attempts to make necrotic tooth alive by the use of certain simple clinical protocols. Earlier apexification was the treatment of choice for treating and preserving immature permanent teeth that have lost pulp vitality. This procedure promoted the formation of apical barrier to seal the root canal of immature teeth and nonvital filling materials contained within root canal space. However with the success of root canal revascularization to regenerate the pulp dentin complex of necrotic immature tooth has made us to rethink if apexification is at the beginning of its end. The objective of this review is to discuss the new concepts of tissue engineering in endodontics and the clinical steps of root canal revascularization. PMID:25571677

Palit Madhu Chanda; Hegde, K Sundeep; Bhat, Sham S; Sargod, Sharan S; Mantha, Somasundar; Chattopadhyay, Sayan

2014-01-01

390

Effect of lead on root growth  

PubMed Central

Lead (Pb) is one of the most widespread heavy metal contaminant in soils. It is highly toxic to living organisms. Pb has no biological function but can cause morphological, physiological, and biochemical dysfunctions in plants. Plants have developed a wide range of tolerance mechanisms that are activated in response to Pb exposure. Pb affects plants primarily through their root systems. Plant roots rapidly respond either (i) by the synthesis and deposition of callose, creating a barrier that stops Pb entering (ii) through the uptake of large amounts of Pb and its sequestration in the vacuole accompanied by changes in root growth and branching pattern or (iii) by its translocation to the aboveground parts of plant in the case of hyperaccumulators plants. Here we review the interactions of roots with the presence of Pb in the rhizosphere and the effect of Pb on the physiological and biochemical mechanisms of root development. PMID:23750165

Fahr, Mouna; Laplaze, Laurent; Bendaou, Najib; Hocher, Valerie; Mzibri, Mohamed El; Bogusz, Didier; Smouni, Abdelaziz

2013-01-01

391

How roots perceive and respond to gravity  

NASA Technical Reports Server (NTRS)

Graviperception by plant roots is believed to occur via the sedimentation of amyloplasts in columella cells of the root cap. This physical stimulus results in an accumulation of calcium on the lower side of the cap, which in turn induces gravicurvature. In this paper we present a model for root gravitropism integrating gravity-induced changes in electrical potential, cytochemical localization of calcium in cells of gravistimulated roots, and the interdependence of calcium and auxin movement. Key features of the model are that 1) gravity-induced redistribution of calcium is an early event in the transduction mechanism, and 2) apoplastic movement of calcium through the root-cap mucilage may be an important component of the pathway for calcium movement.

Moore, R.; Evans, M. L.

1986-01-01

392

Long-term control of root growth  

DOEpatents

A method and system for long-term control of root growth without killing the plants bearing those roots involves incorporating a 2,6-dinitroaniline in a polymer and disposing the polymer in an area in which root control is desired. This results in controlled release of the substituted aniline herbicide over a period of many years. Herbicides of this class have the property of preventing root elongation without translocating into other parts of the plant. The herbicide may be encapsulated in the polymer or mixed with it. The polymer-herbicide mixture may be formed into pellets, sheets, pipe gaskets, pipes for carrying water, or various other forms. The invention may be applied to other protection of buried hazardous wastes, protection of underground pipes, prevention of root intrusion beneath slabs, the dwarfing of trees or shrubs and other applications. The preferred herbicide is 4-difluoromethyl-N,N-dipropyl-2,6-dinitro-aniline, commonly known as trifluralin.

Burton, Frederick G. (West Richland, WA); Cataldo, Dominic A. (Kennewick, WA); Cline, John F. (Prosser, WA); Skiens, W. Eugene (Richland, WA)

1992-05-26

393

Clinical management of infected root canal dentin.  

PubMed

Several hundred different species of bacteria are present in the human intraoral environment. Bacterial penetration of root canal dentin occurs when bacteria invade the root canal system. These bacteria may constitute a reservoir from which root canal reinfection may occur during or after endodontic treatment. The learning objective of this article is to review endodontic microbiology, update readers on the role of bacteria in pulp and periapical disease, and discuss the principles of management of infected root canal dentin. Complete debridement, removal of microorganisms and affected dentin, and chemomechanical cleansing of the root canal are suggested as being the cornerstones of successful endodontic therapy, followed by intracanal medication to remove residual bacteria, when required. PMID:9242125

Love, R M

1996-08-01

394

Biological effects due to weak magnetic fields on plants  

NASA Astrophysics Data System (ADS)

In the evolution process, living organisms have experienced the action of the Earth's magnetic field (MF) that is a natural component of our environment. It is known that a galactic MF induction does not exceed 0.1 nT, since investigations of weak magnetic field (WMF) effects on biological systems have attracted attention of biologists due to planning long-term space flights to other planets where the magnetizing force is near 10-5 Oe. However, the role of WMF and its influence on organisms' functioning are still insufficiently investigated. A large number of experiments with seedlings of different plant species placed in WMF has found that the growth of their primary roots is inhibited during the early terms of germination in comparison with control. The proliferation activity and cell reproduction are reduced in meristem of plant roots under WMF application. The prolongation of total cell reproductive cycle is registered due to the expansion of G phase in1 different plant species as well as of G phase in flax and lentil roots along with2 relative stability of time parameters of other phases of cell cycle. In plant cells exposed to WMF, the decrease in functional activity of genome at early prereplicate period is shown. WMF causes the intensification in the processes of proteins' synthesis and break-up in plant roots. Qualitative and quantitative changes in protein spectrum in growing and differentiated cells of plant roots exposed to WMF are revealed. At ultrastructural level, there are observed such ultrastructural peculiarities as changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells of pea roots exposed to WMF. Mitochondria are the most sensitive organelle to WMF application: their size and relative volume in cells increase, matrix is electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to WMF show the Ca2 + oversaturation both in all organelles and in a hyaloplasm of the cells unlike the control ones. The data presented suggest that prolonged plant exposures to WMF may cause different biological effects at the cellular, tissue and organ level. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca 2 + homeostasis. The understanding of the fundamental mechanisms and sites of interactions between WMF and biological systems are complex and still deserve strong efforts, particular addressed to basic principles of coupling between field energy and biomolecules.

Belyavskaya, N.

395

Anatomical and hydraulic properties of sorghum roots exposed to water deficit. [Sorghum bicolor  

SciTech Connect

The effects of a severe water stress in the upper 0-0.15 m rooting zone on development of the exodermis, endodermis and xylem and on radial (Lp) and axial (Ls) hydraulic conductances were studied for Sorghum bicolor. Lp and Lx were based on water flow rates obtained by applying a negative hydrostatic pressure to the proximal xylem ends of excised roots placed in aerated nutrient solution. The same roots were stained with fluorescent berberine and acid phloroglucinol to describe the development of the exodermal and endodermal cell walls from formation of the Casparian band (State I), to deposition of suberin lamellae (State II), and lignification (State III). Lp of 1.5 {times} 10{sup {minus}11} m{sup 3}s{sup {minus}1}MPa{sup {minus}1} was 80% lower in stressed roots than in unstressed controls. At 0.01 and 0.07 m from the root apex, stressed roots were in State III while control roots were in States I and II, respectively. SEM-image analysis for stressed roots indicated that in the exodermis a greater proportion of the cross sectional area was occupied by lignified walls than in the endodermis. Cellufluor, an apoplastic tracer, was blocked at the lignified exodermis even at 0.01 m from the apex in stressed roots. Uranin, a symplastic tracer, was taken up only in the apical region in stressed roots but farther from the apex in the controls. Lx of 7.1 {times} 10{sup {minus}11}m{sup 3}s{sup {minus}1}MPa{sup {minus}1} was 90% lower in stressed roots compared with the controls. Cellufluor test and image analysis showed that although the protoxylem and early metaxylem were conductive in both treatments, stress caused more than a 50% reduction in the diameter of the xylem elements. Results suggest that lignification of the exodermis and endodermis to a large extent decreased apoplastic and symplastic flows and hence Lp in stressed roots. The low Lx in stressed roots was due to a decrease in the diameters of the conductive xylem elements.

Cruz, R.T.; Jordan, W.R.; Drew, M.C. (Texas A and M Univ., College Station (United States))

1991-05-01

396

Aetiology, incidence and morphology of the C-shaped root canal system and its impact on clinical endodontics  

PubMed Central

The C-shaped root canal constitutes an unusual root morphology that can be found primarily in mandibular second permanent molars. Due to the complexity of their structure, C-shaped root canal systems may complicate endodontic interventions. A thorough understanding of root canal morphology is therefore imperative for proper diagnosis and successful treatment. This review aims to summarize current knowledge regarding C-shaped roots and root canals, from basic morphology to advanced endodontic procedures. To this end, a systematic search was conducted using the MEDLINE, BIOSIS, Cochrane Library, EMBASE, Google Scholar, Web of Science, PLoS and BioMed Central databases, and many rarely cited articles were included. Furthermore, four interactive 3D models of extracted teeth are introduced that will allow for a better understanding of the complex C-shaped root canal morphology. In addition, the present publication includes an embedded best-practice video showing an exemplary root canal procedure on a tooth with a pronounced C-shaped root canal. The survey of this unusual structure concludes with a number of suggestions concerning future research efforts. PMID:24483229

Kato, A; Ziegler, A; Higuchi, N; Nakata, K; Nakamura, H; Ohno, N

2014-01-01

397

Aetiology, incidence and morphology of the C-shaped root canal system and its impact on clinical endodontics.  

PubMed

The C-shaped root canal constitutes an unusual root morphology that can be found primarily in mandibular second permanent molars. Due to the complexity of their structure, C-shaped root canal systems may complicate endodontic interventions. A thorough understanding of root canal morphology is therefore imperative for proper diagnosis and successful treatment. This review aims to summarize current knowledge regarding C-shaped roots and root canals, from basic morphology to advanced endodontic procedures. To this end, a systematic search was conducted using the MEDLINE, BIOSIS, Cochrane Library, EMBASE, Google Scholar, Web of Science, PLoS and BioMed Central databases, and many rarely cited articles were included. Furthermore, four interactive 3D models of extracted teeth are introduced that will allow for a better understanding of the complex C-shaped root canal morphology. In addition, the present publication includes an embedded best-practice video showing an exemplary root canal procedure on a tooth with a pronounced C-shaped root canal. The survey of this unusual structure concludes with a number of suggestions concerning future research efforts. PMID:24483229

Kato, A; Ziegler, A; Higuchi, N; Nakata, K; Nakamura, H; Ohno, N

2014-11-01

398

Direct and indirect effects of glomalin, mycorrhizal hyphae, and roots on aggregate stability in rhizosphere of trifoliate orange.  

PubMed

To test direct and indirect effects of glomalin, mycorrhizal hyphae, and roots on aggregate stability, perspex pots separated by 37-?m nylon mesh in the middle were used to form root-free hyphae and root/hyphae chambers, where trifoliate orange (Poncirus trifoliata) seedlings were colonized by Funneliformis mosseae or Paraglomus occultum in the root/hyphae chamber. Both fungal species induced significantly higher plant growth, root total length, easily-extractable glomalin-related soil protein (EE-GRSP) and total GRSP (T-GRSP), and mean weight diameter (an aggregate stability indicator). The Pearson correlation showed that root colonization or soil hyphal length significantly positively correlated with EE-GRSP, difficultly-extractable GRSP (DE-GRSP), T-GRSP, and water-stable aggregates in 2.00-4.00, 0.50-1.00, and 0.25-0.50 mm size fractions. The path analysis indicated that in the root/hyphae chamber, aggregate stability derived from a direct effect of root colonization, EE-GRSP or DE-GRSP. Meanwhile, the direct effect was stronger by EE-GRSP or DE-GRSP than by mycorrhizal colonization. In the root-free hyphae chamber, mycorrhizal-mediated aggregate stability was due to total effect but not direct effect of soil hyphal length, EE-GRSP and T-GRSP. Our results suggest that GRSP among these tested factors may be the primary contributor to aggregate stability in the citrus rhizosphere. PMID:25059396

Wu, Qiang-Sheng; Cao, Ming-Qin; Zou, Ying-Ning; He, Xin-hua

2014-01-01

399

Phytotoxic allelochemicals from roots and root exudates of Trifolium pratense.  

PubMed

Trifolium pratense, a widespread legume forage plant, is reported to exhibit phytotoxic activity on other plants, but the active metabolites have not been clarified so far. A bioassay-guided fractionation of the root extracts led to the isolation of five isoflavonoids, which were elucidated by spectroscopic analysis. All of the purified compounds observably showed phytotoxic activities against Arabidopsis thaliana . Moreover, the inhibitory effects were concentration-dependent. The furan ring linked at C-4 and C-2' positions by an oxygen atom and a 1,3-dioxolane at C-4' and C-5' positions are considered to be critical factors for the phytotoxic activity. The concentrations of (6aR,11aR)-maackiain and (6aR,11aR)-trifolirhizin, concluded to be allelochemicals from soil around plants of T. pratense, were determined by HPLC and LC-MS to be 4.12 and 2.37 ?g/g, respectively. These allelochemicals, which showed remarkable activities against the weed Poa annua may play an important role in assisting the widespread occurrence of T. pratense in nature. PMID:23738849

Liu, Quan; Xu, Rui; Yan, Zhiqiang; Jin, Hui; Cui, Haiyan; Lu, Liqin; Zhang, Denghong; Qin, Bo

2013-07-01

400

Hydrogen peroxide staining to visualize intracellular bacterial infections of seedling root cells.  

PubMed

Visualization of bacteria in living plant cells and tissues is often problematic due to lack of stains that pass through living plant cell membranes and selectively stain bacterial cells. In this article, we report the use of 3,3'-diaminobenzidine tetrachloride (DAB) to stain hydrogen peroxide associated with bacterial invasion of eukaryotic cells. Tissues were counterstained with aniline blue/lactophenol to stain protein in bacterial cells. Using this staining method to visualize intracellular bacterial (Burkholderia gladioli) colonization of seedling roots of switch grass (Panicum virgatum), we compared bacterial free seedling roots and those inoculated with the bacterium. To further assess application of the technique in multiple species of vascular plants, we examined vascular plants for seedling root colonization by naturally occurring seed-transmitted bacteria. Colonization by bacteria was only observed to occur within epidermal (including root hairs) and cortical cells of root tissues, suggesting that bacteria may not be penetrating deeply into root tissues. DAB/peroxidase with counter stain aniline blue/lactophenol was effective in penetration of root cells to selectively stain bacteria. Furthermore, this stain combination permitted the visualization of the bacterial lysis process. Before any evidence of H2 O2 staining, intracellular bacteria were seen to stain blue for protein content with aniline blue/lactophenol. After H2 O2 staining became evident, bacteria were often swollen, without internal staining by aniline blue/lactophenol; this suggests loss of protein content. This staining method was effective for seedling root tissues; however, it was not effective at staining bacteria in shoot tissues due to poor penetration. PMID:24825573

White, James F; Torres, Mónica S; Somu, Mohini P; Johnson, Holly; Irizarry, Ivelisse; Chen, Qiang; Zhang, Ning; Walsh, Emily; Tadych, Mariusz; Bergen, Marshall

2014-08-01

401

On the occurrence of adventitious branch roots on root axes of trees.  

PubMed

Based on positive results for 11 of 17 species included in an anatomical survey of tree roots, we concluded that the origin of adventitious branch roots (ABR) on established, undisturbed woody parental root axes is a widespread occurrence. ABR were morphologically indistinguishable from branch roots formed in primary tissues of a parental axis, and they occurred without increase in branch root density. We concluded that ABR are an unrecognized component of undamaged root systems. Using continuous serial sectioning to perform a census of branch roots within parental root axes, we obtained definitive evidence that ABR participate in root turnover. Comparisons of older and younger axes, and the chronology of root formation in older axes fulfilled the expectation that with greater age of parental axis, ABR become increasingly predominant among intact branch roots. We confirmed this trend for one of the species scoring negative in the survey, which means that our survey results were probably influenced by age variation. Thus, any of the six negative results obtained in the survey may have been dependent on the young age and slenderness of the axes that were available for examination in those six species. PMID:21652460

Paolillo, Dominick J; Bassuk, Nina L

2005-05-01

402

EFFECT OF ROOT TEMPERATURE ON SINK STRENGTH OF TUBEROUS ROOT IN SWEET POTATO PLANTS (IPOMOEA BATATAS LAM.)  

Microsoft Academic Search

EGUCHI T,. KITANO M. and EGUCHI H. Effect of root temperature on sink strength of tuberous root in sweet potato plants (Ipomoea batatas Lam.). BIOTRONICS 23, 75-80, 1994. Eflect of root temperature on sink strength of tuberous root in sweet potato plants was examined at root temperatures of 20 to 32°C under a constant air condition of 28°C and 70%

T. EGUCHI; M. KITANO; H. EGUCHI

403

Changes in Root Surface Area, Nutrient Absorption Activity, and Root Carbohydrate Concentration during Crop Cycles of Rosa hybrida  

E-print Network

73 Changes in Root Surface Area, Nutrient Absorption Activity, and Root Carbohydrate Concentration, Rural Development Administration, Suwon 441-707, Korea Keywords: roses, cut flowers, root growth, root maturity. The objective of this experiment was to determine how root surface area (RSA), N, P, K absorption

Lieth, J. Heinrich

404

Essential Role of Osterix for Tooth Root but not Crown Dentin Formation.  

PubMed

Tooth is made of crown and root. It is widely believed that dentin formation in crown and root uses the same regulatory mechanism. However, identification of nuclear factor 1?C (NFIC)'s unique function in determining root but not crown dentin formation challenges the old thinking. In searching for the target molecules downstream of NFIC, we unexpectedly found a sharp reduction of osterix (OSX), the key transcription factor in skeleton formation, in the Nfic knockout (Nfic-KO) tooth root. We then demonstrated a dose-dependent increase of Osx in the odontoblast cell line due to a transient transfection of Nfic expression plasmid. Studies of global and conditional Osx-KO mice revealed no apparent changes in the crown dentin tubules and dentin matrix. However, the OSX conditional KO (cKO) mice (crossed to the 2.3-kb collagen type 1 [Col1]-Cre) displayed an increase in cell proliferation but great decreases in expressions of root dentin matrix proteins (dentin matrix protein 1 [DMP1] and dentin sialophosphoprotein [DSPP]), leading to an inhibition in odontoblast differentiation, and short, thin root dentin with few dentin tubules. Compared to the Nfic-KO tooth, which contains essentially no dentin tubules and remains in a "root-less" status at adult stages, the Osx-cKO root phenotype had partially improved at the late stage, indicating that other factors can compensate for OSX function. Thus, we conclude that OSX, one of the key downstream molecules of NFIC, plays a critical role in root, but not crown, formation. © 2014 American Society for Bone and Mineral Research. PMID:25349111

Zhang, Hua; Jiang, Yong; Qin, Chunlin; Liu, Ying; Ho, Sunita P; Feng, Jian Q

2015-04-01

405

Photosynthesis of Root Chloroplasts Developed in Arabidopsis Lines Overexpressing GOLDEN2-LIKE Transcription Factors  

PubMed Central

In plants, genes involved in photosynthesis are encoded separately in nuclei and plastids, and tight cooperation between these two genomes is therefore required for the development of functional chloroplasts. Golden2-like (GLK) transcription factors are involved in chloroplast development, directly targeting photosynthesis-associated nuclear genes for up-regulation. Although overexpression of GLKs leads to chloroplast development in non-photosynthetic organs, the mechanisms of coordination between the nuclear gene expression influenced by GLKs and the photosynthetic processes inside chloroplasts are largely unknown. To elucidate the impact of GLK-induced expression of photosynthesis-associated nuclear genes on the construction of photosynthetic systems, chloroplast morphology and photosynthetic characteristics in greenish roots of Arabidopsis thaliana lines overexpressing GLKs were compared with those in wild-type roots and leaves. Overexpression of GLKs caused up-regulation of not only their direct targets but also non-target nuclear and plastid genes, leading to global induction of chloroplast biogenesis in the root. Large antennae relative to reaction centers were observed in wild-type roots and were further enhanced by GLK overexpression due to the increased expression of target genes associated with peripheral light-harvesting antennae. Photochemical efficiency was lower in the root chloroplasts than in leaf chloroplasts, suggesting that the imbalance in the photosynthetic machinery decreases the efficiency of light utilization in root chloroplasts. Despite the low photochemical efficiency, root photosynthesis contributed to carbon assimilation in Arabidopsis. Moreover, GLK overexpression increased CO2 fixation and promoted phototrophic performance of the root, showing the potential of root photosynthesis to improve effective carbon utilization in plants. PMID:23749810

Kobayashi, Koichi; Sasaki, Daichi; Noguchi, Ko; Fujinuma, Daiki; Komatsu, Hirohisa; Kobayashi, Masami; Sato, Mayuko; Toyooka, Kiminori; Sugimoto, Keiko; Niyogi, Krishna K.; Wada, Hajime; Masuda, Tatsuru

2013-01-01

406

Do ectomycorrhizal and arbuscular mycorrhizal temperate tree species systematically differ in root order-related fine root morphology and biomass?  

PubMed Central

While most temperate broad-leaved tree species form ectomycorrhizal (EM) symbioses, a few species have arbuscular mycorrhizas (AM). It is not known whether EM and AM tree species differ systematically with respect to fine root morphology, fine root system size and root functioning. In a species-rich temperate mixed forest, we studied the fine root morphology and biomass of three EM and three AM tree species from the genera Acer, Carpinus, Fagus, Fraxinus, and Tilia searching for principal differences between EM and AM trees. We further assessed the evidence of convergence or divergence in root traits among the six co-occurring species. Eight fine root morphological and chemical traits were investigated in root segments of the first to fourth root order in three different soil depths and the relative importance of the factors root order, tree species and soil depth for root morphology was determined. Root order was more influential than tree species while soil depth had only a small effect on root morphology All six species showed similar decreases in specific root length and specific root area from the 1st to the 4th root order, while the species patterns differed considerably in root tissue density, root N concentration, and particularly with respect to root tip abundance. Most root morphological traits were not significantly different between EM and AM species (except for specific root area that was larger in AM species), indicating that mycorrhiza type is not a key factor influencing fine root morphology in these species. The order-based root analysis detected species differences more clearly than the simple analysis of bulked fine root mass. Despite convergence in important root traits among AM and EM species, even congeneric species may differ in certain fine root morphological traits. This suggests that, in general, species identity has a larger influence on fine root morphology than mycorrhiza type. PMID:25717334

Kubisch, Petra; Hertel, Dietrich; Leuschner, Christoph

2015-01-01

407

Root phenology at Harvard Forest and beyond  

NASA Astrophysics Data System (ADS)

Roots are hidden from view and heterogeneously distributed making them difficult to study in situ. As a result, the causes and timing of root production are not well understood. Researchers have long assumed that above and belowground phenology is synchronous; for example, most parameterizations of belowground carbon allocation in terrestrial biosphere models are based on allometry and represent a fixed fraction of net C uptake. However, using results from metaanalysis as well as empirical data from oak and hemlock stands at Harvard Forest, we show that synchronous root and shoot growth is the exception rather than the rule. We collected root and shoot phenology measurements from studies across four biomes (boreal, temperate, Mediterranean, and subtropical). General patterns of root phenology varied widely with 1-5 production peaks in a growing season. Surprisingly, in 9 out of the 15 studies, the first root production peak was not the largest peak. In the majority of cases maximum shoot production occurred before root production (Offset>0 in 32 out of 47 plant sample means). The number of days offset between maximum root and shoot growth was negatively correlated with median annual temperature and therefore differs significantly across biomes (ANOVA, F3,43=9.47, p<0.0001). This decline in offset with increasing temperature may reflect greater year-round coupling between air and soil temperature in warm biomes. Growth form (woody or herbaceous) also influenced the relative timing of root and shoot growth. Woody plants had a larger range of days between root and shoot growth peaks as well as a greater number of growth peaks. To explore the range of phenological relationships within woody plants in the temperate biome, we focused on above and belowground phenology in two common northeastern tree species, Quercus rubra and Tsuga canadensis. Greenness index, rate of stem growth, root production and nonstructural carbohydrate content were measured beginning in April 2012 through August 2013 at the Harvard Forest in Petersham, MA, USA. Greenness and stem growth were highest in late May and early June with one clear maximum growth period. In contrast, root growth was characterized by multiple production peaks. Q. rubra root growth experienced many small flushes around day of year (DOY) 156 (early June) and one large peak on 234 (late August). T. canadensis root growth peaked on DOY 188 (early July), 234.5 (late August) and 287 (mid-October). However, particular phenological patterns varied widely from site to site. Despite large spatial heterogeneity, it appears that Q. rubra experiences greater overall root production as well as more allocation to roots during the growing season. The storage pool of nonstructural carbohydrates experiences a mid-summer drawdown in Q. rubra but not T. canadensis roots. Timing of belowground C allocation to root growth and nonstructural carbohydrate accumulation may be regulated by climate factors as well as endogenous factors such as vessel size, growth form, or tradeoffs in C allocated between plant organs. Plant roots supply substrate to microbial communities and hence their production feeds back to other plant and soil processes that affect ecosystem C fluxes.

Abramoff, R. Z.; Finzi, A.

2013-12-01

408

iRootHair: A Comprehensive Root Hair Genomics Database1[W  

PubMed Central

The specialized root epidermis cells of higher plants produce long, tubular outgrowths called root hairs. Root hairs play an important role in nutrient and water uptake, and they serve as a valuable model in studies of plant cell morphogenesis. More than 1,300 articles that describe the biological processes of these unique cells have been published to date. As new fields of root hair research are emerging, the number of new papers published each year and the volumes of new relevant data are continuously increasing. Therefore, there is a general need to facilitate studies on root hair biology by collecting, presenting, and sharing the available information in a systematic, curated manner. Consequently, in this paper, we present a comprehensive database of root hair genomics, iRootHair, which is accessible as a Web-based service. The current version of the database includes information about 153 root hair-related genes that have been identified to date in dicots and monocots along with their putative orthologs in higher plants with sequenced genomes. In order to facilitate the use of the iRootHair database, it is subdivided into interrelated, searchable sections that describe genes, processes of root hair formation, root hair mutants, and available references. The database integrates bioinformatics tools with a focus on sequence identification and annotation. iRootHair is a unique resource for root hair research that integrates the large volume of data related to root hair genomics in a single, curated, and expandable database that is freely available at www.iroothair.org. PMID:23129204

Kwasniewski, Miroslaw; Nowakowska, Urszula; Szumera, Jakub; Chwialkowska, Karolina; Szarejko, Iwona

2013-01-01

409

Variation of the Linkage of Root Function with Root Branch Order  

PubMed Central

Mounting evidence has shown strong linkage of root function with root branch order. However, it is not known whether this linkage is consistent in different species. Here, root anatomic traits of the first five branch order were examined in five species differing in plant phylogeny and growth form in tropical and subtropical forests of south China. In Paramichelia baillonii, one tree species in Magnoliaceae, the intact cortex as well as mycorrhizal colonization existed even in the fifth-order root suggesting the preservation of absorption function in the higher-order roots. In contrast, dramatic decreases of cortex thickness and mycorrhizal colonization were observed from lower- to higher-order roots in three other tree species, Cunninghamia lanceolata, Acacia auriculiformis and Gordonia axillaries, which indicate the loss of absorption function. In a fern, Dicranopteris dichotoma, there were several cortex layers with prominently thickened cell wall and no mycorrhizal colonization in the third- and fourth-order roots, also demonstrating the loss of absorptive function in higher-order roots. Cluster analysis using these anatomic traits showed a different classification of root branch order in P. baillonii from other four species. As for the conduit diameter-density relationship in higher-order roots, the mechanism underpinning this relationship in P. baillonii was different from that in other species. In lower-order roots, different patterns of coefficient of variance for conduit diameter and density provided further evidence for the two types of linkage of root function with root branch order. These linkages corresponding to two types of ephemeral root modules have important implication in the prediction of terrestrial carbon cycling, although we caution that this study was pseudo-replicated. Future studies by sampling more species can test the generality of these two types of linkage. PMID:23451168

Chen, Zhengxia; Zeng, Hui

2013-01-01

410

Transcript expression profiling for adventitious roots of Panax ginseng Meyer.  

PubMed

Panax ginseng Meyer is one of the major medicinal plants in oriental countries belonging to the Araliaceae family which are the primary source for ginsenosides. However, very few genes were characterized for ginsenoside pathway, due to the limited genome information. Through this study, we obtained a comprehensive transcriptome from adventitious roots, which were treated with methyl jasmonic acids for different time points (control, 2h, 6h, 12h, and 24h) and sequenced by RNA 454 pyrosequencing technology. Reference transcriptome 39,304,529 (0.04GB) was obtained from 5,724,987,880 bases (5.7GB) of 22 libraries by de novo assembly and 35,266 (58.5%) transcripts were annotated with biological schemas (GO and KEGG). The digital gene expression patterns were obtained from in vitro grown adventitious root sequences which mapped to reference, from that, 3813 (6.3%) unique transcripts were involved in ?2 fold up and downregulations. Finally, candidates for ginsenoside pathway genes were predicted from observed expression patterns. Among them, 30 transcription factors, 20 cytochromes, and 11 glycosyl transferases were predicted as ginsenoside candidates. These data can remarkably expand the existing transcriptome resources of Panax, especially to predict existence of gene networks in P. ginseng. The entity of the data provides a valuable platform to reveal more on secondary metabolism and abiotic stresses from P. ginseng in vitro grown adventitious roots. PMID:24831831

Subramaniyam, Sathiyamoorthy; Mathiyalagan, Ramya; Natarajan, Sathishkumar; Kim, Yu-Jin; Jang, Moon-Gi; Park, Jun-Hyung; Yang, Deok Chun

2014-08-01

411

Characterization of a chondroitin sulfate hydrogel for nerve root regeneration  

NASA Astrophysics Data System (ADS)

Brachial plexus injury is a serious medical problem that affects many patients annually, with most cases involving damage to the nerve roots. Therefore, a chondroitin sulfate hydrogel was designed to both serve as a scaffold for regenerating root neurons and deliver neurotrophic signals. Capillary electrophoresis showed that chondroitin sulfate has a dissociation constant in the micromolar range with several common neurotrophins, and this was determined to be approximately tenfold stronger than with heparin. It was also revealed that nerve growth factor exhibits a slightly stronger affinity for hyaluronic acid than for chondroitin sulfate. However, E8 chick dorsal root ganglia cultured in the presence of nerve growth factor revealed that ganglia cultured in chondroitin sulfate scaffolds showed more robust growth than those cultured in control gels of hyaluronic acid. It is hypothesized that, despite the stronger affinity of nerve growth factor for hyaluronic acid, chondroitin sulfate serves as a better scaffold for neurite outgrowth, possibly due to inhibition of growth by hyaluronic acid chains.

Conovaloff, Aaron; Panitch, Alyssa

2011-10-01

412

Genome Networks Root the Tree of Life between Prokaryotic Domains  

PubMed Central

Eukaryotes arose from prokaryotes, hence the root in the tree of life resides among the prokaryotic domains. The position of the root is still debated, although pinpointing it would aid our understanding of the early evolution of life. Because prokaryote evolution was long viewed as a tree-like process of lineage bifurcations, efforts to identify the most ancient microbial lineage split have traditionally focused on positioning a root on a phylogenetic tree constructed from one or several genes. Such studies have delivered widely conflicting results on the position of the root, this being mainly due to methodological problems inherent to deep gene phylogeny and the workings of lateral gene transfer among prokaryotes over evolutionary time. Here, we report the position of the root determined with whole genome data using network-based procedures that take into account both gene presence or absence and the level of sequence similarity among all individual gene families that are shared across genomes. On the basis of 562,321 protein-coding gene families distributed across 191 genomes, we find that the deepest divide in the prokaryotic world is interdomain, that is, separating the archaebacteria from the eubacteria. This result resonates with some older views but conflicts with the results of most studies over the last decade that have addressed the issue. In particular, several studies have suggested that the molecular distinctness of archaebacteria is not evidence for their antiquity relative to eubacteria but instead stems from some kind of inherently elevated rate of archaebacterial sequence change. Here, we specifically test for such a rate elevation across all prokaryotic lineages through the analysis of all possible quartets among eight genes duplicated in all prokaryotes, hence the last common ancestor thereof. The results show that neither the archaebacteria as a group nor the eubacteria as a group harbor evidence for elevated evolutionary rates in the sampled genes, either in the recent evolutionary past or in their common ancestor. The interdomain prokaryotic position of the root is thus not attributable to lineage-specific rate variation. PMID:20624742

Dagan, Tal; Roettger, Mayo; Bryant, David; Martin, William

2010-01-01

413

Root Cohesion Controls on Shallow Landslide Size, Shape and Location  

NASA Astrophysics Data System (ADS)

Many environmental factors, including ground cover, local hydrology, and recent weather events interact to cause shallow landslides and determine landslide characteristics. Vegetation is of particular interest, because changes in vegetation density, age, and composition are expected consequences of human land use and climate change. These changes alter effective cohesion due to root reinforcement, which is known to impact landslide abundance, but the effects of root cohesion on landslide size, shape and location have not been quantified. The Elliott State Forest, a 376 km2 managed forest in Douglas County, Oregon, provides an ideal venue to study these effects. There, a single storm in November 1996 triggered 154 shallow landslides, which were subsequently mapped using aerial images onto laser altimetry data, in an area with a range of vegetation ages but relatively uniform soil properties, topography, and lithology. We used aerial imagery to categorize areas with different land use histories into 3 vegetation classes, ranging from clear-cuts to forest with mature trees over 100 years old. Each mapped landslide was then assigned to a class, and its size, shape and location was recorded. Our results show that, in addition to the expected decrease in landslide abundance in more-vegetated areas (which could be influenced by a bias against detecting landslides under trees), landslides in those areas were also larger and more elongated in the down-slope direction. Although landslides in all three classes generally occurred at locations with similar drainage area and slope, we observed that slides with a larger ratio of drainage area to slope were slightly more abundant in areas with lower vegetation cover. To investigate the causes of these variations, we used a new shallow landslide model calibrated for the Oregon Coast Range to predict the size, shape and location of landslides triggered by the 1996 storm under a range of root cohesion values in a subset of the study area. Although this exploratory model did not successfully predict the locations of specific landslides, it correctly predicted the sign of trends in landslide size and aspect ratio with increasing root cohesion. The model indicates that landslides in more densely vegetated areas must be larger to overcome increased root reinforcement, and grow by elongation (rather than widening) as a result of topographic effects on soil depth, pore pressure and basal cohesion. These results give insight into the impacts of changes in root cohesion on shallow landslide characteristics and provide a benchmark for testing the accuracy of regional-scale, shallow landslide models.

Douglas, M.; Bellugi, D. G.; Perron, J.; Coe, J. A.; Schmidt, K. M.

2013-12-01

414

Cyclotomic Swan subgroups and Primitive Roots Timothy Kohl  

E-print Network

Cyclotomic Swan subgroups and Primitive Roots: tkohl@bu.edu dreplogle@cse.edu Proposed running head: Swan subgroups and primitive roots Key terms and phrases: Swan subgroup, normal integral basis, kernel group, prim- itive root, cyclotomic units, tame

415

Bitter Root Irrigation district canal, looking east, typical section and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Bitter Root Irrigation district canal, looking east, typical section and crossing - Bitter Root Irrigation Project, Bitter Root Irrigation Canal, Heading at Rock Creek Diversion Dam, West of U.S. Highway 93, Darby, Ravalli County, MT

416

Bitter Root Irrigation district canal, looking east, typical section (canal ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Bitter Root Irrigation district canal, looking east, typical section (canal full) - Bitter Root Irrigation Project, Bitter Root Irrigation Canal, Heading at Rock Creek Diversion Dam, West of U.S. Highway 93, Darby, Ravalli County, MT

417

21 CFR 872.3820 - Root canal filling resin.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Root canal filling resin. 872.3820 Section 872... Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of...

2012-04-01

418

21 CFR 872.3820 - Root canal filling resin.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Root canal filling resin. 872.3820 Section 872... Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of...

2014-04-01

419

Root-Associated Microbial Communities of Different Strawberry  

E-print Network

Root-Associated Microbial Communities of Different Strawberry Cultivars as Influenced by Soil Type at its fruiting stage.(photo: Srivathsa Nallanchakravarthula) #12;Root-Associated Microbial Communities Abstract Rhizosphere microorganisms and their interactions with plant roots play pivotal roles

420

The Primitive Root 2 And The Generalized Artin Conjecture  

E-print Network

An asymptotic formula for the number of integers with the primitive root 2, and a generalized Artin conjecture for composite integers is presented here. Keywords: Primitive root, Artin primitive root conjecture

N. A. Carella

2015-04-02

421

76 FR 51430 - Roots Pharmaceuticals, Inc.; Revocation of Registration  

Federal Register 2010, 2011, 2012, 2013, 2014

...Drug Enforcement Administration Roots Pharmaceuticals, Inc.; Revocation of Registration...issued an Order to Show Cause to Roots Pharmaceuticals, Inc. (Registrant), of American...Registration BR9610571, issued to Roots Pharmaceuticals, Inc., be, and it hereby...

2011-08-18

422

Ecology of Root Colonizing Massilia (Oxalobacteraceae)  

PubMed Central

Background Ecologically meaningful classification of bacterial populations is essential for understanding the structure and function of bacterial communities. As in soils, the ecological strategy of the majority of root-colonizing bacteria is mostly unknown. Among those are Massilia (Oxalobacteraceae), a major group of rhizosphere and root colonizing bacteria of many plant species. Methodology/Principal Findings The ecology of Massilia was explored in cucumber root and seed, and compared to that of Agrobacterium population, using culture-independent tools, including DNA-based pyrosequencing, fluorescence in situ hybridization and quantitative real-time PCR. Seed- and root-colonizing Massilia were primarily affiliated with other members of the genus described in soil and rhizosphere. Massilia colonized and proliferated on the seed coat, radicle, roots, and also on hyphae of phytopathogenic Pythium aphanidermatum infecting seeds. High variation in Massilia abundance was found in relation to plant developmental stage, along with sensitivity to plant growth medium modification (amendment with organic matter) and potential competitors. Massilia absolute abundance and relative abundance (dominance) were positively related, and peaked (up to 85%) at early stages of succession of the root microbiome. In comparison, variation in abundance of Agrobacterium was moderate and their dominance increased at later stages of succession. Conclusions In accordance with contemporary models for microbial ecology classification, copiotrophic and competition-sensitive root colonization by Massilia is suggested. These bacteria exploit, in a transient way, a window of opportunity within the succession of communities within this niche. PMID:22808103

Ofek, Maya; Hadar, Yitzhak; Minz, Dror

2012-01-01

423

Anti-Helicobacter pylori activity of Terminalia macroptera root.  

PubMed

The root of Terminalia macroptera Guill. & Perr. (Combretaceae) is widely used in African traditional medicine to treat various infectious diseases, including stomach-associated diseases. This study investigates the in vitro activity of T. macroptera root extract against reference strains and clinical isolates of H. pylori and attempts to localize the extract bioactivity. T. macroptera hydroethanol (80% V/V) root extract (Tmr) activity was tested against three standard strains and sixty two clinical strains of H. pylori. Tmr liquid-liquid partition fractions were screened against twenty H. pylori strains. Qualitative analysis of Tmr and its fractions was performed by HPLC-UV/DAD. The antibiotic characterization of the H. pylori strains revealed that 20% of the tested clinical isolates were resistant to at least two of the three antibiotics belonging to the main groups of antibiotics used in multi-therapy to eradicate H. pylori infections. In contrast, Tmr showed anti-H. pylori activity against the majority (92%) of the tested strains (MIC(50) and MIC(90)=200 ?g/ml). The Tmr water liquid-liquid fraction (Tmr-3) and the precipitate obtained from this fraction (Tmr-5) were the most active tested samples, showing a MIC(50) of 100 ?g/ml. The present work proves the in vitro activity of T. macroptera against H. pylori, thus confirming the utility of this traditional medicinal plant to treat stomach complaints due to H. pylori infection. The main compounds of Tmr and of Tmr-3 were the ellagitannins terchebulin and punicalagin. These compounds can be considered as markers of T. macroptera root active extracts against H. pylori. PMID:22465506

Silva, Olga; Viegas, Sílvia; de Mello-Sampayo, Cristina; Costa, Maria João P; Serrano, Rita; Cabrita, José; Gomes, Elsa T

2012-07-01

424

Adventitious root induction in Arabidopsis thaliana as a model for in vitro root organogenesis.  

PubMed

Adventitious root formation, the development of roots on non-root tissue (e.g. leaves, hypocotyls and stems) is a critical step during micropropagation. Although root induction treatments are routinely used for a large number of species micropropagated in vitro as well as for in vivo cuttings, the mechanisms controlling adventitious rooting are still poorly understood. Researchers attempt to gain better insight into the molecular aspects by studying adventitious rooting in Arabidopsis thaliana. The existing assay involves etiolation of seedlings and measurements of de novo formed roots on the elongated hypocotyl. The etiolated hypocotyls express a novel auxin-controlled signal transduction pathway in which auxin response factors (ARFs), microRNAs and environmental conditions that drive adventitious rooting are integrated. An alternative assay makes use of so-called thin cell layers (TCL), excised strips of cells from the inflorescence stem of Arabidopsis thaliana. However, both the etiolated seedling system and the TCL assay are only distantly related to industrial rooting processes in which roots are induced on adult stem tissue. Here, we describe an adventitious root induction system that uses segments of the inflorescence stems of Arabidopsis thaliana, which have a histological structure similar to cuttings or in vitro micropropagated shoots. The system allows multiple treatments with chemicals as well as the evaluation of different environmental conditions on a large number of explants. It is therefore suitable for high throughput chemical screenings and experiments that require numerous data points for statistical analysis. Using this assay, the adventitious root induction capacity of classical auxins was evaluated and a differential response to the different auxins could be demonstrated. NAA, IBA and IAA stimulated adventitious rooting on the stem segment, whereas 2,4-D and picloram did not. Light conditions profoundly influenced the root induction capacity of the auxins. Additionally to the environmental control of adventitious root formation, we also investigated the spatial and temporal aspects of stem-based adventitious root organogenesis. To determine the cells involved in de novo root initiation on the adult stems, we adopted scanning electron microscopy, which allows the visualization of the auxin responsive stem tissue. Using this technique, direct (without callus interface) and indirect (with intermediate callus phase) organogenesis was readily distinguished. The described micro-stem segment system is also suitable for other non-woody species and it is a valuable tool to perform fast evaluations of different treatments to study adventitious root induction. PMID:23299674

Verstraeten, Inge; Beeckman, Tom; Geelen, Danny

2013-01-01

425

Rooting depths of plants relative to biological and environmental factors  

SciTech Connect

In 1981 to 1982 an extensive bibliographic study was completed to document rooting depths of native plants in the United States. The data base presently contains 1034 citations with approximately 12,000 data elements. In this paper the data were analyzed for rooting depths as related to life form, soil type, geographical region, root type, family, root depth to shoot height ratios, and root depth to root lateral ratios. Average rooting depth and rooting frequencies were determined and related to present low-level waste site maintenance.

Foxx, T S; Tierney, G D; Williams, J M

1984-11-01

426

A quantitative description of the sorghum root system  

E-print Network

, alterations in the sorghum root system were quantified after withholding water in the root medium from 14 to 49 DAE under greenhouse conditions. The seminal root of plants grown in controlled conditions showed a constant rate of elongation of 2. 5 cm..., but they represented over 30'/. of the root dry weight. The numbers of first and second order roots could be predicted from the branched length of the seminal root since constant rates of initiation were observed. Root dry weight and total root length were strongly...

Gonzalez Rodriguez, Humberto

1989-01-01

427

Getting to the roots of it: Genetic and hormonal control of root architecture  

PubMed Central

Root system architecture (RSA) – the spatial configuration of a root system – is an important developmental and agronomic trait, with implications for overall plant architecture, growth rate and yield, abiotic stress resistance, nutrient uptake, and developmental plasticity in response to environmental changes. Root architecture is modulated by intrinsic, hormone-mediated pathways, intersecting with pathways that perceive and respond to external, environmental signals. The recent development of several non-invasive 2D and 3D root imaging systems has enhanced our ability to accurately observe and quantify architectural traits on complex whole-root systems. Coupled with the powerful marker-based genotyping and sequencing platforms currently available, these root phenotyping technologies lend themselves to large-scale genome-wide association studies, and can speed the identification and characterization of the genes and pathways involved in root system development. This capability provides the foundation for examining the contribution of root architectural traits to the performance of crop varieties in diverse environments. This review focuses on our current understanding of the genes and pathways involved in determining RSA in response to both intrinsic and extrinsic (environmental) response pathways, and provides a brief overview of the latest root system phenotyping technologies and their potential impact on elucidating the genetic control of root development in plants. PMID:23785372

Jung, Janelle K. H.; McCouch, Susan

2013-01-01

428