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1

Stochastic modeling of salt accumulation in the root zone due to capillary flux from brackish groundwater  

NASA Astrophysics Data System (ADS)

Groundwater can be a source of both water and salts in semiarid areas, and therefore, capillary pressure-induced upward water flow may cause root zone salinization. To identify which conditions result in hazardous salt concentrations in the root zone, we combined the mass balance equations for salt and water, further assuming a Poisson-distributed daily rainfall and brackish groundwater quality. For the water fluxes (leaching, capillary upflow, and evapotranspiration), we account for osmotic effects of the dissolved salt mass using Van`t Hoff's law. Root zone salinity depends on salt transport via capillary flux and on evapotranspiration, which concentrates salt in the root zone. Both a wet climate and shallow groundwater lead to wetter root zone conditions, which in combination with periodic rainfall enhances salt removal by leaching. For wet climates, root zone salinity (concentrations) increases as groundwater is more shallow (larger groundwater influence). For dry climates, salinity increases as groundwater is deeper because of a drier root zone and less leaching. For intermediate climates, opposing effects can push the salt balance either way. Root zone salinity increases almost linearly with groundwater salinity. With a simple analytical approximation, maximum concentrations can be related to the mean capillary flow rate, leaching rate, water saturation, and groundwater salinity for different soils, climates, and groundwater depths.

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

2011-09-01

2

Effect of Ag interlayer on the optical and passivation properties of flexible and transparent Al2O3\\/Ag\\/Al2O3 multilayer  

Microsoft Academic Search

We report on the characteristics of a flexible Al2O3\\/Ag\\/Al2O3 multilayer passivation grown on a polyethylene terephthalate (PET) substrate as a function of Ag thickness. Due to the surface plasmon resonance (SPR) effects and the ductility of the Ag layer that is sandwiched between the dielectric Al2O3 layer, the flexible Al2O3\\/Ag\\/Al2O3 multilayer passivation exhibits a high transparency of 86.44% and improved

Jin-A. Jeong; Han-Ki Kim; Min-Su Yi

2008-01-01

3

Lumbar nerve root compression due to extradural, intraforaminal lipoma. An underdiagnosed entity?  

PubMed

Intraspinal extradural lipomas, not associated with spinal dysraphism, are rare lesions. True adult lipomas have to be distinguished from angiolipomas and from epidural lipomatosis. The authors report a unique case of a patient with unilateral lumbar nerve root compression caused by extradural, intraforaminal, true adult lipoma. A 62-year-old woman suffered severe left L-5 radiculopathy that progressively worsened during the 12 months prior to presentation. She did not experience improvement with conservative therapy. An MR imaging study of the lumbar spine revealed shifting of the left L-5 nerve root caused by a small extradural intrarecessal (that is, the beginning of the intravertebral foramen)/intraforaminal mass with MR imaging characteristics of fatty tissue. No other relevant intraspinal pathology could be identified. A left L4-5 fenestration was carried out. A small fatty intrarecessal/intraforaminal mass compressing severely the left L-5 root was identified and completely resected. The histological examination revealed a lipoma. The patient recovered completely and is fully mobile and symptom free 1 year after the operation. Intraspinal lipomas should be considered in cases of radiculopathy, especially in the absence of relevant degenerative or tumorous pathology and in the presence of nerve root shifting caused by fatty tissue. PMID:18976170

Zevgaridis, Dimitris; Nanassis, Kimon; Zaramboukas, Thomas

2008-11-01

4

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

NASA Astrophysics Data System (ADS)

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

5

Oxygen-ozone therapy for herniated lumbar disc in patients with subacute partial motor weakness due to nerve root compression.  

PubMed

Intradiscal oxygen-ozone (O2-O3) chemonucleolysis is a well-known effective treatment for pain caused by protruding disc disease and nerve root compression due to bulging or herniated disc. The most widely used therapeutic combination is intradiscal injection of an O2-O3 mixture (chemonucleolysis), followed by periradicular injection of O2-O3, steroid and local anaesthetic to enhance the anti-inflammatory and analgesic effect. The treatment is designed to resolve pain and is administered to patients without motor weakness, whereas patients with acute paralysis caused by nerve root compression undergo surgery 24-48h after the onset of neurological deficit. This paper reports on the efficacy of O2-O3 chemonucleolysis associated with anti-inflammatory foraminal injection in 13 patients with low back pain and cruralgia, low back pain and sciatica and subacute partial motor weakness caused by nerve root compression unresponsive to medical treatment. All patients were managed in conjunction with our colleagues in the Neurosurgery Unit of Bellaria Hospital and the IRCCS Institute of Neurological Sciences, Bologna. The outcomes obtained are promising: 100% patients had a resolution of motor weakness, while 84.6% had complete pain relief. Our results demonstrate that O2-O3 therapy can be considered a valid treatment option for this category of patients. PMID:25363257

Dall'Olio, Massimo; Princiotta, Ciro; Cirillo, Luigi; Budai, Caterina; de Santis, Fabio; Bartolini, Stefano; Serchi, Elena; Leonardi, Marco

2014-10-31

6

Microstructure and thermal conduction properties of Al{sub 2}O{sub 3}-Ag composites  

SciTech Connect

Microstructure and thermal conduction properties involving thermal diffusivity and conductivity of composite, Al{sub 2}O{sub 3}-Ag, were investigated. The Ag particles observed in the composites were spread sporadically throughout the composite with inclusion size increasing with Ag content, rather than forming a network of thin film foil. Thermal conductivity of the composite increased with Ag content and followed composite theory prediction with a negligible influence of interfacial contact resistance. The temperature dependence of the thermal conductivity became less pronounced with increasing Ag content reflecting the nature of electron contribution in Ag rather than the typical phonon contribution in polycrystalline Al{sub 2}O{sub 3}. The lower composite conductivity at higher Ag contents as compared to theoretical predictions is due primarily to the residual pore phase, associated with the cavity formation for the composite containing 10 vol.% Ag.

Liu, D.M. [Industrial Technology Research Inst., Hsinchu (Taiwan, Province of China). Materials Research Labs.] [Industrial Technology Research Inst., Hsinchu (Taiwan, Province of China). Materials Research Labs.; Tuan, W.H. [National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Engineering] [National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Engineering

1996-02-01

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

Plasmon-Enhanced Upconversion Fluorescence in Er3+:Ag Phosphate Glass: the Effect of Heat Treatment  

NASA Astrophysics Data System (ADS)

The melt quenching method is used to prepare erbium-doped silver nanoparticle (NP) embedded phosphate glass. The effect of annealing on the glass on the formation of silver NPs produced by the reduction of silver (Ag+ ?Ag°) is studied. The glass samples are characterized by x-ray diffraction, UV-vis-NIR absorption, photoluminescence spectroscopy and transmission electron microscopy (TEM) imaging. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs located around ~442 nm. The TEM imaging shows the homogeneous distribution of silver NPs of almost spherical shape with an average diameter of ~5 nm. Upconversion luminescence spectra show two major emissions at 550 and 638 nm, originating from the 4S3/2 and 4F9/2 energy levels of the Er3+ ions, respectively. The enhancement in the luminescence intensity of both the green and red bands is found to be due to the effective local field of the silver NPs as well as the energy transfer from the nanoclusters, comprised of centers with silver ions bound to silver atoms in dimers or trimers to Er3+ ions, whereas quenching occurred due to the energy transfer from erbium ions to silver NPs (Er3+ ?Ag°).

Raja, J. Amjad; R. Sahar, M.; K. Ghoshal, S.; R. Dousti, M.; Riaz, S.; R. Samavati, A.; N. A Jamaludin, M.; Naseem, S.

2013-02-01

10

Effect of Ag interlayer on the optical and passivation properties of flexible and transparent Al2O3/Ag/Al2O3 multilayer  

NASA Astrophysics Data System (ADS)

We report on the characteristics of a flexible Al2O3/Ag/Al2O3 multilayer passivation grown on a polyethylene terephthalate (PET) substrate as a function of Ag thickness. Due to the surface plasmon resonance (SPR) effects and the ductility of the Ag layer that is sandwiched between the dielectric Al2O3 layer, the flexible Al2O3/Ag/Al2O3 multilayer passivation exhibits a high transparency of 86.44% and improved flexibility at a Ag thickness of 10nm. We found that SPR effects in the Ag layer occur at the transition region from distinct islands to a continuous film at a critical thickness (˜10nm). In addition, the water vapor transmission rate of the Al2O3/Ag/Al2O3/PET sample decreased as the thickness of the Ag layer increased. Using synchrotron x-ray scattering and field emission scanning electron microscopy, we suggest a possible mechanism to explain the SPR in the Ag layer of the flexible and transparent Al2O3/Ag/Al2O3 multilayer passivation.

Jeong, Jin-A.; Kim, Han-Ki; Yi, Min-Su

2008-07-01

11

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...

12

Inhibition of tomato (Solanum lycopersicum L.) root growth by cyanamide is due to altered cell division, phytohormone balance and expansin gene expression.  

PubMed

Cyanamide (CA) has been reported as a natural compound produced by hairy vetch (Vicia villosa Roth.) and it was shown also to be an allelochemical, responsible for strong allelopathic potential in this species. CA phytotoxicity has been demonstrated on various plant species, but to date little is known about its mode of action at cellular level. Treatment of tomato (Solanum lycopersicum L.) roots with CA (1.2 mM) resulted in inhibition of growth accompanied by alterations in cell division, and imbalance of plant hormone (ethylene and auxin) homeostasis. Moreover, the phytotoxic effect of CA was also manifested by modifications in expansin gene expression, especially in expansins responsible for cell wall remodeling after the cytokinesis (LeEXPA9, LeEXPA18). Based on these results the phytotoxic activity of CA on growth of roots of tomato seedlings is likely due to alterations associated with cell division. PMID:22847024

Soltys, Dorota; Rudzi?ska-Langwald, Anna; Gniazdowska, Agnieszka; Wi?niewska, Anita; Bogatek, Renata

2012-11-01

13

Convective Heat Transfer Characteristics of NaHCO3-Ag Nano Compound Material Solution  

NASA Astrophysics Data System (ADS)

Convection heat transfer enhancement is an important issue since this problem is of particular interest in the field of energy and environment. Ag nano-solution is expected not only to enhance heat transfer but also to work for deodorization and antifungal effect. An experimental investigation on the convective heat transfer characteristics for NaHCO3-Ag nano-compound material solution in a long and straight heated pipe has been carried out. NaHCO3 compound materials with 400 ppm or 1000 ppm Ag nano-particle solved in pure water are considered to study the effect of Ag nano-particle on the heat transfer enhancement. The concentration of NaHCO3-Ag compound material in the water is varied 0.1 % to 1.0 %. The results indicate that the convective heat transfer coefficient is increased with an increase in the concentration of NaHCO3-Ag compound solution. At a given concentration, heat transfer coefficient is increased as the content of the Ag nano-particle is increased. Heat transfer enhancement ratio correlation using NaHCO3-Ag compound solution is also suggested.

Kang, Byung Ha; Heo, Juyeong; Kim, Kyung Jae

14

Development of the Pictet-Spengler reaction catalyzed by AuCl3/AgOTf.  

PubMed

Mild and efficient AuCl3/AgOTf-catalyzed Pictet-Spengler reactions were developed to afford in good yields a variety of tetrahydroisoquinoline and tetrahydro-beta-carboline ring systems, which constitute important motifs in biologically active natural and synthetic organic compounds. PMID:16526809

Youn, So Won

2006-03-17

15

Neutron powder diffraction determination of the magnetic structure of Gd(3)Ag(4)Sn(4).  

PubMed

Natural gadolinium is the strongest neutron-absorbing element and neutron diffraction studies of Gd-containing materials rely on the use of either enriched Gd isotopes or short neutron wavelengths where the absorption is weaker but, unfortunately, the neutron flux is also weak. We have employed a new sample-mounting technique to obtain neutron powder diffraction patterns from the intermetallic compound Gd(3)Ag(4)Sn(4) containing natural Gd, at a neutron wavelength of ? 2.37 Å where there is much greater flux. Here, we report the magnetic structure of Gd(3)Ag(4)Sn(4). The magnetic ordering temperature is 28.8(2) K. At 2.8 K the Gd(4e) sublattice is antiferromagnetically ordered along the crystal c-axis, commensurate with the crystal lattice. The Gd(2d) sublattice is also ordered along the c-axis but its magnetic structure is incommensurate with the crystal lattice. PMID:21817443

Cadogan, J M; Ryan, D H; Napoletano, M; Riani, P; Cranswick, L M D

2009-03-25

16

Highly active WO3-Ag-ZnO photocatalyst driven by day light illumination  

NASA Astrophysics Data System (ADS)

The WO3 loaded Ag-ZnO (WO3-Ag-ZnO) was successfully synthesized by precipitation-decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3-Ag-ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3-Ag-ZnO is found to be more efficient than Ag-ZnO, WO3-ZnO, Ag-WO3, WO3, commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.

Subash, B.; Krishnakumar, B.; Sreedhar, B.; Swaminathan, M.; Shanthi, M.

2013-02-01

17

Electroforming and Ohmic contacts in Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown process that changes the diode from its initial high resistance state (HRS) to a low resistance state (LRS). After electroforming, resistance switching memories (RSMs) use voltages to switch from HRS to LRS and back. Many MIM combinations are proposed for use in RSMs. In many cases conduction in the LRS is nearly temperature independent at low temperatures; an Ohmic contact with a barrier to electron injection of ˜0 eV results from electroforming. Electroforming of Al-Al2O3-Ag diodes with amorphous anodic Al2O3 thicknesses between 12 and 41 nm has been studied. Two anodizing electrolytes have been used; 0.1 M ammonium pentaborate (bor-H2O) and a solution of 0.1 M of ammonium pentaborate per liter of ethylene glycol (bor-gly). Polarization of Al2O3 and negative charge in Al2O3 are much larger when Al2O3 is formed in bor-H2O solution than when Al is anodized in bor-gly solution. Electroforming of Al-Al2O3-Ag diodes results in an Ohmic contact at the Al-Al2O3 interface, voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) from filamentary conducting channels. Two distinct modes of electroforming occur for Al-Al2O3-Ag diodes. ?-forming occurs for 2.5 V ? VS ? 5 V, where VS is the applied voltage. It is characterized by an abrupt current jump with the simultaneous appearance of EL and EM. ?-forming occurs for VS ? 7 V. I-V curves, EL, and EM develop gradually and are smaller than for ?-forming. Electroforming occurs more readily for diodes with Al2O3 formed in bor-H2O that have greater defect densities. Fully developed I-V curves have similar VCNR, EL, and EM after ?-forming or ?-forming. A model is proposed in which excited states of F-centers, oxygen vacancies in amorphous anodic Al2O3, form defect conduction bands. Electroforming that results in an Ohmic contact requires injection of positive charge at the Al-Al2O3 interface. ?-forming is the result of ionization of F-center recombination centers with energies that are close to the Al Fermi level. Hole injection by high-field ionization of valence band states of Al2O3 causes ?-forming.

Hickmott, T. W.

2012-03-01

18

Arsenic-induced root growth inhibition in mung bean ( Phaseolus aureus Roxb.) is due to oxidative stress resulting from enhanced lipid peroxidation  

Microsoft Academic Search

Arsenic (As) toxicity and its biochemical effects have been mostly evaluated in ferns and a few higher plants. In this study,\\u000a we investigated the effect of As (10.0 and 50.0 ?M) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde\\u000a and conjugated dienes), electrolyte leakage, H2O2 content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb.). Arsenic

Harminder Pal Singh; Daizy R. Batish; Ravinder Kumar Kohli; Komal Arora

2007-01-01

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

Heterogeneity and topsoil depletion due to tillage erosion and soil co-extraction with root vegetables: a serious threat to sustainable agricultural land use in the UK  

NASA Astrophysics Data System (ADS)

The term soil erosion has become almost synonymous with water erosion and yet tillage erosion and soil loss with root crop harvest, although less visible, may be responsible for the majority of the on-site costs of soil erosion in many arable areas of the UK. The study reported here is a first attempt to model soil erosion associated with these processes in England and Wales, at the National scale. A GIS-based modelling approach in the Arc/Info environment is employed in order to meet the requirement for large-scale evaluation of erosion severity. Existing models that have been subject to independent test are used or adapted and widely available data is employed in model parameterisation. Tillage erosion is simulated using a diffusion-type model and a slope curvature index derived from coarse-scale topographic data. The curvature index is calibrated by statistical comparison to curvature values derived from a high resolution digital terrain model. Soil loss with root crop harvest is simulated using information concerning patterns of sugar beet and potato cultivation and estimation of soil moisture during the crop harvest season. Soil loss associated with root crop harvest may be as high as 1 t ha-1 year-1 if land is permanently used for root crops in a 3 year rotation. However, when the arable area of the UK is considered as a whole root crop harvest is responsible for a mean rate of soil loss of approximately 0.1 t ha-1 year-1. Tillage erosion is found to be the dominant process of soil redistribution and onsite erosion on arable land, in comparison with both soil loss through root crop harvest and with long-term water erosion rates. Mean gross rates of tillage erosion were found to be 3.7 t ha-1 year-1, representing approximately 7.4 t ha-1 year-1 erosion and the same rate of deposition. Soil redistribution at these rates is generating an heterogeneous soilscape in which continued functioning for food and fibre production may be jeopardized. These problems may be exacerbated by increased water stress in eroded soils if climate change does, as predicted, result in hotter and drier summers.

Quine, Timothy; van Oost, Kristof

2010-05-01

21

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

22

Structure and fluorescent properties of TiO 2:Sm 3+-Ag composite  

NASA Astrophysics Data System (ADS)

Composite based on TiO 2 host doped with Sm 3+ ions and co-doped with silver nanoparticles is proposed as new fluorescent material. The co-doped samples were prepared from titanium alkoxide precursor by sol-gel method adjusted for addition of Sm 3+ ions and Ag nanoparticles. Commercial samarium nitrate salt and silver nanopowder (size of primary particle 30-50 nm) were used as dopant and co-dopant. Raman measurements revealed that crystalline anatase TiO 2 phase is typical for the TiO 2:Sm 3+ films, whereas TiO 2:Sm 3+-Ag samples contain regions of rutile and brookite phases distributed in the predominantly amorphous TiO 2 surrounding. Samarium ions were excited either directly ( ?exc = 488 nm) or through the TiO 2 host ( ?exc = 355 nm). Enhancement of Sm 3+ fluorescence up to 20 times was revealed in the vicinity of silver aggregates. Combined plasmonic and sensitizing influences of silver on the Sm 3+ ions are considered as reasons for enhanced Sm 3+ fluorescence.

Dolgov, L.; Reedo, V.; Kiisk, V.; Pikker, S.; Sildos, I.; Kikas, J.

2010-09-01

23

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

24

The inhibitory effect of a Platycodon root extract on ultraviolet B-induced pigmentation due to a decrease in Kit expression.  

PubMed

The signaling of stem cell factor (SCF) through its receptor Kit is known to play an important role in regulating cutaneous melanogenesis. In the course of UVB-induced pigmentation, the expression of membrane-bound SCF by epidermal keratinocytes is upregulated at an early phase and subsequently activates neighboring melanocytes via their Kit receptors. In order to identify effective skin-lightening materials, we screened botanical extracts to determine their abilities to diminish Kit expression in melanocytes. A Platycodon root extract was consequently found to have a remarkable inhibitory activity on Kit expression. When the extract was applied to three-dimensional human skin substitutes in vitro and to human skin in vivo after UVB irradiation, their pigmentation was significantly reduced, confirming the substantial contribution of the suppression of SCF/Kit signaling to preventing or inhibiting melanin synthesis. These data demonstrate that a Platycodon root extract is a promising material for a skin-lightening product to improve pigmentation-related diseases. PMID:24799080

Kasamatsu, Shinya; Hachiya, Akira; Shimotoyodome, Yoshie; Kameyama, Akiyo; Miyauchi, Yuki; Higuchi, Kazuhiko; Fujimori, Taketoshi; Ohuchi, Atsushi; Shibuya, Yusuke; Kitahara, Takashi

2014-07-01

25

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

26

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

27

A paramagnetic trigonal paddlewheel complex with iron-dithiolato ligand paddles: {[(C 9H 18N 2S 2)Fe(NO)] 3Ag 2}(BF 4) 2  

NASA Astrophysics Data System (ADS)

Addition of AgBF 4 to (bme-dach)Fe(NO), (bme-dach, N, N'-bis(2-mercapto-ethyl)-1,4-diazacycloheptane) affords a pentametallic C 3 paddlewheel complex, {[(bme-dach)Fe(NO)] 3Ag 2}[BF 4] 2, resulting from the ability of the thiolate sulfurs of the N 2S 2 complex to serve as a bidentate bridging ligand to Ag + ions. Single crystal X-ray analysis reveals the NO ligands coordinated to each Fe are all pointed in the same direction, resulting in a threefold rotation axis and a pseudo-mirror plane bisecting the Ag⋯Ag axis in the asymmetric unit cell. This Ag 2 trigonal paddlewheel complex of non-bonded Ag⋯Ag average distance = 2.866(3)? has also been characterized by infrared and UV-vis spectroscopies. The complex shows paramagnetism both in solution (Evans' method) and in the solid state due to three S = ½ {Fe(NO)} 7 units. The EPR spectrum shows a single isotropic signal with g = 2.024. SQUID analysis confirms this paramagnetism yielding a ?T value of 1.17 emu-K/mol with the presence of weak ferromagnetic coupling evident at temperatures less than 20 K. To our knowledge this is the first example of a paddlewheel complex in which paramagnetism exists within the bridging bidentate ligand "paddles".

Hess, Jennifer L.; Young, Mark D.; Murillo, Carlos A.; Darensbourg, Marcetta Y.

2008-11-01

28

MoO3/Ag/Al/ZnO intermediate layer for inverted tandem polymer solar cells  

NASA Astrophysics Data System (ADS)

We report an MoO3/Ag/Al/ZnO intermediate layer connecting two identical bulk heterojunction subcells with a poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT and PCBM) active layer for inverted tandem polymer solar cells. The highly transparent intermediate layer with an optimized thickness realizes an Ohmic contact between the two subcells for effective charge extraction and recombination. A maximum power conversion efficiency of 3.76% is obtained for the tandem cell under 100 mW/cm2 illumination, which is larger than that of a single cell (3.15%). The open-circuit voltage of the tandem cell (1.18 V) approaches double that of the single cell (0.61 V).

Qing, Jian; Zhong, Zhen-Feng; Liu, Yong; Li, Bao-Jun; Zhou, Xiang

2014-03-01

29

Solid-Solid Reaction Between Sn-3Ag-0.5Cu Alloy and Au/Pd(P)/Ni(P) Metallization Pad with Various Pd(P) Thicknesses  

NASA Astrophysics Data System (ADS)

The effect of Pd(P) thickness on the solid-solid reaction between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) at 180°C was investigated in this study. The reaction was conducted after reflow, thereby removing the Au/Pd finish before the solid-state reaction. The reaction products included (Cu,Ni)6Sn5, Ni2SnP, and Ni3P, and their growth strongly depended on the Pd(P) thickness, especially for the former phases [i.e., (Cu,Ni)6Sn5 and Ni2SnP]. As the Pd(P) thickness increased from 0 ?m, to 0.1 ?m, to 0.22 ?m, the (Cu,Ni)6Sn5 exhibited a needle-like dense layer, chunk-like morphology, and discontinuous morphology, respectively. The alternative phase (Ni2SnP) behaved in a manner opposite to that of (Cu,Ni)6Sn5, growing with a discontinuous morphology to a dense layer with increasing Pd(P) thickness. However, this strong dependence disappeared when the solder joints were subsequently subjected to solid-state aging. The (Cu,Ni)6Sn5 and Ni2SnP both became layered structures for all cases examined. A high-speed ball shear (HSBS) test was conducted to quantify the mechanical response of the interfacial microstructures. The HSBS test results showed that any initial difference in shear strength caused by the various Pd(P) thicknesses could be reduced after the solid-state aging, which is consistent with the microstructural evolution observed. The mechanical strength of the solder joints was decreased due to the presence of a bi-intermetallic structure of (Cu,Ni)6Sn5/Ni2SnP at the interface. Detailed analysis of the growth of (Cu,Ni)6Sn5 and Ni2SnP is also provided.

Ho, C. E.; Wu, W. H.; Hsu, L. H.; Lin, C. S.

2012-01-01

30

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

31

Root gravitropism  

NASA Technical Reports Server (NTRS)

When a plant root is reoriented within the gravity field, it responds by initiating a curvature which eventually results in vertical growth. Gravity sensing occurs primarily in the root tip. It may involve amyloplast sedimentation in the columella cells of the root cap, or the detection of forces exerted by the mass of the protoplast on opposite sides of its cell wall. Gravisensing activates a signal transduction cascade which results in the asymmetric redistribution of auxin and apoplastic Ca2+ across the root tip, with accumulation at the bottom side. The resulting lateral asymmetry in Ca2+ and auxin concentration is probably transmitted to the elongation zone where differential cellular elongation occurs until the tip resumes vertical growth. The Cholodny-Went theory proposes that gravity-induced auxin redistribution across a gravistimulated plant organ is responsible for the gravitropic response. However, recent data indicate that the gravity-induced reorientation is more complex, involving both auxin gradient-dependent and auxin gradient-independent events.

Masson, P. H.

1995-01-01

32

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

33

Band offsets of novel CoTiO3/Ag3VO4 heterojunction measured by X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The energy band diagram and band offsets of the novel CoTiO3/Ag3VO4 heterojunction photocatalyst are investigated by X-ray photoelectron spectroscopy for the first time. Excluding the strain effect, the valence-band and conduction-band offsets are determined to be 0.2 ± 0.3 eV and -0.6 ± 0.3 eV, respectively. The CoTiO3/Ag3VO4 composite forms a type-II heterojunction, for which the photogenerated charge carriers could be effectively separated. The results suggest that determination of the energy band structure is crucial for understanding the photogenerated charge transfer mechanism at the interfaces, hence the corresponding photocatalytic activity and would also be beneficial to the design of new and efficient heterostructure-based photocatalysts.

Wangkawong, Kanlayawat; Tantraviwat, Doldet; Phanichphant, Sukon; Inceesungvorn, Burapat

2015-01-01

34

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

35

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

36

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 undergroundâmore 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.

Science, Lawrence H.

2008-01-01

37

Repeat aortic root replacement  

Microsoft Academic Search

Background. Aortic root replacement in patients who have undergone previous aortic root replacement presents a formidable technical challenge, which may lead to increased surgical mortality.Methods. We reviewed our experience from January 1989 through November 1995. Seven consecutive patients (6 men and 1 woman) underwent eight repeat aortic root replacements. Mean follow-up was 19 months. Previous root replacement had been performed

Chiwon Hahn; Stanley K. C Tam; Gus J Vlahakes; Alan D Hilgenberg; Cary W Akins; Mortimer J Buckley

1998-01-01

38

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

39

MoO3/Ag/MoO3 anode in organic photovoltaic cells: Influence of the presence of a CuI buffer layer between the anode and the electron donor  

NASA Astrophysics Data System (ADS)

MoO3/Ag/MoO3 (MAM) multilayer structures (layers thickness 20 nm/10 nm/35 nm) are used as anode in CuPc/C60/Alq3/Al organic photovoltaic cells. The averaged transmittance (400 nm-800 nm) of these MoO3/Ag/MoO3 multilayer structures is 70% ± 2% and their sheet resistance is 3.5 ± 1.0 ?/sq. When these multilayer structures are used as anode, the power conversion efficiency of the MoO3/Ag/MoO3/CuPc/C60/Alq3/Al cells is around 1%, this efficiency is increased of 50% when a thin CuI film (3 nm) is introduced at the interface between the anode and the organic film. This improvement is attributed to the templating effect of CuI on the CuPc molecules.

Makha, M.; Cattin, L.; Lare, Y.; Barkat, L.; Morsli, M.; Addou, M.; Khelil, A.; Bernède, J. C.

2012-12-01

40

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

41

Proposal Due: _________________________ Senior Project Due: _________________________  

E-print Network

Proposal Due: _________________________ HURCA & Senior Project Due: _________________________ Priorities: Senior Project Guide #12;2 The Honors College Senior Project Guide Why Research? Research the communication and critical thinking skills necessary for graduate school and professional employment. Honors

Huang, Haiying

42

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

43

Root Development and Nutrient Uptake  

Microsoft Academic Search

Root system formation proceeds in close coordination with shoot growth. Accordingly, root growth and its functions are regulated tightly by the shoot through materials cycling between roots and shoots. A plant root system consists of different kinds of roots that differ in morphology and functions. The spatial configuration and distribution of these roots determine root system architecture in the soil,

H. Wang; Y. Inukai; A. Yamauchi

2006-01-01

44

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

45

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

46

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

47

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...

48

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

49

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

50

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

51

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

PubMed

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

Li, Fumin; Chen, Chong; Tan, Furui; Li, Chunxi; Yue, Gentian; Shen, Liang; Zhang, Weifeng

2014-01-01

52

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

53

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

54

Your Dues  

NASA Astrophysics Data System (ADS)

Your AGU dues, at $20, are truly a bargain and have been so for 40 years. It would be difficult to point to the primary driver for the extraordinary growth in AGU membership during the past 40 years, but surely the low and stable dues have been a major contributor. The low entry fee brings a diverse, worldwide community of scientists into our network. It is also consistent with AGU's commitment to the public good, which is the basis for the tax-exempt status the Union enjoys in the United States.

Spilhaus, Fred

2009-01-01

55

Ethanol reforming using Ba0.5Sr0.5Cu0.2Fe0.8O3-?/Ag composites as oxygen transport membranes  

NASA Astrophysics Data System (ADS)

Cobalt-free oxygen transport membranes (OTMs), Ba0.5Sr0.5Cu0.2Fe0.8O3-? (BSCF) and its composites, Ba0.5Sr0.5Cu0.2Fe0.8O3-?/Ag (BSCF/Ag), were fabricated by conventional solid state synthesis, and their oxygen transport properties were evaluated. The metal (Ag) content in the composite was 10-40 vol.%. Based on oxygen-permeation results, BSCF/40 vol.% Ag with Rh catalyst was selected for testing its ability to supply high-purity oxygen (from air) for ethanol reforming. It was found that the composite played an important role in producing hydrogen from ethanol reforming at 600 °C. The composite with catalyst shifted ethanol conversion toward production of hydrogen and away from production of other products, i.e., using a catalyst increased the selectivity for hydrogen in the reformate. The crystal structure, thermal expansion, coke formation, and the microstructural behavior of the OTMs are discussed.

Park, C. Y.; Lee, T. H.; Dorris, S. E.; Park, J.-H.; Balachandran, U.

2012-09-01

56

Morphology of the Tin Whiskers on the Surface of a Sn-3Ag-0.5Cu-0.5Nd Alloy  

NASA Astrophysics Data System (ADS)

Rapid growth of tin whiskers has been observed on the surface of rosette-shaped NdSn3 intermetallic phase in a Sn-3Ag-0.5Cu-0.5Nd alloy after air storage. It is shown that various cross sections of NdSn3 rosettes in the solder matrix reveal different morphologies of tin whiskers, which can be classified as four types: long fibers, short fibers, tiny sprouts, and hillocks. The fibrous whiskers and tiny sprouts are found on the surfaces of specimens exposed to air at room temperature and 423 K (150 °C), while hillocks appear only after storage at 423 K (150 °C). In addition, it is observed that, in most cases, each oxidized NdSn3 intermetallic phase contains only a single whisker at its center. Through metallographic observations and chemical analyses on the cross sections of the oxidized NdSn3 intermetallics, a "successive compressive stress model" has been proposed to interpret the tin whisker growth on the surface of a rare earth (RE)-containing solder.

Chuang, Tung-Han; Jain, Chao-Chi

2011-03-01

57

Interspecific Variation in Root Growth in Cymbopogon in Root Boxes  

Microsoft Academic Search

Interspecific variation for root growth and development was studied in palmarosa (Cymbopogon martinii), lemongrass (Cymbopogon flexuosus), and citronella (Cymbopogon winterianus) grown in root boxes in a glass house. Cymbopogon winterianus had highest root biomass and deep root growth (between 30–100 cm soil depth) plus a greater total root-to-shoot ratio and deep root-to-shoot ratio than the other species. This root development

N. K. Srivastava; R. Kumar; D. Dixit

2003-01-01

58

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

59

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

60

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

61

“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

62

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

63

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

64

The Roots of Literacy.  

ERIC Educational Resources Information Center

This review of research with children aged two to six on their reading, writing, and oral language development speaks of five roots of a tree of literate life that require nourishment in the soil of a written language environment. The roots discussed are the development of print awareness in situational contexts, the development of print awareness…

Goodman, Yetta M.

65

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

66

Fabrication and characterization of WO3/Ag/WO3 multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes  

PubMed Central

The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 ?/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs. PMID:22587669

2012-01-01

67

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

68

Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields  

PubMed Central

To clarify the effect of deep rooting on grain yield in rice (Oryza sativa L.) in an irrigated paddy field with or without fertilizer, we used the shallow-rooting IR64 and the deep-rooting Dro1-NIL (a near-isogenic line homozygous for the Kinandang Patong allele of DEEPER ROOTING 1 (DRO1) in the IR64 genetic background). Although total root length was similar in both lines, more roots were distributed within the lower soil layer of the paddy field in Dro1-NIL than in IR64, irrespective of fertilizer treatment. At maturity, Dro1-NIL showed approximately 10% higher grain yield than IR64, irrespective of fertilizer treatment. Higher grain yield of Dro1-NIL was mainly due to the increased 1000-kernel weight and increased percentage of ripened grains, which resulted in a higher harvest index. After heading, the uptake of nitrogen from soil and leaf nitrogen concentration were higher in Dro1-NIL than in IR64. At the mid-grain-filling stage, Dro1-NIL maintained higher cytokinin fluxes from roots to shoots than IR64. These results suggest that deep rooting by DRO1 enhances nitrogen uptake and cytokinin fluxes at late stages, resulting in better grain filling in Dro1-NIL in a paddy field in this study. PMID:24988911

Arai-Sanoh, Yumiko; Takai, Toshiyuki; Yoshinaga, Satoshi; Nakano, Hiroshi; Kojima, Mikiko; Sakakibara, Hitoshi; Kondo, Motohiko; Uga, Yusaku

2014-01-01

69

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

70

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

71

Roles of Morphology, Anatomy, and Aquaporins in Determining Contrasting Hydraulic Behavior of Roots1[OA  

PubMed Central

The contrasting hydraulic properties of wheat (Triticum aestivum), narrow-leafed lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus) roots were identified by integrating measurements of water flow across different structural levels of organization with anatomy and modeling. Anatomy played a major role in root hydraulics, influencing axial conductance (Lax) and the distribution of water uptake along the root, with a more localized role for aquaporins (AQPs). Lupin roots had greater Lax than wheat roots, due to greater xylem development. Lax and root hydraulic conductance (Lr) were related to each other, such that both variables increased with distance from the root tip in lupin roots. Lax and Lr were constant with distance from the tip in wheat roots. Despite these contrasting behaviors, the hydraulic conductivity of root cells (Lpc) was similar for all species and increased from the root surface toward the endodermis. Lpc was largely controlled by AQPs, as demonstrated by dramatic reductions in Lpc by the AQP blocker mercury. Modeling the root as a series of concentric, cylindrical membranes, and the inhibition of AQP activity at the root level, indicated that water flow in lupin roots occurred primarily through the apoplast, without crossing membranes and without the involvement of AQPs. In contrast, water flow across wheat roots crossed mercury-sensitive AQPs in the endodermis, which significantly influenced Lr. This study demonstrates the importance of examining root morphology and anatomy in assessing the role of AQPs in root hydraulics. PMID:19321713

Bramley, Helen; Turner, Neil C.; Turner, David W.; Tyerman, Stephen D.

2009-01-01

72

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

73

Topics In Primitive Roots  

E-print Network

This note 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) 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. The last topic deals with an effective lower bound #{p > x/log x for the number of primes p 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

2014-05-01

74

Cotton Root-rot.  

E-print Network

excelsa, Pinus sylvestri.s, Strobw, P. Laricio, Larix Europoea, Acer platanoides. Fagus. This disease manifests itself by the blackening of the roots and rootlets. The Cotylcdons have a spotted appearance. Warm and moist weather causes the fungus... Persimmon (Diospyros Kaki) grafted on the native Per- simmon (D. Tri~~iniana), Silver Maple (Acer dasycarpum), Paper Mulberry (Broussonetia papyrifera). Of this list the China and Paper Mulberry trees suffer most. In August, 1888, the roots of a number...

Pammel, L. H. (Louis Herman)

1889-01-01

75

Roots and Extremal Points  

NASA Astrophysics Data System (ADS)

In computational physics very often roots and local extrema of a function have to be determined. In one dimension bisection is a very robust but rather inefficient root finding method. If a good starting point close to the root is available and the function is smooth enough, the Newton-Raphson method converges much faster. Special strategies are necessary to find roots of not so well behaved functions or higher order roots. The combination of bisection and interpolation as by the methods of Dekker, Brent and more recently Chandrupatla provides generally applicable algorithms. In multidimensions Quasi-Newton methods are a good choice. Whereas local extrema can be found as the roots of the gradient, at least in principle, direct optimization can be more efficient. In one dimension the ternary search method or Brent's more efficient golden section search method can be used. In multidimensions the class of direction set search methods is very popular which includes the methods of steepest descent and conjugate gradients, the Newton-Raphson method and, if calculation of the full Hessian matrix is too expensive, the Quasi-Newton methods.

Scherer, Philipp O. J.

76

Root architecture impacts on root decomposition rates in switchgrass  

NASA Astrophysics Data System (ADS)

Roots strongly contribute to soil organic carbon accrual, but the rate of soil carbon input via root litter decomposition is still uncertain. Root systems are built up of roots with a variety of different diameter size classes, ranging from very fine to very coarse roots. Since fine roots have low C:N ratios and coarse roots have high C:N ratios, root systems are heterogeneous in quality, spanning a range of different C:N ratios. Litter decomposition rates are generally well predicted by litter C:N ratios, thus decomposition of roots may be controlled by the relative abundance of fine versus coarse roots. With this study we asked how root architecture (i.e. the relative abundance of fine versus coarse roots) affects the decomposition of roots systems in the biofuels crop switchgrass (Panicum virgatum L.). To understand how root architecture affects root decomposition rates, we collected roots from eight switchgrass cultivars (Alamo, Kanlow, Carthage, Cave-in-Rock, Forestburg, Southlow, Sunburst, Blackwell), grown at FermiLab (IL), by taking 4.8-cm diameter soil cores from on top of the crown and directly next to the crown of individual plants. Roots were carefully excised from the cores by washing and analyzed for root diameter size class distribution using WinRhizo. Subsequently, root systems of each of the plants (4 replicates per cultivar) were separated in 'fine' (0-0.5 mm), 'medium' (0.5-1 mm) and 'coarse' roots (1-2.5 mm), dried, cut into 0.5 cm (medium and coarse roots) and 2 mm pieces (fine roots), and incubated for 90 days. For each of the cultivars we established five root-treatments: 20g of soil was amended with 0.2g of (1) fine roots, (2) medium roots, (3) coarse roots, (4) a 1:1:1 mixture of fine, medium and coarse roots, and (5) a mixture combining fine, medium and coarse roots in realistic proportions. We measured CO2 respiration at days 1, 3, 7, 15, 30, 60 and 90 during the experiment. The 13C signature of the soil was -26‰, and the 13C signature of plants was -12‰, enabling us to differentiate between root-derived C and native SOM-C respiration. We found that the relative abundance of fine, medium and coarse roots were significantly different among cultivars. Root systems of Alamo, Kanlow and Cave-in-Rock were characterized by a large abundance of coarse-, relative to fine roots, whereas Carthage, Forestburg and Blackwell had a large abundance of fine, relative to coarse roots. Fine roots had a 28% lower C:N ratio than medium and coarse roots. These differences led to different root decomposition rates. We conclude that root architecture should be taken into account when predicting root decomposition rates; enhanced understanding of the mechanisms of root decomposition will improve model predictions of C input to soil organic matter.

de Graaff, M.; Schadt, C.; Garten, C. T.; Jastrow, J. D.; Phillips, J.; Wullschleger, S. D.

2010-12-01

77

Early nodulines in root development  

Microsoft Academic Search

The symbiotic interaction between bacteria of the genus Rhizobium and leguminous plants leads to the formation of root nodules, which are specific nitrogen-fixing organs on the roots of plants. Bacteria enter the root by infection threads, and concomitantly cell divisons are induced in the root cortex, which lead to the formation of a meristern. From this meristern the different tissues

B. Scheres

1990-01-01

78

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

79

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

80

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

PubMed Central

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 magnitude of plasticity relative to differences between species, studies of plasticity can ascertain if plasticity is predictable and whether an environmental factor elicits changes in traits that are functionally advantageous. Methods To compare functional traits and trait plasticities in fine root tissues with natural and reduced levels of colonization by microbial symbionts, trimmed and surface-sterilized root segments of 2-year-old Acer rubrum and Quercus rubra seedlings were manipulated. Segments were then replanted into satellite pots filled with control or heat-treated soil, both originally derived from a natural forest. Mycorrhizal colonization was near zero in roots grown in heat-treated soil; roots grown in control soil matched the higher colonization levels observed in unmanipulated root samples collected from field locations. Key Results Between-treatment comparisons revealed negligible plasticity for root diameter, branching intensity and nitrogen concentration across both species. Roots from treated soils had decreased tissue density (approx. 10–20 %) and increased specific root length (approx. 10–30 %). In contrast, species differences were significant and greater than treatment effects in traits other than tissue density. Interspecific trait differences were also significant in field samples, which generally resembled greenhouse samples. Conclusions The combination of experimental and field approaches was useful for contextualizing trait plasticity in comparison with inter- and intra-specific trait variation. Findings that root traits are largely species dependent, with the exception of root tissue density, are discussed in the context of current literature on root trait variation, interactions with symbionts and recent progress in standardization of methods for quantifying root traits. PMID:24363335

Lee, Mei-Ho; Comas, Louise H.; Callahan, Hilary S.

2014-01-01

81

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

82

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

83

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

84

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

85

LANDFORM, SOIL MORPHOLOGY, AND TILLAGE EFFECTS ON SOYBEAN ROOT DISTRIBUTION FOR CLAYPAN SOILS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Claypans are soil morphological features that limit crop root growth. These extreme argillic horizons alter root development due to physical impedance, altered hydrology, and reduced plant available water capacity. More detailed spatial information about root development is needed for calibration an...

86

Broad compatibility in fungal root symbioses.  

PubMed

Plants associate with a wide range of beneficial fungi in their roots which facilitate plant mineral nutrient uptake in exchange for carbohydrates and other organic metabolites. These associations play a key role in shaping terrestrial ecosystems and are widely believed to have promoted the evolution of land plants. To establish compatibility with their host, root-associated fungi have evolved diverse colonization strategies with distinct morphological, functional and genomic specializations as well as different degrees of interdependence. They include obligate biotrophic arbuscular mycorrhizal (AM), and facultative biotrophic ectomycorrhizal (ECM) interactions but are not restricted to these well-characterized symbioses. There is growing evidence that root endophytic associations, which due to their inconspicuous nature have been often overlooked, can be of mutualistic nature and represent important players in natural and managed environments. Recent research into the biology and genomics of root associations revealed fascinating insight into the phenotypic and trophic plasticity of these fungi and underlined genomic traits associated with biotrophy and saprotrophy. In this review we will consider the commonalities and differences of AM and ECM associations and contrast them with root endophytes. PMID:24929298

Zuccaro, Alga; Lahrmann, Urs; Langen, Gregor

2014-08-01

87

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

88

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...

89

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.

2012-06-26

90

Fine root turnover: a story of root production and root phenology  

NASA Astrophysics Data System (ADS)

Fine root turnover in terrestrial ecosystems partially controls carbon flow from plants into soils as well the amount of roots available for nutrient and water uptake. However, we have poor understanding of basic patterns and variability in fine root turnover. We address this shortfall through the use of a heuristic model and analysis of a multi-year minirhizotron dataset exploring the impacts of fine root phenology and production on fine root turnover rates across 12 temperate tree species in a common garden experiment. The heuristic model allowed us to calculate fine root turnover given different patterns of root production and different fine root lifespans. Using the model we found that patterns of phenology characterized by a single, concentrated peak resulted in slower calculated root turnover rates while broader and bi-modal production patterns resulted in faster turnover rates. For example, for roots with median lifespans of 91 days, estimates of root turnover increased from 1.5 yr-1 to 4.0 yr-1 between the pattern of concentrated root production and the pattern with root production spread equally throughout the year. Turnover rates observed in the common garden ranged from 0.75 yr-1 to 1.33 yr-1 and 0.93 yr-1 to 2.14 yr-1 when calculated as annual production divided by maximum standing root crop or average standing root crop, respectively. Turnover varied significantly across species and interannual variability in root production and turnover was high. Patterns of root phenology observed at the common garden included concentrated root production in late spring as well as several examples of bi-modal and broader patterns of root production with roots produced across spring, summer and fall. Overall, both phenology and total root production impacted estimates of root turnover, particularly for short-lived fine roots with median lifespans of less than one year. Our results suggest that better understanding fine root phenology and production will improve our ability to describe and predict key processes of root turnover and resource uptake belowground in terrestrial ecosystems.

McCormack, M. L.; Adams, T. S.; Smithwick, E. A.; Eissenstat, D. M.

2012-12-01

91

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

92

Hairy roots are more sensitive to auxin than normal roots  

PubMed Central

Responses to auxin of Lotus corniculatus root tips or protoplasts transformed by Agrobacterium rhizogenes strains 15834 and 8196 were compared to those of their normal counterparts. Three different types of experiments were performed, involving long-term, medium-term, or short-term responses to a synthetic auxin, 1-naphthaleneacetic acid. Root tip elongation, proton excretion by root tips, and transmembrane electrical potential difference of root protoplasts were measured as a function of exogenous auxin concentration. The sensitivity of hairy root tips or protoplasts to exogenous auxin was found to be 100-1000 times higher than that of untransformed material. PMID:16593928

Shen, Wen Hui; Petit, Annik; Guern, Jean; Tempé, Jacques

1988-01-01

93

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

94

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

95

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

96

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

97

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

2011-02-24

98

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

99

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

100

The role of hysteresis in modeling root water uptake, both for single root and root system models.  

NASA Astrophysics Data System (ADS)

The water retention curve obtained by progressive extraction of water from an initially saturated soil (desorption) differs from that obtained by gradual addition of water to air-dry soil (absorption). This phenomenon is called hysteresis (Koorevaar et al., 1983). Common as its occurrence is, it is often neglected in the modeling of root water uptake. We will present here a model for the transport of water to a single root. The model solves Richard's equation in cylindrical coordinates where the water uptake rate is a function of the root water potential. The occurrence of hysteresis is accounted for by application of the modified dependent domain model developed by Mualem (1984) and used by Kool and Parker (1987). We will discuss the differences in results due to the inclusion of the hysteresis subroutine, when alternate wetting and drying cycles occur. The influence of soil type and transpiration reduction function will be discussed. The findings obtained for the single root model were used to upscale root water uptake to a root system. This is a part of the FUSSIM2 model of Heinen and de Willigen (1998) and Heinen (2001), where water transport in a soil profile is calculated. We will use an example for a soil profile where the root length density decreases exponentially with depth, and where again wetting and drying cycles alternate. References Heinen M., 2001. FUSSIM2: brief description of the simulation model and application to fertigation scenarios. Agronomie 21: 285-296. Heinen, M., and P. de Willigen, 1998. FUSSIM2 A two-dimensional simulation model for water flow, solute transport and root uptake of water and nutrients in partly unsaturated porous media, QASA No. 20, AB-DLO, Wageningen, The Netherlands, 140 p. Kool J.B. and J.C. Parker, 1987. Development and evaluation of closed form expressions for hysteretic soil hydraulic properties. Water Resour. Res. 23: 105 114. Koorevaar P., G. Menelik and C. Dirksen, 1983. Elements of soil physics. Elsevier, Amsterdam, The Netherlands, Developments in Soil Science 13, 228 p. Mualem Y., 1984. A modified dependent domain theory of hysteresis. Soil Sci. 137: 283 291.

de Willigen, P.; Heinen, M.

2009-04-01

101

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

102

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

103

[Genetically transformed plant roots as a model for studying specific metabolism and symbiotic contacts of the root system].  

PubMed

Genetic transformation of plants mediated by Ri plasmid of Agrobacterium rhizogenes occupies a special place in plant cell engineering, since this technique based on a natural phenomenon allows cultivation of separately growing roots on hormone-free media. Application of wild-type unmodified agrobacterial strains allows us to obtain root cultures capable of long-term growth in vitro due to an increased sensitivity of the cells to auxins while other biochemical properties remain unaltered. A collection of pRi T-DNA transformed roots of certain dicotyledons was constructed; some strains of it are used to study synthesis of secondary metabolites in root cells. The in vitro cultivated roots could synthesize root-specific metabolites, which allows their large-scale application for biotechnological production of ecologically pure crude drugs. Cocultivation of pRi T-DNA transformed roots with arbuscular mycorrhizal fungi makes possible vital study of all stages of obligate symbiont development and interaction with plant roots. Mixed axenic culture of AM fungi and pRi T-DNA transformed plants can be used to construct a collection of the most valuable endomycorrhizal fungal species and to produce considerable quantities of homogeneous fungal inoculums. PMID:15354957

Kuzovkina, I N; Al'terman, I E; Karandashov, V E

2004-01-01

104

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

105

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

106

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

107

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

108

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

109

Gamma-ray irradiation resistance of silver doped GeS2-Ga2S3-AgI chalcohalide glasses  

NASA Astrophysics Data System (ADS)

In the present work, series of silver doped Ge-Ga-S-AgI chalcohalide glasses have been prepared and their optical transmission spectra are compared before and after ?-ray irradiation at different doses. The differential transmission spectra of the irradiated samples with and without Ag doping have been compared to characterize the ?-ray irradiation induced red-shift of electronic absorption and formation of color centers. Ag doping plays an important role in increasing ?-ray irradiation resistance of the chalcohalide glasses due to its specific effect on the valence band and the network structure of glasses.

Shen, W.; Baccaro, S.; Cemmi, A.; Ren, J.; Zhang, Z.; Zhou, Y.; Yang, Y.; Chen, G.

2014-06-01

110

Gamma-Ray Irradiation Resistance of Silver Doped GeS2-Ga2S3-AgI Chalcohalide Glasses  

NASA Astrophysics Data System (ADS)

In the present work, series of silver doped Ge-Ga-S-AgI chalcohalide glasses have been prepared and their optical transmission spectra are compared before and after ?-ray irradiation at different doses. The differential transmission spectra of the irradiated samples with and without Ag doping have been compared to characterize the ?-ray irradiation induced red-shift of electronic absorption and formation of color centers. Ag doping plays an important role in increasing ?-ray irradiation resistance of the chalcohalide glasses due to its specific effect on the valence band and the network structure of glasses.

Zhou, Y.; Shen, W.; Zhang, Z.; Yang, Y.; Chen, G.; Baccaro, S.; Cemmi, A.

2014-06-01

111

The roots of predictivism.  

PubMed

In The Paradox of Predictivism (2008, Cambridge University Press) I tried to demonstrate that there is an intimate relationship between predictivism (the thesis that novel predictions sometimes carry more weight than accommodations) and epistemic pluralism (the thesis that one important form of evidence in science is the judgments of other scientists). Here I respond to various published criticisms of some of the key points from Paradox from David Harker, Jarret Leplin, and Clark Glymour. Foci include my account of predictive novelty (endorsement novelty), the claim that predictivism has two roots, the prediction per se and predictive success, and my account of why Mendeleev's predictions carried special weight in confirming the Periodic Law of the Elements. PMID:24984449

Barnes, Eric Christian

2014-03-01

112

Comparing Morphological Plasticity of Root Orders in Slow- and Fast-growing Citrus Rootstocks Supplied with Different Nitrate Levels  

PubMed Central

Background and Aims Studies of the plasticity of functional root traits involved in resource acquisition have focused mainly on root length without considering such ‘morphological components’ as biomass allocation, specific root length, root fineness, and tissue density that affect root length. The plasticity of the above components in response to nitrate supply was studied in each root order of two co-generic citrus rootstocks, namely the fast-growing Citrus jambhiri ‘Rough Lemon’ (RL) and the slow-growing Citrus reshni ‘Cleopatra Mandarin’ (CM). Methods Morphological traits of individual root orders of CM and RL, grown at different nitrate levels (NO3-N at 0·1, 0·5, 1 and 10 mm) were examined by using an image-specific analysis system. Key Results At high nitrate levels, the root length ratio, root mass ratio and, to a lesser degree, specific root length, root fineness and tissue density of tap and 1st-order laterals in both CM and RL were reduced. In 2nd-order laterals, however, the same treatment led to increased values of each morphological trait in CM but decreased values of the same traits in RL. At low nitrate supply, CM exhibited longer tap roots whereas RL developed longer 2nd-order laterals. These effects were due to root mass ratio and, to a lesser extent, specific root length. Conclusions Biomass allocation was the main component of nitrate-induced changes in root length ratio. The 2nd-order laterals were more sensitive to nitrate availability than the tap root and 1st-order laterals. At low nitrate availability, RL displayed longer 2nd-order lateral roots and lower root plasticity than CM. This suggests a different root growth strategy among citrus rootstocks for adapting to nitrate availability: RL invests in 2nd-order laterals, the preferred zone for acquiring the nutrient, whereas CM responds with longer tap roots. PMID:17881338

Sorgonà', Agostino; Abenavoli, Maria Rosa; Gringeri, Pietro Giorgio; Cacco, Giovanni

2007-01-01

113

Apogeotropic Roots in an Amazon Rain Forest  

Microsoft Academic Search

Roots of some tropical trees grow vertically upward on the stems of neighboring trees. Apogeotropic roots occur in 12 species across five families. These roots, originating as fine roots in the mineral soil, grow upward as fast as 5.6 centimeters in 72 hours. Apogeotropic root growth may be an adaptation to extremely low soil nutrient availability in Amazon forests. In

Robert L. Sanford

1987-01-01

114

Project Work on Plant Roots.  

ERIC Educational Resources Information Center

Methods of investigating plant root growth developed for research purposes can be adopted for student use. Investigations of the effect of water table level and of ethylene concentration are described, and techniques of measuring root growth are explained. (Author/ML)

Devonald, V. G.

1986-01-01

115

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

116

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

117

Root exudates: the hidden part of plant defense.  

PubMed

The significance of root exudates as belowground defense substances has long been underestimated, presumably due to being buried out of sight. Nevertheless, this chapter of root biology has been progressively addressed within the past decade through the characterization of novel constitutively secreted and inducible phytochemicals that directly repel, inhibit, or kill pathogenic microorganisms in the rhizosphere. In addition, the complex transport machinery involved in their export has been considerably unraveled. It has become evident that the profile of defense root exudates is not only diverse in its composition, but also strikingly dynamic. In this review, we discuss current knowledge of the nature and regulation of root-secreted defense compounds and the role of transport proteins in modulating their release. PMID:24332225

Baetz, Ulrike; Martinoia, Enrico

2014-02-01

118

Fungi in neotropical epiphyte roots.  

PubMed

Roots of thirty-eight Ecuadoran vascular epiphytes, representing eleven angiosperm families, were examined for the presence of symbiotic microorganisms. Most orchid roots contained fungal endophytes like those that regularly infect terrestrial counterparts. Hyphae were also common in and on nonorchid roots, but assignments of these relationships to known mycorrhizal morphologies was not possible in all cases. Evidence of vesicular-arbuscular mycorrhizae (VAM) existed in a number of subjects while in Ericaceae and Campanulaceae a fungal association similar to the demateaceous surface fungi (DSF) described for alpine and prarie plants was usually present. Some associations were characterized by multicellular propagules on root surfaces. The significance of these findings and the factors likely to influence occurrence and consequences of root-fungus mutualisms in tropical forest canopies are discussed. Facts and considerations that could aid future inquiry on these systems are provided. PMID:2624888

Bermudes, D; Benzing, D H

1989-01-01

119

Calcium Oxide as a Root Filling Material: a Three-Year Prospective Clinical Outcome Study  

PubMed Central

Calcium oxide, available for decades as a root canal filling material, has been little used in recent years due to its lack of radio-opacity, and an expectation that it would lead to an excess of root fractures. In this study, four general dentists submitted 79 cases of endodontically treated teeth whose roots were filled with either Biocalex 6/9, or Endocal-10, and rendered adequately radio-opaque with yttrium oxide. Fifty-seven teeth were available for follow up at three years. Criteria for success were comfort, function, radiographic signs of healing. The overall success rate was 89%. The percentage of teeth retained in function was 98%; aside from one equivocal case, no teeth were lost due to root fractures. These numbers are indistinguishable from success rates reported for conventional root filling materials. Conclusion: Calcium oxide may be considered as a safe and viable alternative to other current methods of root obturation. PMID:21559188

Koral, Stephen M

2011-01-01

120

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

121

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

122

Comprehensive transcriptional profiling of NaCl-stressed Arabidopsis roots reveals novel classes of responsive genes  

Microsoft Academic Search

BACKGROUND: Roots are an attractive system for genomic and post-genomic studies of NaCl responses, due to their primary importance to agriculture, and because of their relative structural and biochemical simplicity. Excellent genomic resources have been established for the study of Arabidopsis roots, however, a comprehensive microarray analysis of the root transcriptome following NaCl exposure is required to further understand plant

Yuanqing Jiang; Michael K Deyholos

2006-01-01

123

Amyloplast Distribution Directs a Root Gravitropic Reaction  

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. As it is known, roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector, stems - with negative gravitropism, i. e. they grow in the direction opposite to a gravitational vector. According to the Nemec’s and Haberlandt’s starch-statolith hypothesis, amyloplasts in diameter of 1.5 - 3 ? in average, which appear to act as gravity sensors and fulfill a statolythic function in the specialized graviperceptive cells - statocytes, sediment in the direction of a gravitational vector in the distal part of a cell, while a nucleus is in the proximal one. There are reasonable data that confirm the amyloplasts-statoliths participation in gravity perception: 1) correlation between the statoliths localization and the site of gravity sensing, 2) significant redistribution (sedimentation) of amyloplasts in statocytes under gravistimulation in comparison with other cell organelles, 3) root decreased ability to react on gravity under starch removal from amyloplasts, 4) starchless Arabidopsis thaliana mutants are agravitropic, 5) amyloplasts-statoliths do not sediment in the absence of the gravitational vector and are in different parts or more concentrated in the center of statocytes. Plant tropisms have been intensively studied for many decades and continue to be investigated. Nevertheless, the mechanisms by which plants do so is still not clearly explained and many questions on gravisensing and graviresponse remain unanswered. Even accepted hypotheses are now being questioned and recent data are critically evaluated. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence with regard to the participation of calcium ions and cytoskeletal elements in these processes is therefore substantial but still circumstantial and requires new experimental data. Using a new model - weak combined magnetic fields (CMFs), which elicit a variety of responses in plants, growth rate and fresh weight, seed germination, Ca2+ concentration, membrane permeability, with a frequency resonance to cyclotron frequency of calcium ions, we firstly showed that a root positive gravitropic reaction changes on a negative one. In this case, the paradoxical displacement of amylopasts-statoliths to the upper longitudinal cell wall of statocytes occurred in the direction opposite to a gravitational vector. Displacement of amyloplasts, which contain the abundance of free Ca2+ in the stroma, was accompanied with Ca2+ redistribution in the same direction in the cytosol and increasing around amyloplasts in comparison with the state magnetic field. In the elongation zone, calcium ions accumulated in the upper site of a gravistimulated root unlike a positive gravitropic reaction, and a root is bending in the same direction in which amyloplasts are displacing. It seems that a root gravitropic reaction, if it began, occurs by an usual physiological way resulting in root bending with an opposite sign. It is of a special interest that a root is bending to the same direction with displacing of amyloplasts: in positive gravitropism - downwards, in negative gravitropism - upwards. Peculiarities of calcium ion redistribution in statocytes under gravistimulation in such combined magnetic field are a new additional evidence of a Ca2+ ion significant role in gravitropism. Thus, our data support the starch-statolith hypothesis but also pose the question as to which forces displace amyloplasts against the gravity vector? We hope that these data will stimulate new research to better understand the mechanisms of plant graviperception and graviresponse. Gravistimulation of a root in the CMF with the frequency resonance to the cyclotron frequency of Ca2+ ions is an effective model for future

Kordyum, Elizabeth

124

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

125

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

126

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

127

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

NASA Astrophysics Data System (ADS)

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.

Mullen, J. L.; Hangarter, R. P.

2003-05-01

128

Root Absorption and Xylem Translocation  

NSDL National Science Digital Library

Overview: Herbicides must be absorbed into plants inorder to be effective. Plant roots and below ground shoots have fewbarriers to herbicide absorption; however, interactions with soilparticles and soil organic matter have significant impacts on theamount of herbicide available for plant absorption. Plant roots andbelow ground shoots (hypocotyls or coleoptiles) are lipophilic bynature and do not have thick, waxy cuticles like leaves. Lipophilic andhydrophilic herbicides reach the root surface by bulk transport in soilwater; however, there are a few examples of herbicides that reach theroot as a vapor or gas. Soil-applied herbicides can translocate to theshoot or remain in the root system. Soil-applied herbicides translocateto the shoot in the xylem and tend to accumulate in mature leaves thattranspire the most water. The lipophilic/hydrophilic nature of theherbicide will determine if the herbicide translocates to the shoot.Absorption and translocation of phloem-mobile herbicides will bediscussed in another lesson.

129

Ultrasonic cleaning of root canals  

NASA Astrophysics Data System (ADS)

A crucial step during a dental root canal treatment is irrigation, where an antimicrobial fluid is injected into the root canal system to eradicate all bacteria. Agitation of the fluid using an ultrasonically vibrating miniature file has shown significant improvement in cleaning efficacy over conventional syringe irrigation. However, the physical mechanisms underlying the cleaning process, being acoustic streaming, cavitation or chemical activity, and combinations thereof, are not fully understood. High-speed imaging allows us to visualize the flow pattern and cavitation in a root canal model at microscopic scales, at timescales relevant to the cleaning processes (microseconds). MicroPIV measurements of the induced acoustic streaming are coupled to the oscillation characteristics of the file as simulated numerically and measured with a laser vibrometer. The results give new insight into the role of acoustic streaming and the importance of the confinement for the cleaning of root canals.

Verhaagen, Bram; Boutsioukis, Christos; Jiang, Lei-Meng; Macedo, Ricardo; van der Sluis, Luc; Versluis, Michel

2011-11-01

130

Swarming behavior in plant roots.  

PubMed

Interactions between individuals that are guided by simple rules can generate swarming behavior. Swarming behavior has been observed in many groups of organisms, including humans, and recent research has revealed that plants also demonstrate social behavior based on mutual interaction with other individuals. However, this behavior has not previously been analyzed in the context of swarming. Here, we show that roots can be influenced by their neighbors to induce a tendency to align the directions of their growth. In the apparently noisy patterns formed by growing roots, episodic alignments are observed as the roots grow close to each other. These events are incompatible with the statistics of purely random growth. We present experimental results and a theoretical model that describes the growth of maize roots in terms of swarming. PMID:22272246

Ciszak, Marzena; Comparini, Diego; Mazzolai, Barbara; Baluska, Frantisek; Arecchi, F Tito; Vicsek, Tamás; Mancuso, Stefano

2012-01-01

131

Swarming Behavior in Plant Roots  

PubMed Central

Interactions between individuals that are guided by simple rules can generate swarming behavior. Swarming behavior has been observed in many groups of organisms, including humans, and recent research has revealed that plants also demonstrate social behavior based on mutual interaction with other individuals. However, this behavior has not previously been analyzed in the context of swarming. Here, we show that roots can be influenced by their neighbors to induce a tendency to align the directions of their growth. In the apparently noisy patterns formed by growing roots, episodic alignments are observed as the roots grow close to each other. These events are incompatible with the statistics of purely random growth. We present experimental results and a theoretical model that describes the growth of maize roots in terms of swarming. PMID:22272246

Ciszak, Marzena; Comparini, Diego; Mazzolai, Barbara; Baluska, Frantisek; Arecchi, F. Tito; Vicsek, Tamás; Mancuso, Stefano

2012-01-01

132

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 (...

133

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

134

Effect of living roots on soil organic matter decomposition  

Microsoft Academic Search

Contradictory data exist in the literature about the effects of living roots on soil organic matter decom- position. Decomposition of labelled plant material is markedly lowered in the presence of cultivated plant cover or in natural grasslands, when compared to bare soil controls due to the difference of the physical environment between the plant covered soil and the fallow soil

WEIXIN CHENG; D COLEMAN

1990-01-01

135

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

136

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...

137

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

138

Formation of AgFeO2, ?-FeOOH, and Ag2O from mixed Fe(NO3)3-AgNO3 solutions at high pH  

NASA Astrophysics Data System (ADS)

Precipitation of ternary oxide silver ferrite (AgFeO2), iron oxyhydroxide goethite (?-FeOOH) and silver(I) oxide (Ag2O) from mixed Fe(NO3)3-AgNO3 solutions in a whole [Ag+]:[Fe3+] concentration ratio range at high pH was investigated using X-ray powder diffraction (XRD), 57Fe Mössbauer, FT-IR and UV-Vis-NIR spectroscopies and field emission scanning electron microscopy (FE-SEM). Strong alkalis organic tetramethylammonium hydroxide (TMAH) or inorganic NaOH were used as precipitating agents. Monodispersed lath-like ?-FeOOH particles were formed from a pure Fe(NO3)3 solution. The presence of Ag+ ions influenced the formation of the delafossite-type ternary oxide AgFeO2 beside ?-FeOOH. The positions of XRD and Mössbauer lines did not suggest any significant incorporation of Ag+ ions into the ?-FeOOH structure. AgFeO2 was formed in the precipitation system with the equimolar initial [Ag+]:[Fe3+] concentration ratio. The size and shape of AgFeO2 particles, as well as their structural polytype (2H or 3R), were dependent on reaction temperature, aging time and alkali used. In systems with an excess of Ag+ ions mixtures of AgFeO2 and Ag2O were formed. Single phase Ag2O precipitated from a pure AgNO3 solution.

Krehula, Stjepko; Musi?, Svetozar

2013-07-01

139

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

140

Live imaging of root hairs.  

PubMed

Root hairs are single cells specialized in the absorption of water and nutrients. Growing root hairs requires intensive cell wall changes to accommodate cell expansion at the apical end by a process known as tip growth. The cell wall of plants is a very rigid structure comprised largely of polysaccharides and hydroxyproline-rich O-glycoproteins. The importance of root hairs stems from their capacity to expand the surface of interaction between the root and the environment, in search for the necessary nutrients and water to allow plant growth. Therefore, it becomes crucial to deepen our knowledge of them, particularly in the light of the applicability in agriculture by allowing the expansion of croplands. Root hair growth is an extremely fast process, reaching growth rates of up to 1 ?m/min and it also is a dynamic process; there can be situations in which the final length might not be affected but the growth rate is. Consequently, in this chapter we focus on a method for studying growth dynamics and rates during a time course. This method is versatile allowing for it to be used in other plant organs such as lateral root, hypocotyl, etc., and also in various conditions. PMID:25408443

Velasquez, Silvia M; Dinneny, Jose R; Estevez, José M

2015-01-01

141

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

142

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

143

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

144

Rhizoctonia and Bacterial Root Rot in Sugarbeet  

Technology Transfer Automated Retrieval System (TEKTRAN)

Root rot in sugarbeet can cause losses approaching 50% or more in Idaho. To assess the distribution of root rot fungi and their relationship to bacterial root rot, commercial sugar beet roots were collected at harvest time in the Intermountain West (IMW). Isolations for both fungi and bacteria wer...

145

ROOT AND BUTT ROTS OF FOREST TREES  

E-print Network

ROOT AND BUTT ROTS OF FOREST TREES 12th International Conference on Root and Butt Rots IUFRO Medford, Oregon (USA) CONFERENCEPROCEEDINGS #12;ROOT AND BUTT ROTS OF FOREST TREES 12th International Conference on Root and Butt Rots IUFRO Working Party 7.02.01 CONFERENCE PROCEEDINGS M. Garbelotto & P

California at Berkeley, University of

146

On the elimination of extraneous roots  

Microsoft Academic Search

In this paper we develop a technique to eliminate extraneous roots from reduced rank, linear predictive frequency and direction of arrival (DOA) estimation algorithms. These singular value decomposition (SVD) based algorithms produce a noise cleaned linear prediction vector and then root this vector to obtain a subset of roots, whose angles contain the desired frequency or DOA information. The roots

Eric M. Dowling; D. A. Linebarger; Ronald D. DeGroat; Hong Guan

1995-01-01

147

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

148

Apogeotropic roots in an Amazon rain forest.  

PubMed

Roots of some tropical trees grow vertically upward on the stems of neighboring trees. Apogeotropic roots occur in 12 species across five families. These roots, originating as fine roots in the mineral soil, grow upward as fast as 5.6 centimeters in 72 hours. Apogeotropic root growth may be an adaptation to extremely low soil nutrient availability in Amazon forests. In these forests upward-growing roots obtain nutrients via the predictable pathway of precipitation that flows down along the stem. Apogeotropic roots form a nutrient cycling pathway in which nutrients are absorbed and transported directly from plant to plant, without entering the soil solution. PMID:17782254

Sanford, R L

1987-02-27

149

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

150

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

151

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

PubMed

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

Hong, Li-Wei; Yan, Da-Wei; Liu, Wen-Cheng; Chen, Hong-Guo; Lu, Ying-Tang

2014-01-01

152

Enzymes hydrolyzing structural components and ferrous ion cause rusty-root symptom on ginseng (Panax ginseng).  

PubMed

Microbial induction of rusty-root was proved in this study. The enzymes hydrolyzing plant structural materials, including pectinase, pectolyase, ligninase, and cellulase, caused the rusty-root in ginseng. Pectinase and pectolyase produced the highest rusty-color formation. Ferrous ion (Fe+++) caused the synergistic effect on rusty-root formation in ginseng when it was used with pectinase. The effect of ferric ion (Fe++) on rusty-root formation was slow, compared with Fe+++, probably due to gradual oxidation to Fe+++. Other metal ions including the ferric ion (Fe++) did not affect rusty-root formation. The endophytic bacteria Agrobacterium tumefaciens, Lysobacter gummosus, Pseudomonas veronii, Pseudomonas marginalis, Rhodococcus erythropolis, and Rhodococcus globerulus, and the rotten-root forming phytophathogenic fungus Cylindrocarpon destructans, caused rusty-root. The polyphenol formation (rusty color) was not significantly different between microorganisms. The rotten-root-forming C. destructans produced large quantities of external cellulase activity (about 2.3 U[micronM/min/mg protein]), which indicated the pathogenecity of the fungus, whereas the bacteria produced 0.1-0.7 U. The fungal external pectinase activities (0.05 U) and rusty-root formation activity were similar to those of the bacteria. In this report, we proved that microbial hydrolyzing enzymes caused rusty-root (Hue value 15 degrees) of ginseng, and ferrous ion worsened the symptom. PMID:21364303

Lee, Chanyong; Kim, Kwang Yup; Lee, Jo-Eun; Kim, Sunghan; Ryu, Dongkul; Choi, Jae-Eul; An, Gilhwan

2011-02-01

153

When Outgroups Fail; Phylogenomics of Rooting the Emerging Pathogen, Coxiella burnetii  

PubMed Central

Rooting phylogenies is critical for understanding evolution, yet the importance, intricacies and difficulties of rooting are often overlooked. For rooting, polymorphic characters among the group of interest (ingroup) must be compared to those of a relative (outgroup) that diverged before the last common ancestor (LCA) of the ingroup. Problems arise if an outgroup does not exist, is unknown, or is so distant that few characters are shared, in which case duplicated genes originating before the LCA can be used as proxy outgroups to root diverse phylogenies. Here, we describe a genome-wide expansion of this technique that can be used to solve problems at the other end of the evolutionary scale: where ingroup individuals are all very closely related to each other, but the next closest relative is very distant. We used shared orthologous single nucleotide polymorphisms (SNPs) from 10 whole genome sequences of Coxiella burnetii, the causative agent of Q fever in humans, to create a robust, but unrooted phylogeny. To maximize the number of characters informative about the rooting, we searched entire genomes for polymorphic duplicated regions where orthologs of each paralog could be identified so that the paralogs could be used to root the tree. Recent radiations, such as those of emerging pathogens, often pose rooting challenges due to a lack of ingroup variation and large genomic differences with known outgroups. Using a phylogenomic approach, we created a robust, rooted phylogeny for C. burnetii. [Coxiella burnetii; paralog SNPs; pathogen evolution; phylogeny; recent radiation; root; rooting using duplicated genes.] PMID:23736103

Pearson, Talima; Hornstra, Heidie M.; Sahl, Jason W.; Schaack, Sarah; Schupp, James M.; Beckstrom-Sternberg, Stephen M.; O'Neill, Matthew W.; Priestley, Rachael A.; Champion, Mia D.; Beckstrom-Sternberg, James S.; Kersh, Gilbert J.; Samuel, James E.; Massung, Robert F.; Keim, Paul

2013-01-01

154

Life cycles of individual roots in fine root system of Chamaecyparis obtusa Sieb. et Zucc  

Microsoft Academic Search

Recent studies have remarked on differences in the life cycles of individual fine roots. However, the dynamics of individual roots with different life cycles, such as ephemeral and perennial, during root system development are still unknown. We examined individual roots during fine root system development in a mature stand of Chamaecyparis obtusa Sieb. et Zucc. (Cupressaceae) using the sequential ingrowth

Takuo Hishi; Hiroshi Takeda

2005-01-01

155

Root status and future developments  

SciTech Connect

In this talk the authors review the major additions and improvements made to the ROOT system in the last 18 months and present their plans for future developments. The additions and improvements range from modifications to the I/O sub-system to allow users to save and restore objects of classes that have not been instrumented by special ROOT macros, to the addition of a geometry package designed for building, browsing, tracking and visualizing detector geometries. Other improvements include enhancements to the quick analysis sub-system (TTree::Draw()), the addition of classes that allow inter-file object references (TRef, TRefArray), better support for templates and STL classes, amelioration of the Automatic Script Compiler and the incorporation of new fitting and mathematical tools. Efforts have also been made to increase the modularity of the ROOT system with the introduction of more abstract interfaces and the development of a plug-in manager. In the near future, they intend to continue the development of PROOF and its interfacing with GRID environments. They plan on providing an interface between Geant3, Geant4 and Fluka and the new geometry package. The ROOT-GUI classes will finally be available on Windows and they plan to release a GUI inspector and builder. In the last year, ROOT has drawn the endorsement of additional experiments and institutions. It is now officially supported by CERN and used as key I/O component by the LCG project.

Rene Brun et al.

2003-10-01

156

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

157

Stimulation of in vitro root and shoot growth of potato by increasing sucrose concentration in the presence of fluridone, an inhibitor of abscisic acid synthesis  

Microsoft Academic Search

Fluridone, an inhibitor of abscisic acid (ABA) biosynthesis, strongly stimulated rooting of nodal stem segments of potato (Solanum tuberosum L.) cultivar Arran Banner cultured in darkness on tuberisation medium. Inclusion of 10-6 M ABA in the culture medium prevented this rooting response, indicating that root proliferation in the presence of fluridone could be due to inhibition of ABA synthesis. The

B. M. R. Harvey; G. Bowden; C. Reavey; C. Selby

1994-01-01

158

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.

159

Macroinvertebrates associated with water hyacinth roots and a root analog  

E-print Network

are initiated. Key words: Eichhornia crassipes, macroinvertebrates, assemblage, blackwater river, invasive plant J. Hutchens, Jr.1,2,4 , and James O. Luken1,2,5 1 Coastal Marine and Wetland Studies Graduate was to assess whether water hyacinth roots provided unique habitat. Plants representing ambient conditions

Hutchens, John

160

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

161

Neutron Radiography of Root Water Uptake  

NASA Astrophysics Data System (ADS)

Water flow from soil to roots presents still important open questions: which parts of the roots are more active in water uptake? How do the soil properties affect the root uptake? In particular, which are the properties of the soil near the roots , i.e. the rhizosphere? We used neutron radiography and tomography to image the water content distribution in soils during root uptake. Rectangular (quasi 2D) and cylindrical containers were filled with sandy soil and planted with lupins. Three weeks after planting, the samples were equilibrated at -10 and -30 hPa and have been radiographed for 9 days at intervals of 6 hours. A region of water depletion formed around the tap root and the more proximal parts of the lateral roots. As the soil dried up, water was stored around the more distal parts of the lateral roots and it moved into the roots. When the soil was irrigated, steep gradients in water content formed around the roots, indicating a quick root uptake. High water content near roots and quick uptake after irrigation show that the soil near the roots is a region with specific hydraulic properties where fast fluxes and high gradients occur. We expect that the properties and dynamics of this soil region control the root water uptake.

Carminati, A.; Moradi, A.; Oswald, S.

2008-12-01

162

Diplopia due to Dacryops  

PubMed Central

Dacryops is a lacrimal ductal cyst. It is known that it can cause globe displacement, motility restriction, and proptosis because of the mass effect. Diplopia due to dacryops has not been reported previously. Here, we present a 57-year-old man with binocular horizontal diplopia that occurred during left direction gaze due to dacryops. PMID:24368956

Duman, Re?at; Balc?, Mehmet

2013-01-01

163

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.

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

2015-01-01

164

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

165

The effect of various ultrasonic and hand instruments on the root surfaces of human single rooted teeth: A Planimetric and Profilometric study  

PubMed Central

Background: The purpose of this study was to compare the effectiveness of different ultrasonic scalers and a periodontal curette on the root surfaces for calculus removal and root surface roughness. Materials and Methods: 40 single rooted teeth with subgingival calculus destined for extraction were assigned to one of three experimental groups (n = 10, in each group) and one control group (untreated, n = 10). Experimental groups were: Group 1: Piezoelectric ultrasonic group; Group 2: Magnetostrictive ultrasonic group; Group 3: Hand instrumentation group (Curette). After instrumentation, the teeth were extracted and the presence of residual deposits and root surface roughness were analyzed using Planimetric analyzing tool (Tool that measures the area of a plane figure as a mechanically coupled pointer traversing the perimeter of figure) and Surface Profilometer (Instrument used for profiling of an object). Root surface characteristics were evaluated qualitatively using SEM. Standardization of force, angulations and adaptation of instrument couldn’t be achieved in our study due to in vivo study design rather than in vitro design in previous studies where procedure was done on the extracted teeth samples. Results: The results of the study showed that residual deposits were similar in all experimental groups. With respect to roughness parameters, Rq (Root mean square roughness) and Rt (Total roughness) a significant difference was observed (P < 0.001) among hand instrumentation and ultrasonic devices. SEM analysis revealed a similar root surface pattern for the ultrasonic devices, but curette showed many instrument scratches, gouges, and removal of large amount of cementum. Conclusions: Curette produced the rougher root surfaces than two ultrasonic devices used in the study and caused more root surface removal. Piezoelectric devices produced minimum root surface roughness but caused more root substance removal and more cracks than Magnetostrictive ultrasonic devices.

Mittal, Antush; Nichani, Ashish Sham; Venugopal, Ranganath; Rajani, Vuppalapati

2014-01-01

166

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

167

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

168

Excising the Root from STEM  

ERIC Educational Resources Information Center

There are a number of well-intentioned STEM initiatives, some designed to improve the recruitment and retention of science teachers. Sometimes it appears that the initiators are remote from direct contact with the "grass roots" issues that feed the "stem" on which the blossoms of young enthusiastic recruits to the science teaching profession are…

Lock, Roger

2009-01-01

169

EVOLUTIONARY EPIGENETIC THEORY Root Gorelick  

E-print Network

EVOLUTIONARY EPIGENETIC THEORY by Root Gorelick A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy ARIZONA STATE UNIVERSITY May 2004 #12;EVOLUTIONARY EPIGENETIC: Director of the School Dean, Graduate College #12;ABSTRACT Epigenetic effects are important in evolutionary

Gorelick, Root

170

The Social Impact of "Roots"  

ERIC Educational Resources Information Center

A survey revealed that a larger percentage of blacks than of whites had watched the television drama "Roots," considered it accurate, and discussed it with friends. The program's influence on the racial attitude of whites was found to be less than many media observers had believed. (GW)

Hur, Kenneth K.; Robinson, John P.

1978-01-01

171

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...

172

Root Architecture and Plant Productivity  

Microsoft Academic Search

Water and nutrient availability limit plant growth in a11 but a very few natural ecosystems. They limit yield in most agricultural ecosystems, and in the United States and other industrialized nations, intensive irrigation and fertilization have generated serious environmental problems. The ac- quisition of soil resources by plant root systems is therefore a subject of considerable interest in agriculture and

Jonathan Lynch

173

Lesson 10: Extraction of Roots  

NSDL National Science Digital Library

This lesson introduces quadratic equations and graphs. Equations of the form ax^2 + c = 0 are solved via extraction of roots. Later application problems involving volume and surface area and compound interest (problems of the form a(x - p)^2 = q ) are presented.

2011-01-01

174

The pipid root.  

PubMed

The estimation of phylogenetic relationships is an essential component of understanding evolution. Accurate phylogenetic estimation is difficult, however, when internodes are short and old, when genealogical discordance is common due to large ancestral effective population sizes or ancestral population structure, and when homoplasy is prevalent. Inference of divergence times is also hampered by unknown and uneven rates of evolution, the incomplete fossil record, uncertainty in relationships between fossil and extant lineages, and uncertainty in the age of fossils. Ideally, these challenges can be overcome by developing large "phylogenomic" data sets and by analyzing them with methods that accommodate features of the evolutionary process, such as genealogical discordance, recurrent substitution, recombination, ancestral population structure, gene flow after speciation among sampled and unsampled taxa, and variation in evolutionary rates. In some phylogenetic problems, it is possible to use information that is independent of fossils, such as the geological record, to identify putative triggers for diversification whose associated estimated divergence times can then be compared a posteriori with estimated relationships and ages of fossils. The history of diversification of pipid frog genera Pipa, Hymenochirus, Silurana, and Xenopus, for instance, is characterized by many of these evolutionary and analytical challenges. These frogs diversified dozens of millions of years ago, they have a relatively rich fossil record, their distributions span continental plates with a well characterized geological record of ancient connectivity, and there is considerable disagreement across studies in estimated evolutionary relationships. We used high throughput sequencing and public databases to generate a large phylogenomic data set with which we estimated evolutionary relationships using multilocus coalescence methods. We collected sequence data from Pipa, Hymenochirus, Silurana, and Xenopus and the outgroup taxon Rhinophrynus dorsalis from coding sequence of 113 autosomal regions, averaging ?300 bp in length (range: 102-1695 bp) and also a portion of the mitochondrial genome. Analysis of these data using multiple approaches recovers strong support for the ((Xenopus, Silurana)(Pipa, Hymenochirus)) topology, and geologically calibrated divergence time estimates that are consistent with estimated ages and phylogenetic affinities of many fossils. These results provide new insights into the biogeography and chronology of pipid diversification during the breakup of Gondwanaland and illustrate how phylogenomic data may be necessary to tackle tough problems in molecular systematics. [Coalescence; gene tree; high-throughout sequencing; lineage sorting; pipid; species tree; Xenopus.]. PMID:22438331

Bewick, Adam J; Chain, Frédéric J J; Heled, Joseph; Evans, Ben J

2012-12-01

175

Root clumping may affect the root water potential and the resistance to soil-root water transport  

Microsoft Academic Search

We have appraised for clumped root systems the widely-accepted view that the resistance to water flux from soil to roots (‘soil\\u000a resistance’) is low under most field conditions, so that root water potential would closely follow the mean soil water potential.\\u000a Three root spatial arrangements were studied, simulating either the regular pattern generally assumed in models, or two degrees\\u000a of

F. Tardieu; L. Bruckler; F. Lafolie

1992-01-01

176

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

177

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

178

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

179

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

180

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

181

Dynamics of heterorhizic root systems: protoxylem groups within the fine-root system of Chamaecyparis obtusa.  

PubMed

To understand the physiology of fine-root functions in relation to soil organic sources, the heterogeneity of individual root functions within a fine-root system requires investigation. Here the heterogeneous dynamics within fine-root systems are reported. The fine roots of Chamaecyparis obtusa were sampled using a sequential ingrowth core method over 2 yr. After color categorization, roots were classified into protoxylem groups from anatomical observations. The root lengths with diarch and triarch groups fluctuated seasonally, whereas the tetrarch root length increased. The percentage of secondary root mortality to total mortality increased with increasing amounts of protoxylem. The carbon : nitrogen ratio indicated that the decomposability of primary roots might be greater than that of secondary roots. The position of diarch roots was mostly apical, whereas tetrarch roots tended to be distributed in basal positions within the root architecture. We demonstrate the heterogeneous dynamics within a fine-root system of C. obtusa. Fine-root heterogeneity should affect soil C dynamics. This heterogeneity is determined by the branching position within the root architecture. PMID:15998402

Hishi, Takuo; Takeda, Hiroshi

2005-08-01

182

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

183

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

184

Modelling Root Systems Using Oriented Density Distributions  

NASA Astrophysics Data System (ADS)

Root architectural models are essential tools to understand how plants access and utilize soil resources during their development. However, root architectural models use complex geometrical descriptions of the root system and this has limitations to model interactions with the soil. This paper presents the development of continuous models based on the concept of oriented density distribution function. The growth of the root system is built as a hierarchical system of partial differential equations (PDEs) that incorporate single root growth parameters such as elongation rate, gravitropism and branching rate which appear explicitly as coefficients of the PDE. Acquisition and transport of nutrients are then modelled by extending Darcy's law to oriented density distribution functions. This framework was applied to build a model of the growth and water uptake of barley root system. This study shows that simplified and computer effective continuous models of the root system development can be constructed. Such models will allow application of root growth models at field scale.

Dupuy, Lionel X.

2011-09-01

185

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

186

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

187

The Complexity of Boolean Matrix Root Computation  

Microsoft Academic Search

We show that ìnding roots of Boolean matrices is an NP- hard problem. This answers a twenty year old question from semigroup theory. Interpreting Boolean matrices as directed graphs, we further re- veal a connection between Boolean matrix roots and graph isomorphism, which leads to a proof that for a certain subclass of Boolean matrices related to subdivision digraphs, root

Martin Kutz

2003-01-01

188

COâ speeds root growth of cuttings  

Microsoft Academic Search

Researchers have determined that COâ enrichment accelerates cutting root growth on foliage plants and flowering shrubs. For horticultural crops, including most woody ornamentals, apples, pears, and small fruit trees, roots consistently emerged 1 or 2 days earlier in the enriched atmosphere. These tests were conducted as part of a broad, ongoing study to determine how photosynthesis is related to rooting

Yarris

1984-01-01

189

Photographic Technique for Grass Seedling Root Systems  

Microsoft Academic Search

In descriptive studies of seedling root morphology a seedling root system must be clearly visible to develop clear photographs. A technique for photographing grass seedling root systems has been developed for morphological-developmental studies. Seedlings were carefully washed form the growing media and placed in a thin tank with two glass sides filled with water and with a grid pattern on

P. R. Newman; Lowell E. Moser

1988-01-01

190

Involvement of polyamines in root development  

Microsoft Academic Search

Root development is under the control of hormonal, metabolic, and environmental cues that can act on genetically-controlled developmental programmes and thus affect the plasticity of root architecture. These processes involve not only the five `classical' plant hormones, but also other growth regulators, such as polyamines. The present review emphasises the importance of polyamines in the different aspects of root development:

Ivan Couée; Irène Hummel; Cécile Sulmon; Gwenola Gouesbet; Abdelhak El Amrani

2004-01-01

191

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

192

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

193

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...

194

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

195

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

196

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

197

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

198

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

199

Root coverage with enamel matrix derivatives.  

PubMed

Different root coverage procedures have been used to treat cases of gingival recession defects involving single or multiple exposed root surfaces. A therapeutic advantage may be gained if periodontal regeneration is obtained in addition to coverage of the root with gingiva. This article describes the treatment of gingival recession by combining a surgical technique with an enamel matrix derivative. PMID:12365135

Chen, Leon; Cha, Jennifer; Guiha, Rami; Bouwsma, Otis J

2002-09-01

200

FOREST PATHOLOGY Root and Butt Rot Diseases  

E-print Network

FOREST PATHOLOGY Root and Butt Rot Diseases M Garbelotto, University of California ­ Berkeley. Indeed, root and butt rots cause more economic damage to commercial forestry in the temperate world than, and basidiomycetes. Root and butt rots, instead, are exclusively caused by fungi belonging to the homo

California at Berkeley, University of

201

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

202

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.

203

Root-cubing and general root-powering methods for finding the zeros of polynomials  

NASA Technical Reports Server (NTRS)

Mathematical analysis technique generalizes a root squaring and root cubing method into a general root powering method. The introduction of partitioned polynomials into this general root powering method simplifies the coding of the polynomial transformations into input data suitable for processing by computer. The method includes analytic functions.

Bareiss, E. H.

1969-01-01

204

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

E-print Network

are at the tips (or apices) of plant parts. The shoot apical meristem is at the tip of the shoot, while the root;Plants: Roots, Stems and Leaves 87 The basic parts of the leaf are a leaf base, which is the region wherePlants: Roots, Stems and Leaves 85 Plants: Roots, Stems and Leaves Unlike animals, plants only have

Koptur, Suzanne

205

Root-soil mechanical interactions during pullout and failure of root bundles  

Microsoft Academic Search

Roots play a major role in reinforcing and stabilizing steep hillslopes. Most studies in slope stability implement root reinforcement as an apparent cohesion by upscaling the behavior of static individual roots. Recent studies, however, have shown that much better predictions of slope stability can be made if the progressive failure of bundles of roots are considered. The characteristics of progressive

M. Schwarz; D. Cohen; D. Or

2010-01-01

206

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

207

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

208

ROOT FUNCTIONAL ARCHITECTURE: A FRAMEWORK FOR MODELLING THE INTERPLAY BETWEEN ROOTS AND SOIL  

E-print Network

ROOT FUNCTIONAL ARCHITECTURE: A FRAMEWORK FOR MODELLING THE INTERPLAY BETWEEN ROOTS AND SOIL Alain biological activity and associated processes are concentrated in the soil located around living plant roots and influenced by root activity, an environment known as the rhizosphere. Consequently, among the wide array

Paris-Sud XI, Université de

209

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.

210

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: 27 June 200718 6 figures19 6 supplementary figures20 21 hal-00831806,version1- #12;2 ABSTRACT1 Root

Paris-Sud XI, Université de

211

Development of extracellular electric pattern around Lepidium roots: its possible role in root growth and gravitropism  

Microsoft Academic Search

Summary Using a vibrating probe technique, four distinct electric patterns around growing cress roots were observed. The growth rate of the root with a particular one of them was apparently faster than that with the others. No direct correlation between the intensity of electric field and the root growth rate could be found. When gravistimulation was applied to the root,

Akira Iwabuchi; Masafumi Yano; Hiroshi Shimizu

1989-01-01

212

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

213

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

214

Mueller matrix roots depolarization parameters.  

PubMed

The Mueller matrix roots decomposition recently proposed by Chipman in [1] and its three associated families of depolarization (amplitude depolarization, phase depolarization, and diagonal depolarization) are explored. Degree of polarization maps are used to differentiate among the three families and demonstrate the unity between phase and diagonal depolarization, while amplitude depolarization remains a distinct class. Three families of depolarization are generated via the averaging of different forms of two nondepolarizing Mueller matrices. The orientation of the resulting depolarization follows the cyclic permutations of the Pauli spin matrices. The depolarization forms of Mueller matrices from two scattering measurements are analyzed with the matrix roots decomposition-a sample of ground glass and a graphite and wood pencil tip. PMID:22358163

Noble, Hannah D; McClain, Stephen C; Chipman, Russell A

2012-02-20

215

Synergistic action of auxin and ethylene on root elongation inhibition is caused by a reduction of epidermal cell length  

PubMed Central

Auxin and ethylene have been largely reported to reduce root elongation in maize primary root. However the effects of auxin are greater than those caused by ethylene. Although auxin stimulates ethylene biosynthesis through the specific increase of ACC synthase, the auxin inhibitory effect on root elongation is not mediated by the auxin-induced increase of ethylene production. Recently it has been demonstrated that root inhibition by the application of the synthetic auxin NAA (1-naphtalenacetic acid) is increased if combined with the ethylene precursor ACC (1-aminocyclopropane-1-carboxilic acid) when both compounds are applied at very low concentrations. Root elongation is basically the result of two processes: a) cell divisions in the meristem where meristematic cells continuously generate new cells and b) subsequently polarized growth by elongation along the root axis as cells leave the meristem and enter the root elongation zone. Our results indicate that exogenous auxin reduced both root elongation and epidermal cell length. In a different way, ethylene at very low concentrations only inhibited root elongation without affecting significantly epidermal cell length. However, these concentrations of ethylene increased the inhibitory effect of auxin on root elongation and cell length. Consequently the results support the hypothesis that ethylene acts synergistically with auxin in the regulation of root elongation and that inhibition by both hormones is due, at least partially, to the reduction of cell length in the epidermal layer. PMID:24598313

Alarcón, M Victoria; Lloret, Pedro G; Salguero, Julio

2014-01-01

216

Synergistic action of auxin and ethylene on root elongation inhibition is caused by a reduction of epidermal cell length.  

PubMed

Auxin and ethylene have been largely reported to reduce root elongation in maize primary root. However the effects of auxin are greater than those caused by ethylene. Although auxin stimulates ethylene biosynthesis through the specific increase of ACC synthase, the auxin inhibitory effect on root elongation is not mediated by the auxin-induced increase of ethylene production. Recently it has been demonstrated that root inhibition by the application of the synthetic auxin NAA (1-naphtalenacetic acid) is increased if combined with the ethylene precursor ACC (1-aminocyclopropane-1-carboxilic acid) when both compounds are applied at very low concentrations.   Root elongation is basically the result of two processes: a) cell divisions in the meristem where meristematic cells continuously generate new cells and b) subsequently polarized growth by elongation along the root axis as cells leave the meristem and enter the root elongation zone. Our results indicate that exogenous auxin reduced both root elongation and epidermal cell length. In a different way, ethylene at very low concentrations only inhibited root elongation without affecting significantly epidermal cell length. However, these concentrations of ethylene increased the inhibitory effect of auxin on root elongation and cell length. Consequently the results support the hypothesis that ethylene acts synergistically with auxin in the regulation of root elongation and that inhibition by both hormones is due, at least partially, to the reduction of cell length in the epidermal layer. PMID:24598313

Alarcón, M Victoria; Lloret, Pedro G; Salguero, Julio

2014-01-01

217

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

218

Effect of pH and zinc stress on micropore system of rye roots  

NASA Astrophysics Data System (ADS)

After zinc stress the total micropore volume decreased remarkably while the average micropore radius increased remarkably for the rye roots. Pore size distribution functions of the roots after the additional zinc application showed the decrease of the small micropore fraction from ca 2 to 10 nm and the increase of the large micropore from ca 22 to 50 nm. The root surface pores were fractal. After the stress pore fractal dimension increased. The changes of the microporosity observed in the roots surface can be related to the high content of zinc in the cell wall and/or due to the shortage of Ca+2 the intercellular spaces particularly in the tissues of seminal cortex of the studied roots might have grown.

Szatanik-Kloc, A.

2012-07-01

219

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

220

Control and separation of algae particles from WSP effluent by using floating aquatic plant root mats.  

PubMed

In this paper, the potential uses of water hyacinth and its root mats for separating algae particles in the effluent from waste stabilization ponds (WSPs) were discussed. Pilot-scale integrated processes consisting of WSPs and multiple WHPs (water hyacinth ponds) were operated in order to extract effects of the root mats on the reduction of algae concentrations. Root mats in the bottom of WHPs separated significant amount of the algae cells through attachment as the effluent from WSPs passed through them. Attachment of the algae particles to the surface of live roots was found to be similar to adsorption phenomena but it lasted even at saturation, probably due to the continuous reproduction of active attachment sites by detachment and growth of the roots. Additionally, this paper discusses attachment mechanisms and other issues concerning design and polishing of the WSPs effluent by WHPs. PMID:11443978

Kim, Y; Kim, W J; Chung, P G; Pipes, W O

2001-01-01

221

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

PubMed Central

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. PMID:11536685

Tripathy, B C; Brown, C S

1995-01-01

222

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...

223

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

224

Root functioning modifies seasonal climate.  

PubMed

Hydraulic redistribution (HR), the nocturnal vertical transfer of soil water from moister to drier regions in the soil profile by roots, has now been observed in Amazonian trees. We have incorporated HR into an atmospheric general circulation model (the National Center for Atmospheric Research Community Atmospheric Model Version 2) to estimate its impact on climate over the Amazon and other parts of the globe where plants displaying HR occur. Model results show that photosynthesis and evapotranspiration increase significantly in the Amazon during the dry season when plants are allowed to redistribute soil water. Plants draw water up and deposit it into the surface layers, and this water subsidy sustains transpiration at rates that deep roots alone cannot accomplish. The water used for dry season transpiration is from the deep storage layers in the soil, recharged during the previous wet season. We estimate that HR increases dry season (July to November) transpiration by approximately 40% over the Amazon. Our model also indicates that such an increase in transpiration over the Amazon and other drought-stressed regions affects the seasonal cycles of temperature through changes in latent heat, thereby establishing a direct link between plant root functioning and climate. PMID:16301519

Lee, Jung-Eun; Oliveira, Rafael S; Dawson, Todd E; Fung, Inez

2005-12-01

225

Conserved and diverse mechanisms in root development.  

PubMed

The molecular basis of root formation and growth is being analyzed in more and more detail in the dicot model organism Arabidopsis. However, considerable progress has also been made in the molecular and genetic dissection of root system development in the monocot species rice and maize. This review will highlight some recent molecular data that allow for the comparison of cereal and Arabidopsis root development. Members of the COBRA, GRAS, and LOB domain gene families and a gene encoding a subunit of the exocyst complex are associated with root development. Analyses of these genes revealed some common and distinct molecular principles and functions in cereal versus Arabidopsis root formation. PMID:18006363

Hochholdinger, Frank; Zimmermann, Roman

2008-02-01

226

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

227

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

228

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

229

The biomechanics of Pachycereus pringlei root systems.  

PubMed

We report on the root system of the large columnar cactus species Pachycereus pringlei to explore the hypothesis that increasing plant size decreases the ability to resist wind-throw but increases the capacity to absorb and store nutrients in roots (i.e., plant size limits the performance of these functions and may shift the performance of one function in favor of another as size increases). Based on 18 plants differing in size, the root system is characterized by a broad and deep bayonet-like root central to a shallow and extensive lateral system of root elements bearing sinker roots near the stem base. All root types have a living secondary cortex and contain wood with a large volume fraction of ray tissues that increases toward the stem base. Wood stiffness and tensile strength are correlated negatively with the ray tissue volume fraction and thus decrease toward the stem base in lateral and bayonet roots. Calculations show that the ability of the bayonet and proximal lateral root elements to resist wind-throw decreases with increasing plant size, whereas the nutrient absorption/storage capacity of the total root system increases with plant size (i.e., a size-dependent shift between these two root functions occurs). PMID:21669707

Niklas, Karl J; Molina-Freaner, Francisco; Tinoco-Ojanguren, Clara; Paolillo, Dominick J

2002-01-01

230

Root distribution and interactions between intercropped species.  

PubMed

Even though ecologists and agronomists have considered the spatial root distribution of plants to be important for interspecific interactions in natural and agricultural ecosystems, few experimental studies have quantified patterns of root distribution dynamics and their impacts on interspecific interactions. A field experiment was conducted to investigate the relationship between root distribution and interspecific interactions between intercropped plants. Roots were sampled twice by auger and twice by the monolith method in wheat (Triticum aestivum L.)/maize (Zea mays L.) and faba bean (Vicia faba L.)/maize intercropping and in sole wheat, maize, and faba bean up to 100 cm depth in the soil profile. The results showed that the roots of intercropped wheat spread under maize plants, and had much greater root length density (RLD) at all soil depths than sole wheat. The roots of maize intercropped with wheat were limited laterally, but had a greater RLD than sole-cropped maize. The RLD of maize intercropped with faba bean at different soil depths was influenced by intercropping to a smaller extent compared to maize intercropped with wheat. Faba bean had a relatively shallow root distribution, and the roots of intercropped maize spread underneath them. The results support the hypotheses that the overyielding of species showing benefit in the asymmetric interspecific facilitation results from greater lateral deployment of roots and increased RLD, and that compatibility of the spatial root distribution of intercropped species contributes to symmetric interspecific facilitation in the faba bean/maize intercropping. PMID:16211394

Li, Long; Sun, Jianhao; Zhang, Fusuo; Guo, Tianwen; Bao, Xingguo; Smith, F Andrew; Smith, Sally E

2006-03-01

231

Five root canals in peg lateral incisor with dens invaginatus: A case report with new nomenclature for the five canals  

PubMed Central

This case report describes endodontic treatment completed in a peg-shaped maxillary lateral incisor, with single root and five root canals of which, one is due to dens invaginatus. Cone beam computed tomogram scanning confirmed the unique morphology of the tooth. New nomenclature for the five canals is proposed. PMID:25125854

Jaikailash, Shanmugam; Kavitha, Mahendran; Ranjani, Muthukrishnan Sudharshana; Saravanan, Balasubramaniam

2014-01-01

232

Five root canals in peg lateral incisor with dens invaginatus: A case report with new nomenclature for the five canals.  

PubMed

This case report describes endodontic treatment completed in a peg-shaped maxillary lateral incisor, with single root and five root canals of which, one is due to dens invaginatus. Cone beam computed tomogram scanning confirmed the unique morphology of the tooth. New nomenclature for the five canals is proposed. PMID:25125854

Jaikailash, Shanmugam; Kavitha, Mahendran; Ranjani, Muthukrishnan Sudharshana; Saravanan, Balasubramaniam

2014-07-01

233

Patterns of variability in the diameter of lateral roots in the banana root system.  

PubMed

The relative importance of root system structure, plant carbon status and soil environment in the determination of lateral root diameter remains unclear, and was investigated in this study. Banana (Musa acuminata) plants were grown at various moderate levels of soil compaction in two distinct experiments, in a field experiment (FE) and in a glasshouse experiment (GE). Radiant flux density was 5 times lower in GE. The distribution of root diameter was measured for several root branching orders. Root diameters ranged between 0.09 and 0.52 mm for secondary roots and between 0.06 and 0.27 mm for tertiary roots. A relationship was found between the diameter of the parent bearing root and the median diameter of its laterals, which appears to be valid for a wide range of species. Mean lateral root diameter increased with distance to the base of the root and decreased with branching density [number of lateral roots per unit length of bearing root (cm(-1))]. Typical symptoms of low light availability were observed in GE. In this case, lateral root diameter variability was reduced. Although primary root growth was affected by soil compaction, no effects on lateral root diameter were observed. PMID:16101920

Lecompte, François; Pagès, Loïc; Ozier-Lafontaine, Harry

2005-09-01

234

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

235

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

236

Apoplastic transport of abscisic acid through roots of maize: effect of the exodermis.  

PubMed

The exodermal layers that are formed in maize roots during aeroponic culture were investigated with respect to the radial transport of cis-abscisic acid (ABA). The decrease in root hydraulic conductivity (Lp(r)) of aeroponically grown roots was stimulated 1.5-fold by ABA (500 nM), reaching Lp(r) values of roots lacking an exodermis. Similar to water, the radial flow of ABA through roots (J(ABA)) and ABA uptake into root tissue were reduced by a factor of about three as a result of the existence of an exodermis. Thus, due to the cooperation between water and solute transport the development of the ABA signal in the xylem was not affected. This resulted in unchanged reflection coeffcients for roots grown hydroponically and aeroponically. Despite the well-accepted barrier properties of exodermal layers, it is concluded that the endodermis was the more effective filter for ABA. Owing to concentration polarisation effects, ABA may accumulate in front of the endodermal layer, a process which, for both roots possessing and lacking an exodermis, would tend to increase solvent drag and hence ABA movement into the xylem sap at increased water flow (J(Vr)). This may account for the higher ABA concentrations found in the xylem at greater pressure difference. PMID:10664128

Freundl, E; Steudle, E; Hartung, W

2000-01-01

237

Return of function after spinal cord implantation of avulsed spinal nerve roots.  

PubMed

Avulsion of nerve roots from the spinal cord is widely regarded as an untreatable injury. However, a series of experiments in animals has shown that, if continuity is restored between spinal cord and ventral roots, axons from spinal motor neurons can regrow into the peripheral nerves with recovery of motor function. These observations were applied in the treatment of a man with avulsion of the 6th cervical (C6) to 1st thoracic roots due to brachial plexus injury. Two ventral roots were implanted into the spinal cord through slits in the pia mater, C6 directly and C7 via sural nerve grafts. Voluntary activity in proximal arm muscles was detected electromyographically after nine months and clinically after one year. After three years the patient had voluntary activity (with some co-contraction) in the deltoid, biceps, and triceps muscles. To determine whether the improvement was due to spontaneous recovery from C5, the C5 root was blocked pharmacologically, and the results indicated that the repaired roots were contributing substantially to motor function. Repair of spinal nerve roots deserves further exploration in management of brachial plexus injury. PMID:7475770

Carlstedt, T; Grane, P; Hallin, R G; Norén, G

1995-11-18

238

Light Sheet Tomography (LST) for in situ imaging of plant roots.  

PubMed

The production of crops capable of efficient nutrient use is essential for addressing the problem of global food security. The ability of a plant's root system to interact with the soil micro-environment determines how effectively it can extract water and nutrients. In order to assess this ability and develop the fast and cost effective phenotyping techniques which are needed to establish efficient root systems, in situ imaging in soil is required. To date this has not been possible due to the high density of scatterers and absorbers in soil or because other growth substrates do not sufficiently model the heterogeneity of a soil's microenvironment. We present here a new form of light sheet imaging with novel transparent soil containing refractive index matched particles. This imaging method does not rely on fluorescence, but relies solely on scattering from root material. We term this form of imaging Light Sheet Tomography (LST). We have tested LST on a range of materials and plant roots in transparent soil and gel. Due to the low density of root structures, i.e. relatively large spaces between adjacent roots, long-term monitoring of lettuce root development in situ with subsequent quantitative analysis was achieved. PMID:23938474

Yang, Zhengyi; Downie, Helen; Rozbicki, Emil; Dupuy, Lionel X; MacDonald, Michael P

2013-07-15

239

Biotransformation studies using hairy root cultures - A review.  

PubMed

Agrobacterium rhizogenes induced hairy root cultures are entering into a new juncture of functional research in generating pharmaceutical lead compounds by bringing about chemical transformations aided through its inherent enzyme resources. Rational utilization of hairy root cultures as highly effective biotransformation systems has come into existence in the last twenty years involving a wide range of plant systems as well as exogenous substrates and diverse chemical reactions. To date, hairy root cultures are preferred over plant cell/callus and suspension cultures as biocatalyst due to their genetic/biochemical stability, hormone-autotrophy, multi-enzyme biosynthetic potential mimicking that of the parent plants and relatively low-cost cultural requirements. The resultant biotransformed molecules, that are difficult to make by synthetic organic chemistry, can unearth notable practical efficacies by acquiring improved physico-chemical properties, bioavailability, lower toxicity and broader therapeutic properties. The present review summarizes the overall reported advances made in the area of hairy root mediated biotransformation of exogenous substrates with regard to their reaction types, plant systems associated, bacterial strains/molecules involved and final product recovery. PMID:21871554

Banerjee, Suchitra; Singh, Sailendra; Ur Rahman, Laiq

2012-01-01

240

Linking carbon supply to root cell-wall chemistry and mechanics at high altitudes in Abies georgei  

PubMed Central

Background and Aims The mobile carbon supply to different compartments of a tree is affected by climate, but its impact on cell-wall chemistry and mechanics remains unknown. To understand better the variability in root growth and biomechanics in mountain forests subjected to substrate mass movement, we investigated root chemical and mechanical properties of mature Abies georgei var. smithii (Smith fir) growing at different elevations on the Tibet–Qinghai Plateau. Methods Thin and fine roots (0·1–4·0 mm in diameter) were sampled at three different elevations (3480, 3900 and 4330 m, the last corresponding to the treeline). Tensile resistance of roots of different diameter classes was measured along with holocellulose and non-structural carbon (NSC) content. Key Results The mean force necessary to break roots in tension decreased significantly with increasing altitude and was attributed to a decrease in holocellulose content. Holocellulose was significantly lower in roots at the treeline (29·5 ± 1·3 %) compared with those at 3480 m (39·1 ± 1·0 %). Roots also differed significantly in NSC, with 35·6 ± 4·1 mg g?1 dry mass of mean total soluble sugars in roots at 3480 m and 18·8 ± 2·1 mg g?1 dry mass in roots at the treeline. Conclusions Root mechanical resistance, holocellulose and NSC content all decreased with increasing altitude. Holocellulose is made up principally of cellulose, the biosynthesis of which depends largely on NSC supply. Plants synthesize cellulose when conditions are optimal and NSC is not limiting. Thus, cellulose synthesis in the thin and fine roots measured in our study is probably not a priority in mature trees growing at very high altitudes, where climatic factors will be limiting for growth. Root NSC stocks at the treeline may be depleted through over-demand for carbon supply due to increased fine root production or winter root growth. PMID:21186240

Genet, Marie; Li, Mingcai; Luo, Tianxiang; Fourcaud, Thierry; Clément-Vidal, Anne; Stokes, Alexia

2011-01-01

241

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

242

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

243

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

244

Soil bacterial diversity responses to root colonization by an ectomycorrhizal fungus are not root-growth-dependent.  

PubMed

The hypothesis tested in this present study was that the ectomycorrhizosphere effect on the bacterial community was not root-growth-dependent. The impacts of ectomycorrhizal infection (Pisolithus albus COI007) and a chemical fertilization to reproduce the fungal effect on root growth were examined on (1) the structure of bacterial community and (2) fluorescent pseudomonad and actinomycete populations in the mycorrhizosphere of Acacia auriculiformis using both culture-independent and culture-dependent methods. A. auriculiformis plants were grown in disinfested soil in pots with or without addition of the ectomycorrhizal fungus or N/P/K fertilization (to reproduce the fungal effect on root growth) for 4 months and then transferred to 20-L pots filled with nondisinfested sandy soil. The fungal and fertilizer applications significantly improved the plant growth after 4-month culture in the disinfested soil. In the nondisinfested cultural substrate, these positive effects on plant growth were maintained. The total soil microbiota was significantly different within the treatments as revealed from DNA analysis [denaturing gradient gel electrophoresis (DGGE)]. The structure of fluorescent pseudomonad populations was also affected by fungal and fertilizer applications. In contrast, no qualitative effect was observed for the actinomycete communities within each treatment, but fungal inoculation significantly decreased the number of actinomycetes compared to the fertilizer application treatment. These results show that the mycorrhizosphere effect is not root-growth-dependent but is mainly due to the presence of the ectomycorrhizal fungus and more particularly to the extramatrical mycelium. PMID:16254760

Assigbetse, Komi; Gueye, Mariama; Thioulouse, Jean; Duponnois, Robin

2005-10-01

245

Root cause analysis guidance document  

SciTech Connect

DOE Order 5000.3A, Occurrence Reporting and Processing of Operations Information,'' requires the investigation and reporting of occurrences (including the performance of root cause analysis) and the selection, implementation, and follow-up of corrective actions. The level of effort expended should be based on the significance attached to the occurrence. Most off-normal occurrences need only a scaled-down effort while most emergency occurrences should be investigated using on or more of the formal analytical models. A discussion of methodologies, instructions, and worksheets in this document guides the analysis of occurrences as specified by DOE Order 5000.3A.

Not Available

1992-02-01

246

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

247

Analysis of changes in relative elemental growth rate patterns in the elongation zone of Arabidopsis roots upon gravistimulation  

NASA Technical Reports Server (NTRS)

Although Arabidopsis is an important system for studying root physiology, the localized growth patterns of its roots have not been well defined, particularly during tropic responses. In order to characterize growth rate profiles along the apex of primary roots of Arabidopsis thaliana (L.) Heynh (ecotype Columbia) we applied small charcoal particles to the root surface and analyzed their displacement during growth using an automated video digitizer system with custom software for tracking the markers. When growing vertically, the maximum elongation rate occurred 481 +/- 50 microns back from the extreme tip of the root (tip of root cap), and the elongation zone extended back to 912 +/- 137 microns. The distal elongation zone (DEZ) has previously been described as the apical region of the elongation zone in which the relative elemental growth rate (REGR) is < or = 30% of the peak rate in the central elongation zone. By this definition, our data indicate that the basal limit of the DEZ was located 248 +/- 30 microns from the root tip. However, after gravistimulation, the growth patterns of the root changed. Within the first hour of graviresponse, the basal limit of the DEZ and the position of peak REGR shifted apically on the upper flank of the root. This was due to a combination of increased growth in the DEZ and growth inhibition in the central elongation zone. On the lower flank, the basal limit of the DEZ shifted basipetally as the REGR decreased. These factors set up the gradient of growth rate across the root, which drives curvature.

Mullen, J. L.; Ishikawa, H.; Evans, M. L.

1998-01-01

248

[Effects nutrients on the seedlings root hair development and root growth of Poncirus trifoliata under hydroponics condition].  

PubMed

Ahydroponics experiment was conducted to study the effects of nutrients (N, P, K, Ca, Mg, Fe, and Mn) deficiency on the length of primary root, the number of lateral roots, and the root hair density, length, and diameter on the primary root and lateral roots of Poncirus trifoliata seedlings. Under the deficiency of each test nutrient, root hair could generate, but was mainly concentrated on the root base and fewer on the root tip. The root hair density on lateral roots was significantly larger than that on primary root, but the root hair length was in adverse. The deficiency of each test nutrient had greater effects on the growth and development of root hairs, with the root hair density on primary root varied from 55.0 to 174.3 mm(-2). As compared with the control, Ca deficiency induced the significant increase of root hair density and length on primary root, P deficiency promoted the root hair density and length on the base and middle part of primary root and on the lateral roots significantly, Fe deficiency increased the root hair density but decreased the root hair length on the tip of primary root significantly, K deficiency significantly decreased the root hair density, length, and diameter on primary root and lateral roots, whereas Mg deficiency increased the root hair length of primary root significantly. In all treatments of nutrient deficiency, the primary root had the similar growth rate, but, with the exceptions of N and Mg deficiency, the lateral roots exhibited shedding and regeneration. PMID:24066535

Cao, Xiu; Xia, Ren-Xue; Zhang, De-Jian; Shu, Bo

2013-06-01

249

Mueller matrix roots algorithm and computational considerations.  

PubMed

Recently, an order-independent Mueller matrix decomposition was proposed in an effort to elucidate the nine depolarization degrees of freedom [Handbook of Optics, Vol. 1 of Mueller Matrices (2009)]. This paper addresses the critical computational issues involved in applying this Mueller matrix roots decomposition, along with a review of the principal matrix root and common methods for its calculation. The calculation of the pth matrix root is optimized around p = 10(5) for a 53 digit binary double precision calculation. A matrix roots algorithm is provided which incorporates these computational results. It is applied to a statistically significant number of randomly generated physical Mueller matrices in order to gain insight on the typical ranges of the depolarizing Matrix roots parameters. Computational techniques are proposed which allow singular Mueller matrices and Mueller matrices with a half-wave of retardance to be evaluated with the matrix roots decomposition. PMID:22274325

Noble, H D; Chipman, R A

2012-01-01

250

Thermotropism by primary roots of maize  

SciTech Connect

Sensing in the roots of higher plants has long been recognized to be restricted mainly to gravitropism and thigmotropism. However, root responses to temperature gradients have not been extensively studied. We have designed experiments under controlled conditions to test if and how root direction of maize can be altered by thermal gradients perpendicular to the gravity vector. Primary roots of maize grown on agar plates exhibit positive thermotropism (curvature toward the warmer temperature) when exposed to gradients of 0.5 to 4.2{degree}C cm{sup {minus}1}. The extent of thermotropism depends on the temperature gradient and the temperature at which the root is placed within the gradient. The curvature cannot be accounted for by differential growth as a direct effect of temperature on each side of the root.

Fortin, M.-C.; Poff, K.L. (MSU-DOE Plant Research Laboratory, East Lansing, MI (USA))

1990-05-01

251

A Rooted Net of Life  

PubMed Central

Abstract Phylogenetic reconstruction using DNA and protein sequences has allowed the reconstruction of evolutionary histories encompassing all life. We present and discuss a means to incorporate much of this rich narrative into a single model that acknowledges the discrete evolutionary units that constitute the organism. Briefly, this Rooted Net of Life genome phylogeny is constructed around an initial, well resolved and rooted tree scaffold inferred from a supermatrix of combined ribosomal genes. Extant sampled ribosomes form the leaves of the tree scaffold. These leaves, but not necessarily the deeper parts of the scaffold, can be considered to represent a genome or pan-genome, and to be associated with members of other gene families within that sequenced (pan)genome. Unrooted phylogenies of gene families containing four or more members are reconstructed and superimposed over the scaffold. Initially, reticulations are formed where incongruities between topologies exist. Given sufficient evidence, edges may then be differentiated as those representing vertical lines of inheritance within lineages and those representing horizontal genetic transfers or endosymbioses between lineages. Reviewers W. Ford Doolittle, Eric Bapteste and Robert Beiko. PMID:21936906

2011-01-01

252

Genetic ablation of root cap cells in Arabidopsis  

PubMed Central

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. PMID:10536027

Tsugeki, Ryuji; Fedoroff, Nina V.

1999-01-01

253

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

254

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

255

Springback and diagravitropism in Merit corn roots  

NASA Technical Reports Server (NTRS)

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.

Kelly, M. O.; Leopold, A. C.

1992-01-01

256

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

257

Effective field theories for rooted staggered fermions  

E-print Network

We extend the construction of the Symanzik effective action to include rooted staggered fermions, starting from a generalization of the renormalization-group approach to rooted staggered fermions. The Symanzik action, together with the usual construction of a partially quenched chiral effective theory from a local, partially quenched, fundamental theory, can then be used to derive the chiral effective theory. The latter reproduces rooted staggered chiral perturbation theory.

Claude Bernard; Maarten Golterman; Yigal Shamir

2007-09-13

258

DNS measurements at a root server  

Microsoft Academic Search

The Domain Name System (DNS) prescribes domain names to be used in network transactions (email, web requests, etc.) instead of IP addresses. The root of the DNS distributed database is managed by 13 root nameservers. We passively measure the performance of one of them: F.root-servers.net. These measurements show an astounding number of bogus queries: from 60-85% of observed queries were

Nevil Brownlee; K. C. Claffy; E. Nemeth

2001-01-01

259

Root water potential in polycormon plants  

Microsoft Academic Search

Water potential of roots was measured by thermocouple psyohometers in a series of two or more plants ofCynodon dactylon (L.)Pers. interconnected by overground stolons and thus forming one s.c. polycormon. Root water potential was lowest (most negative)\\u000a in the oldest “mother” plant and increased in younger individua to highest walues in the youngest “doughter” plants. This\\u000a gradient of root water

Ji?ina Slavíková

1973-01-01

260

Discoloration and Decay in Severed Tree Roots  

Microsoft Academic Search

Roots of honeylocust (Gleditsia triacanthos var. inermis), pin oak (Quercus palustris), tuliptree (Liriodendron tulip- ifera), and green ash (Fraxinus pennsylvanica) trees were severed at the root flare and 1, 2, or 3 m (3.3, 6.6, and 9.9 ft) from the trunk. After 5 years, the severed roots were excavated and all discolored and decayed portions were removed. The furthest extent

Gary Watson

2008-01-01

261

Temperature sensing by primary roots of maize  

NASA Technical Reports Server (NTRS)

Zea mays L. seedlings, grown on agar plates at 26 degrees C, reoriented the original vertical direction of their primary root when exposed to a thermal gradient applied perpendicular to the gravity vector. The magnitude and direction of curvature can not be explained simply by either a temperature or a humidity effect on root elongation. It is concluded that primary roots of maize sense temperature gradients in addition to sensing the gravitational force.

Poff, K. L.

1990-01-01

262

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

263

Root development under control of magnesium availability.  

PubMed

Roots are reported to be plastic in response to nutrient supply, but relatively little is known about their development in response to magnesium (Mg) availability. Here, we showed the influence of both low and high Mg availability on the development of roots including root hairs and highlighted insights into the regulatory role of Mg availability on root hair development and its mechanism in Arabidopsis with combining our published research. Mg concentration in roots decreased quickly after the removal of Mg from the nutrient solution and increased progressively with increasing exogenous Mg supply in the media. However, transcriptome analysis suggested that Mg starvation did not alter the expression of most genes potentially involved in the transport. Primary root elongation and lateral root formation in Arabidopsis were not influenced by low Mg but inhibited by high Mg after one-week period. Moreover, low Mg availability significantly increased but high Mg reduced the initiation, density and length of root hairs, which through the characterized Ca (2+) and ROS signal transduction pathways. More physiological mechanisms underlying Mg-regulated root development remain to be elucidated in future researches. PMID:25029279

Niu, Yaofang; Jin, Gulei; Zhang, Yong Song

2014-07-16

264

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

265

Deoxyribonucleic Acid synthesis in root cap cells of cultured roots of convolvulus.  

PubMed

Isolated cultured roots of Convolvulus arvensis L. were incubated in 0.2 microcurie per milliliter methyl-(3)H-thymidine for 14 hours, for 64 hours, or for 14 hours followed by transfer to fresh nutrient medium without tritiated thymidine. Autoradiographs of serial, longitudinal sections of roots which were continuously incubated with tritiated thymidine showed that cells of the root cap columella did not undergo DNA synthesis after their formation from the root cap initials. In roots pulse-labeled with tritiated thymidine, the movement of labeled cells through the root cap columella was followed. Labeled cells were displaced at a constant rate of 72 microns per day over a period of 6 to 9 days before they were sloughed off from the root cap. The specialized role of the root cap cells in relation to their distinctive metabolism and longevity is discussed. PMID:16657765

Phillips, H L; Torrey, J G

1971-08-01

266

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...

267

Effects of Rooting Substrates on In Vitro Rooting of Anthurium andraeanum L. cv. Avanti  

Microsoft Academic Search

A study was made of the effects of rooting substrates on in vitro rooting of Anthurium andraeanum L. cv. Avanti, orange flower. Initiation of root was attempted in several rooting substrates with modified ½ MS medium supplemented with 30 g\\/l sucrose. The cut end of the shoot was dipped in 2.5 g\\/l indole-3-butyric acid (IBA) before insertion in substrates. After

Wararat KEATMETHA; Padungsak SUKSA-ARD

268

Does the age of fine root carbon indicate the age of fine roots in boreal forests?  

Microsoft Academic Search

To test the reliability of the radiocarbon method for determining root age, we analyzed fine roots (originating from the years\\u000a 1985–1993) from ingrowth cores with known maximum root age (1–6 years old). For this purpose, three Scots pine (Pinus sylvestris L.) stands were selected from boreal forests in Finland. We analyzed root 14C age by the radiocarbon method and compared it

S. P. Sah; H. Jungner; M. Oinonen; M. Kukkola; H.-S. Helmisaari

2011-01-01

269

Root architecture: Influence of metameric organization and emission of lateral roots  

Microsoft Academic Search

It has yet to be established whether or not root architecture results from a metameric organization similar to that recognizable in the stem. To address this question, we have reviewed the data on the major cytological, histological and anatomical events underlying root development and on the intrinsic factors controlling these events. The evidence emerging from this review indicates that root

D. Chiatante; G. S. Scippa

2006-01-01

270

Effect of soil moisture and phosphate level on root hair growth of corn roots  

Microsoft Academic Search

Summary Root hairs have been shown to enhance P uptake by plants growing in low P soil. Little is known of the factors controlling root hair growth. The objective of this study was to investigate the influence of soil moisture and P level on root hair growth of corn (Zea mays L.). The effect of volumetric soil moistures of 22%

A. D. Mackay; S. A. Barber

1985-01-01

271

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

272

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

273

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...

274

Root susceptibility and inoculum production from roots of eastern oak species to Phytophthora ramorum  

Technology Transfer Automated Retrieval System (TEKTRAN)

Little is known about root susceptibility of eastern tree species to Phytophthora ramorum. In this study, we examined root susceptibility and inoculum production from roots. Oak radicles of several eastern oak species were exposed to zoospore suspensions of 1, 10, 100, or 1000 zoospores per ml at ...

275

Tannins in mangrove tree roots and their role in the root environment  

Microsoft Academic Search

Mangrove trees grow under reductive and sometimes acidic conditions, both of which are injurious to the root growth. In this report, the role of tannins in mangrove tree roots was studied in order to alleviate their detrimental effect on the soil environment.The mangrove tree roots contain a large amount of tannins and it combines with ferric ion in the soil

Makoto Kimura; Hidenori Wada

1989-01-01

276

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

277

Observations on kiwifruit (Actinidia chinensis Planch.) root exploration, root pressure, hydraulic conductivity, and water uptake  

Microsoft Academic Search

The rooting patterns of mature kiwifruit (Actinidia chinensis Planch.) vines were observed in 2 soils of contrasting texture — Ohinepanea sand and Levin silt loam. Near the surface of both soils, roots extended laterally 2.2-2.4 m from the base of the stem. In the Bay of Plenty, rooting depths of 3 m have been observed and in the Ohinepanea sand

K. J. McAneney; M. J. Judd

1983-01-01

278

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

279

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, Frederick G. (Stansbury Park, UT); Cataldo, Dominic A. (Kennewick, WA); Cline, John F. (Prosser, WA); Skiens, W. Eugene (Wilsonville, OR); Van Voris, Peter (Richland, WA)

1993-01-01

280

Influence of Four Nematodes on Root and Shoot Growth Parameters in Grape  

PubMed Central

Two grape cultivars, susceptible French Colombard and tolerant Rubired, and four nematodes, Meloidogyne incognita, Pratylenchus vulnus, Tylenchulus semipenetrans, and Xiphinema index, were used to quantify the equilibrium between root (R) and shoot (S) growth. Root and shoot growth of French Colombard was retarded by M. incognita, P. vulnus, and X. index but not by T. semipenetrans. Although the root growth of Rubired was limited by all the nematodes, the shoot growth was limited only by X. index. The R:S ratios of Rubired were higher than those of French Colombard. The reduced R:S ratios of Rubired were primarily an expression of reduction in root systems without an equal reduction in shoot growth, whereas in French Colombard the reduced R:S ratios were due to a reduction in both shoot growth and root growth and to a greater reduction in root growth than shoot growth. All nematodes reproduced equally well on both cultivars. Both foliage and root growth of French Colombard were significantly reduced by M. incognita and P. vulnus. Nematodes reduced the shoot length by reducing the internode length. Accumulative R:S ratios in inoculated plants were significantly smaller than those in controls in all nematode treatments but not at individual harvest dates. Bud break was delayed by X. index and was initiated earlier by P. vulnus and M. incognita. All buds in nematode treatments were less vigorous than in controls. PMID:19287609

Anwar, S. A.; Van Gundy, S. D.

1989-01-01

281

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

282

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

283

Tissue-specific localization of pea root infection by Nectria haematococca. Mechanisms and consequences.  

PubMed

Root infection in susceptible host species is initiated predominantly in the zone of elongation, whereas the remainder of the root is resistant. Nectria haematococca infection of pea (Pisum sativum) was used as a model to explore possible mechanisms influencing the localization of root infection. The failure to infect the root tip was not due to a failure to induce spore germination at this site, suppression of pathogenicity genes in the fungus, or increased expression of plant defense genes. Instead, exudates from the root tip induce rapid spore germination by a pathway that is independent of nutrient-induced germination. Subsequently, a factor produced during fungal infection and death of border cells at the root apex appears to selectively suppress fungal growth and prevent sporulation. Host-specific mantle formation in response to border cells appears to represent a previously unrecognized form of host-parasite relationship common to diverse species. The dynamics of signal exchange leading to mantle development may play a key role in fostering plant health, by protecting root meristems from pathogenic invasion. PMID:15778461

Gunawardena, Uvini; Rodriguez, Marianela; Straney, David; Romeo, John T; VanEtten, Hans D; Hawes, Martha C

2005-04-01

284

Influence of four nematodes on root and shoot growth parameters in grape.  

PubMed

Two grape cultivars, susceptible French Colombard and tolerant Rubired, and four nematodes, Meloidogyne incognita, Pratylenchus vulnus, Tylenchulus semipenetrans, and Xiphinema index, were used to quantify the equilibrium between root (R) and shoot (S) growth. Root and shoot growth of French Colombard was retarded by M. incognita, P. vulnus, and X. index but not by T. semipenetrans. Although the root growth of Rubired was limited by all the nematodes, the shoot growth was limited only by X. index. The R:S ratios of Rubired were higher than those of French Colombard. The reduced R:S ratios of Rubired were primarily an expression of reduction in root systems without an equal reduction in shoot growth, whereas in French Colombard the reduced R:S ratios were due to a reduction in both shoot growth and root growth and to a greater reduction in root growth than shoot growth. All nematodes reproduced equally well on both cultivars. Both foliage and root growth of French Colombard were significantly reduced by M. incognita and P. vulnus. Nematodes reduced the shoot length by reducing the internode length. Accumulative R:S ratios in inoculated plants were significantly smaller than those in controls in all nematode treatments but not at individual harvest dates. Bud break was delayed by X. index and was initiated earlier by P. vulnus and M. incognita. All buds in nematode treatments were less vigorous than in controls. PMID:19287609

Anwar, S A; Van Gundy, S D

1989-04-01

285

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

286

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

287

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

288

Coupling root architecture and pore network modeling - an attempt towards better understanding root-soil interactions  

NASA Astrophysics Data System (ADS)

Understanding root-soil interactions is of high importance for environmental and agricultural management. Root uptake is an essential component in water and solute transport modeling. The amount of groundwater recharge and solute leaching significantly depends on the demand based plant extraction via its root system. Plant uptake however not only responds to the potential demand, but in most situations is limited by supply form the soil. The ability of the plant to access water and solutes in the soil is governed mainly by root distribution. Particularly under conditions of heterogeneous distribution of water and solutes in the soil, it is essential to capture the interaction between soil and roots. Root architecture models allow studying plant uptake from soil by describing growth and branching of root axes in the soil. Currently root architecture models are able to respond dynamically to water and nutrient distribution in the soil by directed growth (tropism), modified branching and enhanced exudation. The porous soil medium as rooting environment in these models is generally described by classical macroscopic water retention and sorption models, average over the pore scale. In our opinion this simplified description of the root growth medium implies several shortcomings for better understanding root-soil interactions: (i) It is well known that roots grow preferentially in preexisting pores, particularly in more rigid/dry soil. Thus the pore network contributes to the architectural form of the root system; (ii) roots themselves can influence the pore network by creating preferential flow paths (biopores) which are an essential element of structural porosity with strong impact on transport processes; (iii) plant uptake depend on both the spatial location of water/solutes in the pore network as well as the spatial distribution of roots. We therefore consider that for advancing our understanding in root-soil interactions, we need not only to extend our root models, but also improve the description of the rooting environment. Until now there have been no attempts to couple root architecture and pore network models. In our work we present a first attempt to join both types of models using the root architecture model of Leitner et al., (2010) and a pore network model presented by Raoof et al. (2010). The two main objectives of coupling both models are: (i) Representing the effect of root induced biopores on flow and transport processes: For this purpose a fixed root architecture created by the root model is superimposed as a secondary root induced pore network to the primary soil network, thus influencing the final pore topology in the network generation. (ii) Representing the influence of pre-existing pores on root branching: Using a given network of (rigid) pores, the root architecture model allocates its root axes into these preexisting pores as preferential growth paths with thereby shape the final root architecture. The main objective of our study is to reveal the potential of using a pore scale description of the plant growth medium for an improved representation of interaction processes at the interface of root and soil. References Raoof, A., Hassanizadeh, S.M. 2010. A New Method for Generating Pore-Network Models. Transp. Porous Med. 81, 391-407. Leitner, D, Klepsch, S., Bodner, G., Schnepf, S. 2010. A dynamic root system growth model based on L-Systems. Tropisms and coupling to nutrient uptake from soil. Plant Soil 332, 177-192.

Leitner, Daniel; Bodner, Gernot; Raoof, Amir

2013-04-01

289

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

290

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

291

Chloroplast development in isolated roots of Convolvulus arvensis (L.)  

Microsoft Academic Search

The fine structure of chloroplast development is described for isolated roots of Convolvulus arvensis. Stages in the transition from the leucoplast, characteristic of dark-grown roots, to the chloroplast, found in light-grown roots, are defined and related to chlorophyll content of the root tissue. The interdependence of tissue type and organellogenesis has been investigated for three tissues in the primary root:

Jane Heltne; Howard T. Bonnett

1970-01-01

292

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.

Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

2015-01-01

293

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

294

Root gravitropism: a complex response to a simple stimulus?  

Microsoft Academic Search

Roots avoid depleting their immediate environment of essential nutrients by continuous growth. Root growth is directed by environmental cues, including gravity. Gravity sensing occurs mainly in the columella cells of the root cap. Upon reorientation within the gravity field, the root-cap amyloplasts sediment, generating a physiological signal that promotes the development of a curvature at the root elongation zones. Recent

Elizabeth Rosen; Rujin Chen; Patrick H Masson

1999-01-01

295

ROOT AND BUTT ROTS OF FOREST TREES International Conference  

E-print Network

#12;ROOT AND BUTT ROTS OF FOREST TREES 12th International Conference on Root and Butt Rots IUFRO;Proceedings of the 12 th International Conference on Root and Butt Rots of Forest Trees ROOT AND BUTT ROTS OF FOREST TREES 12th International Conference on Root and Butt Rots IUFRO Working Party 7.02.01 M

California at Berkeley, University of

296

CORTICAL CELL DEATH DURING LATERAL ROOT FORMATION  

Microsoft Academic Search

Root segments of Convolvulus arvensis, the field bindweed, were examined with the electron microscope to make possible a description of the fine structural correlates of lateral root protrusion through cortical parenchyma. Particular attention was directed to the outermost primordium cells, derived by meristematic activity from the endodermis, and to the con- tiguous cortical parenchyma cells. By following the fate of

HOWARD T. BONNETT

1969-01-01

297

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

298

Gravitropism and Autotropism in Cress Roots  

NASA Technical Reports Server (NTRS)

The overall purpose of this experiment was to study how cress roots respond to a withdrawal of a gravity stimulus i.e. when and how much the roots straighten (autotropism) after curving (gravitropism). This question was studied both in extensive ground-based research and in microgravity on BioRack.

Sack, Fred D.

1998-01-01

299

Micropropagation Anatomical and biochemical changes during root  

E-print Network

Micropropagation Anatomical and biochemical changes during root formation in oak and apple shoots cultured in vitro * MC San-José, N Vidal, A Ballester * CSIC, Plant Physiology, Apartado 122, 15080 in oak and d 10 in apple. The vascular sys- tems of the primordium and shoot joined just before root

Boyer, Edmond

300

Maize root characteristis that enhance flooding tolerance  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plant root systems have several cellular and molecular adaptations that are important in reducing stress caused by flooding. Of these, two physical properties of root systems provide an initial barrier toward the avoidance of stress. These are the presence of aerenchyma cells and rapid adventitious ...

301

Gene expression in physically impeded maize roots  

E-print Network

clones, TCH1 induced by wind stress in Arabidopsis, and LP2 induced by drought stress in pine, had high homology with the RNA in maize root tips, but they did not reveal an inducible pattern of expression in the impeded maize roots tips. Second, a cDNA...

Huang, Ying-Fei

2012-06-07

302

Soil physical properties and banana root growth  

Microsoft Academic Search

The physical properties of the soil regulate the conditions in which banana roots grow; therefore, they should be among the criteria evaluated to determine the soil's potential for banana production. Under adequate nutritional conditions and with a good water supply (rain or irrigation), banana roots require aeration and low mechanical resistance for normal growth. Therefore, the physical characteristics that affect

Roque Vaquero M

303

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...

304

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

305

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

306

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

307

Microorganisms in root carious lesions in adults  

Microsoft Academic Search

Purpose: Root caries is emerging as a significant prob- lem in the middle aged and elderly subjects because of the improving general health conditions, and medical and tech- nological advances. The purpose of this investigation was to assess the prevalence of aerobic and anaerobic bacteria as well as yeasts of Candida genus in root carious lesions in middle-aged and older

Stokowska W; Klimiuk A; Daniluk T; Cylwik-Rokicka D; Tokajuk G; Abdelrazek S

2006-01-01

308

Evolution: rooting the eukaryotic tree of life.  

PubMed

The root of the eukaryotic tree is a major unresolved question in evolutionary biology. A recent study marshals mitochondrial genes to place that root between the enigmatic Excavates and all other eukaryotes, providing an interesting new perspective on early eukaryotic evolution. PMID:24556435

Williams, Tom A

2014-02-17

309

Roots as a source of food.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Numerous plant species produce edible roots that are an important source of calories and that contribute to human nutrition. This book chapter discusses the origin and domestication, production aspects and nutritional aspects of a number of root crops including; cassava (Manioc), sweetpotato (Ipomo...

310

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

311

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...

312

33 CFR 117.1095 - Root River.  

Code of Federal Regulations, 2010 CFR

...Navigable Waters 1 2010-07-01 2010-07-01 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...

2010-07-01

313

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

314

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

315

33 CFR 117.1095 - Root River.  

Code of Federal Regulations, 2012 CFR

...Navigable Waters 1 2012-07-01 2012-07-01 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...

2012-07-01

316

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

317

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

318

GiA Roots: software for the high throughput analysis of plant root system architecture  

PubMed Central

Background Characterizing root system architecture (RSA) is essential to understanding the development and function of vascular plants. Identifying RSA-associated genes also represents an underexplored opportunity for crop improvement. Software tools are needed to accelerate the pace at which quantitative traits of RSA are estimated from images of root networks. Results We have developed GiA Roots (General Image Analysis of Roots), a semi-automated software tool designed specifically for the high-throughput analysis of root system images. GiA Roots includes user-assisted algorithms to distinguish root from background and a fully automated pipeline that extracts dozens of root system phenotypes. Quantitative information on each phenotype, along with intermediate steps for full reproducibility, is returned to the end-user for downstream analysis. GiA Roots has a GUI front end and a command-line interface for interweaving the software into large-scale workflows. GiA Roots can also be extended to estimate novel phenotypes specified by the end-user. Conclusions We demonstrate the use of GiA Roots on a set of 2393 images of rice roots representing 12 genotypes from the species Oryza sativa. We validate trait measurements against prior analyses of this image set that demonstrated that RSA traits are likely heritable and associated with genotypic differences. Moreover, we demonstrate that GiA Roots is extensible and an end-user can add functionality so that GiA Roots can estimate novel RSA traits. In summary, we show that the software can function as an efficient tool as part of a workflow to move from large numbers of root images to downstream analysis. PMID:22834569

2012-01-01

319

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

320

Formation and separation of root border cells.  

PubMed

Plant roots release a large number of border cells into the rhizosphere, which are believed to play a key role in root development and health. The formation and loss of these cells from the root cap region is a developmentally regulated process that is also controlled by phytohormones and environmental factors. The separation of border cells involves the complete dissociation of individual cells from each other and from root tissue. This process requires the activity of cell wall-degrading enzymes that solubilize the cell wall connections between cells. We present and discuss the solubilization process with an emphasis on pectin-degrading enzymes as well as the recently discovered root border-like cells of Arabidopsis thaliana. PMID:17157548

Driouich, Azeddine; Durand, Caroline; Vicré-Gibouin, Maïté

2007-01-01

321

The origin and early evolution of roots.  

PubMed

Geological sites of exceptional fossil preservation are becoming a focus of research on root evolution because they retain edaphic and ecological context, and the remains of plant soft tissues are preserved in some. New information is emerging on the origins of rooting systems, their interactions with fungi, and their nature and diversity in the earliest forest ecosystems. Remarkably well-preserved fossils prove that mycorrhizal symbionts were diverse in simple rhizoid-based systems. Roots evolved in a piecemeal fashion and independently in several major clades through the Devonian Period (416 to 360 million years ago), rapidly extending functionality and complexity. Evidence from extinct arborescent clades indicates that polar auxin transport was recruited independently in several to regulate wood and root development. The broader impact of root evolution on the geochemical carbon cycle is a developing area and one in which the interests of the plant physiologist intersect with those of the geochemist. PMID:25187527

Kenrick, Paul; Strullu-Derrien, Christine

2014-10-01

322

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

323

Systems approaches to study root architecture dynamics  

PubMed Central

The plant root system is essential for providing anchorage to the soil, supplying minerals and water, and synthesizing metabolites. It is a dynamic organ modulated by external cues such as environmental signals, water and nutrients availability, salinity and others. Lateral roots (LRs) are initiated from the primary root post-embryonically, after which they progress through discrete developmental stages which can be independently controlled, providing a high level of plasticity during root system formation. Within this review, main contributions are presented, from the classical forward genetic screens to the more recent high-throughput approaches, combined with computer model predictions, dissecting how LRs and thereby root system architecture is established and developed. PMID:24421783

Cuesta, Candela; Wabnik, Krzysztof; Benková, Eva

2013-01-01

324

Long-term control of root growth  

SciTech Connect

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. 7 figs.

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

1992-05-26

325

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

326

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

327

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

328

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

329

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

330

Drought stress and leaf herbivory affect root terpenoid concentrations and growth of Tanacetum vulgare.  

PubMed

Plant responses of both shoots and roots to combined abiotic and biotic stress have been rarely investigated. However, stresses such as drought and aboveground herbivory might lead to conflicting resource allocation patterns and pronounced shifts in shoot vs. root defenses. In the present study, the effects of water availability and leaf herbivory by caterpillars of a generalist on various shoot and root traits of the aromatic plant Tanacetum vulgare L. were investigated. This species contains terpenoids in leaves and roots, which can differ in composition among individuals, forming so-called chemotypes. To test for intraspecific variation, responses were investigated in two chemotypes, the thujone and the carvyl acetate chemotype. Furthermore, effects of differences in plant quality on the herbivores were studied. Shoot biomass significantly decreased due to drought and herbivory, whereas the root/shoot ratio increased following drought but was unaffected by herbivory. No shifts in C/N ratios were found. In contrast to our expectation, leaf terpenoid concentrations decreased only slightly due to drought, whereas root terpenoids were significantly induced by both drought and herbivory. Chemotypes showed distinct responses to drought at least in the root/shoot ratio, with a higher drought sensitivity of the carvyl acetate chemotype. The body mass of the caterpillars was unaffected by the irrigation treatment but depended on chemotype and terpenoid concentration of the plants. Thus, both qualitative and quantitative defenses strongly affect herbivore development. The present results offer new insights into the above- and belowground organ-specific responses of plants. They highlight the importance of roots in response to various environmental challenges. PMID:25315354

Kleine, Sandra; Müller, Caroline

2014-10-01

331

Root cap influences root colonisation by Pseudomonas fluorescens SBW25 on maize.  

PubMed

We investigated the influence of root border cells on the colonisation of seedling Zea mays roots by Pseudomonas fluorescens SBW25 in sandy loam soil packed at two dry bulk densities. Numbers of colony forming units (CFU) were counted on sequential sections of root for intact and decapped inoculated roots grown in loose (1.0 mg m(-3)) and compacted (1.3 mg m(-3)) soil. After two days of root growth, the numbers of P. fluorescens (CFU cm(-1)) were highest on the section of root just below the seed with progressively fewer bacteria near the tip, irrespective of density. The decapped roots had significantly more colonies of P. fluorescens at the tip compared with the intact roots: approximately 100-fold more in the loose and 30-fold more in the compact soil. In addition, confocal images of the root tips grown in agar showed that P. fluorescens could only be detected on the tips of the decapped roots. These results indicated that border cells, and their associated mucilage, prevented complete colonization of the root tip by the biocontrol agent P. fluorescens, possibly by acting as a disposable surface or sheath around the cap. PMID:16329978

Humphris, Sonia N; Bengough, A Glyn; Griffiths, Bryan S; Kilham, Ken; Rodger, Sheena; Stubbs, Vicky; Valentine, Tracy A; Young, Iain M

2005-09-01

332

Resistance to compression of weakened roots subjected to different root reconstruction protocols  

PubMed Central

Objective This study evaluated, in vitro, the fracture resistance of human non-vital teeth restored with different reconstruction protocols. Material and methods Forty human anterior roots of similar shape and dimensions were assigned to four groups (n=10), according to the root reconstruction protocol: Group I (control): non-weakened roots with glass fiber post; Group II: roots with composite resin by incremental technique and glass fiber post; Group III: roots with accessory glass fiber posts and glass fiber post; and Group IV: roots with anatomic glass fiber post technique. Following post cementation and core reconstruction, the roots were embedded in chemically activated acrylic resin and submitted to fracture resistance testing, with a compressive load at an angle of 45º in relation to the long axis of the root at a speed of 0.5 mm/min until fracture. All data were statistically analyzed with bilateral Dunnett's test (?=0.05). Results Group I presented higher mean values of fracture resistance when compared with the three experimental groups, which, in turn, presented similar resistance to fracture among each other. None of the techniques of root reconstruction with intraradicular posts improved root strength, and the incremental technique was suggested as being the most recommendable, since the type of fracture that occurred allowed the remaining dental structure to be repaired. Conclusion The results of this in vitro study suggest that the healthy remaining radicular dentin is more important to increase fracture resistance than the root reconstruction protocol. PMID:22231002

ZOGHEIB, Lucas Villaça; SAAVEDRA, Guilherme de Siqueira Ferreira Anzaloni; CARDOSO, Paula Elaine; VALERA, Márcia Carneiro; de ARAÚJO, Maria Amélia Máximo

2011-01-01

333

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

334

Establishment of a Protein Reference Map for Soybean Root Hair Cells1[W][OA  

PubMed Central

Root hairs are single tubular cells formed from the differentiation of epidermal cells on roots. They are involved in water and nutrient uptake and represent the infection site on leguminous roots by rhizobia, soil bacteria that establish a nitrogen-fixing symbiosis. Root hairs develop by polar cell expansion or tip growth, a unique mode of plant growth shared only with pollen tubes. A more complete characterization of root hair cell biology will lead to a better understanding of tip growth, the rhizobial infection process, and also lead to improvements in plant water and nutrient uptake. We analyzed the proteome of isolated soybean (Glycine max) root hair cells using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and shotgun proteomics (1D-PAGE-liquid chromatography and multidimensional protein identification technology) approaches. Soybean was selected for this study due to its agronomic importance and its root size. The resulting soybean root hair proteome reference map identified 1,492 different proteins. 2D-PAGE followed by mass spectrometry identified 527 proteins from total cell contents. A complementary shotgun analysis identified 1,134 total proteins, including 443 proteins that were specific to the microsomal fraction. Only 169 proteins were identified by the 2D-PAGE and shotgun methods, which highlights the advantage of using both methods. The proteins identified are involved not only in basic cell metabolism but also in functions more specific to the single root hair cell, including water and nutrient uptake, vesicle trafficking, and hormone and secondary metabolism. The data presented provide useful insight into the metabolic activities of a single, differentiated plant cell type. PMID:19036831

Brechenmacher, Laurent; Lee, Joohyun; Sachdev, Sherri; Song, Zhao; Nguyen, Tran Hong Nha; Joshi, Trupti; Oehrle, Nathan; Libault, Marc; Mooney, Brian; Xu, Dong; Cooper, Bret; Stacey, Gary

2009-01-01

335

FNOCT as a fluorescent probe for in vivo localization of nitric oxide distribution in tobacco roots.  

PubMed

The nitric oxide-specific fluorescent probe Fluorescent Nitric Oxide Cheletropic Trap (FNOCT) 8a was applied to intact tobacco (Nicotiana tabacum cv. Samsun) roots to detect sites of nitric oxide formation and NO distribution. Three week old tobacco seedlings were gently removed from the sand culture pots with intact roots and transferred to small Petri dishes, whose base was replaced by a thin coverslip. Intact roots were subjected to FNOCT 8a to localize NO-dependent fluorescence in these roots; controls with an exogenous NO donor confirmed the presence and distribution of the probe in the roots. To confirm the NO-dependent fluorescence, roots were incubated with the three different NO scavengers cPTIO {2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-L-oxyl-3-oxide}, methylene blue and sodium diethyl dithiocarbamate (DCC) followed by incubation with FNOCT 8a. Methylene blue and DCC were able to completely quench NO-dependent fluorescence, cPTIO quenched partially. The roots were incubated in the presence of NaNO? and NaNO?, which are substrates for nitrite:nitric oxide reductase (NI-NOR) and plasma membrane-bound nitrate reductase (PM-NR), respectively. The NO-dependent fluorescence was more or less same at the root tips upon treatment with NaNO?, while the overall fluorescence was reduced in the presence of NaNO. Fluorescence from the living roots was visualized by inverted confocal laser scanning microscope (CLSM) using UV laser (excitation 360 nm and emission 408 nm). A specialized apparatus has been devised by the authors for analysis of intact roots as described in the methods section of this paper. Intact roots were chosen for microscopic observation rather than incised roots to avoid production of NO due to stress or physical injury. PMID:22277729

Vandana, Shweta; Sustmann, Reiner; Rauen, Ursula; Stöhr, Christine

2012-10-01

336

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

337

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

338

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

339

The Course of Due Process.  

ERIC Educational Resources Information Center

Discussion of due process rights for children with disabilities considers common issues leading to due process requests, due process procedures, hearing officers, procedural violations, effects of due process meetings, and areas for improvement (i.e., accountability, paperwork). Tables list categories of procedural violations with examples and…

Getty, Laura A.; Summy, Sarah E.

2004-01-01

340

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

341

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

342

Transcriptional profile of maize roots under acid soil growth  

PubMed Central

Background Aluminum (Al) toxicity is one of the most important yield-limiting factors of many crops worldwide. The primary symptom of Al toxicity syndrome is the inhibition of root growth leading to poor water and nutrient absorption. Al tolerance has been extensively studied using hydroponic experiments. However, unlike soil conditions, this method does not address all of the components that are necessary for proper root growth and development. In the present study, we grew two maize genotypes with contrasting tolerance to Al in soil containing toxic levels of Al and then compared their transcriptomic responses. Results When grown in acid soil containing toxic levels of Al, the Al-sensitive genotype (S1587-17) showed greater root growth inhibition, more Al accumulation and more callose deposition in root tips than did the tolerant genotype (Cat100-6). Transcriptome profiling showed a higher number of genes differentially expressed in S1587-17 grown in acid soil, probably due to secondary effects of Al toxicity. Genes involved in the biosynthesis of organic acids, which are frequently associated with an Al tolerance response, were not differentially regulated in both genotypes after acid soil exposure. However, genes related to the biosynthesis of auxin, ethylene and lignin were up-regulated in the Al-sensitive genotype, indicating that these pathways might be associated with root growth inhibition. By comparing the two maize lines, we were able to discover genes up-regulated only in the Al-tolerant line that also presented higher absolute levels than those observed in the Al-sensitive line. These genes encoded a lipase hydrolase, a retinol dehydrogenase, a glycine-rich protein, a member of the WRKY transcriptional family and two unknown proteins. Conclusions This work provides the first characterization of the physiological and transcriptional responses of maize roots when grown in acid soil containing toxic levels of Al. The transcriptome profiles highlighted several pathways that are related to Al toxicity and tolerance during growth in acid soil. We found several genes that were not found in previous studies using hydroponic experiments, increasing our understanding of plant responses to acid soil. The use of two germplasms with markedly different Al tolerances allowed the identification of genes that are a valuable tool for assessing the mechanisms of Al tolerance in maize in acid soil. PMID:20828383

2010-01-01

343

Genome networks root the tree of life between prokaryotic domains.  

PubMed

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

344

10. PHOTOCOPY OF 'P. H. & F. M. ROOTS FOUNDARY ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. PHOTOCOPY OF 'P. H. & F. M. ROOTS FOUNDARY MANUFACTURERS OF ROOTS BLOWERS' FROM INDIANAPOLIS STAR, June 13, 1926, Gravure Section, p. 2 - P. H. & F. M. Roots Company, Eastern Avenue, Connersville, Fayette County, IN

345

21 CFR 872.3820 - Root canal filling resin.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Root canal filling resin. 872.3820 Section...DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device...

2010-04-01

346

21 CFR 872.3820 - Root canal filling resin.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Root canal filling resin. 872.3820 Section...DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device...

2013-04-01

347

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...DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device...

2012-04-01

348

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...DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device...

2014-04-01

349

76 FR 51430 - Roots Pharmaceuticals, Inc.; Revocation of Registration  

Federal Register 2010, 2011, 2012, 2013, 2014

...JUSTICE Drug Enforcement Administration Roots Pharmaceuticals, Inc.; Revocation of...Administration, issued an Order to Show Cause to Roots Pharmaceuticals, Inc. (Registrant...Certificate of Registration BR9610571, issued to Roots Pharmaceuticals, Inc., be, and it...

2011-08-18

350

21 CFR 872.3820 - Root canal filling resin.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 false Root canal filling resin. 872.3820 Section...DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device...

2011-04-01

351

Root Xylem Embolisms and Refilling. Relation to Water Potentials of Soil, Roots, and Leaves, and Osmotic Potentials of Root Xylem Sap  

Microsoft Academic Search

Embolism and refilling of vessels was monitored directly by cryo- microscopy of field-grown corn (Zea mays L.) roots. To test the reliability of an earlier study showing embolism refilling in roots at negative leaf water potentials, embolisms were counted, and root water potentials (Croot) and osmotic potentials of exuded xylem sap from the same roots were measured by isopiestic psychrometry.

Margaret E. McCully

1999-01-01

352

Cytokinins in Seedling Roots of Pea  

PubMed Central

The natural occurrence of cytokinins existing both in a free form and as a constituent of transfer RNA was examined in serial segments of young seedling roots of pea. Purified ethanol extracts of root apices were resolved into four factors capable of inducing soybean callus tissue proliferation. The most active factor was identified as zeatin or some closely related compound; it produced polyploid divisions and tracheary element differentiation when tested on cultured pea root segments. The terminal 0- to 1-millimeter root tip contained 43 to 44 times more free cytokinin on a fresh weight or a per cell basis than the next 1- to 5-millimeter root segment. Extracts of more proximal segments behind the tip contained no measurable free cytokinin. Acid hydrolysates of transfer RNA exhibited reproducible cytokinin activity. Bioassays revealed that the predominant amounts of free cytokinin and that present in transfer RNA were restricted to the extreme root tip. There was approximately 27 times more free cytokinin than the amount detected in transfer RNA in root apices. PMID:16657915

Short, Keith C.; Torrey, John G.

1972-01-01

353

Root Hypoxia Reduces Leaf Growth 1  

PubMed Central

This study examined the potential role of restricted phloem export, or import of substances from the roots in the leaf growth response to root hypoxia. In addition, the effects of root hypoxia on abscisic acid (ABA) and zeatin riboside (ZR) levels were measured and their effects on in vitro growth determined. Imposition of root hypoxia in the dark when transpirational water flux was minimal delayed the reduction in leaf growth until the following light period. Restriction of phloem transport by stem girdling did not eliminate the hypoxia-induced reduction in leaf growth. In vitro growth of leaf discs was inhibited in the presence of xylem sap collected from hypoxic roots, and also by millimolar ABA. Disc growth was promoted by sap from aerated roots and by 0.1 micromolar ZR. The flux of both ABA and ZR was reduced in xylem sap from hypoxic roots. Leaf ABA transiently increased twofold after 24 hours of hypoxia exposure but there were no changes in leaf cytokinin levels. Images Figure 3 Figure 4 PMID:16667366

Smit, Barbara A.; Neuman, Dawn S.; Stachowiak, Matthew L.

1990-01-01

354

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

355

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

356

Light as stress factor to plant roots – case of root halotropism  

PubMed Central

Despite growing underground, largely in darkness, roots emerge to be very sensitive to light. Recently, several important papers have been published which reveal that plant roots not only express all known light receptors but also that their growth, physiology and adaptive stress responses are light-sensitive. In Arabidopsis, illumination of roots speeds-up root growth via reactive oxygen species-mediated and F-actin dependent process. On the other hand, keeping Arabidopsis roots in darkness alters F-actin distribution, polar localization of PIN proteins as well as polar transport of auxin. Several signaling components activated by phytohormones are overlapping with light-related signaling cascade. We demonstrated that the sensitivity of roots to salinity is altered in the light-grown Arabidopsis roots. Particularly, light-exposed roots are less effective in their salt-avoidance behavior known as root halotropism. Here we discuss these new aspects of light-mediated root behavior from cellular, physiological and evolutionary perspectives. PMID:25566292

Yokawa, Ken; Fasano, Rossella; Kagenishi, Tomoko; Baluška, František

2014-01-01

357

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

358

BOREAS TE-2 Root Respiration Data  

NASA Technical Reports Server (NTRS)

The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set includes means of tree root respiration measurements on roots having diameters ranging from 0 to 2 mm conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Ryan, Michael G.; Lavigne, Michael; Hall, Forrest G. (Editor); Papagno, Andrea (Editor)

2000-01-01

359

Composite Cucurbita pepo plants with transgenic roots as a tool to study root development  

PubMed Central

Background and Aims In most plant species, initiation of lateral root primordia occurs above the elongation zone. However, in cucurbits and some other species, lateral root primordia initiation and development takes place in the apical meristem of the parental root. Composite transgenic plants obtained by Agrobacterium rhizogenes-mediated transformation are known as a suitable model to study root development. The aim of the present study was to establish this transformation technique for squash. Methods The auxin-responsive promoter DR5 was cloned into the binary vectors pKGW-RR-MGW and pMDC162-GFP. Incorporation of 5-ethynyl-2?-deoxyuridine (EdU) was used to evaluate the presence of DNA-synthesizing cells in the hypocotyl of squash seedlings to find out whether they were suitable for infection. Two A. rhizogenes strains, R1000 and MSU440, were used. Roots containing the respective constructs were selected based on DsRED1 or green fluorescent protein (GFP) fluorescence, and DR5::Egfp-gusA or DR5::gusA insertion, respectively, was verified by PCR. Distribution of the response to auxin was visualized by GFP fluorescence or ?-glucuronidase (GUS) activity staining and confirmed by immunolocalization of GFP and GUS proteins, respectively. Key Results Based on the distribution of EdU-labelled cells, it was determined that 6-day-old squash seedlings were suited for inoculation by A. rhizogenes since their root pericycle and the adjacent layers contain enough proliferating cells. Agrobacterium rhizogenes R1000 proved to be the most virulent strain on squash seedlings. Squash roots containing the respective constructs did not exhibit the hairy root phenotype and were morphologically and structurally similar to wild-type roots. Conclusions The auxin response pattern in the root apex of squash resembled that in arabidopsis roots. Composite squash plants obtained by A. rhizogenes-mediated transformation are a good tool for the investigation of root apical meristem development and root branching. PMID:22553131

Ilina, Elena L.; Logachov, Anton A.; Laplaze, Laurent; Demchenko, Nikolay P.; Pawlowski, Katharina; Demchenko, Kirill N.

2012-01-01

360

Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings.  

PubMed

Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots. PMID:23726884

Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

2013-09-01

361

Lauric acid in crown daisy root exudate potently regulates root-knot nematode chemotaxis and disrupts Mi-flp-18 expression to block infection  

PubMed Central

Tomato (Solanum lycopersicum) crops can be severely damaged due to parasitism by the root-knot nematode (RKN) Meloidogyne incognita, but are protected when intercropped with crown daisy (Chrysanthemum coronarium L.). Root exudate may be the determining factor for this protection. An experiment using pots linked by a tube and Petri dish experiments were undertaken to confirm that tomato–crown daisy intercropping root exudate decreased the number of nematodes and alleviated nematode damage, and to determine crown daisy root exudate-regulated nematode chemotaxis. Following a gas chromatography–mass spectrometry assay, it was found that the intercropping protection was derived from the potent bioactivity of a specific root exudate component of crown daisy, namely lauric acid. The Mi-flp-18 gene, encoding an FMRFamide-like peptide neuromodulator, regulated nematode chemotaxis and infection by RNA interference. Moreover, it was shown that lauric acid acts as both a lethal trap and a repellent for M. incognita by specifically regulating Mi-flp-18 expression in a concentration-dependent manner. Low concentrations of lauric acid (0.5–2.0mM) attract M. incognita and consequently cause death, while high concentrations (4.0mM) repel M. incognita. This study elucidates how lauric acid in crown daisy root exudate regulates nematode chemotaxis and disrupts Mi-flp-18 expression to alleviate nematode damage, and presents a general methodology for studying signalling systems affected by plant root exudates in the rhizosphere. This could lead to the development of economical and feasible strategies for controlling plant-parasitic nematodes, and provide an alternative to the use of pesticides in farming systems. PMID:24170741

Zuo, Yuanmei

2014-01-01

362

Lauric acid in crown daisy root exudate potently regulates root-knot nematode chemotaxis and disrupts Mi-flp-18 expression to block infection.  

PubMed

Tomato (Solanum lycopersicum) crops can be severely damaged due to parasitism by the root-knot nematode (RKN) Meloidogyne incognita, but are protected when intercropped with crown daisy (Chrysanthemum coronarium L.). Root exudate may be the determining factor for this protection. An experiment using pots linked by a tube and Petri dish experiments were undertaken to confirm that tomato-crown daisy intercropping root exudate decreased the number of nematodes and alleviated nematode damage, and to determine crown daisy root exudate-regulated nematode chemotaxis. Following a gas chromatography-mass spectrometry assay, it was found that the intercropping protection was derived from the potent bioactivity of a specific root exudate component of crown daisy, namely lauric acid. The Mi-flp-18 gene, encoding an FMRFamide-like peptide neuromodulator, regulated nematode chemotaxis and infection by RNA interference. Moreover, it was shown that lauric acid acts as both a lethal trap and a repellent for M. incognita by specifically regulating Mi-flp-18 expression in a concentration-dependent manner. Low concentrations of lauric acid (0.5-2.0mM) attract M. incognita and consequently cause death, while high concentrations (4.0mM) repel M. incognita. This study elucidates how lauric acid in crown daisy root exudate regulates nematode chemotaxis and disrupts Mi-flp-18 expression to alleviate nematode damage, and presents a general methodology for studying signalling systems affected by plant root exudates in the rhizosphere. This could lead to the development of economical and feasible strategies for controlling plant-parasitic nematodes, and provide an alternative to the use of pesticides in farming systems. PMID:24170741

Dong, Linlin; Li, Xiaolin; Huang, Li; Gao, Ying; Zhong, Lina; Zheng, Yuanyuan; Zuo, Yuanmei

2014-01-01

363

Plant Structure--Leaves, Stems, and Roots  

NSDL National Science Digital Library

Page one consists of a full color illustration of an idealized plant, showing various leaf, stem and root features. Page two illustrates various adaptations of plant flowers, leaves and stems. All illustrations are accompanied by explanations of the structures' functions.

2000-01-01

364

Root Apex Transition Zone As Oscillatory Zone  

PubMed Central

Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen, and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command center. In accordance with the early proposal of Charles and Francis Darwin, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone. PMID:24106493

Baluška, František; Mancuso, Stefano

2013-01-01

365

Root gravitropism in maize and Arabidopsis  

NASA Technical Reports Server (NTRS)

Research during the period 1 March 1992 to 30 November 1993 focused on improvements in a video digitizer system designed to automate the recording of surface extension in plants responding to gravistimulation. The improvements included modification of software to allow detailed analysis of localized extension patterns in roots of Arabidopsis. We used the system to analyze the role of the postmitotic isodiametric growth zone (a region between the meristem and the elongation zone) in the response of maize roots to auxin, calcium, touch and gravity. We also used the system to analyze short-term auxin and gravitropic responses in mutants of Arabidopsis with reduced auxin sensitivity. In a related project, we studied the relationship between growth rate and surface electrical currents in roots by examining the effects of gravity and thigmostimulation on surface potentials in maize roots.

Evans, Michael L.

1993-01-01

366

Queen Angelfish Hides in Mangrove Prop Roots  

USGS Multimedia Gallery

A Queen Angelfish peers through the safety of the mangrove roots across the rich colors and textures of corals, sponges, urchins, and algae. Queen Angelfish feed almost exclusively on sponges, which are abundant in these mangroves....

367

Phytochromes play a role in phototropism and gravitropism in Arabidopsis roots  

NASA Technical Reports Server (NTRS)

Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Correll, Melanie J.; Coveney, Katrina M.; Raines, Steven V.; Mullen, Jack L.; Hangarter, Roger P.; Kiss, John Z.

2003-01-01

368

On the use of antibiotics to reduce rhizoplane microbial populations in root physiology and ecology investigations  

NASA Technical Reports Server (NTRS)

No straightforward method exists for separating the proportion of ion exchange and respiration due to rhizoplane microbial organisms from that of root ion exchange and respiration. We examined several antibiotics that might be used for the temporary elimination of rhizoplane bacteria from hydroponically grown wheat roots (Triticum aestivum cv. Veery 10). Each antibiotic was tested for herbicidal activity and plate counts were used to enumerate bacteria and evaluate antibiotic kinetics. Only lactam antibiotics (penicillins and cephalosporins) did not reduce wheat growth rates. Aminoglycosides, the pyrimidine trimethoprim, colistin and rifampicin reduced growth rates substantially. Antibiotics acted slowly, with maximum reductions in rhizoplane bacteria occurring after more than 48 h of exposure. Combinations of nonphytotoxic antibiotics reduced platable rhizoplane bacteria by as much as 98%; however, this was generally a reduction from about 10(9) to 10(6) colony forming units per gram of dry root mass, so that many viable bacteria remained on root surfaces. We present evidence which suggests that insufficient bacterial biomass exists on root surfaces of nonstressed plants grown under well-aerated conditions to quantitatively interfere with root nitrogen absorption measurements.

Smart, D. R.; Ferro, A.; Ritchie, K.; Bugbee, B. G.

1995-01-01

369

Early steps of adventitious rooting: morphology, hormonal profiling and carbohydrate turnover in carnation stem cuttings.  

PubMed

The rooting of stem cuttings is a common vegetative propagation practice in many ornamental species. A detailed analysis of the morphological changes occurring in the basal region of cultivated carnation cuttings during the early stages of adventitious rooting was carried out and the physiological modifications induced by exogenous auxin application were studied. To this end, the endogenous concentrations of five major classes of plant hormones [auxin, cytokinin (CK), abscisic acid, salicylic acid (SA) and jasmonic acid] and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid were analyzed at the base of stem cuttings and at different stages of adventitious root formation. We found that the stimulus triggering the initiation of adventitious root formation occurred during the first hours after their excision from the donor plant, due to the breakdown of the vascular continuum that induces auxin accumulation near the wounding. Although this stimulus was independent of exogenously applied auxin, it was observed that the auxin treatment accelerated cell division in the cambium and increased the sucrolytic activities at the base of the stem, both of which contributed to the establishment of the new root primordia at the stem base. Further, several genes involved in auxin transport were upregulated in the stem base either with or without auxin application, while endogenous CK and SA concentrations were specially affected by exogenous auxin application. Taken together our results indicate significant crosstalk between auxin levels, stress hormone homeostasis and sugar availability in the base of the stem cuttings in carnation during the initial steps of adventitious rooting. PMID:24117983

Agulló-Antón, María Ángeles; Ferrández-Ayela, Almudena; Fernández-García, Nieves; Nicolás, Carlos; Albacete, Alfonso; Pérez-Alfocea, Francisco; Sánchez-Bravo, José; Pérez-Pérez, José Manuel; Acosta, Manuel

2014-03-01

370

Phytochromes play a role in phototropism and gravitropism in Arabidopsis roots  

NASA Astrophysics Data System (ADS)

Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli.

Correll, Melanie J.; Coveney, Katrina M.; Raines, Steven V.; Mullen, Jack L.; Hangarter, Roger P.; Kiss, John Z.

2003-05-01

371

Reference gene selection for quantitative reverse transcription-polymerase chain reaction normalization during in vitro adventitious rooting in Eucalyptus globulus Labill  

Microsoft Academic Search

BACKGROUND: Eucalyptus globulus and its hybrids are very important for the cellulose and paper industry mainly due to their low lignin content and frost resistance. However, rooting of cuttings of this species is recalcitrant and exogenous auxin application is often necessary for good root development. To date one of the most accurate methods available for gene expression analysis is quantitative

Márcia R de Almeida; Carolina M Ruedell; Felipe K Ricachenevsky; Raul A Sperotto; Giancarlo Pasquali; Arthur G Fett-Neto

2010-01-01

372

Glucosamine:chondroitin or ginger root extract have little effect on articular cartilage in swine  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sows are culled at a high rate from breeding herds due to musclo-skeletal problems and lameness. Research in our laboratory has shown that even first-parity sows have significant amounts of osteochondritic lesions of their articular cartilage. Glusoamine chondroitin and ginger root extract have both...

373

How does fertilizer/manure placement affect P and K availability in the root zone?  

Technology Transfer Automated Retrieval System (TEKTRAN)

Proper placement of fertilizer nutrients in soil is just as important as choosing the correct amount to apply. Optimum placement of added nutrients improves utilization by the crop root system, which sets the stage for maximum yields. Due to the complexity of the plant-soil system, the most effectiv...

374

First report of root rot of Chicory caused by Phytophthora cryptogea in Chile  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chicory (Cichorium intybus L. var sativum Bisch.), a relatively new high value crop in Chile, was introduced for commercial production of inulin. Inulins are polysaccharides extracted from chicory tap roots that are used in processed foods due to their beneficial gastrointestinal properties. Approxi...

375

Mitotic effects of sodium nucleate in root tips of Rhoeo discolor Hance  

Microsoft Academic Search

The induction by sodium nucleate (8%) of the following effects has been studied quantitatively in roots fixed at close time intervals during and shortly after six hours of treatment:(1)A decrease in the frequency of nuclei entering prophase.(2)A prolongation of late prophase, presumably due to an inhibition of the breakdown of the nuclear membrane. This prolongation seems to be the cause

Klaus Patau; Ramakant P. Patil

1950-01-01

376

Tomato root transcriptome response to a nitrogen-enriched soil patch  

Microsoft Academic Search

BACKGROUND: Nitrogen (N), the primary limiting factor for plant growth and yield in agriculture, has a patchy distribution in soils due to fertilizer application or decomposing organic matter. Studies in solution culture over-simplify the complex soil environment where microbial competition and spatial and temporal heterogeneity challenge roots' ability to acquire adequate amounts of nutrients required for plant growth. In this

Daniel R Ruzicka; Felipe H Barrios-Masias; Natasha T Hausmann; Louise E Jackson; Daniel P Schachtman

2010-01-01

377

Capillary-Effect Root-Environment System  

NASA Technical Reports Server (NTRS)

Capillary-effect root-environment system (CERES) is experimental apparatus for growing plants in nutrient solutions. Solution circulated at slight tension in cavity filled with plastic screen and covered by porous plastic membrane. By adsorptive attraction, root draws solution through membrane. Conceived for use in microgravity of space, also finds terrestrial application in germinating seedlings, because it protects them from extremes of temperature, moisture, and soil pH and from overexposure to fertilizers and herbicides.

Wright, Bruce D.

1991-01-01

378

Mycorrhizal fungi in roots of Texas crops  

E-print Network

in the moisture content of the soil may have had an adverse effect on the mycorrhizae. The soil temperature may have also had an adverse effect on the growth of the mycorrhizae. The temperature was above that normally observed under field conditions... by glomus sp. 63 57. Enlargement of Glomus sp. spore hypha 1 attachment 64 Figure page 58. Arbuscules formed by Glomus sp. in corn root 64 59. Chlamydospore developed between cells in corn root tissue 65 INTRODUCTION Growth of productive healthy...

Yeh, May-Wei Mavix

2012-06-07

379

Anatomical aspects of angiosperm root evolution  

PubMed Central

Background and Aims Anatomy had been one of the foundations in our understanding of plant evolutionary trends and, although recent evo-devo concepts are mostly based on molecular genetics, classical structural information remains useful as ever. Of the various plant organs, the roots have been the least studied, primarily because of the difficulty in obtaining materials, particularly from large woody species. Therefore, this review aims to provide an overview of the information that has accumulated on the anatomy of angiosperm roots and to present possible evolutionary trends between representatives of the major angiosperm clades. Scope This review covers an overview of the various aspects of the evolutionary origin of the root. The results and discussion focus on angiosperm root anatomy and evolution covering representatives from basal angiosperms, magnoliids, monocots and eudicots. We use information from the literature as well as new data from our own research. Key Findings The organization of the root apical meristem (RAM) of Nymphaeales allows for the ground meristem and protoderm to be derived from the same group of initials, similar to those of the monocots, whereas in Amborellales, magnoliids and eudicots, it is their protoderm and lateral rootcap which are derived from the same group of initials. Most members of Nymphaeales are similar to monocots in having ephemeral primary roots and so adventitious roots predominate, whereas Amborellales, Austrobaileyales, magnoliids and eudicots are generally characterized by having primary roots that give rise to a taproot system. Nymphaeales and monocots often have polyarch (heptarch or more) steles, whereas the rest of the basal angiosperms, magnoliids and eudicots usually have diarch to hexarch steles. Conclusions Angiosperms exhibit highly varied structural patterns in RAM organization; cortex, epidermis and rootcap origins; and stele patterns. Generally, however, Amborellales, magnoliids and, possibly, Austrobaileyales are more similar to eudicots, and the Nymphaeales are strongly structurally associated with the monocots, especially the Acorales. PMID:23299993

Seago, James L.; Fernando, Danilo D.

2013-01-01

380

ROOT EFFICIENCY AND MINERAL NUTRITION IN APPLE  

Microsoft Academic Search

Among deciduous fruit crops, maximum sustained yields under ideal conditions reportedly range from 22 MT\\/ha in sweet cherry to 112 MT\\/ha in apple: about a 5-fold difference. Root length densities under fruit trees, however, range from about 0.2 km\\/m2 in apple to about 12 km\\/m2 in kiwifruit: a 60-fold difference. What causes these differences among the root systems of different

D. M. Eissenstat; C. E Wells; L. Wang

381

Mapping gene activity of Arabidopsis root hairs  

PubMed Central

Background Quantitative information on gene activity at single cell-type resolution is essential for the understanding of how cells work and interact. Root hairs, or trichoblasts, tubular-shaped outgrowths of specialized cells in the epidermis, represent an ideal model for cell fate acquisition and differentiation in plants. Results Here, we provide an atlas of gene and protein expression in Arabidopsis root hair cells, generated by paired-end RNA sequencing and LC/MS-MS analysis of protoplasts from plants containing a pEXP7-GFP reporter construct. In total, transcripts of 23,034 genes were detected in root hairs. High-resolution proteome analysis led to the reliable identification of 2,447 proteins, 129 of which were differentially expressed between root hairs and non-root hair tissue. Dissection of pre-mRNA splicing patterns showed that all types of alternative splicing were cell type-dependent, and less complex in EXP7-expressing cells when compared to non-root hair cells. Intron retention was repressed in several transcripts functionally related to root hair morphogenesis, indicative of a cell type-specific control of gene expression by alternative splicing of pre-mRNA. Concordance between mRNA and protein expression was generally high, but in many cases mRNA expression was not predictive for protein abundance. Conclusions The integrated analysis shows that gene activity in root hairs is dictated by orchestrated, multilayered regulatory mechanisms that allow for a cell type-specific composition of functional components. PMID:23800126

2013-01-01

382

Four-Rooted Mandibular First Molar with an Unusual Developmental Root Fusion Line: A Case Report  

PubMed Central

The paper describes the anatomical variation of four roots in a mandibular permanent first molar diagnosed using multiple angulated preoperative radiographs and its successful nonsurgical endodontic management. Careful observation and exploration of the pulpal floor using a dental operating microscope revealed a peculiar developmental root fusion line on the pulp chamber floor. Based on the above observation, a correlation between this unusual line and the existence of additional roots has been proposed and discussed. PMID:22792498

Kottoor, Jojo; Albuquerque, Denzil Valerian; Velmurugan, Natanasabapathy; Sumitha, Mylswamy

2012-01-01

383

Chemical root pruning and its effects on water relations and root morphology of photinia  

E-print Network

differences. Root pruning also induced reductions in net photosynthesis, transpiration and stomatal conductance, and stomatal resistance to water loss (Arnold and Struve, 1989a). Effect of root pruning on root morphology The effect of cupric carbonate... was induced, stomatal closure appeared first in mature peach leaves. Jordan et al. (1975) and Field (1987) document examples of stomatal closure progressing from older to younger leaves in response to decreasing leaf water potential. Each square millimeter...

Vartak, Diptish Ramesh

2012-06-07

384

Root water uptake by kiwifruit vines following partial wetting of the root zone  

Microsoft Academic Search

Rates of sap flow and root-water uptake by two 7-year old kiwifruit vines (Acinidia deliciosa) were studied in an orchard with the aim of determining the ability of the vines to alter their spatial pattern of root-water uptake following differential wetting of the root zone. Time-domain reflectometry (TDR) was used to monitor changes in the soil's volumetric water content, p.

S. R. Green; B. E. Clothier

1995-01-01

385

Vertical root fractures and their management  

PubMed Central

Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

2014-01-01

386

Extracellular DNA: the tip of root defenses?  

PubMed

This review discusses how extracellular DNA (exDNA) might function in plant defense, and at what level(s) of innate immunity this process might operate. A new role for extracellular factors in mammalian defense has been described in a series of studies. These studies reveal that cells including neutrophils, eosinophils, and mast cells produce 'extracellular traps' (ETs) consisting of histone-linked exDNA. When pathogens are attracted to such ETs, they are trapped and killed. When the exDNA component of ETs is degraded, trapping is impaired and resistance against invasion is reduced. Conversely, mutation of microbial genes encoding exDNases that degrade exDNA results in loss of virulence. This discovery that exDNases are virulence factors opens new avenues for disease control. In plants, exDNA is required for defense of the root tip. Innate immunity-related proteins are among a group of >100 proteins secreted from the root cap and root border cell populations. Direct tests revealed that exDNA also is rapidly synthesized and exported from the root tip. When this exDNA is degraded by the endonuclease DNase 1, root tip resistance to fungal infection is lost; when the polymeric structure is degraded more slowly, by the exonuclease BAL31, loss of resistance to fungal infection is delayed accordingly. The results suggest that root border cells may function in a manner analogous to that which occurs in mammalian cells. PMID:21497709

Hawes, Martha C; Curlango-Rivera, Gilberto; Wen, Fushi; White, Gerard J; Vanetten, Hans D; Xiong, Zhongguo

2011-06-01

387

Adaptive significance of root grafting in trees  

SciTech Connect

Root grafting has long been observed in forest trees but the adaptive significance of this trait has not been fully explained. Various authors have proposed that root grafting between trees contributes to mechanical support by linking adjacent root systems. Keeley proposes that this trait would be of greatest advantage in swamps where soils provide poor mechanical support. He provides as evidence a greenhouse study of Nyssa sylvatica Marsh in which seedlings of swamp provenance formed between-individual root grafts more frequently than upland provenance seedlings. In agreement with this within-species study, Keeley observed that arid zone species rarely exhibit grafts. Keeley also demonstrated that vines graft less commonly than trees, and herbs never do. Since the need for mechanical support coincides with this trend, these data seem to support his model. In this paper, the authors explore the mechanisms and ecological significance of root grafting, leading to predictions of root grafting incidence. Some observations support and some contradict the mechanical support hypothesis.

Loehle, C.; Jones, R.

1988-12-31

388

Genome beginnings: rooting the tree of life  

PubMed Central

A rooted tree of life provides a framework to answer central questions about the evolution of life. Here we review progress on rooting the tree of life and introduce a new root of life obtained through the analysis of indels, insertions and deletions, found within paralogous gene sets. Through the analysis of indels in eight paralogous gene sets, the root is localized to the branch between the clade consisting of the Actinobacteria and the double-membrane (Gram-negative) prokaryotes and one consisting of the archaebacteria and the firmicutes. This root provides a new perspective on the habitats of early life, including the evolution of methanogenesis, membranes and hyperthermophily, and the speciation of major prokaryotic taxa. Our analyses exclude methanogenesis as a primitive metabolism, in contrast to previous findings. They parsimoniously imply that the ether archaebacterial lipids are not primitive and that the cenancestral prokaryotic population consisted of organisms enclosed by a single, ester-linked lipid membrane, covered by a peptidoglycan layer. These results explain the similarities previously noted by others between the lipid synthesis pathways in eubacteria and archaebacteria. The new root also implies that the last common ancestor was not hyperthermophilic, although moderate thermophily cannot be excluded. PMID:19571238

Lake, James A.; Skophammer, Ryan G.; Herbold, Craig W.; Servin, Jacqueline A.

2009-01-01

389

Profiling Gene Expression in Germinating Brassica Roots.  

PubMed

Based on previously developed solid-phase gene extraction (SPGE) we examined the mRNA profile in primary roots of Brassica rapa seedlings for highly expressed genes like ACT7 (actin7), TUB (tubulin1), UBQ (ubiquitin), and low expressed GLK (glucokinase) during the first day post-germination. The assessment was based on the mRNA load of the SPGE probe of about 2.1 ng. The number of copies of the investigated genes changed spatially along the length of primary roots. The expression level of all genes differed significantly at each sample position. Among the examined genes ACT7 expression was most even along the root. UBQ was highest at the tip and root-shoot junction (RS). TUB and GLK showed a basipetal gradient. The temporal expression of UBQ was highest in the MZ 9 h after primary root emergence and higher than at any other sample position. Expressions of GLK in EZ and RS increased gradually over time. SPGE extraction is the result of oligo-dT and oligo-dA hybridization and the results illustrate that SPGE can be used for gene expression profiling at high spatial and temporal resolution. SPGE needles can be used within two weeks when stored at 4 °C. Our data indicate that gene expression studies that are based on the entire root miss important differences in gene expression that SPGE is able to resolve for example growth adjustments during gravitropism. PMID:24563578

Park, Myoung Ryoul; Wang, Yi-Hong; Hasenstein, Karl H

2014-01-01

390

Relationship between Root Growth of Potato, Root Diffusate Production, and Hatching of Globodera rostochiensis  

PubMed Central

Hatching response of Globodera rostochiensis in potato root diffusate (PRD) collected by soaking individual potato, Solanum tuberosum, root systems in water for 2 hours was used to assess the relationship between root growth and PRD production. Resistant potato cultivars Hudson and Rosa were used as test plants. Maximum hatch occurred in PRD collected 3 weeks after plant emergence (AE) in the greenhouse, and declined after this time. Hatch was positively correlated with increased root weight only during the first 3 weeks AE. Hudson PRD was consistently more active than Rosa PRD in stimulating hatch, except when adjusted for root weight. Although the results indicated that cells at the root tip produced a more active PRD than cells located elsewhere, PRD appeared to be produced along the entire root. Differences in time length of the vegetative growth phase, extent of root growth, and volume of roots, rather than the production of a more active PRD per se, may explain why Hudson is more effective than Rosa in reducing G. rostochiensis population densities in soil. PMID:19294195

Rawsthorne, Denise; Brodie, B. B.

1986-01-01

391

Salinity induced the changes of root growth and antioxidative responses in two wheat cultivars.  

PubMed

This study aimed to investigate the inhibitory mechanism of root growth and to compare antioxidative responses in two wheat cultivars, drought-tolerant Ningchun and drought-sensitive Xihan, exposed to different NaCl concentrations. Ningchun exhibited lower germination rate, seedling growth, and lipid peroxidation than Xihan when exposed to salinity. The loss of cell viability was correlated with the inhibition of root growth induced by NaCl stress. Moreover, treatments with H2O2 scavenger dimethylthiourea and catalase (CAT) partly blocked salinity-induced negative effects on root growth and cell viability. Besides, the enhancement of superoxide radical and H2O2 levels, and the stimulation of CAT and diamine oxidase (DAO) as well as the inhibition of glutathione reductase (GR) were observed in two wheat roots treated with salinity. However, hydroxyl radical content increased only in Xihan roots under NaCl treatment, and the changes of soluble peroxidase (POD), ascorbate peroxidase (APX), superoxide dismutase (SOD), and cell-wall-bound POD activities were different in drought-tolerant Ningchun and drought-sensitive Xihan exposed to different NaCl concentrations. In conclusion, salinity might induce the loss of cell viability via a pathway associated with extracellular H2O2 generation, which was the primary reason leading to the inhibition of root growth in two wheat cultivars. Here, it was also suggested that increased H2O2 accumulation in the roots of drought-tolerant Ningchun might be due to decreased POD and GR activities as well as enhanced cell-wall-bound POD and DAO ones, while the inhibition of APX and GR as well as the stimulation of SOD and DAO was responsible for the elevation of H2O2 level in drought-sensitive Xihan roots. PMID:24318673

Zhang, Jing; Duan, Xiaohui; Ding, Fan; Ma, HaiZhen; Zhang, Tengguo; Yang, Yingli

2014-07-01

392

A Simple Analytical Model of Evaporation in the Presence of Roots  

E-print Network

Root systems can influence the dynamics of evapotranspiration of water out of a porous medium. The coupling of evapotranspiration remains a key aspect affecting overall root behavior. Predicting the evapotranspiration curve in the presence of roots helps keep track of the amount of water that remains in the porous medium. Using a controlled visual set-up of a 2D model soil system consisting of monodisperse glass beads, we first perform experiments on actual roots grown in partially saturated systems under different relative humidity conditions. We record parameters such as the total mass loss in the medium and the resulting position of the receding fronts and use these experimental results to 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 flux and includes empirical assumptions on the quantity of stoma in the leaves and the transition time between regime 1 and regime 2. The model also underscores the importance of a much prolonged root life as long as the root is exposed to a partially saturated zone composed of a mixture of air and water. Comparison between the model and experimental results shows good prediction of the position of the evaporating front as well as the total mass loss from evapotranspiration in the presence of real root systems. These results provide additional understanding of both complex evaporation phenomenon and its influence on root mechanisms.

Cesare M. Cejas; Larry Hough; Jean-Christophe Castaing; Christian Fretigny; Remi Dreyfus

2014-06-17

393

Filter strip as a method of choice for apoplastic fluid extraction from maize roots.  

PubMed

Apoplastic fluid was extracted from maize (Zea mays L.) roots using two procedures: collection from the surface of intact plant roots by filter paper strips (AF) or vacuum infiltration and/or centrifugation from excised root segments (AWF). The content of cytoplasmic marker (glucose-6-phosphate, G-6-P) and antioxidative components (enzymes, organic acids, phenolics, sugars, ROS) were compared in the extracts. The results obtained demonstrate that AF was completely free of G-6-P, as opposed to AWF where the cytoplasmic constituent was detected even at mildest centrifugation (200×g). Isoelectric focusing of POD and SOD shows the presence of cytoplasmic isoforms in AWF, and HPLC of sugars and phenolics a much more complex composition of AWF, due to cytoplasmic contamination. Organic acid composition differed in the two extracts, much higher concentrations of malic acid being registered in AF, while oxalic acid due to intracellular contamination being present only in AWF. EPR spectroscopy of DEPMPO spin trap in the extracts showed persistent generation of hydroxyl radical adduct in AF. The results obtained argue in favor of the filter strip method for the root apoplastic fluid extraction, avoiding the problems of cytoplasmic contamination and dilution and enabling concentration measurements in minute regions of the root. PMID:24767115

Dragiši? Maksimovi?, Jelena J; Zivanovi?, Branka D; Maksimovi?, Vuk M; Mojovi?, Miloš D; Nikolic, Miroslav T; Vu?ini?, Zeljko B

2014-06-01

394

Characterization of new natural cellulosic fiber from Cissus quadrangularis root.  

PubMed

Fiber reinforced polymer composites are replacing many metallic structures due to its high specific strength and modulus. However commonly used man-made E-glass fibers are hazardous for health and carcinogenic by nature. Comprehensive characterization of Cissus quadrangularis root fiber such as anatomical study, chemical analysis, physical analysis, FTIR, XRD, SEM analysis and thermo gravimetric analysis are done. The results are very encouraging for its application in fiber industries, composite manufacturing, etc. Due to its light weight and the presence of high cellulose content (77.17%) with very little wax (0.14%) provide high specific strength and good bonding properties. The flaky honeycomb outer surface and low microfibril angle revealed through electron microscopy contributes for its high modulus. The thermo gravimetric analysis indicates better thermal stability of the fiber up to 230°C, which is well within the polymerization process temperature. PMID:24906775

Indran, S; Raj, R Edwin; Sreenivasan, V S

2014-09-22

395

Root Exudates from Grafted-Root Watermelon Showed a Certain Contribution in Inhibiting Fusarium oxysporum f. sp. niveum  

PubMed Central

Grafting watermelon onto bottle gourd rootstock is commonly used method to generate resistance to Fusarium oxysporum f. sp. niveum (FON), but knowledge of the effect of the root exudates of grafted watermelon on this soil-borne pathogen in rhizosphere remains limited. To investigate the root exudate profiles of the own-root bottle gourd, grafted-root watermelon and own-root watermelon, recirculating hydroponic culture system was developed to continuously trap these root exudates. Both conidial germination and growth of FON were significantly decreased in the presence of root exudates from the grafted-root watermelon compared with the own-root watermelon. HPLC analysis revealed that the composition of the root exudates released by the grafted-root watermelon differed not only from the own-root watermelon but also from the bottle gourd rootstock plants. We identified salicylic acid in all 3 root exudates, chlorogenic acid and caffeic acid in root exudates from own-root bottle gourd and grafted-root watermelon but not own-root watermelon, and abundant cinnamic acid only in own-root watermelon root exudates. The chlorogenic and caffeic acid were candidates for potentiating the enhanced resistance of the grafted watermelon to FON, therefore we tested the effects of the two compounds on the conidial germination and growth of FON. Both phenolic acids inhibited FON conidial germination and growth in a dose-dependent manner, and FON was much more susceptible to chlorogenic acid than to caffeic acid. In conclusion, the key factor in attaining the resistance to Fusarium wilt is grafting on the non-host root stock, however, the root exudates profile also showed some contribution in inhibiting FON. These results will help to better clarify the disease resistance mechanisms of grafted-root watermelon based on plant-microbe communication and will guide the improvement of strategies against Fusarium-mediated wilt of watermelon plants. PMID:23700421

Wang, Dongsheng; Mao, Jiugeng; Huang, Qiwei; Guo, Shiwei; Shen, Qirong

2013-01-01

396

Effects of Nutrient Heterogeneity and Competition on Root Architecture of Spruce Seedlings: Implications for an Essential Feature of Root Foraging  

PubMed Central

Background We have limited understanding of root foraging responses when plants were simultaneously exposed to nutrient heterogeneity and competition, and our goal was to determine whether and how plants integrate information about nutrients and neighbors in root foraging processes. Methodology/Principal Findings The experiment was conducted in split-containers, wherein half of the roots of spruce (Picea asperata) seedlings were subjected to intraspecific root competition (the vegetated half), while the other half experienced no competition (the non-vegetated half). Experimental treatments included fertilization in the vegetated half (FV), the non-vegetated half (FNV), and both compartments (F), as well as no fertilization (NF). The root architecture indicators consisted of the number of root tips over the root surface (RTRS), the length percentage of diameter-based fine root subclasses to total fine root (SRLP), and the length percentage of each root order to total fine root (ROLP). The target plants used novel root foraging behaviors under different combinations of neighboring plant and localized fertilization. In addition, the significant increase in the RTRS of 0–0.2 mm fine roots after fertilization of the vegetated half alone and its significant decrease in fertilizer was applied throughout the plant clearly showed that plant root foraging behavior was regulated by local responses coupled with systemic control mechanisms. Conclusions/Significance We measured the root foraging ability for woody plants by means of root architecture indicators constructed by the roots possessing essential nutrient uptake ability (i.e., the first three root orders), and provided new evidence that plants integrate multiple forms of environmental information, such as nutrient status and neighboring competitors, in a non-additive manner during the root foraging process. The interplay between the responses of individual root modules (repetitive root units) to localized environmental signals and the systemic control of these responses may well account for the non-additive features of the root foraging process. PMID:23762405

Nan, Hongwei; Liu, Qing; Chen, Jinsong; Cheng, Xinying; Yin, Huajun; Yin, Chunying; Zhao, Chunzhang

2013-01-01

397

Rhizoctonia damping off stem canker and root rot  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani has been reported to cause damping-off and root rot of rhododendrons and azaleas. Damping-off often includes groups of dying and dead seedlings. Decline of rooted plants in containers results from both root rot and stem necrosis below or above the soil line. Root rot is usually no...

398

Competition between plant populations with different rooting depths  

Microsoft Academic Search

The model proposed in the first paper in this series predicts that in mixtures of plant species with different rooting depths there will be an inverse correlation between the relative crowding coefficient of the deep rooting species with respect to the shallow rooting one and the frequency of the deep rooting plants. Two field experiments are reported in which this

Frank Berendse

1982-01-01

399

Root cortical burden influences drought tolerance in maize  

PubMed Central

Background and Aims Root cortical aerenchyma (RCA) increases water and nutrient acquisition by reducing the metabolic costs of soil exploration. In this study the hypothesis was tested that living cortical area (LCA; transversal root cortical area minus aerenchyma area and intercellular air space) is a better predictor of root respiration, soil exploration and, therefore, drought tolerance than RCA formation or root diameter. Methods RCA, LCA, root respiration, root length and biomass loss in response to drought were evaluated in maize (Zea mays) recombinant inbred lines grown with adequate and suboptimal irrigation in soil mesocosms. Key Results Root respiration was highly correlated with LCA. LCA was a better predictor of root respiration than either RCA or root diameter. RCA reduced respiration of large-diameter roots. Since RCA and LCA varied in different parts of the root system, the effects of RCA and LCA on root length were complex. Greater crown-root LCA was associated with reduced crown-root length relative to total root length. Reduced LCA was associated with improved drought tolerance. Conclusions The results are consistent with the hypothesis that LCA is a driver of root metabolic costs and may therefore have adaptive significance for water acquisition in drying soil. PMID:23618897

Jaramillo, Raúl E.; Nord, Eric A.; Chimungu, Joseph G.; Brown, Kathleen M.; Lynch, Jonathan P.

2013-01-01

400

Fine Root Architecture of Nine North American Trees  

Microsoft Academic Search

The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often been studied according to arbitrary size classes, e.g., all roots less than 1 or 2 mm in

Kurt S. Pregitzer; Jared L. DeForest; Andrew J. Burton; Michael F. Allen; Roger W. Ruess; Ronald L. Hendrick

2002-01-01

401

Research Paper High-throughput phenotyping technology for maize roots  

E-print Network

Research Paper High-throughput phenotyping technology for maize roots T.E. Grift a, *, J. Novais b-throughput measurement techniques allowing acquisition of phenotypical data describing maize roots. One of a maize root maize inbreds B73 and CML333. B73 and CML333 are known to have different root characteristics

402

Effect of Pectin Methylesterase Gene Expression on Pea Root Development  

Microsoft Academic Search

Expression of an inducible gene with sequences common to genes encoding pectin methylesterase (PME) was found to be tightly correlated, both spatially and temporally, with border cell separation in pea root caps. Partial inhibition of the gene's expression by antisense mRNA in transgenic pea hairy roots prevented the normal separation of root border cells from the root tip into the

Fushi Wen; Yanmin Zhu; Martha C. Hawes

1999-01-01

403

Sonic Hedgehog Signaling is Important in Tooth Root Development  

Microsoft Academic Search

Hertwig's epithelial root sheath (HERS) is important for tooth root formation, but the molecular basis for the signaling of root development remains uncertain. We hypothesized that Sonic hedgehog (Shh) signaling is involved in the HERS function, because it mediates epithelial-mesenchymal interactions during embryonic odontogenesis. We examined the gene expression patterns of Shh signaling in murine developing molar roots. Shh and

M. Nakatomi; I. Morita; K. Eto; M. S. Ota

2006-01-01

404

ROOT GROWTH: HOMOGENIZATION IN DOMAINS WITH TIME DEPENDENT PARTIAL PERFORATIONS  

E-print Network

ROOT GROWTH: HOMOGENIZATION IN DOMAINS WITH TIME DEPENDENT PARTIAL PERFORATIONS YVES CAPDEBOSCQ AND MARIYA PTASHNYK Abstract. In this article we derive a macroscopic model for root length density evolution, starting from a discrete mesh of roots, using homogenization techniques. In the microscopic model each root

Rheinisch-Westfälische Technische Hochschule Aachen (RWTH)

405

A Root Isolation Algorithm for Sparse Univariate Polynomials  

E-print Network

A Root Isolation Algorithm for Sparse Univariate Polynomials Maria Emilia Alonso Garcia root smaller or equal to d. Our target is to find for each real root of f an interval isolating this root from the others. The usual subdivision methods

Paris-Sud XI, Université de

406

Root growth inhibition by NH4 in Arabidopsis is mediated  

E-print Network

Root growth inhibition by NH4 + in Arabidopsis is mediated by the root tip and is linked to NH4 Military Trail, Toronto, Ontario, M1C 1A4, Canada ABSTRACT Root growth in higher plants is sensitive to excess ammo- nium (NH4 + ). Our study shows that contact of NH4 + with the primary root tip is both

Kronzucker, Herbert J.

407

Original article Measuring the impact of Collybiafusipes on the root  

E-print Network

Original article Measuring the impact of Collybiafusipes on the root system of oak trees Benoit - This work describes the aetiology of Collybia fusipes root rot and the impact of the parasite on the structure of mature oak root systems. The collar roots were examined and rated for C. fusipes infection

Paris-Sud XI, Université de

408

ROOT SYSTEMS AND THE QUANTUM COHOMOLOGY OF ADE RESOLUTIONS  

E-print Network

ROOT SYSTEMS AND THE QUANTUM COHOMOLOGY OF ADE RESOLUTIONS JIM BRYAN AND AMIN GHOLAMPOUR Abstract root system canonically associated to G. We generalize the resulting Frobenius manifold to non-simply laced root systems to obtain an n parameter family of algebra structures on the affine root lattice

Bryan, Jim

409

Seasonal soil–water availability influences snakeweed root dynamics  

Microsoft Academic Search

We tested a hypothesis that variable precipitation may induce altered rooting patterns. A nursery study was conducted over 2 years to evaluate the effect of seasonally variable soil moisture on the rooting pattern of shallow-rooted shrub broom snakeweed (Gutierrezia sarothrae Britt and Rusby). Plants irrigated during the spring–summer, but grown under rainout shelters in the winter (S) produced more roots

Changgui Wan; Ibrahim Yilmaz; Ronald E. Sosebee

2002-01-01

410

ROOTBOX FOR QUANTITATIVE OBSERVATIONS ON INTACT ENTIRE ROOT SYSTEMS  

EPA Science Inventory

A rootbox is described which allows observation of an intact, entire root system. oots are sandwiched against a plexiglass surface by a nylon mesh that is impermeable to roots, but permeable to water and nutrients. o quantify root growth non-destructively, roots of different size...

411

Root profile in Multi-layered Dehesas: an approach to plant-to-plant Interaction  

NASA Astrophysics Data System (ADS)

Assessing plant-to-plant relationship is a key issue in agroforestry systems. Due to the sessile feature of plants most of these interactions take place within a restricted space, so characterizing the zone where the plant alters its environment is important to find overlapping areas where the facilitation or competition could occur. Main part of plan-to-plant interactions in the dehesa are located at belowground level, thus the main limited resources in Mediterranean ecosystems are soil nutrient and water. Hence a better knowledge of rooting plant profile can be useful to understand the functioning of the dehesa. The Iberian dehesa has always been considered as a silvopastoral system where, at least, two strata of vegetation coexist: native grasses and trees. However the dehesa is also a diverse system where cropland and encroached territories have been systematically combined, more or less periodically, with native pasture in order to obtain agricultural, pastoral and forestry outputs. These multipurpose mosaic-type systems generate several scenarios where the plant influence zone may be overlapped and the interaction, competition or facilitation, between plants can play an important role in the ecosystem functioning in terms of productivity and stability. In the present study our aim was to characterize the rooting profile of multi-layered dehesas in order to understand the competitive, and/or facilitative, relationships within the different plant strata. The root profile of Quercus ilex subsp. ballota, Cistus ladanifer, Retama spaherocarpa and natural grasses was studied. So 48 trenches, up to 2 meters deep, were excavated in 4 different environments: (i) grass; (ii) tree-grass; (iii) tree-shrub and (iv) tree-shrub-grass (12 trenches in each environment). The study was carried out in 4 dehesas, 2 encroached with C. ladanifer and 2 with R. spaherocarpa. In every trench soil samples were taken each 20 cm. Subsequently, all samples were sieved using different mesh size filters in order to avoid fine root loosing. Different plant roots were separated visually. Q. ilex roots were identified by their black cork, pasture roots were white, C. ladanifer roots were dark red and R. spaherocarpa roots were yellow clear. Besides, all them exhibited a different texture. Weight, length, surface and average diameter were measured in each root sample using the WinRHIZOpro program. The results showed a clear rooting pattern, high root density in the first soil layers decreasing in depth, in all the plant strata studied. The coexistence of, at least, two plant stratas modified most of the rooting profiles. In this way, natural grasses growing alone kept 90% of root density in the first 30 cm. In R. sphaerocarpa dehesas pasture reached up to 170 cm although the root density decreased much faster than in C. ladanifer dehesas where pasture had a higher density in the overall profile, but reaching a much lower depth. The introduction of shrubs lowered highly the pasture root density. This effect was higher growing with C. ladanifer than with R. sphaerocarpa, which slightly modified the pasture rooting profile. The effect of trees in the pasture root system was less clear. Trees growing alone stored 70 % of their root density in the first 30 cm. The tree root system reached the deepest soil layer explored in all the profiles. The introduction of shrub reduced highly the tree root density in the first soil layer. This effect was higher in presence of C. ladanifer whose influence reduced 40 % of tree root density in the first soil layer; nevertheless tree root density increased in deep layers when growing with C. ladanifer while it decreased throughout the profile when growing with R. sphaerocarpa. R. sphaerocarpa root system stored less root density in the first soil layer than C. ladanifer, reaching up to 190 cm depth. The influence of the tree increased a 20% the R. sphaerocarpa root density in the first soil layers; however the rest of the profile was highly overlapped. The C. ladanifer root density decreased much faster growing alone tha

Rolo, V.; Moreno, G.

2009-04-01

412

Integration and Improvement of Geophysical Root Biomass Measurements for Determining Carbon Credits  

NASA Astrophysics Data System (ADS)

Carbon trading schemes fundamentally rely on accurate subsurface carbon quantification in order for governing bodies to grant carbon credits inclusive of root biomass (What is Carbon Credit. 2013). Root biomass makes up a large chunk of the subsurface carbon and is difficult, labor intensive, and costly to measure. This paper stitches together the latest geophysical root measurement techniques into site-dependent recommendations for technique combinations and modifications that maximize large-scale root biomass measurement accuracy and efficiency. "Accuracy" is maximized when actual root biomass is closest to measured root biomass. "Efficiency" is maximized when time, labor, and cost of measurement is minimized. Several combinations have emerged which satisfy both criteria under different site conditions. Use of ground penetrating radar (GPR) and/or electrical resistivity tomography (ERT) allow for large tracts of land to be surveyed under appropriate conditions. Among other characteristics, GPR does best with detecting coarse roots in dry soil. ERT does best in detecting roots in moist soils, but is especially limited by electrode configuration (Mancuso, S. 2012). Integration of these two technologies into a baseline protocol based on site-specific characteristics, especially soil moisture and plants species heterogeneity, will drastically theoretically increase efficiency and accuracy of root biomass measurements. Modifications of current measurement protocols using these existing techniques will also theoretically lead to drastic improvements in both accuracy and efficiency. These modifications, such as efficient 3D imaging by adding an identical electrode array perpendicular to the first array used in the Pulled Array Continuous Electrical Profiling (PACEP) technique for ERT, should allow for more widespread application of these techniques for understanding root biomass. Where whole-site measurement is not feasible either due to financial, equipment, or physical limitations, measurements from randomly selected plots must be assumed representative of the entire system and scaled up. This scaling introduces error roughly inversely proportional to the number and size of plots measured. References Mancuso, S. (2012). Measuring roots: An updated approach Springer. What is carbon credit. (2013). Retrieved 7/20, 2013, from http://carbontradexchange.com/knowledge/what-is-carbon-credit

Boitet, J. I.

2013-12-01

413

Root Throw and Sediment Transport in the Rocky Mountains of Western Canada: Field and Modelling Investigations  

NASA Astrophysics Data System (ADS)

Sediment transport associated with root throw was investigated in Kootenay National Park in southeastern British Columbia. Tree toppling and root throw may result in sediment transport, as soil associated with the root wad is upheaved in the form of a root plate, which eventually disintegrates and deposits on the ground forming a mound. Although root throw is a widely recognized process, its role as an agent of sediment transport has not been widely considered. This study provides critical field data documenting the role of episodic root throw on sediment transport at a local scale (order of magnitude approximately 1 m). We then use these data in conjunction with a forest population dynamics model to consider the contribution of root throw to larger-scale sediment routing and its temporal dynamics. A detailed field measurement program documented characteristics associated with root throw in burned and pre- fire scenarios (e.g., root plate dimensions, direction of tree fall, root wad disintegration). Sediment transport rates due to root throw are relatively low; approximately two orders-of-magnitude lower than typical creep rates defined in the literature. However, in a landscape where larger mass movements are relatively uncommon, this small transport plays a role in sediment transfers, and contributes to soil mixing and formation of microtopography. In the post-fire scenario, an increase in root throw occurred as fire-killed trees toppled in the first years following the fire. The removal of vegetation also exposed root plates to erosion, and disintegration rates increased. A tree population model is developed to simulate tree recruitment, growth, mortality, and toppling rates over time scales greater than 1000 years. In the model, fire events occur as a stochastic disturbance which kills all trees, and recruits new trees. Thus, the model cycles through forest generations with lifespan determined by fire events. The number of trees at any time interval is the net result of recruits minus the proportion that die within the time interval by either wildfire or other ecological causes e.g., competition. Tree dbh is based on tree age and age- related growth rate, with a minimum dbh required before a tree will uproot significant amounts of sediment. Root plate volume, width, height are based on dbh and calibrated using the field data. Some literature suggests that dead trees uproot significantly less sediment than live trees when they fall over, and this option can be incorporated in the model. Subsequent disintegration rates of root plates are calibrated using the field data to derive transport rates in the model. The temporal sequencing of sediment transport rates due to tree topple over millennial time scales is influenced by the tree population dynamics and the associated fire return intervals. Results of the simulations show that peaks in sediment transport occur at approximately one half and one forth of the average fire interval. The sediment transport becomes more continuous and less pulsed as the fire interval increases. Both of these effects are a result of the interaction of tree topple with fire and competition and old age.

Gallaway, J.; Martin, Y. E.; Johnson, E. A.

2007-12-01

414

The evolution of root hairs and rhizoids  

PubMed Central

Background Almost all land plants develop tip-growing filamentous cells at the interface between the plant and substrate (the soil). Root hairs form on the surface of roots of sporophytes (the multicellular diploid phase of the life cycle) in vascular plants. Rhizoids develop on the free-living gametophytes of vascular and non-vascular plants and on both gametophytes and sporophytes of the extinct rhyniophytes. Extant lycophytes (clubmosses and quillworts) and monilophytes (ferns and horsetails) develop both free-living gametophytes and free-living sporophytes. These gametophytes and sporophytes grow in close contact with the soil and develop rhizoids and root hairs, respectively. Scope Here we review the development and function of rhizoids and root hairs in extant groups of land plants. Root hairs are important for the uptake of nutrients with limited mobility in the soil such as phosphate. Rhizoids have a variety of functions including water transport and adhesion to surfaces in some mosses and liverworts. Conclusions A similar gene regulatory network controls the development of rhizoids in moss gametophytes and root hairs on the roots of vascular plant sporophytes. It is likely that this gene regulatory network first operated in the gametophyte of the earliest land plants. We propose that later it functioned in sporophytes as the diploid phase evolved a free-living habit and developed an interface with the soil. This transference of gene function from gametophyte to sporophyte could provide a mechanism that, at least in part, explains the increase in morphological diversity of sporophytes that occurred during the radiation of land plants in the Devonian Period. PMID:22730024

Jones, Victor A.S.; Dolan, Liam

2012-01-01

415

How can science education foster students' rooting?  

NASA Astrophysics Data System (ADS)

The question of how to foster rooting in science education points towards a double challenge; efforts to prevent (further) uprooting and efforts to promote rooting/re-rooting. Wolff-Michael Roth's paper discusses the uprooting/rooting pair of concepts, students' feeling of alienation and loss of fundamental sense of the earth as ground, and potential consequences for teaching science in a rooted manner. However, the argumentation raises a number of questions which I try to answer. My argumentation rests on Husserl's critique of science and the "ontological reversal", an ontological position where abstract models from science are considered as more real than the everyday reality itself, where abstract, often mathematical, models are taken to be the real causes behind everyday experiences. In this paper, measures towards an "ontological re-reversal" are discussed by drawing on experiences from phenomenon-based science education. I argue that perhaps the most direct and productive way of promoting rooting in science class is by intentionally cultivating the competencies of sensing and aesthetic experience. An aesthetic experience is defined as a precognitive, sensuous experience, an experience that is opened up for through sensuous perception. Conditions for rooting in science education is discussed against three challenges: Restoring the value of aesthetic experience, allowing time for open inquiry and coping with curriculum. Finally, I raise the question whether dimensions like "reality" or "nature" are self-evident for students. In the era of constructivism, with its focus on cognition and knowledge building, the inquiry process itself has become more important than the object of inquiry. I argue that as educators of science teachers we have to emphasize more explicitly "the nature of nature" as a field of exploration.

Østergaard, Edvin

2014-06-01

416

Potassium Transport in Corn Roots 1  

PubMed Central

The relative transport capabilities of the cells of the root periphery and cortex were investigated using a variety of experimental techniques. Brief (30 seconds to 1 minute) exposures with the penetrating sulfhydryl reagent, N-ethyl maleimide (NEM), and the impermeant reagent, p-chloromercuribenzene sulfonic acid (PCMBS), dramatically reduced 86Rb+ (0.2 millimolar RbCl) uptake into 2 centimeter corn (Zea mays [A632 × (C3640 × Oh43)]) root segments. Autoradiographic localization studies with [3H]NEM and [203Hg]PCMBS demonstrated that, during short term exposures with either reagent, sulfhydryl binding occurred almost exclusively in the cells of the root periphery. Corn root cortical protoplasts were isolated, and exhibited significant K+(86Rb+) influx. The kinetics for K+ uptake were studied; the influx isotherms were smooth, nonsaturating curves that approached linearity at higher K+(Rb+) concentrations (above 1 millimolar K+). These kinetics were identical in shape to the complex kinetics previously observed for K+ uptake in corn roots (Kochian, Lucas 1982 Plant Physiol 70: 1723-1731), and could be resolved into a saturable and a first order kinetic component. The existence of a hypodermal apoplastic barrier was investigated. The apoplastic, cell wall binding dye, Calcofluor White M2R, appeared to be excluded from the cortex by the hypodermis. However, experiments with damaged roots indicated that this result may be an artifact resulting from the binding of dye to the epidermal cell walls. Furthermore, [203Hg] PCMBS autoradiography demonstrated that the hypodermis was not a barrier to apoplastic movement of PCMBS. These results suggest that although cortical cells possess the capacity to absorb ions, K+ influx at low concentrations is limited to the root periphery. Cortical cell uptake appears to be repressed under these conditions. At higher concentrations, cortical cells may function to absorb K+. Such a model may involve regulation of cortical cell ion transport capacity. Images Fig. 3 Fig. 4 Fig. 6 PMID:16663196

Kochian, Leon V.; Lucas, William J.

1983-01-01

417

Unleashing the potential of the root hair cell as a single plant cell type model in root systems biology  

PubMed Central

Plant root is an organ composed of multiple cell types with different functions. This multicellular complexity limits our understanding of root biology because -omics studies performed at the level of the entire root reflect the average responses of all cells composing the organ. To overcome this difficulty and allow a more comprehensive understanding of root cell biology, an approach is needed that would focus on one single cell type in the plant root. Because of its biological functions (i.e., uptake of water and various nutrients; primary site of infection by nitrogen-fixing bacteria in legumes), the root hair cell is an attractive single cell model to study root cell response to various stresses and treatments. To fully study their biology, we have recently optimized procedures in obtaining root hair cell samples. We culture the plants using an ultrasound aeroponic system maximizing root hair cell density on the entire root systems and allowing the homogeneous treatment of the root system. We then isolate the root hair cells in liquid nitrogen. Isolated root hair yields could be up to 800 to 1000~mg of plant cells from 60 root systems. Using soybean as a model, the purity of the root hair was assessed by comparing the expression level of genes previously identified as soybean root hair specific between preparations of isolated root hair cells and stripped roots, roots devoid in root hairs. Enlarging our tests to include other plant species, our results support the isolation of large quantities of highly purified root hair cells which is compatible with a systems biology approach. PMID:24324480

Qiao, Zhenzhen; Libault, Marc

2013-01-01

418

Unleashing the potential of the root hair cell as a single plant cell type model in root systems biology.  

PubMed

Plant root is an organ composed of multiple cell types with different functions. This multicellular complexity limits our understanding of root biology because -omics studies performed at the level of the entire root reflect the average responses of all cells composing the organ. To overcome this difficulty and allow a more comprehensive understanding of root cell biology, an approach is needed that would focus on one single cell type in the plant root. Because of its biological functions (i.e., uptake of water and various nutrients; primary site of infection by nitrogen-fixing bacteria in legumes), the root hair cell is an attractive single cell model to study root cell response to various stresses and treatments. To fully study their biology, we have recently optimized procedures in obtaining root hair cell samples. We culture the plants using an ultrasound aeroponic system maximizing root hair cell density on the entire root systems and allowing the homogeneous treatment of the root system. We then isolate the root hair cells in liquid nitrogen. Isolated root hair yields could be up to 800 to 1000~mg of plant cells from 60 root systems. Using soybean as a model, the purity of the root hair was assessed by comparing the expression level of genes previously identified as soybean root hair specific between preparations of isolated root hair cells and stripped roots, roots devoid in root hairs. Enlarging our tests to include other plant species, our results support the isolation of large quantities of highly purified root hair cells which is compatible with a systems biology approach. PMID:24324480

Qiao, Zhenzhen; Libault, Marc

2013-01-01

419

Spatial and temporal distribution of the root system and root nutrient content of an established Miscanthus crop  

Microsoft Academic Search

Although a high biomass yield is obtained from established Miscanthus crops, previous studies have shown that fertilizer requirements are relatively low. As little information on the role of the Miscanthus roots in nutrient acquisition is available, a study was conducted to gather data on the Miscanthus root system and root nutrient content. Therefore in 1992, the root distribution pattern of

D. Neukirchen; M. Himken; J. Lammel; U. Czypionka-Krause; H.-W. Olfs

1999-01-01

420

The Mode of Origin of Root Buds and Root Sprouts in the Clonal Tree Sassafras albidum (Lauraceae)  

Microsoft Academic Search

The developmental anatomy of root buds and root sprouts was examined in the clonal tree Sassafras albidum. Root samples from 13 clones that varied widely in age and vigor were sectioned and two types of buds were found, ''additional'' buds and ''reparative'' buds. Additional buds form during the early growth of uninjured roots and they perennate by growing outwards in

Michael J. Bosela; Frank W. Ewers

1997-01-01

421

Effect of acute nerve root compression on endoneurial fluid pressure and blood flow in rat dorsal root ganglia  

Microsoft Academic Search

The objective of the current study was to test the hypothesis that crush injury to nerve root increases endoneurial fluid pressure (EFP) and decreases blood flow in the associated dorsal root ganglion (DRG). A total of 21 adult, female Sprague–Dawley rats had their left L5 nerve root and DRG exposed. The L5 nerve root was clamped for 2 s with

Tamaki Igarashi; Shoji Yabuki; Shinichi Kikuchi; Robert R. Myers

2005-01-01

422

Stored carbon partly fuels fine-root respiration but is not used for production of new fine roots  

E-print Network

Stored carbon partly fuels fine-root respiration but is not used for production of new fine roots), post-carboxylation fractionation, root respiration, root turnover, stored carbon (C), Liquidambar photosynthate, while nearly one-quarter of respired C was from a storage pool. Changes in the isotopic

423

Abstract Root respiration rates have been shown to be correlated with temperature and root N concentration in  

E-print Network

Abstract Root respiration rates have been shown to be correlated with temperature and root N. In order to test for broad, cross-species relationships, we measured fine root respiration, as O2 America in 1997. Significant differences existed among study sites in root respiration rates

Ruess, Roger W.

424

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

E-print Network

NAME: Chedella QUESTION: In patients with a nonvital asymptomatic tooth, will a singlevisit root 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

Goldman, Steven A.

425

for estimates of root production and the ca-pacity of soils to store carbon. If most root  

E-print Network

1345 for estimates of root production and the ca- pacity of soils to store carbon. If most root biomass is long-lived, the amount of plant carbon used to grow roots has been overes- timated in the past. However, if root popu- lations are skewed significantly, the rela- tionship between the mean age

von der Linde, D.

426

The importance of root gravitropism for inter-root competition and phosphorus acquisition efficiency: results from a geometric simulation model  

Microsoft Academic Search

We have observed that low soil phosphorus availability alters the gravitropic response of basal roots in common bean (Phaseolus vulgaris L.), resulting in a shallower root system. In this study we use a geometric model to test the hypotheses that a shallower\\u000a root system is a positive adaptive response to low soil P availability by (1) concentrating root foraging in

Zhenyang Ge; Gerardo Rubio; Jonathan P Lynch

2000-01-01

427

Rooting of clematis microshoots and stem cuttings in different substrates  

Microsoft Academic Search

Microshoots and softwood stem cuttings of five clematis varieties (Clematis section Atragene) were rooted in different substrates (perlite, peat–perlite, and sand–perlite). Microshoots rooted better and quicker than stem cuttings, independent of the substrate. Root dry mass of microshoots was more than twice as high compared to root dry mass of stem cuttings.For microshoots, number of primary roots was highest in

Silja Kreen; Margaret Svensson; Kimmo Rumpunen

2002-01-01

428

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength  

PubMed Central

Objective To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. Results The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario. PMID:25025556

RIPPE, Marília Pivetta; SANTINI, Manuela Favarin; BIER, Carlos Alexandre Souza; BALDISSARA, Paolo; VALANDRO, Luiz Felipe

2014-01-01

429

Viewing Polynomial Roots With Matrix Eyes: Part 1: Irrational Roots via Matrix Dynamics  

E-print Network

1 Viewing Polynomial Roots With Matrix Eyes: Part 1: Irrational Roots via Matrix Dynamics Part 2 that converges to 0 #12;8 Dynamical View · Consider the orbits under repeated application of A starting from entries · Orbits from lattice points all converge to the line L · Let v be any integer vector. Let vn = A

Kalman, Dan

430

Response of grape root borer (lepidoptera: sesiidae) neonates to root extracts from vitaceae species and rootstocks  

Technology Transfer Automated Retrieval System (TEKTRAN)

Observations at regular intervals of the location of newly hatched grape root borer larvae moving freely within Petri dish bioassays were used to measure and compare their response to filter paper discs treated with ethanol- and hexane-based extracts of roots from known and potential Vitaceae hosts ...

431

Identification of coniferous fine roots to species using ribosomal PCR products of pooled root samples  

EPA Science Inventory

Background/Question/Methods To inform an individual-based forest stand model emphasizing belowground competition, we explored the potential of using the relative abundances of ribosomal PCR products from pooled and milled roots, to allocate total root biomass to each of the thre...

432

Reactive Oxygen Species and Root Hairs in Arabidopsis Root Response to Nitrogen, Phosphorus and Potassium Deficiency  

Microsoft Academic Search

; Plant root sensing and adaptation to changes in the nutrient status of soils is vital for long-term productivity and growth. Reactive oxygen species (ROS) have been shown to play a role in root response to potassium depriva- tion. To determine the role of ROS in plant response to nitrogen and phosphorus deficiency, studies were con- ducted using wild-type Arabidopsis

Ryoung Shin; R. Howard Berg; Daniel P. Schachtman

2005-01-01

433

Cortical cell death during lateral root formation.  

PubMed

Root segments of Convolvulus arvensis, the field bindweed, were examined with the electron microscope to make possible a description of the fine structural correlates of lateral root protrusion through cortical parenchyma. Particular attention was directed to the outermost primordium cells, derived by meristematic activity from the endodermis, and to the contiguous cortical parenchyma cells. By following the fate of the Casparian strip through numerous divisions of the endodermal cell, information has been obtained relating to the minimum contribution of the endodermis to the root primordium structure. Cortical parenchyma cells during lateral root growth are specifically degraded so that only the cell wall remains. A layer of cell wall material, representing numerous cortical parenchyma cells, accrues at the tip of the advancing root primordium. It is suggested that the intensive coated-vesicle activity along the plasmalemma of the outermost primordium cell and the appearance of the vesicle contents in the outer wall of this cell are indicative of the secretion of hydrolases which move through the wall and attack the adjacent cortical parenchyma cells. PMID:5782442

Bonnett, H T

1969-01-01