The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Andrew N. Tyler - One of the best experts on this subject based on the ideXlab platform.
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Estimation of maize properties and differentiating moisture and Nitrogen Deficiency stress via ground - Based remotely sensed data
Agricultural Water Management, 2020Co-Authors: A. H. Elmetwalli, Andrew N. TylerAbstract:Abstract Moisture and Nitrogen Deficiency are major determinant factors for cereal production in arid and semi arid environments. The ability to detect stress in crops at an early stage is crucially important if significant reductions in yield are to be averted. In this context, remotely sensed data has the possibility of providing a rapid and accurate tool for site specific management in cereal crop production. This research examined the potential of hyperspectral and broad band remote sensing for predicting maize properties under Nitrogen and moisture induced stress. Spectra were collected from drip irrigated maize subjected to various rates of irrigation regimes and Nitrogen fertilization. 60 spectral vegetation indices were derived and examined to predict maize yield and other properties. Highly significant correlations between maize crop properties and various vegetation indices were noticed. RVI and NDVI were found to be sensitive to maize grain yield in both tested seasons. Cred edge demonstrated the strongest significant correlations with maize yield. The correlations with grain yield were found to be strongest at the flowering stage. Penalized linear discriminant analysis (PLDA) showed the possibility to distinguish moisture and Nitrogen Deficiency stress spectrally. The implications of this work for the use of satellite based remote sensing in arid zone precision agriculture are discussed.
A. H. Elmetwalli - One of the best experts on this subject based on the ideXlab platform.
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Estimation of maize properties and differentiating moisture and Nitrogen Deficiency stress via ground - Based remotely sensed data
Agricultural Water Management, 2020Co-Authors: A. H. Elmetwalli, Andrew N. TylerAbstract:Abstract Moisture and Nitrogen Deficiency are major determinant factors for cereal production in arid and semi arid environments. The ability to detect stress in crops at an early stage is crucially important if significant reductions in yield are to be averted. In this context, remotely sensed data has the possibility of providing a rapid and accurate tool for site specific management in cereal crop production. This research examined the potential of hyperspectral and broad band remote sensing for predicting maize properties under Nitrogen and moisture induced stress. Spectra were collected from drip irrigated maize subjected to various rates of irrigation regimes and Nitrogen fertilization. 60 spectral vegetation indices were derived and examined to predict maize yield and other properties. Highly significant correlations between maize crop properties and various vegetation indices were noticed. RVI and NDVI were found to be sensitive to maize grain yield in both tested seasons. Cred edge demonstrated the strongest significant correlations with maize yield. The correlations with grain yield were found to be strongest at the flowering stage. Penalized linear discriminant analysis (PLDA) showed the possibility to distinguish moisture and Nitrogen Deficiency stress spectrally. The implications of this work for the use of satellite based remote sensing in arid zone precision agriculture are discussed.
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THE POTENTIAL OF REMOTELY SENSED DATA TO PREDICT WHEAT YIELD UNDER MOISTURE AND Nitrogen Deficiency STRESS
Misr Journal of Agricultural Engineering, 2010Co-Authors: A. H. ElmetwalliAbstract:Moisture and Nitrogen Deficiency are major limiting factors for cereal production in many regions worldwide. Detecting stress in crops at an early growth stage is important if significant reductions in yield are to be averted. In this context, remote sensing has the potential of providing a rapid and accurate tool for precision farming in cereal production. This research was undertaken to investigate the potential of broad band and hyperspectral remote sensing for predicting grain yield of wheat (Triticum aestivum L.) under moisture and Nitrogen Deficiency stress. A controlled greenhouse experiment was conducted to (i) investigate the influence of moisture and Nitrogen induced stress on wheat and the resulting spectral reflectance characteristics at the leaf and canopy scale (ii) assess the effectiveness of different vegetation indices to predict wheat grain yield and (iii) assess the possibility of distinguishing between moisture and Nitrogen Deficiency stressors. Strong significant correlations between crop grain yield and some vegetation indices were observed. Ratio Vegetation Index (RVI) and Simple Ratio (SR) were found to be sensitive to wheat grain yield (r > 0.80). The correlations with grain yield were found to be strongest at the grain filling stage. Principle Component Analysis (PCA) demonstrated low ability to distinguish between moisture and Nitrogen Deficiency stress.
Weizhou Chen - One of the best experts on this subject based on the ideXlab platform.
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Physiological effects of Nitrogen Deficiency and recovery on the macroalga Gracilariopsis lemaneiformis (Rhodophyta).
Journal of phycology, 2019Co-Authors: Xiaojuan Liu, Jinyan Wen, Weizhou ChenAbstract:Algal metabolites are the most promising feedstocks for bio-energy production. Gracilariopsis lemaneiformis seems to be a good candidate red alga for polysaccharide production, especially relating to the agar production industry. Nitrogen Deficiency is an efficient environmental pressure used to increase the accumulation of metabolites in algae. However, there are no studies on the physiological effects of G. lemaneiformis in response to Nitrogen Deficiency and its subsequent recovery. Here we integrated physiological data with molecular studies to explore the response strategy of G. lemaneiformis under Nitrogen Deficiency and recovery. Physiological measurements indicated that amino acids and protein biosynthesis were decreased, while endogenous NH4 + and soluble polysaccharides levels were increased under Nitrogen stress. The expression of key genes involved in these pathways further suggested that G. lemaneiformis responded to Nitrogen stress through up-regulation or down-regulation of genes related to Nitrogen metabolism, and increased levels of endogenous NH4 + to complement the Deficiency of exogenous Nitrogen. Consistent with the highest accumulation of soluble polysaccharides, the gene encoding UDP-glucose pyrophosphorylase, a molecular marker used to evaluate agar content, was dramatically up-regulated more than 4-fold compared to the relative expression of actin after 4 d of Nitrogen recovery. The present data provide important information on the mechanisms of nutrient balance in macroalgae.
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The impact of Nitrogen Deficiency and subsequent recovery on the photosynthetic performance of the red macroalga Gracilariopsis lemaneiformis
Journal of Applied Phycology, 2019Co-Authors: Xiaojuan Liu, Jinyan Wen, Canqi Zheng, Haojie Jia, Weizhou ChenAbstract:The effect of Nitrogen Deficiency and subsequent recovery on photosynthetic performance of the red macroalga Gracilariopsis lemaneiformis was measured in terms of algal growth rate, accumulation of photosynthetic pigments (i.e., phycoerythrin and chlorophyll-a), maximum effective quantum yield of photosystem II (Fv/Fm), and the transcript levels of genes related to photosynthesis and photorespiration. Nitrogen Deficiency and then recovery notably promoted the growth of G. lemaneiformis, significantly inhibited the accumulation of phycoerythrin and chlorophyll-a, but had no significant influence on Fv/Fm. In addition to physiological performance of algae under Nitrogen stress, the key genes encoding photorespiratory and photosynthetic enzymes (i.e., gdct, gdcp, hpr, shmt, sgat, sbp, and rub) were up-regulated which might have led to more increased in growth rate than that of control after the recovery of Nitrogen. While the down-regulation of gdct, gdcp, and shmt genes at the 4th day of Nitrogen Deficiency might be linked to the reduced accumulation of phycoerythrin and chlorophyll-a, the up-regulation of gdct and gdcp at the beginning of Nitrogen Deficiency and Nitrogen recovery might associate with Fv/Fm that did not change significantly. Briefly, the up- and down-regulation of these genes at different times might be due to an algal complex regulatory mechanism. Thus, the combined action of these genes allows the algae to display higher photosynthetic efficiency and better growth, eventually acclimate to the varying environmental stresses. The data provided here represent a rich source for exploring the function of genes related to photorespiration and photosynthesis as well as the mechanism of algal acclimation under environmental stress.
Hans Schnyder - One of the best experts on this subject based on the ideXlab platform.
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Nitrogen Deficiency increases the residence time of respiratory carbon in the respiratory substrate supply system of perennial ryegrass.
Plant cell & environment, 2009Co-Authors: Christoph A. Lehmeier, Fernando A. Lattanzi, Rudi Schäufele, Hans SchnyderAbstract:Plant respiration draws on substrate pools of different functional/biochemical identity. Little is known about the effect of Nitrogen Deficiency on those pools' sizes, half-lives and relative contribution to respiration, and consequently, of carbon residence time in respiratory metabolism. Here we studied how Nitrogen fertilization affects the respiratory carbon supply system of shoots and roots of Lolium perenne, a perennial grass. Plants grown at two Nitrogen supply levels in continuous light were labelled with (13)CO(2)/(12)CO(2) for intervals ranging from 1 h to 1 month. The rate and isotopic composition of shoot, root and plant respiration were measured, and the time-courses of tracer incorporation into respired CO(2) were analysed by compartmental modelling. Nitrogen Deficiency reduced specific respiration rate by 30%, but increased the size of the respiratory supply system by 30%. In consequence, mean residence time of respiratory carbon increased with Nitrogen Deficiency (4.6 d at high Nitrogen and 9.2 d at low Nitrogen supply). To a large extent, this was due to a greater involvement of stores with a long half-life in respiratory carbon metabolism of Nitrogen-deficient plants. At both Nitrogen supply levels, stores supplying root respiration were primarily located in the shoot, probably in the form of fructans.
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Nitrogen Deficiency inhibits leaf blade growth in Lolium perenne by increasing cell cycle duration and decreasing mitotic and post‐mitotic growth rates
Plant cell & environment, 2008Co-Authors: Monika Kavanová, Fernando A. Lattanzi, Hans SchnyderAbstract:Nitrogen Deficiency severely inhibits leaf growth. This response was analysed at the cellular level by growing Lolium perenne L. under 7.5 mm (high) or 1 mm (low) nitrate supply, and performing a kinematic analysis to assess the effect of Nitrogen status on cell proliferation and cell growth in the leaf blade epidermis. Low Nitrogen supply reduced leaf elongation rate (LER) by 43% through a similar decrease in the cell production rate and final cell length. The former was entirely because of a decreased average cell division rate (0.023 versus 0.032 h−1) and thus longer cell cycle duration (30 versus 22 h). Nitrogen status did not affect the number of division cycles of the initial cell's progeny (5.7), and accordingly the meristematic cell number (53). Meristematic cell length was unaffected by Nitrogen Deficiency, implying that the division and mitotic growth rates were equally impaired. The shorter mature cell length arose from a considerably reduced post-mitotic growth rate (0.033 versus 0.049 h−1). But, Nitrogen stress did not affect the position where elongation stopped, and increased cell elongation duration. In conclusion, Nitrogen Deficiency limited leaf growth by increasing the cell cycle duration and decreasing mitotic and post-mitotic elongation rates, delaying cell maturation.
Xiaojuan Liu - One of the best experts on this subject based on the ideXlab platform.
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Physiological effects of Nitrogen Deficiency and recovery on the macroalga Gracilariopsis lemaneiformis (Rhodophyta).
Journal of phycology, 2019Co-Authors: Xiaojuan Liu, Jinyan Wen, Weizhou ChenAbstract:Algal metabolites are the most promising feedstocks for bio-energy production. Gracilariopsis lemaneiformis seems to be a good candidate red alga for polysaccharide production, especially relating to the agar production industry. Nitrogen Deficiency is an efficient environmental pressure used to increase the accumulation of metabolites in algae. However, there are no studies on the physiological effects of G. lemaneiformis in response to Nitrogen Deficiency and its subsequent recovery. Here we integrated physiological data with molecular studies to explore the response strategy of G. lemaneiformis under Nitrogen Deficiency and recovery. Physiological measurements indicated that amino acids and protein biosynthesis were decreased, while endogenous NH4 + and soluble polysaccharides levels were increased under Nitrogen stress. The expression of key genes involved in these pathways further suggested that G. lemaneiformis responded to Nitrogen stress through up-regulation or down-regulation of genes related to Nitrogen metabolism, and increased levels of endogenous NH4 + to complement the Deficiency of exogenous Nitrogen. Consistent with the highest accumulation of soluble polysaccharides, the gene encoding UDP-glucose pyrophosphorylase, a molecular marker used to evaluate agar content, was dramatically up-regulated more than 4-fold compared to the relative expression of actin after 4 d of Nitrogen recovery. The present data provide important information on the mechanisms of nutrient balance in macroalgae.
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The impact of Nitrogen Deficiency and subsequent recovery on the photosynthetic performance of the red macroalga Gracilariopsis lemaneiformis
Journal of Applied Phycology, 2019Co-Authors: Xiaojuan Liu, Jinyan Wen, Canqi Zheng, Haojie Jia, Weizhou ChenAbstract:The effect of Nitrogen Deficiency and subsequent recovery on photosynthetic performance of the red macroalga Gracilariopsis lemaneiformis was measured in terms of algal growth rate, accumulation of photosynthetic pigments (i.e., phycoerythrin and chlorophyll-a), maximum effective quantum yield of photosystem II (Fv/Fm), and the transcript levels of genes related to photosynthesis and photorespiration. Nitrogen Deficiency and then recovery notably promoted the growth of G. lemaneiformis, significantly inhibited the accumulation of phycoerythrin and chlorophyll-a, but had no significant influence on Fv/Fm. In addition to physiological performance of algae under Nitrogen stress, the key genes encoding photorespiratory and photosynthetic enzymes (i.e., gdct, gdcp, hpr, shmt, sgat, sbp, and rub) were up-regulated which might have led to more increased in growth rate than that of control after the recovery of Nitrogen. While the down-regulation of gdct, gdcp, and shmt genes at the 4th day of Nitrogen Deficiency might be linked to the reduced accumulation of phycoerythrin and chlorophyll-a, the up-regulation of gdct and gdcp at the beginning of Nitrogen Deficiency and Nitrogen recovery might associate with Fv/Fm that did not change significantly. Briefly, the up- and down-regulation of these genes at different times might be due to an algal complex regulatory mechanism. Thus, the combined action of these genes allows the algae to display higher photosynthetic efficiency and better growth, eventually acclimate to the varying environmental stresses. The data provided here represent a rich source for exploring the function of genes related to photorespiration and photosynthesis as well as the mechanism of algal acclimation under environmental stress.