Nitrogen metabolism of wheat genotypes in relation to heat stress tolerance
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Date
2014
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Punjab Agricultural University, Ludhiana
Abstract
In present study a set of wheat genotypes (40) have been evaluated for their potential to withstand heat stress. For this one laboratory experiment, two periodic field experiments (2011-12 and 2012 -13) with normal sowing (November 29) and late sowing (December 29) and a pot experiment (2013-14) were conducted. The cell membrane thermo stability supported lesser lipid peroxidation (MDA) and minimal changes in mitochondrial activity (TTC) of heat tolerant genotypes which ultimately increased the survival potential under laboratory conditions after heat stress (35 and 40±2°C). Delay in sowing date caused significant decrease in several physiological parameters viz., nitrogen use efficiency and grain growth and yield parameters. Nitrogen uptake efficiency (NupE), grain nitrogen utilization efficiency (GNutE), nitrogen remobilization efficiency (NRE) was significantly higher in timely sown and biomass nitrogen utilization efficiency (BNutE) was higher in late sown genotypes. Grain yield had positive correlation with NupE, GNutE, NRE and N partitioning in grain but negative correlation with BNutE, N partitioning in leaves and chaff indicating that N mobilization from leaves and chaff to the grain limited grain yield and GNutE. A significant increase in seed protein content and sedimentation value and the decrease in grain yield, biomass yield, plant height, harvest index, grain filling period, grain hardness and moisture content was recorded under the late sown conditions. Under the pot conditions relatively higher proline content, total amino acids, quaternary ammonium compounds and ascorbate content was recorded in heat stressed plants as compared to control. Yield contributing parameters (grain yield, grain weight plant-1, number of grain plant-1) showed significant reduction under heat stress. The genotypes G3, G4, G6, G7, G9, G10, G31 and G32 had sustained yield contributing parameters under heat stress better as compared with others.
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Keywords
Botany, wheat genotypes, Biotechnology, N efficiency, Nitrogen metabolism