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2010 - 20143
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Subject: Botany × Author: Sanghera, Amritpal Kaur × End date: 2019 × Start date: 2010 × Type: Thesis ×
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    ThesisItemOpen Access
    Nitrogen Metabolism of Wheat Genotypes in Relation to Heat Stress Tolerance
    (PAU, 2014) Sanghera, Amritpal Kaur; Thind, S.K.
    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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    ThesisItemOpen Access
    SCREENING AND CHARACTERIZATION OF PHYSIOLOGICAL TRAITS IN WHEAT VARIETIES FOR NITROGEN EFFICIENCY
    (Punjab Agricultural University, Ludhiana, 2010) Sanghera, Amritpal Kaur
    A field experiment was conducted at the research farm of Department of Soils Punjab Agricultural University, Ludhiana with an objective to screen wheat cultivars (cvs) for N efficiency and determine the physiological traits for N efficiency. Fifteen wheat cvs (10 bread wheat, 3 durum wheat and 2 triticale genotypes) were grown on soil low in available N at four levels of fertilizer N (0, 50, 100 and 150 N kg ha-1). On the basis of grain yield, N uptake efficiency (NupE), Biomass N utilization efficiency (BNutE) and Grain N utilization efficiency (GNutE), three bread wheats (PBW 509, PBW 502, PBW 343) were selected as efficient and three durum wheats (PDW 274, PDW 291 and PDW 233) as inefficient cultivars. Efficient cultivars had significantly higher grain yield, NupE and GNutE while BNutE was more in inefficient cvs. Grain yield had significant positive correlation (r = 0.973) with NupE. Normalized difference vegetative index at different stages was significantly higher in efficient cultivars and had positive correlation with grain yield both at low and high N. Root distribution in the profile indicated that roots of efficient cvs penetrated into deeper layers compared to inefficient cvs which had denser root system but only in the surface layers. Nitrate reductase activity had a negative correlation with grain yield (r = -0.93) and NupE (r = -0.92) but positive correlation with BNutE (r = 0.73), suggesting that this enzyme cannot be used as index of N efficiency in wheat genotypes. Efficient cultivars had higher number of leaves and tillers, total N uptake and dry matter production than inefficient cvs. Grain yield and GNutE had positive correlation with N partitioning in grain (r = 0.75) but negative correlation with N partitioning in leaves (r = -0.77) and chaff (r = -0.76) under low N indicating that N mobilization from leaves and chaff to the grain limited grain yield and GNutE. Our study indicates the possibility of genetic modification for deeper rooting to increased N uptake, vegetative growth, biomass and grain production. Early flowering genotypes with grain filling period coinciding with favourable temperature are another characteristic of wheat development related to N efficiency.
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    ThesisItemOpen Access
    Nitrogen metabolism of wheat genotypes in relation to heat stress tolerance
    (Punjab Agricultural University, Ludhiana, 2014) Sanghera, Amritpal Kaur; Thind, S. K.
    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.