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ThesisItem Embargo Residue mulch, tillage and irrigation effects on crop and water productivity of pigeonpea-wheat cropping system(Punjab Agricultural University, 2022) Satinder Singh; K.B. SinghA two-year field experiment on effect of variable irrigation regimes, crop residue mulch and tillage treatments on pigen pea was conducted in loamy sand and sandy loam soil at research farm of Department of Soil Science. The treatments were combination of three irrigation regimes of 0, 0.2 and 0.4 (based on IW/ Pan-E ratios) in main plots, tillage practises (conventional (CT) and deep tillage (DT)) and two rice straw mulch rates (0 and 6 t ha-1) in sub plots. Irrigation regime I2, Soil temperature recorded under I2 was lower than I1 and I0 irrigation regime. Rice straw mulch and CT reduced soil temperature at 0.5 m depth during both years. Frequent irrigation (I2) with mulching recorded higher periodic soil moisture content and storage than limited irrigation regimes without mulch. Leaf water potential, relative leaf water content, soil plant analysis development (SPAD), normalized difference vegetation index (NDVI), leaf area index (LAI) , periodic biomass and plant height were significantly higher in I2 compared to I1 and I0, in DT compared to CT and in mulching compared to no mulch. With I2, DT and mulching significantly higher pigeon pea grain and stover yield were recorded as compared to I1 and I0, CT and no mulch. In grain and stover yield significant intercations were observed between irrigation x mulch, tillage x mulch and irrigation x tillage x mulch. The residual effect of different treatments imposed in pigeon pea on yield and yield attributing of wheat were non significant. The simulated seasonal water balance in pigeon pea was in proximate agreement with observed values for irrigation regimes, tillage and mulching treatments. Good coefficient of determination between simulated and predicted values of LAI, biomass and evapotranspiration indicated that the DSSAT (CROPGRO) model simulations were satisfactory.ThesisItem Restricted Allelic diversity of alpha amylase genes in relation to heat stress tolerance in wheat (Triticum aestivum L.)(Punjab Agricultural University, Ludhiana, 2021) Satinder Singh; Saini, Johar SinghWheat is one of the most important cereal cultivated across the world that forms the staple food of many communities in one way or another. Heat stresses associated with climate change scenarios and increased greenhouse gases, particularly CO2, delimit the genotypic potential of wheat cultivars. Alpha amylase is one of the key enzymes involved in starch metabolism at germination. Therefore, a panel of 96 wheat genotypes was screened for diversity of alpha amylase gene copies and response to heat stress under in vitro and in vivo conditions. In vitro screening based on germination percentage, coleoptile length, root length, coleoptile weight, root weight, speed of germination and seed vigour index 1 & 2 at different temperature treatments were used to scrutinize the genotypes for their stress tolerance. KSG1172, KSG0243 and KSG1214 were the best entries for seed vigour and thus show promise for early heat stress tolerance. SNP genotyping was used to construct a diversity based phylogenetic tree of the genotypes. The 96 genotypes were classified into three broad groups based on diversity in alpha amylase gene copies using UPGMA. Association analysis allowed identification of different gene copies under normal and heat stress conditions. Significant genotypic variations for germination, seedling vigour and yield characters under early, normal and late sown conditions were observed. Genotypes KSG0296 and KSG0025 were the best genotypes performing good in both early and late temperature stress as well as maintaining good germination percentage under elevated temperatures.
