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ThesisItem Open Access Growth and development of wheat (Triticum aestivum L.) genotypes as affected by drought stress and PGRs(Punjab Agricultural University, Ludhiana, 2017) Aparjot Kaur; Thind, S.K.The most important challenge in production of most of the crops including wheat (Triticum aestivum L.) is drought stress. Presently, growth and development of wheat genotypes (HD2967, PBW660, WH1105 and PBW658) as effected by drought stress and plant growth regulators like cytokinins [Kinetin (Kn) and Benzyl adenine (BA)] on various morpho-physiological and biochemical parameters under the lab conditions were studied to select the best concentration of Kn (@ 10, 20 and 40mg/L) and BA (@ 25 and 50mg/L). Drought stress in laboratory was induced by PEG-6000 creating -0.4MPa of stress. Under laboratory conditions, Kn@40mg/L and BA@50mg/L was performed better as compared to lower concentrations of Kn and BA tested and these were studied in combination with osmoprotectants like [Trehalose (Tre) and Glycine Betaine (GB)] in different combinations like Kn@40mg/L along with Tre@1mM, Kn@40mg/L along with Tre@ 1.5mM, BA @50mg/L along with Tre@1mM, BA @50mg/L along with Tre @ 1.5mM, Kn@40mg/L along with GB 50mM, Kn@40mg/L along with GB100mM, BA @50mg/L along with GB 50mM, BA @50mg/L along with GB 100mM in the field experiments on three wheat genotypes (HD2967, PBW660 and WH1105. Drought stress significantly reduced various morpho-physiological parameters like Relative Growth rate (RGR), Specific leaf area (SLA), Relative leaf water content (RLWC) and photosynthetic gas exchange parameters like net photosynthetic rate (NPR), transpiration rate (TR), stomatal conductance (SC) and intercellular CO2 concentration (ICC) at vegetative as well as flag leaf stage. Cytokinins along with different concentrations of osmoprotectants significantly decreased the negative effect of drought stress on various morpho-physiological parameters. Significant negative effect of drought stress was studied on biochemical parameters like Hill reaction activity, MDA content, membrane stability and cell viability. Drought stress significantly increased the photosynthetic pigments like chlorophyll and carotenoid content. Drought stress significantly increased the total soluble sugars, reducing sugars and decreased the non-reducing sugars. Enzymatic activities of various antioxidants like SOD, catalase, APx, DHAR and MDHAR were increased significantly under drought stress. Nonenzymatic ROS were alleviated significantly under drought stress and by application of cytokinins in combination with osmoprotectants. Under drought stress a significant reduction in yield contributing parameters like number of kernels per spike, number of productive tillers/m2, peduncle extrusion, thousand grain weight, grain yield/m2, biological yield/m2 and harvest index was recorded. Cytokinins in combination with different concentrations of osmoprotectants significantly ameliorated the negative effect of drought stress. From among the tested combinations, Kn@40mg/L in combination with Tre@ 1.5mM had more pronounced effect in ameliorating the adverse effect of drought stress on yield contributing parameters of selected wheat genotypes.