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Subject: Plant Physiology × Author: Preety Rani × End date: 2020 × Start date: 2020 ×
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    ThesisItemOpen Access
    Physiological responses of various biostimulants in Vigna unguiculata L. under rainfed condition
    (CCSHAU,HiSAR, 2020-09) Preety Rani; Sarita Devi
    The present investigation entitled ―Physiological responses of various bio-stimulants in Vigna unguiculata L. under rainfed condition‖ was studied during the summer season of 2019. Seeds of cowpea genotype (CS-88) were procured from Forage Section, Department of Genetics and Plant Breeding, CCS HAU, Hisar. Experiment was conducted at Dry land Research Farm, Forage Section under rainfed conditions. Bio-stimulants were applied exogenously at flower initiation stage. Sampling was done after 10 day of foliar spray at flower initiation stage. The physiological parameters in cowpea plant like water relation, gaseous exchange studies, chlorophyll stability index, chlorophyll content (SPAD units) and photochemical quantum yield showed declining trend in rainfed condition. But with the imposition of different bio-stimulants at flower initiation stage, values of physiological parameters found to be increased. Values ranged from control to biostimulant application in osmotic potential (-MPa) (-1.24 to -1.09), RWC (%) (72.7 - 88.7), assimilation rate (23.31 - 29.73 μmol CO2 m-2 s-1), transpiration rate (1.70 - 2.07 mmol H2O m-2 s-1) and stomatal conductance (0.02 - 0.03 mmol H2O m-2 s-1). Similarly, chlorophyll content (SPAD units) and photochemical quantum yield also showed the increasing trend after foliar application of different biostimulants and the values varied from (41.0 - 51.4) and (0.678 - 0.718), respectively. Reversibly, relative stress injury was found to be decreased from control (35.51) to biostimulants application (20.58) in cowpea under moisture stress. Specific activity of antioxidative enzymes and osmolytes enhanced under moisture stress and further increased rapidly after imposition of different biostimulants at flower initiation stage. The value of antioxidative enzymes and biochemical parameters ranges from SOD (130.4 - 165.9 units mg-1 protein min-1), CAT (0.38 - 1.18 units mg-1 protein min-1), POX (0.71 - 1.40 units mg-1 protein min-1), proline (131.4 - 381.9 μg g-1 DW) and glycine betaine (144.0 - 424.2 μmol g-1 DW) over their respective control. Yield and yield attributes reduced significantly under drought stress i.e. seed yield per plant, 100 seed weight and harvest index, but after the foliar application of different biostimulants the yield parameters were found to be increased. The value of seed yield per plant was varied from (0.92 - 1.64 g). Conclusively, based on the above studies it could be concluded that after foliar spray of different biostimulants under rainfed condition, cowpea performed better by maintaining higher plant water status, photosynthetic rate, antioxidant defence system, seed yield and lower values of RSI (%). Biostimulants treatments not only ameliorate the effect of moisture stress on plants, but also showed a stimulating effect. Application of 2 % complex N, P, K was found more effective which was at par with SA 100 ppm spray at flower initiation than others biostimulants in cowpea.