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20202
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Subject: Plant Physiology × End date: 2020 × Start date: 2020 × Type: Thesis × Thesis Type: M.Sc ×
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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.
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    ThesisItemOpen Access
    Response of Orthosilicic Acid and Seaweed Extract for Mitigation in Brassica juncea
    (CCSHAU,HiSAR, 2020-08) Sujata; Goyal, Vinod
    The present study entitled “Response of Orthosilicic acid and seaweed extract for drought mitigation in Brassica juncea” was conducted at Field Crop Research Area of Oilseeds Section, Department of Genetics & Plant Breeding. Foliar application of biostimulants viz. Orthosilicic acid (2ml/L & 4ml/L), Seaweed extract (3ml/L & 4ml/L) and water spray were done two times at 25-30 DAS and 40-45DAS in two environments i.e., irrigated and rain fed in Brassica variety RH 725. Sampling was done after 5 days of second application of biostimulants. Foliar application of OSA & Seaweed had a positive impact on the physiological processes of the crop under normal and stress conditions, however they help to minimize the degree of stress impact over normal conditions. At sowing time 13.6% soil moisture content was observed which was reduced to (4.8%) at the time of harvesting in upper layer of the soil (0-30 cm). The data was recorded for Growth, physiological, biochemical and yield parameters, which had a positive impact on application of orthosilicic acid and seaweed extract under rainfed conditions. Physiological parameters like photosynthetic rate, transpiration rate, stomatal conductance, relative water content, chlorophyll fluorescence, chlorophyll stability index decrease significantly but this reduction was reduced by foliar application of OSA and seaweed extract in both environments. The percent decrease was minimum with treatment of 2ml/L OSA tracked by 3ml/L seaweed extract treated plants. The percent reduction recorded for photosynthesis rate (18.0% & 18.70%), transpiration rate (31.31% & 29.62%), RWC (12.30% & 14.03%) and water potential (17.39% & 18.31%) in 2ml/L OSA and 3ml/L seaweed extract treated plants respectively. These results were supported with the biochemical results viz. H2O2, MDA, RSI, proline, glycine betaine content that decreased in treated plants as compared to their respective controls. Total soluble sugars, total soluble protein and antioxidant enzyme activities like SOD, CAT, APX increased after applying orthosilic acid and seaweed extract which may be the contributing factors for yield increment. Seed yield along with plant height, number of siliqua, seeds per siliqua, 1000seed weight and biological yield decreases due to unavailability of water in the soil under normal conditions. As compared to control ones, plants treated with orthosilicic acid and seaweed extract significantly increased the yield and its attributes like plant height, 1000seed weight, number of siliqua per plant, seeds per siliqua. Minimum reduction in yield was reported in 2ml/L OSA and then in 3ml/L seaweed extract. Seed yield was reduced by 17.34% in control plants and by application of OSA (2ml/L) and seaweed extract (3ml/L) this effect was lowered to 10.22% and 13.30%. Drought susceptibility index was calculated to see the overall effect of treatments and it was found minimum in 2ml/L OSA treated plants, showing its superiority over other treatments. From our results, it is concluded that twice foliar application of 2ml/L of OSA at vegetative stage results into higher yields, with better physiological efficiencies as this concentration maintains best plant water relations and source to sink strength which is self explanatory in our results.