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20191
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Subject: Plant Physiology × Author: Preeti × Start date: 2000 ×
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    ThesisItemOpen Access
    Role of salicylic acid to ameliorate the effect of salt stress in chickpea (Cicer arietinum L.)
    (CCSHAU, 2019) Preeti; Neeraj Kumar
    The present investigation entitled “Role of salicylic acid to ameliorate the effect of salt stress in chickpea (Cicer arietinum L.)” was investigated in the screen house during the Rabi season of 2018. Before sowing, the desired levels of salinity (control, 4 and 6 dS m-1) were developed by saturating each pot. Salicylic acid (25, 50, 75 and 100 ppm) was applied exogenously after 35 and 70 days after sowing (DAS) under stressed as well as non- stressed plants. Plants at 6 dS m-1 did not survive and hence, data of only 4 dS m-1 was given. Sampling was done at 45 and 80 DAS. Growth parameters i.e. plant height and dry weight of shoot and roots decreased with increasing levels of salinity, whereas foliar application of salicylic acid enhanced the growth of plants at both stages. Similarly, the water potential (ψw) of leaves (from -0.40 to -0.46 MPa), osmotic potential (ψs) of leaves (from -0.890 to -1.027 MPa) and roots (from -0.763 to -0.850 MPa) decreased with increasing level of salinity from control to 4 dS m-1 at 45 DAS. With increase in salinity levels, RWC (%) of leaves and roots also declined at 45 DAS. A similar trend of change in the ψw of leaves, ψs of leaves and roots and RWC (%) was observed at 80 DAS. However, exogenous application of different concentrations (25, 50, 75 and 100 ppm) of salicylic acid helps in the amelioration of plant water status by increasing water and osmotic potential to the less negative value and by increasing the RWC at both the sampling stages. The level of osmolytes i.e. proline, glycinebetaine and total soluble carbohydrates increase with increasing salinity levels (control to 4 dS m-1) and application of salicylic acid further enhanced these values at both 45 and 80 DAS. A marked increase in hydrogen peroxide (H2O2), lipid peroxidation (MDA) and relative stress injury (RSI %) was notices in leaves and roots at 45 DAS. A similar trend was observed at 80 DAS. But application of SA ameliorates the adverse effect of salinity to some extent at both stages. Salinity levels increased the Cl- concentration in leaves by 41.96% and SO42- content in leaves by 8.1% at 4 dS m-1 as compared to their respective control. This concentration of Cl- and SO42- content was decreased by foliar application of SA. Similarly, CSI and photochemical quantum yield also showed declining trend from control to 4.0 dS m-1 of salinity at 45 DAS. Application of SA helps in the amelioration of salinity stress at 45 and 80 DAS. Specific activity of antioxidative enzymes (SOD, CAT and POX) and glutathione content enhanced abruptly under salinity and application of salicylic acid further enhanced these values at both 45 and 80 DAS. Despite, the increase in the activity of these enzymes, AsA decreased at 4 dS m-1 salinity respective to their control. Similar trend was observed at 80 DAS. Higher Na+/K+ ratio was observed under salt stress but Na+/K+ ratio was further lowered upon application of SA. Pollen viability (%), in vitro pollen germination and pollen tube length were also adversely affected by salinity and its effect was mitigated by SA. SDS-PAGE revealed more deletion than addition of polypeptide bands with increasing levels of salinity and salicylic acid in leaves and roots at both sampling stages. The yield parameters like number of pods plant-1, number of seeds pod-1, seed weight pod-1, 100 seed weight, biological yield and seed yield plant-1 decreased with increasing salinity levels. Conclusively, based on the above studies it can be concluded that foliar spray of SA (25, 50, 75 and 100 ppm) mitigates salinity stress by maintaining higher plant water status, antioxidant defence system, seed yield and lower values of MDA content, electrolyte leakage and H2O2 content. SA treatments not only mitigate the inhibitory effect of salinity on plants, but also showed, a stimulating effect and 100 ppm of SA was found to be more effective at both sampling stages i.e. 45 and 80 DAS.