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Subject: Plant Physiology × Author: Monika × Start date: 1996 ×
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    ThesisItemOpen Access
    Ameliorating effect of mepiquat chloride and gibberellic acid on Sorghum bicolor L. under salt stress
    (CCSHAU, Hisar, 2023-06) Monika; Sarita Devi
    The present study entitled “Ameliorating effect of mepiquat chloride and gibberellic acid on Sorghum bicolor L. under salt stress.” was investigated in the screen house during the kharif season of 2022. Before sowing the pots were saturated to maintain desired levels of salt stress (control, 4, 6 and 8 dS m-1). On 16th August 2022, Sorghum bicolor L. seeds were sown in pots under controlled condition. After 50 days from sowing (DAS), exogenous application of mepiquat chloride (200 and 300 ppm) and gibberellic acid (200 and 400 ppm) under stressed and non-stressed plants of CSV 32F and CSV 35F genotypes. Sampling was done at 30 and 60 DAS. Increasing levels of salt stress led to a decrease in the growth parameters, while the application of mepiquat chloride and gibberellic acid resulted in enhanced plant growth. After the application of mepiquat chloride and gibberellic acid, the physiological characteristics were improved, counteracting the negative effects of salt stress. Parameters such as gaseous exchange, chlorophyll index and photochemical quantum yield exhibited a gradual decline from the control to 8 dS m-1 of salt stress in both genotypes. However, a higher percentage decrease was observed at the 8 dS m-1 salt stress level in CSV 35F over the respective control. For instance, there was a 20.29% decrease in RWC, a 42.36% decrease in assimilation rate, a 69.21% decrease in transpiration rate and a 79.35% decrease in stomatal conductance. The application of mepiquat chloride and gibberellic acid improving gas exchange and chlorophyll index, regardless of salt stress in both sorghum genotypes. On the other hand, the negative effects of salt stress, such as electrolyte leakage and ash content, increased with higher salt levels. However, the application of mepiquat chloride and gibberellic acid partially mitigated these adverse effects of salt stress. Specific activity of enzymes increases in salt stress as well as after application of mepiquat chloride and gibberellic acid. Salt stress enhanced the Na+ content but a decrease in K+ and Ca2+ content. Conversely, after applying mepiquat chloride and gibberellic acid, there was a reversal of this trend. Conclusively, sorghum genotype CSV 32F exhibited slightly better performance under salt stress and showed a more favorable response in mitigating salt stress when mepiquat chloride and gibberellic acid was applied exogenously.