Mitigation of salt stress using exogenous ortho-silicic acid and analysing its effect on physiological traits in forage sorghum (Sorghum bicolor L.)
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Date
2022-07-19
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CCSHAU, Hisar
Abstract
The present study entitled “Mitigation of salt stress using exogenous ortho-silicic acid and analysing its effect on physiological traits in forage sorghum (Sorghum bicolor L.)” was investigated in the screen house during the kharif season of 2021. Before sowing, the desired levels of salt stress (control, 4, 6 and 8 dS m-1) were maintained by saturating each pot. Seeds of Sorghum bicolor L. were grown in pots under screen house conditions on 16th July 2021. Ortho-silicic acid (1.5 and 2.5 ppm) was applied exogenously after 30 days after sowing (DAS) under stressed as well as non-stressed plants in both genotypes (CSV33MF and SSG 59-3). Sampling was done at 40 DAS and at the time of harvest. Growth parameters decreased with increasing levels of salt stress, whereas foliar application of ortho-silicic acid enhanced the growth of plants. Similarly, physiological parameters of leaf were enhanced after the
application of ortho-silicic acid which were negatively affected by salt stress. Plant water relation, gaseous exchange studies, chlorophyll index and photochemical quantum yield also showed declining trend from control to 8 dS m-1 of salt level in both genotypes, but more percent decrease was observed at 8 dS m- 1 of salt stress like in ψw (71.83%), ψs (55.29), photosynthetic rate (46.45%), transpiration rate (93.22%) and stomatal conductance (84.21%) in SSG 59-3, over their respective control. The values ranged from 8.89 to 6.61, 25.9 to 22.4 and 52.6 to 51.5 in protein, fiber and in- vitro dry matter digestibility, respectively, at 8 dS m-1 of salt stress in CSV33MF at 40 DAS. Application of OSA helped in the maintenance of plant water status, enhanced the exchange of gases and chlorophyll index irrespective of salt stress in both genotypes. Reversibly, electrolyte leakage and ash content enhanced with every increment of salt stress but application of OSA ameliorated the adverse effect of salt stress to some extent. Increment in Na+ but a decrease in K+ and Ca2+ content was noted under salt stress. While, the reverse trend was noticed after application of OSA. In nut shell, sorghum genotypes CSV33MF and SSG 59-3 performed better under salt stress and showed better response in alleviating salt stress with foliar application of 2.5 ppm ortho-silicic acid.