Physiological Tools to Identify the Amelioration Effect of Salicylic Acid Under Salinity in Sorghum at Bloom Stage

Abstract

Little is known about the impact of salicylic acid in sorghum under salt stress. Sorghum genotype HJ 513 was used for the experiment, which was carried out as factorial in a completely randomized design. Plants were grown in screen houses under four salt levels (0, 5.0, 7.5 and 10.0 dS m-1 NaCl) and three salicylic acid, SA (0, 25 and 50 ppm) levels with twelve different combinations. Sorghum leaves were harvested at bloom stage (80 DAS) and assayed for electrolytic leakage percentage (ELP) i.e. 93.81% in HJ 513, osmolytes content (Proline value increased from 59.75 to 86.56 (µg g-1 DW) in HJ 513 under 10 dS m-1 with respect to control, total soluble carbohydrate content also increased from control to 10 dS m-1 i.e. 0.21 to 0.42 (mg g-1 DW) in HJ 513, glycine betaine content increased from control to 10 dS m-1 i.e. 135.67 to 286.63 (µmole g-1 DW) in HJ 513 The specific activities of the superoxide dismutase, catalase and peroxidase under salt stress (10 dS m-1) increased 69.12%, 255.29% and 92.65% in HJ 513 respectively. Compared with the plants treated with salt alone, added salicylic acid significantly decreased ELP and significantly enhanced osmolytes concentration and also the antioxidant enzymatic activity in salt-stressed leaves of that genotype. That SA effect was time-dependent and became stronger as the experiment continued. It could be concluded that higher activities of SOD, CAT and POX in salt-stressed leaves induced by SA addition may protect the plant tissues from membrane oxidative damage under salt stress, thus mitigating salt toxicity and improving the growth of sorghum plants. The results of the present experiment coincided with the conclusion that SA may be involved in metabolic or physiological changes in plants