Enhancement of physiological and biochemical attributes of okra by application of salicylic acid under drought stress

Abstract

Horticultural crops especially vegetables are most vulnerable to drought due to their higher irrigation needs. Hence, this study was undertaken to evaluate the adverse effects of drought stress and the beneficial effects of salicylic acid (SA) on physiological and biochemical attributes of okra plants under drought stress. For this purpose, a pot experiment was laid out in Complete Randomized Design (CRD) design. Okra seeds were primed with four different SA treatments i.e., 0 (control), 1, 2 and 3 mM and sown in pots (Ø 20 cm). After 14 days of germination, the plants were subjected to two drought levels i.e., 25% and 50% field capacity (FC) and after 20 days of germination regular foliar sprays of SA at 7 days interval were performed with aforementioned SA levels. Physiological parameters like fresh weight, dry weight, and length of plants along with biochemical attributes like chlorophyll (‘a’, ‘b’ and total), total carotenoids, total protein and proline contents, and electrolyte leakage were recorded. Results revealed that drought stress (25% FC) significantly reduced all the studied parameters and resulted in the lowest values of fresh weight (5.04 g), dry weight (1.33 g), length of plants (11.68 cm), chlorophyll ‘a’ content (5.97 mg/g FW), chlorophyll ‘b’ content (8.86 mg/g FW), total chlorophyll (14.84 mg/g FW), total carotenoids (4.96 mg/g FW) and total protein (1.05 mg/g FW), except proline content (6.81 mg/g FW) and electrolyte leakage (77.31%) which was increased. Application of SA under drought stress reduced the harmful effects of drought and application of 2 mM SA produced the maximum fresh weight (8.60 g), dry weight (2.51 g), length of plants (16.23 cm), chlorophyll ‘b’ content (14.47 mg/g FW), total protein (3.73 mg/g FW) and proline content (5.11 mg/g FW); whereas application of 3 mM SA showed the highest values of chlorophyll ‘a’ (8.91 mg/g FW), total chlorophyll content (23.20 mg/g FW) and carotenoids (7.93 mg/g FW), and the lowest value for electrolyte leakage (62.00%).