Investigating the effect of salicylic acid on enzymes activity and antioxidant compounds of chickpea (Cicer arietinum L.) cultivars under drought stress

Salicylic acid (SA), as a plant growth regulator, has an important role in alleviating the oxidative damages caused by drought stress in plant cells. In order to study the effect of different levels of SA on soluble protein content, the activity of enzymatic and non-enzymatic antioxidants including peroxidase, superoxide dismutase, ascorbate peroxidase enzymes, ascorbic acid and hydrogen peroxide and malondialdehyde levels and some physiological characteristics of two chickpea cultivars, [Kaka (MCC414) and Jam (MCC361)] under drought stress conditions, a factorial experiment was arranged based on completely randomized design with three levels of SA (0, 0.5 and 1 mM) and two moisture regimes, including drought stress (25% of field capacity) and control (100% field capacity) with three replications. Salicylic acid solutions at 0.5 and 1 mM concentrations were sprayed on leaves at intervals of 15, 25 and 35 days after sowing. Control plants were sprayed with distilled water. Results showed that at 25% field capacity, just peroxidase activity was enhanced in both cultivars. Drought stress reduced membrane stability index and PSΙΙ photochemical efficiency. Only in MCC414 cultivar, SA increased hydrogen peroxide and malondialdehyde contents under drought stress. SA significantly increased the activity of antioxidant enzymes including peroxidase and superoxide dismutase in MCC414 cultivar and ascorbate peroxidase enzyme activity in both MCC414 and MCC361. SA had not significant effect on the ascorbic acid content (P<0.05). Results suggested that SA at 0.5 and 1 mM concentrations could considerably improve membrane stability index and enhance PSΙΙ photochemical efficiency through reducing chlorophyll fluorescence under 25% field capacity.