Evaluation of physiological characteristics and antioxidant activity of sweet basil (Ocimum basilicum cv. Keshkeni luvelou) under different levels of methyl jasmonate and lead toxicity

This study was performed in order to evaluate the effect of methyl jasmonate on some physiological characteristics and antioxidant activity of basil under lead toxicity, based on a factorial and completely randomized design with three replications at Ferdowsi University of Mashhad Research Greenhouse. The experimental treatments included Pb (NO3)2) at three levels of (0, 200, and 400 mg/kg soil) and foliar application of methyl jasmonate at three concentrations (0, 0.5, and 1 mM). Measured traits included chlorophyll a, b, and total, carotenoids, electrolyte leakage, relative water content, antioxidant activity, soluble carbohydrate, total phenol, and proline. Results showed that in the plants treated with lead, the amount of proline, relative water content, chlorophyll a, antioxidant activity and total phenol reduced in comparison with control plants and application of methyl jasmonate (0.5 mM) under lead stress increased these traits. Furthermore, electrolyte leakage increased significantly under lead stress, while it was decreased by spraying with methyl jasmonate. Therefore, using methyl jasmonate is justified for protecting economic performance of plants under stress. Also, application of 0.5 and 1 mM methyl jasmonate reduced and adjusted the effects of stress in the plants under lead stress through stimulating production of antioxidants.