Effects of Melatonin Priming on Seed Germination of Wheat under Salt Stress

Melatonin (N-acetyl-5-methoxytryptamine) has been identified as a new growth regulator in plants due to its beneficial effect in abiotic stress reduction. The experiment was conducted at the Wheat Cultivation Department Laboratory, Gezira Scheme, Sudan. To investigate the effects of melatonin priming in alleviating the negative effect of salt stress on seed germination of winter wheat (Triticum aestivum L. cv Elnilein and Imam). Six concentrations were used: control, salt (300 mM NaCl) and four concentrations of melatonin (M) 10, 100, 500 and 1000 μM with salt (300 mM NaCl) add to each concentration: CT, ST, M1+ST, M2+ST, M3+ST, M4+ST. The treatments were arranged in a Randomized Complete Block Design with three replications. The parameters studied included: seed germination rate (%), germination index, mean germination time (d), lengths (cm) and dry weight (mg) of coleoptile and radicle, starch, soluble sugar, and sucrose concentrations, amylase activities, activities of the antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX) and catalase (CAT), reactive oxygen species (ROS) including malondialdehyde (MDA), Hydrogen peroxide (H2O2) contents and superoxide (O2-) production rate, abscisic acid (ABA). The parameters of seedling establishment were: Shoot height, root length, fresh and dry weight of shoot and root. The treatment M3+ST (500 μM Melatonin + 300 mM NaCl) had the highest seed germination rate, germination index lengths and dry weights of coleoptile and radicle, soluble sugar, sucrose concentrations, amylase and antioxidant enzymes activities, and ABA concentration, seedling shoot and root length, and fresh and dry weight of shoot and root in Imam and Elnilein cultivars, respectively. The study revealed that melatonin priming effectively alleviates salt stress during seed germination and seedling establishment in winter wheat.