Effect of Exogenous Melatonin on Seed Germination and Seedling Growth in Melon (Cucumis melo L.) Under Salt Stress

An investigation was carried out to evaluate the effect of different application forms and concentrations of melatonin on germination and initial growth of melon plants in several different salinity conditions. We evaluated germination percentage and growth of seedlings and measured total chlorophyll content, relative electrolyte leakage, peroxidase activity, root viability, proline concentration, relative water content, Na+/K+ ratio in green parts and K+ leakage from roots. Seed germination percentage under salt stress increased with treatments of 10 and 50 mu mol.L-1 melatonin. Seed treatment and plant watering with melatonin at 50 mu molL(-1) improved growth parameters and plants showed higher chlorophyll content as well as better biochemical parameters than non-treated plants. Results suggest that melatonin can alleviate the effect of salt stress during seed germination and first stages of plant development.