Effect of Seed Priming and Foliar Treatment of Melatonin on Stress Alleviation in Brassica juncea L. Grown in Waste Water

Seed germination and seedling growth are vital plant stages that can be affected by stresses such as drought and aging, which cause deterioration and reduce seed viability. The rapid increase in the industries at or along the banks of rivers is leading to serious health hazards for the population consuming the contaminated water and the crops irrigated by the contaminated water. The present study was conducted to determine the effect of melatonin (100 µm) treatment viz., seed priming, foliar spray and seed priming + foliar spray on the plants grown in the waste water. In the experiment, significant reductions in the morphological and yield traits were recorded in the plants grown in waste water. A reduction in shoot length, root length, dry weight, number of leaves, number of internodes, pod length, number of pods, number of seeds and 100 seed weight was observed in the plants grown in waste water as compared to the plants irrigated with tap water.. Melatonin (MT)-treated plants also showed significant improvements in morphological and yield parameters as compared to the control. The highest increase was observed in fresh weight of the plants by the co-application of MT(seed priming + foliar spray) in comparison to the control plants. Further, MT-treated plants exhibited less reduction in morphological and yield components under waste water irrigation as compared to plants grown in waste water without MT treatment. The plants grown in waste water under foliar MT(100 µm) treatment showed increase in shoot length, fresh weight, dry weight, number of leaves, number of internodes, number of pods, pod length and number of seeds per pod in comparison to plants grown in waste water only. The study revealed that the foliar MT (100 µm) treatment was most effective in increasing the morphological and yield parameters of mustard grown under waste water compared to seed priming and seed priming + foliar spray treatment.Application of MT at concentration of 100 µmol L-1 by foliar spraying can be helpful in alleviation of stress in mustard growing in waste water. This can be further used in harnessing the photoremediation properties of Brassica juncea L. and reclamation of the soil.