Alleviation of salt stress on seed germination and seedling growth in wheat by seed priming with melatonin

The present study was conducted at the Department of Laboratory, China.To know the impact of melatonin priming in alleviating the negative impact of salt stress on seed germination and seedling establishment of winter wheat (Triticum aestivum L. cv Elnilein).Wheat seeds were primed with melatonin and then subjected seedlings under salt stress.Six concentrations were used: control, salt (300 mM NaCl) four concentrations of melatonin (M) 10, 100, 500, 1000 μM with salt (300 mM NaCl) to each concentration: CT, ST, M1+ST, M2+ST, M3+ST, M4+ST.Effect of melatonin priming on seed germination under salt stress was studied and optimum melatonin concentration screened.Thereafter, three-leaf seedlings from the melatonin-primed subjected to two levels of salt stress for evaluation of the alleviation effect of melatonin on seedling establishment.Five concentrations used as follows: Control, salt stress (300 mM NaCl), salt stress (100 mM NaCl), 500 μM of melatonin (M) +300 mM NaCl, 500 μM of melatonin (M) + 100 mM NaCl: CK, S1, S2, M+S1, M+S2.The data obtained on different seed germination and seedling.Parameters measured under study were analyzed statistically using SPSS (SPSS Inc, Chicago, IL).Significantly different means of the measured data separated at the 0.05 probability level using Duncan's Multiple Range Test (DMRT).The results revealed that salt stress caused significant reduction in seed germination rate, germination index, lengths, dry weights of radicle and coleoptile, amylase, antioxidant enzymes activities, soluble sugar, sucrose contents, while melatonin priming alleviated these reductions.Also, salt stress decreased seedling growth attributes, water content (RWC), leaf area, and chlorophyll content, whereas melatonin priming increased these parameters.The photosynthetic rate (Pn), actual photosynthetic efficiency (ΦPSII), maximum photochemical efficiency (Fv/Fm), and potassium content (K+) in stressed seedlings inhibited, where melatonin priming improved these traits.We found that salt stress plants had increased the reactive oxygen species (ROS) malondialdehyde (MDA), hydrogen peroxide (H2O2) contents, superoxide (O2-)