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-) production rate, and sodium (Na+) content, in contrast, seed primed with melatonin lowered these attributes. Then, we recommended that Melatonin well be used as priming sources to enhance salt stress present new opportunities for it is employ in agriculture.
Keywords: Melatonin priming, antioxidant enzymes, gas exchange, wheat (Triticum aestivum L.), salt stress
