| 要約: | Abiotic stress and climatic changes pose a serious threat to the agricultural sector. So, a pot experiment was performed at the National Research Centre greenhouse, Dokki, Cairo, Egypt, to investigate the influence of foliar spraying of melatonin (1.25, 2.50, 5.0 mM) on soybean plants exposed to irrigation with saline solution (6.25 dS/m). Results show that salinity stress (S1: 6.25 dS/m) significantly decreased vegetative growth parameters, photosynthetic pigments, indole acetic acid (IAA), membrane stability index (MSI), seed yield quantity and quality, accompanied by significant increases in carotenoid, phenolic content, osmolytes, and antioxidant enzymes activity. On the other hand, melatonin treatments at all levels showed the opposite trend of salinity stress. Melatonin treatments significantly improved the growth and productivity of soybean plants, either irrigated with tap water or saline solution (6.25 dS/m), relative to corresponding controls. The optimum treatment was 2.50 mM melatonin. Since, it increased plant dry weight by 2.04 times in plant irrigated with tap water and by 2.79 times in plant irrigated with saline solution (6.25 dS/m) as well as increased seed yield /plant by 116.13% in plant irrigated with tap water (0.23 dS/m) and by 74.64% in plant irrigated with saline solution (6.25 dS/m) relative to corresponding controls. In addition, melatonin treatments increased salinity tolerance of soybean plants via increasing total photosynthetic pigments, IAA, phenolic content, osmolytes contents (free amino acids, proline, total soluble sugar), membrane stability index, activity of antioxidant enzymes (superoxide dismutase, catalase, peroxide), quality of seed (oil, protein, and carbohydrate contents) and decreasing hydrogen peroxide, malondialdehyde, membrane leakage (ML) either in soybean plants irrigated with tap water (0.23 dS/m) or saline solution (6.25 dS/m). It could be recommended that melatonin treatments ameliorate the harmful effects of salinity on soybeans.
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