Seed priming mitigates the effects of saline-alkali stress in soybean seedlings

Soda saline-alkali soil has double adverse effects on growth, morphogenesis and yield of the crops by creating a salinity stress and a high pH value in the rhizosphere surroundings of the plant. Seed priming can be an effective approach to enhance stress adaptation in seedlings growing in salinity stressed conditions. The present study examined the role of hydropriming and comprehensive seed priming with ZnSO4, CaCl2, betaine hydrochloride and GA(3) to enhance the soda saline-alkali tolerance in soybeans (Glycine max [L.] Merr.) seedlings. An unprimed control treatment was also maintained for comparison. The results show that two seed priming treatments can effectively mitigate the negative effects of soda saline-alkali stress. Nevertheless, compared with hydropriming, soybean seedlings from the comprehensive seed priming treatment had better growth performance through accumulation of soluble sugar and free proline contents, enhancing the activities of superoxide dismutase (SOD) and catalase (CAT), decreasing the malondialdehyde (MDA) content formed from lipid peroxidation, increasing the photosynthetic pigment contents, maintaining a better membrane integrity of the chloroplasts and mitochondria, and generating more starch grains in the chloroplasts of spongy mesophyll cells under soda saline-alkali stress. In conclusion, our results suggest that soybean seedlings from comprehensive seed priming exhibited a higher tolerance to soda saline-alkali stress than the unprimed control treatment.