Physiological Mechanism of GABA Soaking to Tomato Seed Germination and Seedling Development under NaCl Stress

The purpose of this paper was to study the effects of exogenous GABA in different concentration on seed germination,reactive oxygen species(ROS) metabolism and chlorophyll fluorescence parameters in seedlings of under NaCl stress.Also,tomato plug-seedlings were irrigated with nutrient solution containing 200 mmol·L-1 NaCl in vermiculite.The results showed that:(1)Tomato seed germination ratio and radical growth were inhibited,and photosynthetic systemⅡactivity was significantly decreased by increasing ROS accumulation(O-·2,H2O2) and membrane lipid peroxidation level,which severely inhibited the growth of tomato seedlings.(2)Tomato seeds pretreated with different concentration GABA solution showed increased seed germination ratio and radical growth,in which 10.00 mmol·L-1 GABA treatment was the best under saline stress.(3)With 200 mmol·L-1 NaCl stress,seedlings treated with exogenous GABA soaking especially 10.00 mmol·L-1 GABA showed significantly increased antioxidant enzyme(SOD,POD,CAT) activities,as well as decrease in accumulation of O-·2,H2O2 and membrane lipid peroxidation,so alleviated salt injury induced by NaCl.Furthermore,seedling height and biomass with GABA treatment were improved accordingly through maintaining higher photosynthetic system Ⅱ activity.In summary,soaking treatment with 10.00 mmol·L-1 GABA had more favorable effects on tomato seed germination and seedlings growth under saline stress.