Physiological Responses of Tomato Seedlings (Lycopersicon Esculentum) to Salt Stress

Tomato seedling was treated under different concentration of NaCl ranged from 0 to 300 mM. Effects of salt stress on the content of growth and osmotic adjustment substance, the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activities and generation rate of O2.- of tomato seedling were studied. The result showed that the content of fresh weight (FW), dry weight(DW), K+, K+/ Na+ and soluble sugar(SS) decreased with the increasing of NaCl concentration. Conversely, the contention of Na+, Proline and malondialdehyde (MDA), SOD, POD, CAT and APX activities and generation rate of O2.- increased. Growth of seedling shoots was suppressed by salt treatment. Osmotic adjustment substance play a critical role in the growth of tomato seedling under the condition of salt stress, and meanwhile the continual increasing bioactivity of antioxidant enzymes could scavenge reactive oxygen species (ROS) resulted from salt stress to exert the existence of tomato seedling.