Studies On Physiological Mechanisms Of Salt Tolerance Improved By Selenium In Tomato (lycopersicon Esculentum Mill)

In this paper, tomato cultivars "Jinpeng 1#" were grown hydroponically to study the effects of exogenous four different Se (Selenium)concentrations on the growth and physiological parameters of tomato under NaCl (50 mM) stress by measuring changes of protective system against active oxygen, the characteristics of photosynthesis and osmotic regulation substances in leaves of tomato seedlings.The objective was to clarify the possible physiological mechanisms of Se on alleviating salt stress in tomato.The main results were as follows:1. Application of Se (0.025-0.1 mmol/1) increased dry weight, stem diameter, leaf area, dry matter accumulation and root activity of tomato under salt stress, which indicated the application of Se (0.025-0.1 mmol/1) could effectively decreased and alleviated inhibit of salt stress on tomato growth.2. Contrast to NaCl treatment, application of four Se concentrations promoted remarkably the growth of tomato seedings, dry weight of shoot and root, but decreased proline and soluble sugar content in leaves of tomato under salt stress. Among four Se treatments, the phenomena that the lower proline and soluble sugar content in leaves of tomato were companied with the stronger resistance to salt stress indicated that tomato salt-tolerance capability improved by Se is not by accumulating the content of osmotic regulation substances to slow down osmotic stress.3. Application of four Se concentrations could effectively enhanced the activities of POD(peroxidase), CAT(catalase) and APX (ascobate peroxidase) and the content of antioxidant such as GSH(glutathione),but decreased SOD (superoxide dismutase)activity and AsA content in the leaves of tomato under salt stress. These results indicated that all of four Se treatments could increased the ability of scavenging ROS by improved some antioxidant enzymes and antioxidants,which eventually led to decrease and alleviate harm of salt stress on tomato.4. Under NaCl (50 mmol/L) stress, photosynthesis of tomato seedings severely inhibited and chl content decreased. Four Se treatments could alleviate differently the effect of salt stress on the photosynthesis of tomato seedings by increasing the transpiration rate, the stomatal conductance and decreasing the intercellular CO2 concentration.5. Application of Se concentration (0.025-0.1 mmol/1) alleviated the harm of salt stress on tomato seedlings, and increased salt tolenrance of tomato. But the best concentration of Se was 0.05mmol/l.