Abstract:

【Objective】 The objective of this study was to investigate the effects of timing of exogenous calcium application on the alleviation of tomato injury of salt stress. 【Method】 The exogenous calcium (10 mmol•L-1) was applied to the growth medium of tomato (Lycopersico esculentum Mill. cv. Liaoyuanduoli) seedling before three days, together with, or after three days of NaCl (100 mmol•L-1) application. Some physiological and biochemical responses (amount of growth ,extravasation conductivity, relative water content, proline content and soluble sugar content, malondialdehyde (MDA) content, Ca2 +-ATPase activity) were studied, and then Ca2+ application on the alleviation of salt stress was investigated. 【Result】 The growth of tomato seedling was suppressed and physiological metabolism of tomato was going worse under 100 mmol•L-1NaCl (T2)stress compared with the control (T1). Solution without NaCl or 10 mmol.L-1CaCl2 was added 3 d(T5) immediately before being grown in the solution with 100 mmol•L-1 NaCl, alleviation of NaCl stress was not significantly achieved. Solution with 100 mmol•L-1 NaCl and 10 mmol•L-1CaCl2 (T3) significantly alleviated the harm of salt stress to tomato seedlings, but solution added with CaCl2 3 d before being grown in the solution with 100 mmol•L-1 NaCl and 10 mmol•L-1 CaCl2 (T4), the role of alleviation of salt stress did not increase compared with T3. 【Conclusion】 Effects of exogenous calcium application on the alleviation of salt stress of tomato were significantly achieved, but the alleviation of salt stress was achieved when Ca2+and Na+ coexisted in the growth medium, and no effect of Ca2+ on salt stress was observed when Ca2+ was applied before NaCl stress. The alleviation of salt stress on tomato was not Ca2+-induced, but the competitive effect of coexistence of Ca2+ and Na+.

Key words: tomato')">tomato, salt stress, Ca2+, alleviatory effects