外源钙施用时期对缓解盐胁迫番茄幼苗伤害的作用

【目的】探讨钙施用时期对提高番茄耐盐性的作用。【方法】以番茄辽园多丽为材料,研究不同时期(提前3d、同时、延后3d)营养液增施Ca2+(10mmol·L-1)对NaCl(100mmol·L-1)胁迫下番茄幼苗的生物量、外渗电导率、相对含水量、脯氨酸含量、可溶性糖含量、丙二醛含量、Ca2+-ATPase活性的影响,探讨Ca2+对盐胁迫伤害的缓解作用。【结果】在各处理中,100mmol·L-1NaCl(T2)胁迫条件下,番茄幼苗的生长较对照(T1)显著受到抑制,上述相关生理代谢受到影响;提前3d(T5)营养液增施钙,在NaCl胁迫时停止增施钙,结果对缓解盐胁迫伤害无显著作用;在NaCl胁迫情况下同时增施10mmol·L-1CaCl2(T3),显著缓解了盐胁迫对番茄幼苗的伤害,但提前3d增施钙处理(T4),未能进一步显著增强这种缓解作用。【结论】盐胁迫同时增施外源Ca2+具有显著缓解NaCl盐胁迫对番茄幼苗伤害的作用,但盐胁迫之前增施外源Ca2+不具备这种作用,可见外源钙提高番茄耐盐性不是诱导效应,而主要是与Na+共存的离子竞争效应。

Effects of Timing of Exogenous Calcium Application on the Alleviation of Salt Stress in the Tomato Seedlings

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,Ca~(2+)-ATPase activity) were studied,and then Ca~(2+) 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~(-1) NaCl (T2)stress compared with the control (T1).Solution without NaCl or 10 mmol·L~(-1) CaCl_2 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~(-1) CaCl_2 (T3) significantly alleviated the harm of salt stress to tomato seedlings,but solution added with CaCl_2 3 d before being grown in the solution with 100 mmol·L~(-1) NaCl and 10 mmol·L~(-1) CaCl_2 (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 Ca~(2+) and Na+ coexisted in the growth medium,and no effect of Ca~(2+) on salt stress was observed when Ca~(2+) was applied before NaCl stress.The alleviation of salt stress on tomato was not Ca~(2+)-induced,but the competitive effect of coexistence of Ca~(2+) and Na+.