秋茄幼苗对低温的反应及钙的效应

Responses of seedlings of Kandelia candel to low temperature and effects of calcium

本文研究了400mmol／dim3NaCl及不同CaCl2浓度培养28d的秋茄幼苗，在低温4℃、0℃、-4℃处理48h后叶片SOD、POD活性，MDA含量，以及电解质渗漏率和叶绿素含量的变化。结果表明，秋茄幼苗叶片在4℃和0℃处理后电解质渗漏率均低于50％，-4℃造成叶片死亡（电解质渗漏率高于90％），表明秋茄幼苗对零上低温有较强的适应能力，而不能耐受较长时间的零下低温；培养液中适宜的Ca浓度能够缓解零上低温造成的电解质渗漏率增加，当CaCl2浓度为15mmol／dm3时，电解质渗漏率增加幅度最小。Ca能够增加秋茄幼苗盐肋、迫下叶片SOD、POD活性，常温下15mmol／dm3CaCl2时，SOD和POD的活性分别比对照组高出0．4倍和1．23倍，低温造成的SOD和POD活性的下降以15mmol／dm3CaCl2时幅度最小。脂质过氧化产物MDA的含量均以15mmol／dm3CaCl2时为最低，0℃时较对照组低38．95％。Ca能增加幼苗叶片的叶绿素含量，减少低温造成的叶绿素含量下降。这些作用均以15mmol／dm3CaCl2时最佳，高于或低于15mmol／dm3时这些作用都下降。表明400mmol／dm3NaCl盐度下秋茄幼苗最适宜的Na／Ca值为26．67。

SOD and POD activities,MDA content,electrolytic leakage rate, and chloroplyll contentof the leaves of Kandelia candel seedlings which were treated with 400 mmol/dm3 NaCl anddifferent concentrations CaCl2 for 28d, and then treated with 4 ℃℃, 0℃ and - 4℃ for 48dwere investigated. Results showed that electrolytic leakage rate of the leaves did not increasevery much (less than 50% ) after treatment at 4℃ and 0℃. Electrolytic leakage rate of theleaves was more than 90% after treatment at - 4℃, the leaves died. It indicated that theseedlings of K. Candel were well adapted to above zero low temperature but could not liveunder -4℃ for 48h. Moderate Ca concentration in the culture mitigated the increase of elec-trolytic leakage rate under low temperature. When CaCl2 concentration was 15mmol/dm3 theelectrolytic leakage rate increased slower than that of other CaCl2 concentrations. Ca in-creased SOD, POD activity, and declined MDA content under salt stress and low tempera-ture. When CaCl2 concentration was 15mmol/dm3,SOD, POD activity of the leaves were 0. 4and 1. 23 times more than that of the control under 28℃,and declined flatter than that ofother CaCl, concentrations under low temperature. The content of MDA-(product of lipidperoxidation) was the lowest when CaCl2 was 15 mmol/dm3,it was 38. 95 % lower than'thatof the control after treatment at 0℃ Ca increased chlorophyll content of the Ieaves and mit-igated the decline of chlorophyll under low temperature. These effects of ca1cium were thelargest when CaCl, concentration was 15 mmol/dm3,lower or higher than this concentrationthese effects of calcium declined. These results indicated that the optimum Na/Ca of theseedlings of K. candel under 400mmol/dm3 NaCl salinity was 26. 27.