外源钙对镉胁迫下茶苗的缓解作用及茶叶品质的影响

Effects of exogenous calcium on the growth of tea seedling and the quality of tea under cadmium stress

通过土培实验,研究茶苗镉胁迫下施加不同浓度外源钙,对茶叶的过氧化物酶(POD)、过氧化氢酶(CAT)和丙二醛(MDA)等生理指标及茶多酚、氨基酸和可溶性糖等茶叶品质指标的影响。结果表明,5.0 mg·kg^(-1)的镉胁迫下,茶叶的CAT、POD等防御酶指标均显著提高,MDA含量上升,茶多酚氨基酸、可溶性糖等茶叶品质指标下降。当施加外源钙时,镉胁迫下的茶苗CAT、POD和MDA出现了一定程度下降趋势,茶叶的茶多酚、氨基酸和可溶性糖各项品质指标均得到提高,表明了外源钙可以缓解镉胁迫对茶苗产生的毒害作用,并改善茶叶品质。特别是施加50.0 mg·kg^(-1)的外源钙对防御酶系统的调节效果最好,其CAT、POD较无外源钙添加的5.0 mg·kg^(-1) Cd胁迫下的茶苗下降了58.25%和80.76%,MDA下降15.25%。另外,外源钙添加,使5.0 mg·kg^(-1)Cd胁迫下茶叶品质得以改善,当添加50.0 mg·kg^(-1)的外源钙时,茶多酚含量上升97.44%、氨基酸提高32.69%,但对可溶性糖含量没有显著影响。100.0 mg·kg^(-1)的外源钙对镉毒害也有较好的缓解作用并能提高茶叶品质,其CAT、POD和MDA相比较无外源钙添加的5.0 mg·kg^(-1) Cd胁迫下的茶苗分别下降了58.83%、61.54%和32.82%;茶多酚含量上升97.43%,氨基酸含量上升7.69%,可溶性糖含量上升22.35%。随着外源钙浓度升高,其缓解镉胁迫的能力下降,当外源钙施加量超过150.0 mg·kg^(-1),不能缓解镉胁迫茶苗的毒性。

We investigated the effects of different concentrations of exogenous calcium on the physical signs of tea plants, including peroxidase（POD）, catalase（CAT）, malondialdehyde（MDA）, as well as the quality of tea such as tea polyphenols, amino acids, soluble sugar in tea with pot experiment under cadmium stress. The results showed that under cadmium stress of 5.0 mg.kg~, the antioxidative defense system of tea including CAT and POD were significantly improved, MDA content increased, while tea polyphenols, amino acids and soluble sugar were declined. When we applied exogenous calcium, CAT, POD and MDA under cadmium stress of tea seedling appeared a certain degree of decline; tea polypbenols, amino acids and soluble sugar in tea were improved, which indicated that exogenous calcium could alleviate the toxicity of cadmium stress on tea seedlings and improve the quality of tea. Especially, when exogenous calcium concentration reached to 50.0mg·kg^-1, the effect of the regulation of the defense enzyme system got best. CAT and POD decreased 58.25% and 80.76%, respectively, and MDA also decreased by 15.25% when 50.0mg·kg^-1 exogenous calcium was added under 5.0mg·kg^-1 Cd stress. In addi- tion, the quality of tea was improved under 5.0mg·kg^-1 Cd stress with adding exogenous calcium. With 50.0mg·kg^-1 exogenous calcium, tea polyphenols and amino contents increased by 97.44% and 32.69%, respectively, but which had no significant influence on the soluble sugar content. 100.0 mg·kg^-1 exogenous calcium could also give a relief to cadmium poisoning better and improve the quality tea. The CAT, POD and MDA fell by 58.83%,61.54% and 32.82%, respectively. The contents of tea polyphenols, amino acids and soluble sugar increased by 97.43%, 7.69% and 22.35%, correspondingly. As the exogenous calcium concentration increased, its ability to alleviate cadmium dropped. If the concentration of exogenous calcium exceeded 150.0 mg·kg^-1, the exogenous calcium could not alleviate the toxicity of tea seedling caused by cadmium stresses.