Physiological and biochemical responses of rice root to La3+, Ce3+ and Zn2+ stress | 水稻根系对镧、铈、锌胁迫的生理生化应答

صينى. [目的]研究镧（La3+）、铈（Ce3+）、锌（Zn2+）对水稻根系的生理生化影响，探讨过量施用稀土的环境效应。[方法]以稀土元素镧（La3+）、铈（Ce3+）和兼具营养与毒性的重金属元素锌（Zn2+）为胁迫因子，采用组织培养法比较三者对水稻种子萌发及幼苗生长发育的影响。[结果]La3+、Ce3+和Zn2+对水稻种子萌发率影响很小，但对幼苗根、苗的生长具有显著的抑制作用，且在高浓度下稀土离子的抑制作用均大于Zn2+。水稻根可溶蛋白质含量随3种金属离子浓度的升高均呈先升后降的趋势，且La3+、Ce3+较Zn2+更为敏感；CAT和POD的活性随La3+、Ce3+和Zn2+浓度的增加逐渐上升，而SOD活性则先降后升；3种金属离子均能显著地刺激水稻根内MDA迅速积累。在高浓度下， La3+、Ce3+表现出比Zn2+更强的毒性。[结论]稀土元素La3+、Ce3+同重金属元素Zn2+对水稻的毒害机制相似。从长远来看，稀土有可能是一种新型的污染。

إنجليزي. [Objective] This study aimed to study the physiological and biochemical effects of lanthanum (La3 +), cerium (Ce3 +), zinc (Zn2 +) on rice roots and to explore the environmental effects of excessive application of rare earth. [Method] By using rare earth elements La3 + and Ce3 +, and nutritional and toxic heavy metal element Zn2 + as stress factors, the effects of these three elements on the germination of rice seeds and growth and development of seedlings were studied and compared with tissue culture method. [Result] La3+, Ce3+ and Zn2+ had shown no significant effects on germination rate of rice seeds but significant inhibition effects on the growth of roots and shoots of rice seedlings, and the inhibition effects of rare earth elements in high concentrations were stronger than Zn2+; the content of soluble protein in rice roots had shown the tendency of increased first and decreased later with the increasing concentrations of three metal ions, La3+ and Ce3+ were more sensitive than Zn2+; the activities of CAT and POD had increased with the increasing concentrations of La3+ and Ce3+, while the SOD activity had shown the tendency of decreased first and increased later; the three metal ions all could significantly stimulate the rapid accumulation of MDA in rice roots. La3+ and Ce3+ had shown stronger toxic effects in high concentrations than Zn2+. [Conclusion] Toxic mechanism of rare earth elements La3+ and Ce3 + was similar to that of heavy metal element Zn2+. Rare earth might become a new type of pollution in the long run.