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[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。
[Objective] The research aimed to study the physiological and biochemical effects of La3 +, Ce3 + and Zn2 + on rice root system and to explore the environmental effects of excessive application of rare earth elements. [Method] The effects of lanthanum (La3 +), cerium (Ce3 +) and zinc (Zn2 +), both of nutrients and toxicity, on the seed germination and seedling growth of rice were compared by tissue culture method. [Result] La3 +, Ce3 + and Zn2 + had little effect on the germination rate of rice seeds, but significantly inhibited the growth of seedling roots and seedlings. The inhibitory effect of rare earth ions was higher than that of Zn2 + at high concentration. The contents of soluble protein in rice roots increased first and then decreased with increasing concentrations of three metal ions, and La3 + and Ce3 + were more sensitive than Zn2 +. The activity of CAT and POD increased gradually with the increase of La3 +, Ce3 + and Zn2 + , While the activity of SOD decreased first and then increased. All the three metal ions could significantly stimulate the rapid accumulation of MDA in rice roots. At high concentrations, La3 + and Ce3 + show more toxicity than Zn2 +. [Conclusion] The toxic mechanism of rare earth elements La3 +, Ce3 + and Zn2 + on rice was similar. In the long run, rare earths may be a new type of pollution.