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以水稻为研究对象,利用CIRAS-1系统和配有能量色散X光谱扫描电镜(SEM-X-EDS)研究不同浓度镧(La3+)处理下幼苗期和灌浆期水稻净光合速率和叶绿体功能元素及La含量变化。实验结果表明,La3+浓度在0.08 mmol·L-1时,幼苗期水稻叶片叶绿体Ca、Mg、K、Mn、Fe含量和灌浆期Ca、Mg、K含量增加,其余元素未发生明显变化,两生育期净光合速率均上升;当La3+浓度达到1.20 mmol·L-1后,幼苗期和灌浆期水稻叶绿体功能元素含量均呈下降趋势,净光合速率下降。La3+处理下,幼苗期水稻净光合速率对La响应比灌浆期更敏感,净光合速率与叶绿体各功能元素均呈正相关关系。La可以在叶绿体中富集,且与处理La3+浓度呈明显剂量-效应关系,随着处理时间的延长,叶绿体内的La含量越高。总之,1.20 mmol·L-1是La3+引发水稻净光合速率和叶绿体功能元素含量降低的临界点,环境中累积的La3+能影响水稻叶片叶绿体功能元素含量,并通过改变叶绿体元素含量而影响水稻光合作用的正常进行。
Using rice CIRAS-1 system and energy dispersive X-ray scanning electron microscopy (SEM-X-EDS), the effects of La3 + on net photosynthetic rate and chloroplast functional elements in rice seedling and grain filling stage were studied. La content changes. The results showed that when La3 + concentration was 0.08 mmol·L-1, the content of Ca, Mg, K, Mn and Fe in chloroplast and the content of Ca, Mg and K in chloroplast of seedling increased at seedling stage, while the other elements did not change significantly. The net photosynthetic rate increased. When the concentration of La3 + reached 1.20 mmol·L-1, the content of chloroplast functional elements in rice seedlings decreased and the net photosynthetic rate decreased at seedling stage and grain filling stage. Under La3 + treatment, the net photosynthetic rate of rice at seedling stage was more sensitive to La than filling stage, and the net photosynthetic rate was positively correlated with each functional element of chloroplast. La could be enriched in chloroplasts and showed a dose-effect relationship with the concentration of La3 +. With the prolongation of treatment time, the content of La in chloroplasts was higher. In summary, 1.20 mmol·L-1 was the critical point for La3 + -induced decrease of net photosynthetic rate and chloroplast functional elements in rice. La3 + accumulated in the environment could affect chloroplast functional elements content in rice leaves and affected photosynthesis of rice by changing chloroplast element content The normal progress.