中文摘要：

采用正交实验设计及微核检测方法，探讨了6种硝酸稀土[Ce（NO3）3，Er（NO3）3，Sm（NO3）3，La（N0O3）3，Y（NO3）3，Eu（NO3）3]对玉米根尖细胞的遗传毒性。实验设置了6种硝酸稀土作为处理因素，每种硝酸稀土分别取5个不同的浓度水平，共25组实验，然后用微核测试法检测了玉米根尖细胞的微核率。结果表明，5种硝酸稀土（除硝酸镧外）对玉米根尖细胞微核的产生具有显著眭（P〈0．05或者P〈0．01）的影响，并且随着浓度的增加，微核率呈现先上升后下降的趋势，而硝酸镧对玉米根尖细胞微核的产生没有显著性影响。与阴性对照组（蒸馏水处理）相比，混合稀土化合物溶液随总浓度的增加，玉米根尖细胞微核率显著上升，表现出一定的联合毒作用。提示5种硝酸稀土（除硝酸镧外）对玉米根尖细胞具有遗传毒性，相互间没有明显的交互作用，不同硝酸稀土的混合物具有一定的联合毒作用。

英文摘要：

The genotoxicity of 6 kinds of rare earth nitrates （including Ce（NO3）3, Er（NO3）3, Sm（NO3）3, La（NO3）3, Y（NO3）3, Eu（NO3）3） to root tip cells of maize were detected using micronucleus test （MNT）. According to the orthogonal experimental design method, 6 kinds of rare earth nitrates were chosen as experimental factors with 5 different levels respectively. The frequencies of micronuclei （FMN） in root-tip cells of maize under different concentrations of rare earth nitrates were examined by micronucleus test. The results showed that the FMN increased significantly （P〈0.05 or P〈0.01） at the concentration of Ce（NO3）3≤25 mg·L^-1, Er（NO3）3≤5 mg·L^-1, Sm（NO3）3≤125 mg·L^-1, Y（NO3）3≤5 mg·L^-1 and Eu（NO3）3≤125 mg·L^-1, but decreased significantly at above the concentration, indicating that the 5 kinds of rare earth nitrates were dominant factors in the formation of micronuclei in root-tip cells of maize, while, lanthanum nitrate had no significant influences. With the concentration increasing, the FMN in root-tip cells of maize treated by rare earth compounds increased significantly compared with the nega- tive control group treated by distilled water. Combined toxic effect was also observed. Ce（NO3）3, Er（NO3）3, Sm（NO3）3, Y（NO3）3 and Eu（NO3）3 had genotoxicity to root tip cells of maize and showed no interaction with each other. The mixture of different rare earth nitrates may have some combined toxicity to root tip cells of maize.