摘要： 研究了不同浓度氯化镉溶液对大蒜（AlliumsativumL）根生长和根尖细胞超微结构的影响。结果表明，在一定Cd²⁺浓度的范围内（10-5~10-2 mol/L），随Cd²⁺浓度增加和处理持续时间的延长，根的生长速率递减或停止；Cd处理出现最明显的特征是在10-3mol/L浓度处理组中，细胞质中沉积许多电子稠密颗粒，这些颗粒大小不等，外部着色较深，中心部分较浅，多分布于细胞质中大、小液泡周围；大部分细胞核中的核质高度凝集；出现质壁分离现象；细胞器严重受损；大部分细胞液泡化程度提高。X 射线微区分析结果表明，这些电子稠密颗粒中均未含有Cd²⁺。扫描电镜观察表明，高浓度Cd²⁺（10-2mol/L）处理的根尖表皮细胞呈板结状，细胞壁明显增厚，细胞壁表面沉积许多分泌物。

关键词: 大蒜, 氯化镉, 根尖细胞, 超微结构, X射线微区分析

Abstract: The effects of cadmium chloride solution of different concentrations (10-7~10-2 mol/L) on root growth ultrastructural alterations in root tip cells of garlic (Allium sativum L.) were studied. The results showed that with the increase of Cd²⁺ concentration or treatment time, the rate of root growth decreased successively or stopped. The major change was that the higher concentration of cadmium (10-3mol/L) exhibits unusual deposition of electron dense globules in the root cells. These globules whose electron density was greater outside than inside were big or small, and were distributed nearby vacuoles in the cytoplasm. The nucleoplasm in most of nuclei was highly condensed. The other toxic effects that were observed in treated cells included formation of plasmolysis, disintegration of cell organelles and increase in vacuolation. The results from X-ray microanalysis showed that there were no cadmium ions in these globules. The results from scanning electron microscope indicated that the epidermal cells of the root tips treated with higher concentration of Cd²⁺(10-2 mol/L) appeared more hardened; the cell walls obviously increased in thickness and many mucilage exudates were deposited in the cell walls.

Key words: Allium sativum L., Cadmium chloride, Root tip cells, Ultrastructure, X-microanalysis