红壤模拟铜污染下紫云英根表形态及其组织和细胞结构变化

采用根形态研究、显微镜观察和透射电子显微镜观察,研究了红壤模拟铜污染下紫云英根表形态及其组织、细胞结构变化.结果表明:当污染铜为0～40mg·kg^-1时,紫云英生长发育正常,根形态完好,功能正常.当污染铜水平在50 mg·kg^-1以上时,紫云英根开始出现受害症状:表现在根粗短呈淡褐色,根毛少且短,主根弯曲,并分出较短的叉根;表皮层出现皱缩;细胞壁略呈波浪形,厚薄不均,质膜界线不明显.紫云英地上部分生长发育受影响,产量开始下降.铜污染水平达到200mg·kg^-1时,根腐烂、组织黑色化、细胞壁断裂,胞质严重收缩解离,紫云英死亡,表明供试红壤临界铜污染浓度为50mg·kg^-1,并且紫云英根对土壤铜污染的耐性随生育期延长而增强,根细胞壁是根耐毒的主要部位.

Change of Superficial Shape and Cell Microstructure of Milk-vetch (Astragalus L.) Root under Simulated Cu Pollution in a Red Soil

This study carried out experiments to investigate changes of shape, inter-structures and cell microstructures of milk-vetch root under simulated Cu stress at non- or contaminated levels in a red soil using observation and bio-microscopic technique. It resulted that when Cu concentration ranged from 0 to 40mg·kg^-1 soil, the milk-vetch grew well and it had a whole root which worked normally. When Cu concentration reached 50mg·kg^-1 soil, the growth of milk-vetch began to get influence with decline of biomass, the taproot crooked and was less branched, root became short and hazel and had fewer shorter hairs, tubby appeared, epidermis began to shrink and cell wall cockled slightly and unevenly, the boundary between plasmalemma and organelle blurred as well. When treatment concentration reaching to 200mg·kg^-1 soil, milk-vetch roots became rotted and black, the cell wall broke and cytoplasm shrank so severely that plasmolysis happened and the plant died. So the critical Cu concentration in experimented soil was 50mg·kg^-1 soil, and the resistance of milk-vetch root to Cu contamination buildup with the growth of aboveground part, and cell wall was the main part to Cu tolerance.