Effects of La on the growth of kidney bean seedling under Cd stress
镧对镉胁迫下菜豆(Phaseolus vulgaris)幼苗生长的影响

In this study, kidney bean (Phaseolus vulgaris) was used as experiment-material, and effects of lanthanum on growth and metabolism of kidney bean seedling under cadmium stress was studied by water culture. The results showed that kidney bean seedling was chronically harmed by 30 mumol.L-1 Cd2+, however, its height and main root were reduced about 31.1% and 39.2%, meanwhile, leaf area, fresh and dry weight of leaf, stem and root were decreased 48.0%, 42.7%, 29.6%, 61.3% and 49.4% respectively. With acute damage of 50 mumol.L-1 Cd2+, physiological and biochemical characteristics of seedling changed greatly, e.g., chlorophyll content and root activity were decreased about 23.5% and 28.7%, cell membrane permeability, the malonydialdehyde (MDA) content, activities of catalase (CAT) and peroxidase (POD) were increased 5.58%, 28.6%, 0.6% and 7.0% respectively. And with longer treatment time, the damage became more serious. When 10 mg.L-1 La was used to spray on kidney bean seedling under cadmium stress one time, growth and metabolism of seedling was obviously reconditioned and the damage of Cd pollution was reduced. It is proved, by the experiment, that La can improve chlorophyll content(30.0%) and reduce cell membrane permeability (0.87%) and content of MDA(9.5%), and keep the activities of CAT (0.1%) and POD(1.6%) of kidney bean seedling.