Effects of Cadmium Stress on Seed Germination and Seedling Growth of Brassica napus L.
To investigate the effects of the heavy metal cadmium (Cd) on seed germination and seedling growth of Brassica napus L., 25 B. napus lines with different genetic background were treated with four concentrations (0, 1, 5 and 10 mg/L) of Cd, and then, their germination potential, germination rate, seedling length, main root length, seedling fresh weight, and seedling dry weight were measured. The results showed that the response of the B. napus lines to Cd stress was different.With the increase of Cd concentration, the relative germination potential and relative seedling rate increased first and then decreased, and reached the maximum levels when the Cd concentration was 5 mg/L. The inhibitory effects of Cd stress on seedling growth indices in a decreasing order were root length >seedling length >seedling fresh weight>seedling water content. There were extremely significant differences in the relative root length, relative seedling length, relative seedling fresh weight and relative seedling water content among the B. napus lines treated by different concentrations of Cd, while there were no significant differences in the relative germination potential and relative seedling rate among the lines, except that the relative seedling rate was significantly different among the lines treated by 5 mg/L Cd. The results suggested that seedling growth was more sensitive than seed germination to heavy metal stress.