Effects of Different Cadmium Levels on the Growth and Nutrient Elements in Pakchoi

A hydroponic experiment was carried out to determine the effects of different Cd levels (0, 1, 10 mg·L-1 Cd) on the growth and nutrient elements in two pakchoi cultivars, cv. Huqing No.1 and cv. Hangzhouyoudong. The results showed that Cd inhibited the growth and reduced chlorophyll contents of two cultivars. The root dry weight (DW), shoot dry weight, and chlorophyll content (SPAD value) decreased with increasing Cd concentrations in the culture solution. Cd was easily taken up by the plants and concentrations in shoots and roots in both of two cultivars increased with increasing Cd concentrations in the medium. Most of Cd absorbed by plants remained in the roots, and the shoot was more sensitive than the root to Cd stress. Cd affected the nutrient elements absorption and transport. The contents of K and Mg in shoots of both cultivars showed no significant differences in the three treatments, but contents of S in shoots of both cultivars had a rise-fall tendency with increasing Cd concentrations. 1 mg·L-1 Cd had no significant effect on K contents, but 10 mg·L-1 Cd significantly decreased K contents in roots of both cultivars. Ca contents decreased, but S contents increased significantly in roots of both cultivars under the two Cd treatments. Mn contents both in roots and shoots were decreased under the Cd treatment. The effects of Cd on the other nutrient elements were dependent on the elements, plant tissue, Cd concentrations and cultivars.