Intercropping affects the physiology and cadmium absorption of pakchoi, lettuce, and radish seedlings

Intercropping can affect the growth and elemental absorption of vegetables. This study investigated the physiology and cadmium (Cd) content of pakchoi (Brassica chinensis L.), lettuce (Lactuca sativa L. var. ramosa Hort.), and radish (Raphanus sativus L.) seedlings under monoculture, mutual intercropping of two or three varieties. Intercropping is not conducive to the accumulation of chlorophyll and biomass content of pakchoi, lettuce, and radish. When three seedlings were intercropped together, the antioxidant enzyme activity of pakchoi, lettuce, and radish increased and the content of malondialdehyde decreased, except that the superoxide dismutase activity of radish is inferior to the value of radish and pakchoi intercropping. Intercropping increased the soluble sugar and proline content in the lettuce seedlings, while those in the radish and lettuce seedlings reduced or had no significant effect. When intercropped with pakchoi and lettuce, the Cd content in the roots and shoots of pakchoi is higher and lower, respectively. At the same time, root or shoot bio-concentration factors also performed the same trend, and TF was the smallest and less than 1; however, the TF of lettuce is greater than 1. When intercropping with pakchoi or lettuce separately or together, it promoted the accumulation of Cd in radish root; when intercropping with pakchoi, the value of TF was the smallest. From the antioxidant system, the performance of the three seedlings intercropped together is better than the two; however, the accumulation of Cd shows the opposite trend, and the participation of cabbage in the intercropping is relatively conducive to reducing the Cd content in the edible parts.