Effects of cadmium and copper mixtures to carrot and pakchoi under greenhouse cultivation condition

A pot experiment was undertaken to investigate the effects of Cd and Cu mixtures to growth and nutrients (sugar, carotene or vitamin C) of carrot and pakchoi under greenhouse cultivation condition. The study included: (a) physical-chemical properties of soil and soil animals in response to Cd and Cu stress; (b) bioaccumulation of heavy metals, length, biomass, contents of sugar and carotene (vitamin C) of carrot and pakchoi; (c) estimation the effects of Cd and Cu mixtures by multivariate regression analysis. The results implied that heavy metals impacted negative influence on soil animals' abundance. The metals contents in plants increased obviously with Cd and Cu contamination in soil. The biomass production and nutrients declined with Cd and Cu contents increasing. Cd (20 mg kg−1) treatment caused maximum reduction of sugar content (45.29%) in carrot root; maximum reduction in carotene content (75.73%) in carrot, 75.1% sugar content reduction and 70.58% vitamin C content reduction in pakchoi shoots were observed with addition of Cd (20 mg kg−1) and Cu (400 mg kg−1) mixture. The results of multivariate regression analysis indicated that combination of Cd and Cu exerts negative effects to both carrot and pakchoi, and both growth and nutrients were negatively correlated with metals concentrations. It is concluded that the Cd and Cu mixtures caused toxic damage to vegetable plants as Cd and Cu gradient concentrations increased.