Joint toxicity of cadmium (II) and microplastic leachates on wheat seed germination and seedling growth

Abstract

Cadmium (Cd) and microplastics are widely distributed in soil and pose potential threats to agricultural production and human health. However, the joint toxicity of Cd and microplastics on crop growth remain largely unknown. In this study, the toxic effects of Cd 2+ solution and two kinds of microplastic leachates, polyvinyl chloride (PVC) and lowdensity polyethylene (LDPE), on wheat seeds germination and seedlings' growth were explored under the single and combined conditions. The results showed that Cd 2+ solution and two kinds of microplastic leachates stimulated wheat seeds germination process but inhibited the germination rate by 0-8.6%. The combined treatments promoted wheat seeds germination but inhibited the growth of wheat seedlings on different degree. In especial, the combination of 2.0 mg L -1 Cd 2+ and 1.0 mgC L -1 PVC could promote both wheat seeds germination and seedlings' growth, but they synergistically increased the antioxidant enzyme activity of seedlings. The physiological and biochemical indicators showed that the possible mechanism through which Cd 2+ and microplastics leachates and their combination affected wheat seedlings involved oxidative stress. The toxicity of the PVC leachate to wheat seedlings was stronger than LDPE leachate. The addition of Cd 2+ could alleviate the toxicity of PVC leachate on wheat seedlings, and reduce the toxicity of LDPE leachate on wheat seedlings under the same concentration class combinations but aggravated stress under different concentration class combinations, consistent with the effect on wheat seedlings' growth. Overall, our study has important implications for the joint toxicity of Cd 2+ solution and microplastic leachates in agriculture. HighlightsThe germination rate of wheat seeds was inhibited by 0-8.6% under single treatments All Cd 2+ -PVC combined treatments enhanced wheat seeds germination Cd 2+ -PVC promoted wheat seeds germination better than Cd 2+ -LDPE The possible mechanism that affects wheat seedlings' growth involves oxidative stress Cd2 + PVC1 promoted both wheat seeds germination and seedlings' growth