Screening for Low-Cadmium Accumulation in Maize Varieties Based on Species Sensitivity Distribution and Research on Soil Environmental Thresholds

Screening for low-accumulation varieties is an effective way to reduce the cadmium (Cd) content in crops and decrease human Cd intake. In this study, a field experiment was conducted to analyze the characteristics of Cd absorption and accumulation in 24 maize varieties at maturity in farmland with different levels of Cd pollution. Cluster analysis and Pareto analysis methods were used to screen for maize varieties with low Cd absorption. In addition, the environmental threshold of Cd in farmland in the study area was estimated based on the Species Sensitivity Distribution (SSD) characteristics of different maize Cd enrichment coefficients (1/BCF). The results showed that maize in the study area was subject to varying degrees of Cd pollution, with total soil Cd content ranging from 1.81 to 2.71 mg.kg(-1) at test site 1 and from 0.95 to 1.76 mg.kg(-1) at test site 2. Only the Cd content of heavy metals in maize kernels at test site 2 did not exceed China's national food safety standard (GB 2762-2022, 0.1 mg.kg(-1)), with the Cd content of different maize varieties at test site 2 ranging from 0.008 to 0.073 mg.kg(-1) and the bioconcentration factor (BCF) of maize kernels for Cd ranging from 0.004 to 0.054. According to cluster analysis and Pareto analysis, the low-Cd accumulation maize varieties suitable for local planting were identified as Yufeng 303, Nongda 372, Jingnongke 728, MC121 (Fengda Seed Industry), and Jinyu 1233. In addition, the soil Cd environmental threshold for ensuring that 95% of maize would not be polluted by Cd in soil was derived as 1.39 mg.kg(-1).