Cadmium accumulation and migration of 3 peppers varieties in yellow and limestone soils under geochemical anomaly

The high geological background of heavy metal cadmium (Cd) in geochemical anomaly areas in Southwest China and the anthropogenic pollution superposition effect in some typical areas due to mining exploitation have attracted special attention for several decades. The accumulation and migration of Cd in the farmland soil-crop system was worth discussing. In this study, the representative yellow soil and limestone soil in Guizhou Province, as well as three types of pepper (Capsicum annuum L.) were selected to investigate Cd accumulation and migration regulation from soil to plants using pot tests at different Cd concentration levels. For red cluster pepper, line pepper and hybrid pepper, the accumulation capacity of Cd in various parts was similar as follows: Cd_root > Cd_stem ≈ Cd_leaf > Cd_fruit. The differences in the Cd concentration between pepper varieties were as follows: Cd in line pepper roots was higher than that in red cluster pepper and hybrid pepper, but for leaves and fruits, the Cd concentration of red cluster pepper was higher than the others. A higher accumulation and lower transport capacity of Cd in yellow soil as well as a lower accumulation and higher transport capacity of Cd in limestone soil were achieved based on the results of enrichment coefficients and transport coefficients in yellow soil. The red pepper Cd concentration was higher than that of the other two types. The accumulation and transformation of Cd for peppers in yellow soil is more significant (p < 0.05), which results in a higher risk of migration through the food chain.