Cadmium accumulation and translocation in maize cultivars on contaminated soils in southern China

Rapid industrialization in China has led to widespread soil contamination, particularly with heavy metals like cadmium (Cd). This study investigates Cd accumulation and translocation in 12 commercial maize cultivars grown on contaminated soils. Initial soil Cd concentrations averaged 0.68 mg kg−1, exceeding safe limits for agricultural soils. Post-harvest results indicated that the soil Cd concentration decreased under all cultivars, with values ranging from 0.25 to 0.55 mg kg−1, indicating effective Cd uptake by maize. The bio-concentration factor (BCF) values indicated Cd accumulation, varying between 0.016 and 0.051, while translocation factor (TF) values ranged from 0.04 to 0.12. Cultivar C868 (pollution index (Pi) = 0.048, BCF = 0.016 and TF = 0.05) and C380 (Pi = 0.071, BCF = 0.023 and TF = 0.09) were the best cultivars on contaminated soils, which demonstrated reduced Cd uptake and limited translocation to grains. In addition, a strong positive correlation (r = 0.72, p < 0.05) was observed between soil Cd, Pi, BCF and TF, indicating that cultivars grown on high Pi soils, with higher Cd uptake and translocation result in higher accumulation of Cd in grains. The combined VNIR-PLSR model showed strong predictive performance for the prediction of Cd (R2 = 0.67 and RPD = 2.4). Spectral analysis revealed significant increases of reflectance at 450–500 and 600–700 nm associated with Cd absorption. Our findings indicated the capability of VNIR spectroscopy coupled with PLSR method as a reliable and efficient method for soil Cd assessment.