Genotypic differences in cadmium and nitrate co-accumulation among the Chinese cabbage genotypes under field conditions

•Seven Chinese genotypes were identified as low co-accumulators of Cd and nitrate.•Decreased N and increased K and Zn fertilizers reduced Cd and nitrate in Chinese cabbage.•Application of Ca, Mg and Mn can improve vegetable quality.

Information is needed for breeding and soil management regarding the difference in the tolerance and accumulation of co-contaminants among the genotypes of vegetable crops. A field experiment was conducted to screen low co-accumulator genotypes of both Cd and nitrate from 62Chinese cabbage genotypes grown in a moderately Cd (1.10 mg/kg) and nitrate (235.2 mg/kg) combined contaminated soil. Seven genotypes, i.e., SIYM, TCCS, 28TS, DGAF, CANB, FBSY and SJXH, were identified as low co-accumulators of Cd and nitrate based on their containing low Cd (<0.5 mg/kg DW) and nitrate (<3100 mg/kg FW) concentration in the edible parts even when grown in contaminated soils. These genotypes were suitable for growing in slightly or moderately contaminated soils without risk to food safety. The concentration of nitrate in edible parts of the cabbages was positively related with concentration of N, Ca, Mg and Mn in the soil, whereas Cd concentrations in vegetables were negatively correlated with K and Zn concentrations in soil. These results indicate that improved management practices, such as reduced N and increased K application rate, and foliar application of water soluble Zn, may be useful for reducing Cd and nitrate concentrations in Chinese cabbages on contaminated soils. Besides, soil conditioners may be used to improve calcareous soil so that plant-availability of calcium, magnesium and manganese can be enhanced, thus reducing Cd and nitrate concentrations in edible parts and improving vegetables quality.