Study on Chromium Uptake and Transfer of Different Maize Varieties in Chromium-Polluted Farmland

Abstract

The objective of this research was to study the differences in the enrichment and transport capacity of heavy metal chromium in farmland soil by different maize cultivars, and it is of great significance to screen out the maize varieties that meet the food safety standards and repair the heavy metal chromium in farmland soil. To complete the experiment, under the conditions of field experiments, 72 maize cultivars were selected to study the growth of maize in chromium-polluted arable land and the differences in Cr accumulation and transshipment of different maize cultivars. From the experiment, we found that among 72 maize varieties, 49 of them, accounting for 68.06% of the total, had kernel chromium content lower than the China kernel limit standard value of 1.0 mg kg−1. There were significant differences in Cr content in the kernels, stems, leaves and roots of all cultivars, with Cr content in root > stems > kernels. The contents of Cr in roots and stems and kernels were 4.06–93.09 mg kg−1 and 5.54–24.13 mg kg−1 and 0.46–2.61 mg kg−1, respectively, and the coefficients of variation were 51.21%, 36.36% and 46.11%. By cluster analysis, maize varieties were divided into five groups according to kernel chromium content, and the maize varieties were also divided into three categories according to the content of chromium in stem and leaf. At the same time, we found that the low accumulation of kernel, high accumulation of stem and leaf, seven varieties: Nongyu662, HongyuNO.9, Wankenyu125, Shuxinyu228, Kewei702, Liyu16, JinchengNo.6. The enrichment coefficients (BCF) of each maize cultivar ranged from 0.026 to 0.194, the transport coefficients TF (kernel/stem) and TF (stem/root) were between 0.028 and 0.064, and 0.064 and 0.864, and the enrichment coefficient and transport coefficient were less than 1. In the end, according to the comprehensive evaluation of the maize growth status, kernel Cr content, enrichment coefficient, transport coefficient and other indicators, it is believed that Nongyu662, HongyuNo.9, Wankenyu125, ShuXinYu228, Weike702, Liyu16, and JinchengNo.6 could be promoted as Cr maize cultivars with low kernel and high stem–leaf accumulation; also, planting these seven varieties can achieve the goal of restoring the heavy metal chromium in farmland soil while ensuring maize food security.