Screening of low-Cd-accumulating and Cd-remediating oilseed rape varieties using a newly indicator system for risk management of Cd-contaminated agricultural land

Abstract

Although oilseed rape is frequently used as an alternative planting crop in the phytoremediation of cadmium (Cd)-contaminated agricultural land, methods for screening excellent oilseed rape varieties in this regard are inadequate. Herein, we developed a screening method that incorporates Cd accumulation, distribution, and removal, economic output, adaptability to Cd-contaminated agricultural land, and trace element variation. A Cd-adaptability index (Cd-AI) based on 10 agronomic traits was used to measure the adaptability of varieties to Cd-contaminated agricultural land. Moreover, to simplify the evaluation of adaptability, yield, biomass, and pod number with high weightings were selected to construct a discriminant function for Cd-contaminated agricultural land adaptability (correctly classified 94.20%). In a 2 year field trial, we evaluated 225 oilseed rape varieties, among which we identified two promising low-Cd-accumulating and two Cd-remediating varieties. For the low-Cd-accumulating varieties (HuYou17 and DeXingYou558), we obtained grain bioaccumulation factor (BAF) values of 0.07 and 0.08, BAF_soil-stalk values of <1, and economic outputs of RMB 25,054 and 32,292 yuan hm^-2, respectively. Similarly, the Cd-remediating varieties (ZaoZa8 and YuYou61) were characterized by BAF_soil-stalk values of 4.65 and 3.61, BAF_soil-grain values of 0.16 and 0.16, Cd removals of 69.02 and 58.25 g hm^-2, and economic outputs of RMB 31,189 and 24,962 yuan hm^-2, respectively. Compared with the control variety, we detected lower uptakes of multiple trace elements (3-43%) in the low-Cd-accumulating varieties, whereas the Cd-remediating varieties were characterized by 15.40% and 8.30% increases in the accumulation of magnesium and zinc, respectively. Our findings augment the evaluation indices used for evaluating oilseed rape varieties and provide valuable insights from the perspectives of varietal screening and promotional application. The effective varieties identified have application potential for safe production and the remediation of agricultural land without interrupting annual agricultural production, and provide an economically sustainable approach for the utilization of Cd-contaminated agricultural land.

Keywords: Adaptability; Cd-contaminated agricultural land; Economic output; Oilseed rape; Remediation; Safe production.