To examine the safety of producing edible rapeseed in heavy-metal-contaminated farmland, field experiments were performed with 25 varieties of edible rapeseed on farmland lightly polluted with Cd in the central southern part of Hunan Province. Growing characteristics and Cd contents in rapeseed tissues were measured, and Cd uptake, translocation and removal potential were calculated. The results showed that the growth of 25 rapeseed varieties was not inhibited without withering or inconsistent changes in the shoot. The shoot and root Cd contents of rapeseed varieties ranged from 0.05 to 0.26 mg·kg⁻¹ and 0.04 to 0.26 mg·kg⁻¹, respectively. The bioaccumulation factor (BCF) showed that the shoot had a greater capacity for Cd transport than roots. The total Cd removed by rapeseed varieties ranged from 1.606 to 16.159 μg·plant⁻¹. There were significant differences in plant height, BCF of soil available Cd in the shoot, translocation factor (TCF) of Cd from root to shoot and Cd intake by rapeseed among the edible rapeseed varieties. Cluster analysis of Cd accumulation in the 25 rapeseed varieties indicated that Lvjin 1, Guanyou Qingjing and Guanyou brassica not only reduced soil pollution but also allowed for the production of safe leafy rapeseed, although Cd contents in the shoot of 25 rapeseed varieties did not exceed the national safety standards of China.

In this study, the accumulation characteristics of As, Hg, Cd, Cr, and Pb in 63 soil samples from 28 organic farms in Beijing, China, were analyzed to investigate the risk of heavy metal pollution in organic agriculture, and the key related factors were evaluated. The results revealed that the As, Hg, Cd, Cr, and Pb concentrations in the soil samples were below the risk screening values and substantially lower than those in the soil under conventional agriculture. However, the coefficients of variation for Hg and Cd were 112.45% and 38.34%, respectively, indicating a notable anthropogenic impact. Notably, 35.92% of the sampling sites had medium to high potential ecological risk values for Cd, and the Cd concentration increased considerably as the number of planting years increased. Different crop types impacted the soil heavy metal concentrations. The concentrations of Cd and As in the soil of Brassica crops were 0.265 and 12.915 mg/kg, respectively, which were substantially higher than those in the soil of other crop types. The Random Forest model indicated that soil nutrients had the most significant impact on soil heavy metal accumulation, particularly phosphorus. In conclusion, compared with conventional agriculture, organic agricultural soils have lower heavy metal concentrations and exhibit lower ecological risks, with no significant heavy metal pollution detected. However, there is a risk of Cd accumulation, and preventive measures should be implemented, especially for soils under prolonged cultivation and with potential sources of heavy Cd inputs.

To investigate the differences in cadium (Cd) uptake and translocation among edible rapes and select suitable rape varieties for safe production, a field experiment was carried out with 25 varieties of edible rapes on a farmland polluted with Cd in the central souothern part of Hunan Province. The growing characteristics and Cd contents in rape tissues were measured, and the amount of Cd removed was calculated. The results showed that the growth of 25 rape varieties was not inhibited without withering or inconsistent changes in leaf and so on. The Cd contents in stem-leaf and root of rapes were in the range 0.05-0.26mg·kg-1 and 0.04-0.26mg·kg-1, respectively. Basing on BCF, the stem-leaf showed a greater capacity for Cd transport than root. And the total Cd removed by rape were 0.002-0.016 mg·plant-1. Except for plant height, BCF of soil available Cd from soil to stem-leaf, TCF of Cd from root to stem-leaf and Cd taken away by rape, there was no significant difference among edible rape varieties. Although Cd contents in stem-leaf of 25 rape varieties does not exceed the national safety standards, planting “Lvjin 1”, “Guanyou Qingjing” and “Guanyou brassica” not only reduced soil pollution but also allowed the production of safe leafy rape.