Objective The aims were to understand the differences in physiological response and antioxidant capacity among different rape varieties under Cd stress conditions.

Method Hydroponic experiments were conducted using two rapeseed varieties ( L87 and L36) as test materials. Three Cd concentrations were set: 0 mg L⁻¹ (control, CK), 15 mg L⁻¹ (Treatment 1, T1), and 30 mg L⁻¹ (Treatment 2, T2). The plant height, root length, shoot fresh weight (S), root fresh weight (R), root/shoot ratio (R/S), chlorophyll (Chl), and carotenoids, relative water content, relative electrical conductivity, malondialdehyde (MDA), proline (Pro), hydrogen peroxide (H₂O₂), soluble sugars contents, and superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities were determined in different rapes after Cd stress, and the physiological changes and differences in antioxidant capacity of different rapes varieties were discussed under Cd stress.

Result ① Compared with CK, after Cd stress (T1, T2), the plant height, root length, shoot fresh weight, root fresh weight, relative water content, Chl, carotenoids contents and CAT activities of the rape L87 and L36 decreased, while relative electrical conductivity, MDA, Pro, H₂O₂, soluble sugar contents, and SOD, POD activities increased. Except for root length, the amplitude of other indicators was T2>T1. ② The Cd transport factors of L87 (TF: 0.06, 0.09) in T1 and T2 were greater than L36 (TF: 0.05, 0.06), but the difference was not significant (P > 0.05). ③ The comprehensive evaluation results of principal component analysis and membership function method showed that L36 (Comprehensive score: 0.77) has higher antioxidant capacity than L87 (Comprehensive score: 0.24).

Conclusion After Cd stress, the growth of the rape L87 and L36 was inhibited, the R/S increased, the leaves lost water and wilted, the pigment content decreased, the membrane was damaged, the osmoregulatory substances increased, SOD and POD increased, CAT decreased, and the Cd transport capacity was comparable. The comprehensive antioxidant capacity of the rape L36 was greater than that of L87.