ObjectiveIn order to study the effects of heavy metal stress on physiological and biochemical properties of trees, the response mechanism of trees to Cd stress was discussed to provide a theoretical basis for the increasingly serious soil heavy metal pollution problem.

MethodSand culture experiments were carried out on five Aigeiros clones, ground diameter, seedling height and 8 physiological and biochemical indexes were measured to evaluate the resistance of different clones to Cd stress.

ResultThe content of CAT and MDA of Aigeiros clones increased first and then decreased under Cd stress compared with control. POD and SOD activities also increased first and then decreased compared with control. The POD activities of ‘L35’, ‘Lulin 9’ and ‘Lulin 16’ were always in the top three. With the increase of Cd²⁺ concentration, the proline and soluble sugar contents of ‘L35’, ‘I-107’ and ‘Zhonghe 1’ increased gradually, while the chlorophyll contents increased first and then decreased. The chlorophyll contents of ‘L35’, ‘I-107’ and ‘Zhonghe 1’ were always in the top three.There were differences in ground diameter and seedling height among clones under the Cd stress, the seedling height reached a significant level, while the ground diameter did not reach a significant level, which indicated that the seedling height traits of the tested clones were more sensitive to Cd stress than the ground diameter.

ConclusionThe growth and physiological and biochemical properties of five clones were comprehensively evaluated by principal component analysis, ‘L35’, ‘Zhonghe 1’ and ‘I-107’ had strong resistance to Cd stress, which could be used as ideal clones for remediation of cadmium-contaminated soils.