Effects of cadmium stress on biomass and cadmium ion content of Sect. Aigeiros clones

  Objective  In order to study the effects of heavy metal stress on biomass and cadmiumion content of Sect. Aigeiros clones, the response mechanism of clones to Cd stress was discussed, which provided a theoretical basis for the increasingly serious soil heavy metal pollution problem.

  Method  Sand culture experiments were carried out on five Sect. Aigeiros clones, growth, biomass and cadmium content of different organs were measured to evaluate the resistance of different clones to Cd stress.

  Result  With the increase of Cd²⁺ mass concentration, the seedling height and ground diameter decreased under Cd stress, the height traits of tested clones were more sensitive to Cd stress than the ground diameter; the number of leaves decreased after Cd stress. Based on the analysis of the mean value of leaf biomass of different clones, it was found that clones ‘I-107’ , ‘L-35’ and ‘Zhonghe 1’ were in the top three, except for the mass concentration of Cd²⁺ being 15mg/L, the difference was significant under other mass concentrations. With the increase of Cd²⁺ mass concentration, the variation trend of stem biomass and root biomass of different clones was the same, the whole trend was first decreased, then increased and then decreased. The average of stem and root biomass under different mass concentrations of Cd stress were analyzed, the stem biomass of ‘I-107’ , ‘Lulin 9’ and ‘L-35’ were in the top three, and the root biomass of ‘ I-107’, ‘Lulin 16’ and ‘L-35’ were in the top three. The Cd content in stems of different clones increased with the increase of Cd²⁺ mass concentration, and ‘I-107’had the highest growth rate compared with the control, followed by ‘Lulin 9’. Under the highest mass concentration, the difference between ‘Lulin 9’and other clones was significant. The Cd content in leaves and roots of different clones increased with the increase of Cd²⁺ mass concentration. Under the highest mass concentration, the content of Cd²⁺ in the leaves of ‘I-107’ , ‘Zhonghe 1’ and ‘Lulin 9’ was in the top three compared with the growth rate of the control; and the content of Cd²⁺ in roots of ‘Zhonghe 1’,‘I-107’and ‘L-35’ was in the top three compared with the growth rate of control. The total biomass increased first and then decreased; the total Cd content increased first, then decreased and then increased.

  Conclusion  The growth, biomass and Cd content of five clones were comprehensively evaluated by principal component analysis, ‘I-107’ ,‘Lulin 9’ and ‘L-35’ had strong resistance to Cd, which could be used as ideal clones for remediation of cadmium-contaminated soils.