Effects of cadmium stress on plant growth and element distribution of four soybean genotypes

Objective  To analyze cadmium (Cd) sensitivity differences of different soybean genotypes, and screen Cd-tolerant genotypes for soybean breeding.

Method  Different Cd concentrations were set, four soybean genotypes of ‘Baxi No. 10’, ‘Bendi No. 2’, ‘Guixiadou No. 2’ and ‘Huaxia No. 3’ were selected as test materials. The taproot length, biomass, total root length, root surface area, Cd concentration and nutrient element concentrations were determined.

Result  Under 11 mg/kg Cd treatment, the taproot length of ‘Huaxia No. 3’ did not obviously change compared with the control while the taproot growths of other three soybean genotypes were distinctly inhibited. The taproot growths of four soybean genotypes were severely inhibited when Cd concentrations were higher than 46 mg/kg. Cd treatment reduced soybean biomass. ‘Baxi No. 10’ and ‘Bendi No. 2’ were more severely Cd-toxic. ‘Guixiadou No. 2’ and ‘Huaxia No. 3’ showed significantly higher biomasses than ‘Baxi No. 10’ and ‘Bendi No. 2’ under 10 and 20 mg/kg Cd stress treatments. The Cd concentrations in roots of four soybean genotypes were far higher than those in shoots. In 10 mg/kg Cd treatment, Cd concentration in the shoot of ‘Bendi No. 2’ was significantly higher than those in shoots of ‘Guixiadou No. 2’ and ‘Huaxia No. 3’, indicating that Cd-resistant ‘Guixiadou No. 2’ and ‘Huaxia No. 3’transfered less Cd from root to shoot. The root growths of four soybean genotypes were significantly inhibited by Cd stress. The total root length and root surface area of ‘Huaxia No. 3’ were less inhibited compared with other three soybean genotypes. There were significant differences among nutrient element concentrations of four soybean genotypes treated by different Cd concentrations.

Conclusion  There are significant genotypic differences of Cd tolerances among four soybean genotypes. ‘Baxi No. 10’ and ‘Bendi No. 2’ are Cd-sensitive genotypes while ‘Guixiadou No. 2’ and ‘Huaxia No. 3’ are Cd-tolerant genotypes. The differences of Cd tolerance may relate to root growth and element distribution in soybean under Cd treatments.