关键词: 土壤容重, 土地整治, 土壤呼吸, 微团聚体, 玉米产量

Abstract: The effects of Cd²⁺ with different concentrations (0, 5, 10, 20, 50, 100, 200 mg·L^-1) on seed germination and seedling growth of seven alfalfa varieties were examined in a germination experiment with Petri dish filter paper. The results showed that germination indices of different alfalfa varieties were promoted by different extents with Cd²⁺ treatments in the range of 5-20 mg·L^-1. The fresh weight of Gannong No. 1 and Algonquin was significantly increased under 10 mg·L^-1 treatment. The inhibiting effects of Cd²⁺ treatments on the examined indices of different alfalfa varieties were greatly different. The germination potential of Empress, Amerigraze, Zhonglan No. 1 and Zhonglan No. 2 was significantly decreased under 5-200, 20-200, 50-200 and 200 mg·L^-1 treatments, respectively. The germination rates and germination indices of Zhonglan No. 1, Algonquin (Amerigraze), and Zhonglan No. 2 (Empress) were significantly reduced under treatments with Cd²⁺ concentration of 50-200, 100-200 and 200 mg·L^-1, respectively. Cd²⁺ concentration of 20-200 mg·L^-1 significantly decreased vigor index of all varieties. Fresh weight of all varieties significantly were decreased under treatments with Cd²⁺ concentrations of 50-200 mg·L^-1. All Cd²⁺ treatments significantly inhibited root and/or bud length of seven varieties. The correlations between germination rate, germination index, fresh weight and Cd²⁺ concentration were significant, with R² values being higher than 0.83. The tolerances of seven alfalfa varieties to Cd²⁺ stress, as evaluated comprehensively using the average value of subordinate function of all measurement indices, followed an order of Gannong No. 1 >Empress > Zhonglan No. 2 > Tianshui Alfalfa > Algonquin > Amerigraze > Zhonglan No. 1. In conclusion, the Empress, with high germination rate and tolerance to Cd²⁺ stress, could be recommended as potential candidate variety for the remediation of cadmium contaminated soil.

Key words: soil respiration, maize yield, soil bulk density, microaggregates., land restoration