Abstract: [Objective] In this paper, we aimed at studying the impact of soil Pb on the physiological indicators and growth of Populus seedlings. [Method] Potting seedlings of Populus canadensis were subjected to five different concentrations of the soil lead, and the physiological indicators, including the content of chlorophyll、the net photosynthetic rate (P_n), the activity of CAT, POD, SOD, the content of MDA, the height and biomass of plants and the content of Pb, were measured. According to the variation of physiological indicators, the five groups were classified into three categories, no pollution, light pollution and severe pollution. Data were analyzed with the methods of ANOVA, comprehensive correlation analysis, vector comprehensive and correlation analysis as well as discriminant analysis. [Result] Firstly, the growth indicators (biomass and plant height) and positive physiological indicator (chlorophyll content, the net photosynthetic rate (P_n)) of the seedlings were decreased as the concentration of Pb was increased, but negative physiological indicators (SOD, POD, CAT and MDA) were subsequently increased. Secondly, there were no significant differences in growth and positive physiological indicators among the five groups when the concentrations of Pb were less than 1045 mg·kg^-1, however, when the concentrations of Pb were more than 1045 mg·kg^-1, the differences were significant. However, the negative physiological indicators (SOD, POD, CAT and MDA) were opposite. Thirdly, The correct discrimination rate of growth index, positive and negative physiological indicators in no pollution, light pollution and severe pollution groups was very high, indicating that the partition of Pb concentration was correct, and can well reflect the variation of growth and physiological indicators. Fourthly, the growth (biomass and plant height) showed significantly positive correlation with the positive physiological indicators (chlorophyll content, the net photosynthetic rate (P_n)), but exhibited significantly negative correlation with negative physiological indicators (SOD, POD, CAT and MDA). Fifthly, the concentrations of Pb in the root, stem and leaf of seedlings were all increased as the concentration of the soil Pb increased, especially in the root. The transfer coefficients of Pb in roots, stems, leaves and whole plants were highest when the concentration of the soil Pb was 1045 mg·kg^-1. [Conclusion] The concentration of 1045 mg·kg^-1 Pb in soil was a key critical value, below which Populus can maintain normal growth and keep a higher transfer coefficient with the ability of stress resistance. But when the concentration of Pb in soil is more than 1045 mg·kg^-1, growth of seedlings was inhibited and the transfer coefficient decreased sharply. Combined methods of ANOVA, correlation analysis, and discriminant analysis, applied in this studies, can reveal the comprehensive correlation between seedling growth and concentration of soil Pb.

Key words: Pb, seedling of Populus canadensis, physiological indicator, comprehensive factor analysis