Abstract: In this study, Juglans mandshurica seeds were drenched in different concentrations (12.5, 25, 50 and 100 g·kg^-1) aqueous extracts from adult Larix gmelini root, bark, branch and leaf for one week, and cultured in greenhouse in midApril, 2004. The germination rate and germination index were calculated 18 days later, and the seedling’s height and collar diameter were measured on August 1st. The results suggested that 25 g·kg^-1 root and 12.5 g·kg^-1 bark and branch aqueous extracts of L. gmelini could significantly increase the seed germination rate and germination index of J.mandshurica (P＜0.05), and 12.5 g·kg^-1 root and bark aqueous extracts could significantly increase the seedling height and collar diameter (P＜0.05). High concentrations of L. gmelini leaf aqueous extract could significantly promote the seed germination and seedling growth of J. mandshurica, but the promotion effect decreased gradually with decreasing concentration of leaf aqueous extract. The promotion of L. gmelini aqueous extracts to J.mandshurica seed germination and seedling growth might be related to the allelopathy between these two tree species.

Key words: Combined pollution, Interaction, Mechanism