Allelopathic effects of aqueous extracts from Taxus chinensis var. mairei on seed germination and seedling growth of Camptotheca acuminata

Allelopathy is one of the important factors that affect the interspecific relationship of artificial mixed forest. Previous studies have shown that Taxus chinensis var. mairei has a significant promoting effect on the growth of Camptotheca acuminata in the mixed forest of T. chinensis var. mairei and C. acuminata, which was explained from the perspective of improving the microclimate of mixed forest land, but not from the perspective of interspecific allelopathy. In order to explore whether T. chinensis var. mairei has potential allelopathy promoting effect on C. acuminata, so as to understand more comprehensively the interspecific relationship of T. chinensis var. mairei and C. acuminata mixed forest, the effects of water extracts from fresh leaves, litter leaves, branches and roots of T. chinensis var. mairei with different concentrations(25 g/L, 50 g/L, and 100 g/L) on seed germination and seedling growth of C. acuminata were studied in this study. The results showed that(1) the litter extract of T. chinensis var. mairei had no significant effect on seed germination and seedling growth of C. acuminata(P > 0.05), but the fresh leaves, branches and roots extracts had the promoting effects on C. acuminata germination and seedling growth in different degrees(P < 0.05), and the intensity was positively correlated with the concentration of extracts.(2) The germination percentage of C. acuminata seeds soaked in 100 g/L extracts of fresh leaves, branches and roots from T. chinensis var. mairei was 8.1%, 14.9% and 25.6% higher than that of the control group, respectively.(3) The fresh leaves extract of T. chinensis var. mairei could promote the basal diameter growth of C. acuminata seedlings at high concentration(100 g/L)(P < 0.05), but had no significant effect on plant height, total dry weight and net photosynthetic rate regardless of extracts concentration. The root and branch extracts of T. chinensis var. mairei had the promoting effects on plant height, basal stem, dry weight and net photosynthetic rate of C. acuminata seedlings(P < 0.05). Compared with the control group, 100 g/L of root and branch extracts could increase the height of C. acuminata seedlings by 14.2% and 8.4%, the basal diameter by 19.0% and 15.3%, the dry weight by 23.1% and 15.9%, and the net photosynthetic rate by 11.6% and 6.1%, respectively. The results showed that the positive allelopathy of T. chinensis var. mairei to C. acuminata may be one of the important factors to promote the gr