Effect of extracts of Chinese pine on its own seed germination and seedling growth

The allelopathic potential of Chinese pine (Pinus tabulaeformis Carr.) against its own seed germination and seedling growth was tested with aqueous extracts (0.01, 0.02, 0.05, and 0.10 g·mL⁻¹) obtained from different organs (roots and litter needles) at different individual ages (12, 52, and 110 years old). The results showed that root and litter extracts had different effects on seed germination and seedling growth, and the effects varied with the concentrations, the organs, and the tree age of extracts. The strongest stimulatory effect on seed germination of Chinese pine was exposed to 0.02 g·mL⁻¹ root extract from the 110 years old Chinese pine trees and exposed to 0.02 g·mL⁻¹ litter extract from the 12 years old Chinese pine trees. Meanwhile, the strongest stimulatory effect on growth of Chinese pine seedlings was exposed not only to 0.01 g·mL⁻¹ root extracts from the 110 years old Chinese pine but also to 0.01 g·mL⁻¹ litter extract from the 12 years old Chinese pine. The promoting effect of the extracts of root on seed germination and seedling growth increased in the order of 12, 52, and 110 years old. The promoting effect of the extracts of litter on seed germination and seedling growth increased in the order of 110, 52, and 12 years old. Our results suggested that litter leachates or root exudates of Chinese pine may influence the natural regeneration within Chinese pine stands via the release of allelochemicals into the environment.