Abstract: Understanding the effects of Pinus yunnanensis leaf litter decomposition on the physiological characteristics and medicinal quality would lay a foundation for the cultivation of high-quality Paris polyphylla var. yunnanensis. A pot experiment was conducted with five litter application levels, i.e. 0, 50, 100, 150, and 200 g·pot^-1. Samplings were taken in June (T1), July (T2), and August (T3) in 2019. The results showed that different doses of P. yunnanensis leaf litter had significant inhibitory effects on root vitality, photosynthetic pigment content and antioxidant enzyme activity in Paris polyphylla var. yunnanensis, and significant promotion effects on foliar MDA content. In each sampling period, such inhibitory and promotion effects gradually increased with increasing application levels of P. yunnanensis leaf litter. The growth and development of P. polyphylla var. yunnanensis were inhibited by the allelochemicals derived from the decomposition of P. yunnanensis leaf litter, with the total saponins content in the new and old rhizomes being inhibited. With the extension of the sampling period, the total saponin contents of new rhizomes were decreased by 3.68%-31.27% (T1), 17.23%-34.69% (T2), and 10.88%-31.03% (T3), and the total saponin contents of old rhizomes were decreased by 2.07%-25.78% (T1), 9.47%-20.90% (T2) and 5.58%-47.81% (T3), respectively. Therefore, different amounts of P. yunnanensis leaf litter reduced the medicinal value of P. polyphylla var. yunnanensis to varying degrees. Pinus yunnanensis leaf litter can affect the growth of P. polyphylla var. yunnanensis seedlings, and thus P. polyphylla var. yunnanensis is not suitable for the forest-medicine compound model under P. yunnanensis forests.

Key words: allelopathy, photosynthetic pigment, protective enzyme, total saponins.