Abstract: To investigate the effects of different planting densities on the growth, yield, medicinal component contents, and economic benefits of Polygonum cuspidatum, five planting densities were set up: 15 cm × 30 cm, 25 cm × 40 cm, 35 cm × 50 cm, 40 cm × 40 cm, and 45 cm × 60 cm. The optimal planting density for field production was selected by comparing seed-stock input, per-plant yield increase and hectare-scale yield, rhizome bioactive ingredient contents, and economic returns. The results showed that the seed-stock input was the highest in the 15 cm × 30 cm treatment. After one year of cultivation, the per-plant yield increases in the 35 cm × 50 cm and 25 cm × 40 cm treatments were higher than those in the other treatments; after four years, the per-plant yield increases in the 40 cm × 40 cm, 25 cm × 40 cm, and 45 cm × 60 cm treatments were relatively higher. In terms of hectare-scale yield, the 15 cm × 30 cm treatment had the highest yield for both annual and four-year-old Polygonum cuspidatum plants; however, in the four-year-old plants, the actual effective plant number in this treatment decreased by about 50%, resulting in no significant difference in actual hectare-scale yield compared with the 25 cm × 40 cm treatment. Although the 40 cm × 40 cm and 45 cm × 60 cm treatments had relatively higher per-plant yields at four years, their hectare-scale yields remained consistently low throughout, and were not suitable for field application. The contents of polydatin, emodin, and other active components in the four-year-old Polygonum cuspidatum rhizomes all met the quality standards specified in the Chinese Pharmacopoeia 2025 edition, among which the 25 cm × 40 cm treatment showed the highest overall contents of various medicinal components. In terms of economic benefits, the 15 cm × 30 cm treatment had the highest total benefit and net return per hectare, but it also had problems such as a decrease in effective plant number and relatively low per-plant yield. Among the other planting density treatments, only the 25 cm × 40 cm treatment could be profitable in the high-yield range, while the rest were in a loss state. Therefore, the 25 cm × 40 cm density treatment could achieve a balance between per-plant and hectare-scale yield and the optimal accumulation of medicinal components, and was a suitable density for the field cultivation of Polygonum cuspidatum.

Key words: Polygonum cuspidatum Sieb.et Zucc., planting density, yield, medicinal components, economic benefits