Abstract: Seedlings of Cynanchum stauntonii were transplanted into five types of previous crop soils (rice, wheat, Dianthus superbus, rapeseed, and Elsholtzia splendens) and five soil textures, namely pure sandy loam, pure clay, and their mixtures at volume ratios of 2∶1, 1∶2, and 1∶1. At harvest, eight growth indicators including plant height, crown width, leaf length, leaf width, ground diameter, thick root length, fresh weight per plant, and fresh rhizome weight per plant were measured, together with the contents of total saponins, polysaccharides, total alkaloids, and total flavonoids in the rhizomes. Correlation among these indicators was also analyzed. The results showed that previous crops significantly affected both the growth and medicinal component accumulation of Cynanchum stauntonii. The rice previous crop resulted in the greatest growth, while the wheat previous crop yielded the lowest fresh rhizome weight per plant. Based on a comprehensive evaluation of all growth indicators and rhizome yield, the five previous crop soils ranked as follows in terms of their promoting effects on the growth of Cynanchum stauntonii: Rice > Dianthus superbus > rapeseed > Elsholtzia splendens > wheat. The wheat previous crop resulted in the highest total saponin content, the Elsholtzia splendens previous crop yielded the highest polysaccharide and total flavonoid contents, and the rice previous crop produced the highest total alkaloid content. Among the five soil textures, pure sandy loam resulted in the greatest growth, while pure clay resulted in the smallest; pure clay resulted in the highest total saponin content, the 2∶1 sand-to-clay ratio resulted in the highest polysaccharide and total flavonoid contents, and pure sandy loam resulted in the highest total alkaloid content. Correlation analysis showed that fresh weight per plant was positively correlated with fresh rhizome weight per plant at a significant level, and total saponin content was positively correlated with total alkaloid content at a significant level. Under different previous crop treatments, total flavonoid content showed a significant negative correlation with polysaccharide content, while total saponins showed no significant correlation with polysaccharide content in either treatment group.

Key words: Cynanchum stauntonii, previous crops, soil texture, medicinal components