LAUSR

This study compared the characterisations of polysaccharides from Chinese yam (Dioscorea opposita Thunb.) growing in sandy soil (SSCY), loessial soil (LSCY) and second-year continuous cropping (CCCY). SSCY contained the highest total polysaccharides (36.55%) and 80.19% glucose, CCCY from sandy soil obtained 24.55% polysaccharides with 43.66% glucose, whereas LSCY contained 27.54% total polysaccharides and 7.94% glucose. The results indicated that Dioscorea opposita from sandy soil may obtain higher level of glucose. CCCY increased the galacturonic acids in yams from 7.03% to 26.19%, which may have been caused by the decrease in soil pH due to continuous cropping. The starches of SSCY and CCCY from sandy soil belongs to C-type, whereas the starch of LSCY from loessial soil has the A-type pattern. The results suggested that the two types of soil and continuous cropping change the compounds and contents of yams, which provide valuable evidences for cropping management and allelopathy effects.