Abstract: To explore the relationships between podophyllotoxin content in Sinopodophyllum hexandrum and environmental factors and to screen the leading affecting factor, the samples of rhizosphere soil and underground parts were collected from six populations of S. hexandrum in Gansu. The podophyllotoxin contents of underground parts and 14 soil factors including moisture, pH, organic matter, total nitrogen, available phosphorus, available potassium, available iron, available copper, available manganese, available magnesium, total iron, total copper, total manganese, and total magnesium were determined. The correlations between podophyllotoxin contents in underground parts and soil factors, elevation and climate factors (annual temperature, annual rainfall, annual sunshine hours, annual maximum temperature, and annual minimum temperature) were analyzed by stepwise regression analysis and path analysis. The results showed that significant differences in podophyllotoxin contents existed among six populations and were relatively consistent within populations, basically with normal distributions. Stepwise regression analysis revealed a significant negative correlation between podophyllotoxin content and annual temperature, annual sunshine hours and total nitrogen in soil, which indicated that the three factors play a predominant role in affecting the podophyllotoxin content in S. hexandrum. Path analysis further revealed that the degree of effect of each factor on the podophyllotoxin content decreased in order of annual temperature, annual sunshine hours, and total nitrogen. These results indicated that appropriate low temperature, shortened sunshine time and decreased nitrogen fertilization could improve the podophyllotoxin content in cultivated S. hexandrum.

Key words: bacterial community, edaphic factor, driving force., seasonal dynamic, copper mine tailings