Effects of successive cropping Rehmannia glutinosa on rhizosphere soil microbial flora and enzyme activities
地黄连作对根际微生物区系及土壤酶活性的影响

With the soils cropped Rehmannia glutinosa for one and two years as test materials, this paper studied the variations of microbial flora and enzyme activities in rhizosphere. The results showed that with increasing year of cropping, the numbers of bacteria and fungi in rihzosphere had a slight decrease. In the soil successively cropped R. glutinosa for two years, the number of aetinomyeetes in rihzosphere was 4 times higher, the ammonifier, aerobic azotobaeter, sulphate reducer, denitrifier, and anaerobic cellulose-decomposer increased by 25. 99, 45. 39, 11.43, 1.36, and 1.43 folds, respectively, while aerobic cellulose-decomposer reduced by 86. 74% , compared with those in the soil cropped R. glutinosa for one year. The root exudates of successively cropped R. glutinosa increased the activities of urease, polyhphenol oxidase, sucrase, protease and cellulase in rhizosphere by 62. 87%, 9. 43%, 47.91%, 139. 62% and 31.33%, respectively, but inhibited the activity of catalase. The findings suggested that successive cropping R. glutinosa would destroy the balance of rhizosphere soil microbial flora.