LIU Hong-Mei, ZHAO Jian-Ning, HUANG Yong-Chun, ZHANG Gui-Long, ZHANG Hai-Fang, YANG Dian-Lin
A pot experiment compared transgenic Bt+CpTI cotton cultivar sGK321 with conventional cotton cultivar Shiyuan 321 (check) to investigate the effects of nutrients in rhizosphere soil (total nitrogen, total phosphorus, available phosphorus, organic matter) and the activities of some enzymes (urease, alkaline phosphatase, and catalase) in four growing stages(seedling, budding, flower and boll, boll opening). Results showed that there were no significant differences between the two cotton cultivars in total and available phosphorus in rhizosphere soil during the experimental period. Remarkable differences, however, existed between the transgenic Bt+CpTI cotton cultivar and its conventional check in terms of total nitrogen, organic matter, and enzyme activity in rhizosphere soil. For transgenic Bt+CpTI cotton, total nitrogen at the budding stage, catalase activity at the seedling stage, and alkaline phosphatase activity at the seedling and budding stages were significantly higher than its conventional check Shiyuan 321. By contrast, organic matter in rhizosphere soil at the budding stage, catalase activity at the budding stage, urease activity at the seedling and flower and boll stages, and alkaline phosphatase activity at the seedling stage were significantly lower than the check. Cluster analysis showed that the changes of nutrients and enzyme activities in rhizosphere soil were mainly affected by the growth stages, whereas the impact of transgenic Bt+CpTI cotton planting on the main nutrients and enzyme activities was very limited.