The Study On Dynamic Changes Of Soil Nutients, Enzymes Activities And Microorganism In Rhizosphere Of Tobacco

In order to reveal the mutative regularity of soil fertility in different soil types during flue-cured tobacco(N icotianatobacum L ) growth, leaching Cinnamon soil, infant Cinnamon soil, calcareous Cinnamon soil and red clay were typical soils and selected for measuring soil nutrient, enzymes activities and microbial community in the rhizosphere of tobacco during its growth periods. Addtionally, the rhizosphere of four typical soils during the resettling growth stage, fast- growing stage and maturing stage were also selected for studing community structures of microorganisms and their dynamics by PCR-DGGE. The main results are as follows:(1) Contrary to rhe changes of the organic matter, the soil PH changes of four typical soils were descend first, reaching the minimum at fast growing stage, and then ascend. The changes of hydrolysis-N, available-K and available-P in calcareous Cinnamon soil were different from the other three types soils, and their maximum of 4 different soil types were at different stage, but hydrolysis-N were descend first, reaching the minimum at different stage, and then ascend. The five soil nutritions of the four typical soils varied significantly at 0.05 level among most adjacent periods. Moreover, the organic matter and hydrolysis-N contents of calcareous Cinnamon and leaching Cinnamon soil were higher, and the available-K and available-P contents of infant Cinnamon and calcareous Cinnamon soil wre also higher.(2) The five enzymes activities of four typical soils were all descend first, and then ascend. The catalase activities varied significantly at 0.05 level among the first and last stage, and the other four types enzymes activities changed significantly at 0.05 level at most adjacent periods. Moreover, the maximum of this five enzyme activities in four typical soils were at different stages. In resettling growth, fast-growing or mature stage, the peroxidase, polyphenol oxidase and invertase activities of infant Cinnamon soil and calcareous Cinnamon soil were higer, meanwhile urease acitivity of infant Cinnamon soil and polyphenol oxidase acitivity of red clay were both higher too.(3) K-releasing bacteria's amount of four soil types all rose first, decreased second, rose third and decreased at last, and changed significantly at 0.05 level at most adjacent periods. But the other six varieties rose first and then decreased. Bacteria, actiomycetes, fungi, ammonifying bacteria and phosphobacteria varied significantly at 0.05 level among most adjacent periods. Bacteria, actiomycetes, ammonifying bacteria, abiogenous azotobacter, phosphobacteria and K-releasing bacteria's amout of infant Cinnamon and calcareous Cinnamon soil were higher in rosette, fast-growing or mature stage, meanwhile leaching Cinnamon soil's fungi and actiomycetes amout were also higher.(4) There are a close relationship among soil nutrients, enzyme activities and microorganisms in rhizosphere soil. The seven varieties of bacteria, soil nutients and soil enzyme activities were all more or less relationship. Morever, many positive relationship were significant at 0.05 or 0.01 level.(5) The quantity and Shannon-Wiener index (H) of leaching Cinnamon were the highest at fast-growing stage, the infant Cinnamon soil at resettling growth and fast-growing stage. Shannon-Wiener index (H) of the red clay was the highest at fast-growing stage, but the Shannon-Wiener index (H) of calcareous Cinnamon soil nearly unchanged. Addtionally, the four soil types had its own characteristic bacteria. By comparison at the same period, the Shannon-Wiener index (H) of infant Cinnamon soil were higher at the resettling growth stage, the calcareous Cinnamon soil at the resettling growth and maturing stage, the red clay at fast- growing and maturing stage. The changes of Simpson index (D) were oppsite to Shannon-Wiener index (H).