棉花抗枯萎病品种连作田微生物数量变化*⒇Ⅱ棉花枯萎病抑病土成因

Changes of Microflora and Number of Microorganisms on the Monoculture of Resistance Cotton Varieties

从棉花抗病品种连作３、６、８、９、１０ａ的土样中分离出３８３０个真菌菌落，其主要类群归入１１个真菌属。随着棉花抗病品种连作年限的增长，土壤中真菌和放线菌的种类和数量逐渐增加，而棉花枯萎菌的数量则逐渐减少。对棉枯萎菌抑制性较强的种类有：细黄链霉菌（Ｓｔｒｅｐｔｏｍｙｃｅｓｍｉｃｒｏｆｌａｖｕｓ）、球孢链霉菌黄色变种（Ｓ．ｇｌｏｂｉｓｐｖａｒ．ｆｌａｖｕｓ）和紫链霉菌淡红变种（Ｓ．ｖｉｏｌａｃｅｕｓ）。供试土样中分离到的３３１５个细菌菌落按菌落特征可分为９个类型，其中Ⅲ型和Ⅸ型对棉枯萎菌有较强的抑菌作用，初步鉴定为枯草芽孢杆菌Ｂａｃｉｌ－ｌｕｓｓｕｂｔｉｌｉｓ．和Ｂ．ｓｐ．，它们在连作年限较长的土样中出现的频率较高，但土样中细菌的总数量与棉花抗病品种连作的年代成反相关。供试土样中分离出５种主要线虫，其中螺旋线虫、滑刃线虫、真滑刃线虫的数量也随抗病棉花连作时间的延长而增加。

The major groups of the 3 830 fungi colonies from soil samples have been divided into 11 genera. As monoculture of resistance cotton varieties(MRCV) is increasing in years,the species and number of fungi are augmenting,but pathogens of fusarium wilt are getting less and less.The species and amount of actinomyces are more and more as MRCV is increasing in years. Actinimyces restricting Fusarium oxysporium f.sp. vasinfectum are Streptomyces globisporus var . flavus,S.microflavus, S.violaceus . The more years of MRCV are, the more number of Bacillus subtilis, B .sp.and some nematodes, but amount of bacterium are diminishing.