球孢白僵菌在玉米根际的定殖及对根际微生物的影响

通过分生孢子诱变法获得了球孢白僵菌抗多菌灵突变株,测定球孢白僵菌不同抗性突变株对多菌灵的抗性水平及遗传稳定性.选择其中对多菌灵EC50为245.0697,抗性水平指数达到229.29的抗性突变株BC-8菌株作为定殖菌株.采用盆栽接种试验和涂抹平皿法测数等方法研究球孢白僵菌抗性突变株BC-8菌株在玉米根际的定殖能力及对根际微生物数量的影响.结果表明:BC-8菌株可以在玉米外根际和根表定殖,但未在根内分离到;玉米移栽后28 d,外根际、根表的分离数量达到最大值；用BC-8菌株分生孢子悬浮液处理玉米幼苗后,玉米根际细菌、真菌及放线菌的数量均比对照减少;玉米移栽后14d,根际细菌、真菌、放线菌的数量与对照相比都有大幅度的减少;移栽后28 d,根际各种微生物的数量都有所增加,但与对照相比,仍呈减少趋势;移栽后42 d,根际微生物的数量趋于稳定.

Colonization of Beauveria bassiana in Corn Rhizosohere and its Effect on Rhizosohere Microorganisms

The carbendazim-resistant strains of Beauveria bassiana were induced by conidia mutagenesis method. Among them, the BC-8 strain showed the highest resistant level about 229.29 and its EC50 was 245.069 7. In the colonization test, the colonization ability of B. bassiana in the corn rhizosphere and the numbers of corn rhizosphere microorganisms were studied by means of pot planted and Petri dish smearing method. The results showed that BC-8 could colonize in the corn rhizosphere and corn root surface, but not in the roots. The number of propagules isolated from corn rhizosphere and root surface was the largest at the 28th day. The various microorganisms in rhizosphere were influenced by BC-8 and the number of them reduced compared to control group. The number of fungi, bacteria and actinomyces reduced distinctively compared to control group at the 14th day, while at the 28th day after transplanting, the number of rhizosphere microorganisms have rebounded, but continued to show decreasing trend. When at the 42th day after transplanting, the numbers of all the microbes were as same as the control group.