稻瘟病菌拮抗细菌的筛选及其防效作用研究

Screening and Evaluation of Antagonistic Bacteria against Rice Blast

从黑龙江省16个市县采集水稻根系土壤,利用平板画线分离获得579株细菌。通过平板对峙法进行抑菌试验,筛选获得一株拮抗细菌Sc2。该菌株对稻瘟病菌抑菌率达73.44%。经形态、生理生化特性和16S r DNA序列分析,Sc2被初步鉴定为枯草芽孢杆菌。Sc2无菌发酵上清液对稻瘟病菌菌丝生长和分生孢子萌发均有显著的抑制作用。随着稀释倍数的增加,抑制效果逐渐下降,其中将浓度为1.8×108cfu/m L的无菌发酵上清液稀释至40倍时,对稻瘟病菌分生孢子萌发的24 h抑制率及菌丝生长的7 d抑制率仍达60%以上。室内盆栽试验结果表明,Sc2对稻瘟病的防治作用主要在预防,Sc2与三环唑按1∶2混配,防治稻瘟病的防效达90.33%。

579 bacteria strains were isolated from rice rhizosphere soil in 16 counties of Heilongjiang Province by way of streak plate method. A strain of Sc2 was finally selected to have strong inhibitory activity against Magna- porthe oryzae with the inhibition rate of 73.44% by plate confrontation method screening. Combined with its colony morphology, biochemical characteristics and 16s rDNA sequence analysis, the strain Sc2 was confirmed to be Bacillus subtilis. The Sc2 had strong inhibitory activity against the hypha growth and spore germination of M. oryzea. With increase of dilution ratio, inhibitory activity was gradually decline. The inhibition rate of spore germination after 24 h and hypha growth on 7 d was more than 60% with 40 times diluent of 1.8× 10^8 cfu/mL fermentation liquid. Resuits of indoor pot experiment showed that the Sc2 prevention was mainly in the prevention of rice blast. Preventive efficacy was 90.33% when Sc2 was mixed with tricyclazole by 1：2.