防治稻瘟病芽胞杆菌的筛选及效果评价

从232株细菌中筛选获得2株对稻瘟病菌具有明显抑菌活性的菌株S09和S170，对稻瘟病菌Magnaporthe oryzae P131菌丝的抑制率分别为90.44%和92.38%；离体叶片法测定表明，菌株S09和S170抑菌效果分别为74.62%和75.52%，与绿地康1号无显著差异。16S rDNA序列分析比对，菌株S09与短小芽胞杆菌Bacillus pumilus基因序列的同源性最高；gyrA基因测序结果表明，菌株S170与解淀粉芽胞杆菌B.amyloliquefaciens基因序列的同源性最高。结合形态观察，确定菌株S09为短小芽胞杆菌，菌株S170为解淀粉芽胞杆菌。菌株S09和S170对稻瘟病的温室防治效果分别是76.56%和80.57%。田间试验结果表明，菌株S09和S170对水稻有明显的促生和增产作用，分别提高水稻种子发芽17.37%和12.34%、促进根长18.68%和33.85%、增加株高12.44%和28.49%、降低空秕率25.17%和35.59%，还可以有效改善稻米的垩白粒率和垩白度。短小芽胞杆菌S09和解淀粉芽胞杆菌S170对叶瘟的田间防治效果分别是70.59%和73.19%，对穗颈瘟的田间防治效果分别是71.55%和74.82%，菌株S170对稻瘟病的防治效果与75%三环唑可湿性粉剂、绿地康1号处理无显著差异。

Screening and Control Efficiency Evaluation of Bacillus against Rice Blast Magnaporthe oryzae

232 bacterial strains were isolated from rice rhizosphere of cultivar Ningjin NO. 48 in Ningxia Hui Autonomous Region. Only two isolates, S09 and S170 strongly inhibited the growth of Magnaporthe oryzae in dual culture technique and leaf blade in vitro. The hyphal growth inhibition rate of strains S09 and S170 on M. oryzae cultured after 4 d were 90.44% and 92.38%, respectively. The control efficacies in leaf blades were 74.62% and 75.52%, respectively, without significant difference from that of Lvdikang NO. 1. 16S rDNA sequence analysis indicated that strain S09 had the highest homology with B. pumilus. gyrA gene sequence analysis indicated that S170 had the highest homology with B. amyloliquefacien. Combining with its the morphological characteristic, the strains S09 and S170 were identified as B. pumilus and B. amyloliquefaciens, respectively. The control efficacies of strains S09 and S170 against rice blast were 76.56% and 80.57% under greenhouse condition, respectively. Field trials showed that strains S09 and S170could promote rice growth, increase the germination rate by 17.37% and 12.34%, promote rice root length by 18.68% and 33.85%, enhance rice plant height by 12.44% and 28.49%, and reduce empty-grain percentage by 25.17% and 35.59%, respectively. Moreover, both trains could improve chalky grain rate and chalkiness ratio. Field control efficacies of B. pumilus S09 and B. amyloliquefaciens S170 were 70.59% and 73.19% against leaf blast, and 71.55% and 74.82% against neck blast, respectively. The control efficacy of strain S170 had no significant difference with that of 75% tricyclazole wettable powder or Lvdikang NO. 1.