辣椒疫病拮抗菌株筛选、鉴定及其防效

从疫病发病严重田块的健康辣椒植株根际分离到98株拮抗菌,从中筛选出两株具有广谱抗性并可在贫营养条件下生长良好的高效拮抗菌株HL-3和LZ-8.通过形态观察、生理生化特性和16S rDNA序列分析,确定HL-3为多粘类芽孢杆菌,LZ-8为短小芽孢杆菌.HL-3和LZ-8对辣椒疫霉菌丝生长抑制率分别为72%和68%.HL-3和LZ-8还对黄瓜枯萎病菌、辣椒枯萎病菌、棉花黄萎病菌、黄瓜立枯病菌、烟草黑胫病菌和番茄青枯病菌具有显著的抑制作用.盆栽试验表明,HL-3和LZ-8对辣椒苗期疫病防治效果分别为72%和83%,且对辣椒生长表现出明显的促生作用.

Screening,identification,and biocontrol effect of antagonistic bacteria against Phytophthora capsici

A total of 98 isolates with antagonistic activity against Phytophthora capsici were isolated from the rhizosphere soil of healthy pepper plants inthe fields seriously infected by pepper Phytophthora capsicit, and two strains named as HL-3 and LZ-8 were screened, which had the characteristics of wide-spectrum antagonism and good growth under poor soil condition. The HL-3 and LZ-8 were identified as Paenibacillus polymyxa and Bacillus pumilus, respectively, based on their morphological and biochemical characteristics and 16S rDNA sequences. The two strains could inhibit the mycelium growth of P. capsici, and the inhibitory effect of HL-3 and LZ-8 was 72% and 68%, respectively. The two strains also had antifungal activities toward other plant pathogens such as Verticillium dahliae, Fusarium oxysporum f. sp. cucumerinum, F. oxysporum f. sp. vasinfectum, Rhizoctonia solani, Phtophthora parasitica var. nicotiana, and Ralstonia solanacearum. Pot experiment showed that the biocontrol effects of HL-3 and LZ-8 against P. capsici at the seedling stage of pepper were 72% and 83 %, respectively, and both of the strains had significant growth-promoting effect on pepper plants.