向日葵菌核病拮抗菌的筛选、鉴定及防效测定

背景] 由核盘菌（Sclerotinia sclerotiorum）引起的菌核病是影响向日葵产量的重要病害，近年来在我国内蒙古和甘肃等地频繁发生。目的] 挖掘能够对向日葵菌核病进行生物防治的拮抗菌株和有效方法。方法] 用4种不同的培养基通过稀释涂布法对向日葵健康植株的根际土壤菌群进行分离，利用平板对峙实验筛选出对核盘菌有抑制作用的菌株。选取拮抗作用较强的菌株进行向日葵离体叶片防效测定，采用形态学特征、生理生化特性结合16S rRNA基因序列分析进行菌种鉴定，并配制成不同单菌剂和复合菌剂进行盆栽实验，测定活体防效。结果] 从土壤中共分离出142株菌，从中筛选到12株抑菌圈明显的拮抗菌株。其中拮抗菌Bacillus sp.NM63、JQ134、J7、J33和Streptomyces sp.Z9、ZX6抑菌圈直径大于25 mm，这6株菌在向日葵离体叶片防效测定实验中效果显著。菌株NM63、JQ134、J7、Z9、J33和ZX6单菌剂盆栽实验的防治效果依次为79.06%、74.10%、70.72%、67.83%、65.11%和57.11%。菌株配比为Z9：NM63：JQ134：J7=1：1：1：1的复合发酵菌剂Ⅰ对向日葵盆栽的活体防效为81.43%，菌株配比为Z9：NM63：JQ134：J7=1：2：2：1的复合发酵菌剂Ⅱ对向日葵盆栽的活体防效为85.88%。结论] 筛选鉴定出多株对核盘菌具有较强抑制作用的拮抗菌株，复合菌剂Ⅱ对向日葵菌核病的防治具有显著效果。

Screening, identification, and biocontrol effect of antagonistic strains for control of sunflower sclerotinia rot

Background] Sclerotinia rot caused by Sclerotinia sclerotiorum is a major disease affecting the yield of sunflower and has occurred frequently in Inner Mongolia and Gansu of China in recent years. Objective] In order to discover antagonistic strains and effective methods for the biocontrol of sunflower sclerotinia rot. Methods] The microorganisms in the rhizosphere soil of healthy sunflower plants were isolated by dilution plating method with 4 different media, and then plate confrontation experiments were conducted to select the strains with antagonistic effects on S. sclerotiorum. The selected antagonistic strains were then tested for the control effect with detached leaves. They were identified based on the morphological characteristics, physiological and biochemical properties, and 16S rRNA gene sequence analysis. Finally, we mixed these strains at different ratios into different microbial inoculants for pot experiment to determine the in vivo control effects. Results] A total of 142 strains of bacteria were isolated from the soils, among which 12 antagonistic strains with an obvious inhibition zone were screened out. Bacillus sp. NM63, JQ134, J7, J33, and Streptomyces sp. Z9 and ZX6 exhibited the inhibition zone diameters greater than 25 mm and significant control effects in detached leaves. Strains NM63, JQ134, J7, Z9, J33, and ZX6 exhibited the control effects of 79.06%, 74.10%, 70.72%, 67.83%, 65.11%, and 57.11% on potted sunflower seedlings, respectively. The microbial inoculants I and II prepared with strains Z9, NM63, JQ134, and J7 mixed at the ratios of 1:1:1:1 and 1:2:2:1 had the control effects of 81.43% and 85.88%, respectively, for potted sunflower. Conclusion] The antagonistic strains with strong inhibitory effects on S. sclerotiorum were screened out and identified, and the compound microbial inoculant II had good performance in the prevention and treatment of sunflower sclerotinia rot.