生防菌芽孢杆菌可湿性粉剂的研制及其对油菜菌核病和黑胫病防效评价

Water wettable powder formulation of Bacillus velezensis CanL-30 and evaluation for biological control of Sclerotinia stem rot and blackleg of oilseed rape

将健康油菜植株中分离到的贝莱斯芽孢杆菌菌株CanL-30,分别在10 L发酵罐以及1 t和10 t发酵罐发酵,观察其发酵过程中菌体增长及芽孢发育动态,并制备成可湿性粉剂,研究该可湿性粉剂的抗真菌活性及防病增产效果。结果显示:菌株CanL-30在3种发酵罐中发酵时均可产生芽孢,在1 t和10 t发酵罐中发酵36 h后,芽孢形成率达到93%,活菌量分别达到1×10^(10)和3.3×10^(9) cfu/mL。采用喷雾干燥的方法制备CanL-30菌粉,添加助剂后制备成可湿性粉剂(每克粉剂活菌数量达到1000亿,54℃粉剂的热贮稳定性、悬浮性和湿润性等指标均符合农药可湿性粉剂国家标准)。在培养基上的活性测试结果显示:可湿性粉剂对油菜菌核病菌菌丝生长及菌核形成,以及对油菜黑胫病菌分生孢子萌发均有抑制作用。室内防病试验结果显示:可湿性粉剂能有效抑制油菜菌核病菌和黑胫病菌的侵染。田间防病试验结果显示:在蕾薹期和花期喷施可湿性粉剂防治油菜菌核病和黑胫病的效果分别为55%和42%,与杀菌剂咪鲜胺的防效(对菌核病和黑胫病的防效分别为51%和37%)没有显著差异,与自来水对照处理相比,在天门市和赤壁市试验点使用CanL-30可湿性粉剂导致油菜籽产量分别增加14%和12%。以上结果表明,芽孢杆菌CanL-30可湿性粉剂对油菜菌核病和黑胫病都有一定的防效,并可提高油菜籽产量。

Strain CanL-30 of Bacillus velezensis was incubated in 10-L,1-ton and 10-ton jar fermenters for characterization of bacterial growth and endospore development.A water wettable powder of CanL-30 was formulated based on the endospores from the bacterial cultures,and the powder was evaluated for efficacy in control of Sclerotinia stem rot and blackleg of oilseed rape.The results showed that CanL-30 could grow and form endospores in the fermenters.After incubation at 30℃for 48 h in the 10-L fermenter,for 36 h in the 1-t fermenter and for 40 h in the 10-t fermenter,the endospore formation rates were 74%,93%and 92%,respectively.In the 1-t and 10-t fermenters,the final bacterial yield reached 1×10^(10) cfu/mL and 3.3×10^(9) cfu/mL,respectively.The resulting bacterial cultures were dried by heat spray,and a water wettable bacterial powder(1×10^(11) cfu/g)was prepared by amending the bacterial powder with related additives.The formulated powder conforms to the national standard of wettable powder pesticides regarding the thermal stability(54℃),suspension ability and wettability.The results of the bioactivity tests on agar medium showed that the powder had the antifungal activity against mycelial growth/sclerotial formation by S.sclerotiorum,and conidial germination of L.biglobosa.The result of the indoor biocontrol assay showed that the powder effectively suppressed infection by S.sclerotiorum and L.biglobosa on leaves of oilseed rape.The result of the field biocontrol assays in Tianmen City and Chibi City of Hubei Province showed that the powder suppressed Sclerotinia stem rot and blackleg by 55%and 42%,respectively,and the efficacy were not significantly different(P>0.05)from those in the treatment of the fungicide prochloraz,which suppressed Sclerotinia stem rot by 51%and blackleg by 37%.Compared to the control treatment,the application of the CanL-30 powder significantly(P<0.05)increased the yield of seeds of oilseed rape by 14%in the Tianmen trial and 12%in Chibi trial.These results suggest that the water wettable powder of CanL-30 can effectively suppress Sclerotinia stem rot and blackleg of oilseed rape,and meanwhile,it can enhance the seed yield of oilseed rape.