Study On The Biocontrol Of Wheat Scab (Fusarium Graminearum) With Bacillus Subtilis BS_3-1 Strain

According to the morphological and physilological characteristics, it was identified to B.subtilis isolated from the healthy leaf and ear of the sickly wheat, which was strong antognistic to wheat scab and was named as BS3.1.BS3.1 strain was strong antognistic to Wheat scab. The inhibition zone of leavening of BS3.1 strain for 72 hour to pathogen of wheat scab was 5mm when they faced with each other. The inhibition could be strenghthened one times than forming strain through DES inducing. The result showed that the inhibition zone to F.graminearum could become 10mm from 5mm.BS3.1 can produce a kind of volately fat dissolving antifungal component which can get a sort of water solving protein through the unpack purification on Sephadex G-100 and DEAE 52 layers. This kind of protein is tolerant of higher temperature and the basic condition. The molecular weight of untifungal protein whose inhibition zone to hypha reaches to 18mm is between 31.OKD~43.OKD. The inhibition zone could be 18mm, if the value of purified protein was 3.23mg/ml.Antifungal protein had a significant activity against the germination of spore and the growth of hypha, whose mechanism is that it can prevent the germination of spore and make the spore and hypha malformed, make the inclusion of hypha let out until the hypha be collapsed completely, in which course the cell play the part of competition and the antifungal protein play the part of inhibition.This study had proved that BS3.1 can gain such the most sporulation number as 3.38 109CFU/ml , if the media is corn plasm with 4.8mmol/L Mn2+and other condition is pH7.2,32 , 4/5 provided oxygen supply and 72h. The powder made of the spore of BS3.1 endured storing and had higher survival rate.BS3.1 can effectively prevent Wheat scab, but it can't cure Wheat scab efficiently. The best method of controlling Wheat scab is that we should spray the leavening of BS3.1 for 72 hour whose concentration is 2 108CFU/ml before anthesis of wheat for 5 dayes, in this way we can get so highest relative control effect in field as 69.01% which had be close to the relative effect of Bavistin fungicid (70.66%).When we use the powder made of the spore of BDS3.1 whose concentration is 2 108CFU/ml before anthesis of wheat for 5 dayes, its relative control effect in field was 58.1%, which had potential marked value.