Screening Nonhost Crops Resistant To Fusarium Oxysporum F.SP. Niveum And Research On The Antifungal Mechanism

Watermelon under monocropping is susceptible to e.g., fusarium wilt. Fusarium wilt is a destructive disease causing severe yield and quality losses. Infections in watermelon are difficult to cure and seriously hamper the expansion of watermelon production. Hence, we hope to apply a practical and safe method based on allelopathy for control of watermelon wilt. Ideally, this control method would be based on the microbial ecology of the rhizosphere and would be compatible with existing agricultural practices. Screening plant and root exudates for biocidal activity on Fusarium oxysporum f.sp. niveum might allow identification of the antifungals involved. Analysis the root exudates composition then find out which compound inhibit the pathogen and research its resistance mechanism of the active ingredient. The research project to ameliorate the ecological environment of watermelon planting soil, establish the ecological basis for the safety system of watermelon production, develop biological antagonists of melon wilt.Content and results of this study as the following:1The effects of root exudates from pepper, bean, wheat, oat, and onion were evaluated on Fusarium oxysporum f.sp. niveum. Different concentrations of root exudates were added to potato dextrose agar (PDA) medium to investigate their effects on mycelial growth, and spore and fungal biomass production. Mycelial growth was stimulated by root exudates of pepper, suffered no effect by those of bean, and was inhibited by those of wheat, oat and onion. The inhibitory effects wheat, oat, and onion root exudates on growth of Fusarium oxysporum f.sp. niveum was concentration-dependent. Onion root exudates exerted the highest antifungal effect on the growth of Fusarium oxysporum f.sp. niveum, followed, in order of inhibitory effect, by wheat and oat.2The effects on watermelon Fusarium wilt of oat intercropping with watermelon, onion intercropping with watermelon and wheat intercropping with watermelon applied in nursing media (the turf and the vermiculite in the volume ratio of1to1) inoculated with Fusarium oxysporum f.sp. niveum were studied. The results showed that:oat intercropping with watermelon, onion intercropping with watermelon and wheat intercropping with watermelon could relieve watermelon Fusarium wilt. 3The root exudates composition of nine varieties wheat analysis by GC-MS and correlation analysis between the detected compounds of the nine varieties wheat and the inhibition of the pathogen showed that:the roots exudates of different varieties wheat are disparity; Compound10exist in the root exudates of the four varieties which inhibition of the pathogen is not obvious; on the other hand Compound22is only exist in the root exudates of the five varieties which inhibition is significant. There are Compound5、10and13, the content of which positively related to colony diameter of108h level Fusarium oxysporum f.sp. niveum. And the content of Compound17、19、20、21and22negatively related to108h level colony diameter.