Isolation And Identification Of Herbicidal Fungi From Soil Against Wild Oats

In this study,25 strains were isolated from soil samples collected in Kanbula.A strain NO.6 with strong herbicidal activity was obtained by screening the fermentation filtrate of each strain.The inhibition rates of NO.6 on the plumule and radicle of wild oat seeds were 91.20%and 93.10%,respectively.The strain NO.6 was identified by morphology and molecular biology,and we isolated and purified its herbicidal active components,in order to provide new materials for the development of new herbicides,as well as theoretical basis for the development of biopesticides with higher efficiency,lower toxicity and lower residue.The main findings were summarized below:1.ITS rDNA sequencing of strain NO.6 indicated that the homology between strain NO.6 and Beauveria sp.were more than 99.0%.Combining with morphological characteristics,strain NO.6 was identified as Beauveria bassiana.2.The extraction organic solvent of herbicidal substance of metabolite of strain NO.6 was determined.Petroleum,ethyl acetate and n-butanol of equal volume were extracted three times.The crude extract was obtained by reducing pressure.The results showed that ethyl acetate was the best organic solvent for extraction.The crude extract had the best inhibiting activity on the germination of wild oat seeds,and its inhibiting rates on plumule and radicle were 97.09%and 96.08%,respectively.3.The crude extract of ethyl acetate was separated and purified by silica gel column chromatography and thin layer chromatography.The results indicated that 16fractions were obtained,of which fraction Fr4 had obvious inhibitory effect on the germination of wild oat seeds.The inhibitory rates of Fr4 on plumule and radicle were96.90%and 96.88%,respectively.4.Analysis of herbicidal active components of metabolites of strain NO.6 by HPLC.The results showed that under the condition of the mobile phase was 48%methanol,the wave length was 220 nm and the flow rate was 3 mL min^-1,the herbicidal active component 3 with retention time of 66.868 min was obtained.The inhibition rates on the plumule and radicle of wild oat were 87.74%and 93.17%,respectively.