摘要：The loss of crop production caused by weeds has become a serious threat to many important crops. The utilization of microorganism metabolites is considered as an effective method towards a wide variety of weeds in the field. In this study, sixty-eight strains were isolated from weed plants with infections symptom. Each strain was cultured in submerged liquid medium. Culture filtrate was obtained from fermented broth by filtration and it was used to determine herbicidal activity both in vitro and in vivo with two target weeds: Avena fatua and Brassica juncea. The results indicated that seven strains exhibited potent herbicidal activity against A. fatua and B. juncea and therefore chosen for secondary screening. Notably, GD-2 and PA-2 strain showed different highest toxicity to target weeds. Culture filtrate of GD-2 was most toxic to A. fatua while PA-2 was most toxic to B. juncea. Further deep study on crop safety indicated that GD-2 was least toxic to broad-bean, pea and oil rapeseed while the effects of PA-2 were varied on crop tested and range from moderate to high toxicity. Culture filtrates from both strains induce protective enzyme activity in weeds and an obvious decrease in chlorophyll content, soluble sugar and protein content. It could increase the malondialdehyde content and conductivity value. Based on the culture characteristics and the internal transcribed spacer (ITS) sequence, the GD-2 and PA-2 strain were identified as Fusarium avenaceum and Aureobacidium pullulans, respectively. Overall, two fungi strain might have potential to be developed as herbicidal agents against A. fatua and B. juncea and hope to be further applied to sustainable agriculture.
