Abstract:Fusarium head blight (FHB) caused by Fusarium graminearum which utilizes straw as main growth media in field is the main factor leading to reduction of wheat yield and quality. Biological control with various antagonistic organisms is one of the most effective methods to prevent and control FHB, however, it is not clear whether the antagonistic effect of antagonistic organisms in straw degradation process is in accordance with that in plate confrontation experiment. In this study, three kinds of strains with potential antagonistic effects on F. graminearum CGMCC3.4598 were primarily screened out through plate confrontation culture, they were Streptomyces hygroscopicus ACCC41648, S. hygroscopicus var. jingganggensis ACCC40051, and S. rochei ACCC41594, and the average width of their antifungal bands were 2.67, 1.67 and 1.12 mm, respectively. Next, based on indoor 70-day culture experiment, we found that after 7, 42 and 70 d of straw degradation, S. hygroscopicus ACCC41648 and its variant ACCC40051 did not show any antagonistic effect on the growth of F. graminearum in residual straw, while S. rochei ACCC41594 respectively reduced the abundance of F. graminearum in residual straw by 30.91% and 69.28% after 7 d and 42 d of straw degradation. Compared with the control (no antagonistic organisms were added), S. rochei ACCC41594 significantly promoted straw degradation, increased cumulative emission amount of CO2-C, and reduced the size of easily mineralizable carbon in straw. Further correlation analysis found that the abundance of F. graminearum in residual straw had significant negative correlation with total potassium content of straw at 7 d (P<0.01), positive correlation with easily mineralizable carbon content of straw at 42 d (P<0.05), and positive correlation with total nitrogen content of straw and negative correlation with C/N of straw at 70 d (P<0.01). The above results indicated that the antagonistic strains screened from the plate confrontation may not always reappear their antagonistic effects during straw degradation. The results further indicated that the inhibition effect of S. rochei ACCC41594 on the growth of F. graminearum CGMCC3.4598 during straw degradation may be through its direct antagonism, or through its indirect effect that changing residual straw properties when it promoted straw degradation.