Effects and mechanisms of application with different bio-organic fertilizers in controlling Fusarium wilt of cucumber

Two kinds of strains, Bacillus subtilis SQR9 and Trichoderma harzianum T37 which are antagonistic to Fusarium oxysporum, were used in this study. Bioorganic fertilizers containing the antagonists either in nursery or in transplanted soils were applied to investigate the effects of three types of bio-organic fertilizers (BIOⅠ, BIO Ⅱ and BIO Ⅲ) on the controlling efficiency of Fusarium wilt in cucumber growth, and profile the colonization of these two strains on cucumber roots. Results showed: 1) As control, the incidence rate in pot experiment was assigned 100%, and the treatment with organic fertilizer (OF) was 88.2%, while the incidence rates of treated with BIOⅠ, BIOⅡ BIOⅢ were 51.0%, 19.6% and 13.7%, respectively. 2) The biomasses of cucumber treated with BIOⅠ, BIO Ⅱ and BIO Ⅲ, were 2.55, 2.46 and 2.58 times of the control, respectively. 3) Application of BIOⅡ and BIOⅢ could reduce the quantity of Fusarium oxysporum in rhizosphere of cucumber to 103 copies/g soil detected by realtime PCR, but 107 copies/g soil of Fusarium oxysporum was found in the control. SQR9 and T37 could be effectively colonized on the cucumber root surface and thus occupied the ecological sites in the rhizosphere. Study suggested that application of BIO could not only effectively suppress the occurrence of Fusarium wilt in cucumber, but also promote the cucumber growth.