ارزیابی تعدادی جدایه ی باسیلوس در کنترل قارچ بیمارگر فوزاریوم سولانی خیار

Several pests and diseases from the time of seed planting and seedling production to the time of fruit harvest reduce the yield of greenhouse cucumber. Fusarium is one of the most important plant pathogenic fungi, which causes serious damage to the cucurbit plants in Iran. Several species of the genus Fusarium have been identified as pathogens in the Cucurbitaceae, one of the most important of which is Fusarium solani f.sp. cucurbitae and is associated with wilting, crown, root and stem rot. Usually, the initial symptoms appear as wilting of the leaves in the field, followed by crown rot and finally the death of the plant. No commercial cultivars resistant to this disease have been identified. Given the soilborne and seedborne nature of the pathogen, various agricultural, physical, and chemical methods are used in greenhouses and cucumber fields for control, but no completely effective control method exists. Among these, the use of biological compounds such as various species of the genus Bacillus provides an appropriate solution for controlling soilborne diseases alongside other methods. In the present study, the effect of volatile and non-volatile metabolites of fourteen isolates from the genus Bacillus against Fusarium solani f.sp. cucurbitae was investigated. The analysis of volatile metabolites was carried out using two Petri sandwich method and the use of two-compartment Petri dishes over two time periods of three and five days. Investigation of non-volatile metabolites was carried out by investigating the possibility of antibiotic production in PDA culture medium in the presence of pathogenic fungi in laboratory conditions. Also, the effect of the selected isolates on the morphology of the mycelia of pathogenic fungus was investigated in vitro. Additionally, the impact of selected isolates on the morphology of the pathogenic fungus mycelium was examined. In all laboratory tests, after the specified duration, the growth of the pathogenic fungus colony in the bacterial treatments was compared to the control (P < 0.05). Based on the results, all Bacillus isolates restricted the growth of the pathogenic fungal colony compared to the control, but the Bacillus mojavensis -Ba1 strain showed the best performance with 29.72% and 61.02% inhibition on the third and fifth days respectively in the volatile metabolites assay, and 83.73% inhibition in the non-volatile metabolites test. Compounds produced by the Ba1 strain led to wall degradation and fragmentation of the fungal mycelium. Greenhouse experiments regarding the antagonistic ability of the B. mojavensis-Ba1 strain in interaction with the fungal pathogen Fusarium solani f.sp. cucurbitae are currently underway.