جداسازی سویه‌های باسیلوس سوبتیلیس از خاک چند منطقه در استان یزد و بررسی اثر ضد قارچی آن‌ها بر روی قارچ Fusarium oxysporum f.sp. radices-cucumerinum عامل پوسیدگی ریشه گیاه خیار

Greenhouse cucumber is one of the important agricultural products in the country, particularly in Yazd province. Many factors are known as limiting the growth and development of greenhouse cucumber in the country, among the most important of these factors is the stem and root rot of greenhouse cucumber caused by the fungus Fusarium oxysporum f.sp. radices-cucumerinum, which every year causes great damage to the cultivation and production of this important crop in the country, including Yazd province. Currently, the most common control method is the use of chemical fungicides, and due to the soil-borne nature of the disease, the use of chemical methods does not have much effect in controlling this disease, and farmers are forced to repeatedly use chemical compounds, which in addition to the cost It causes pollution and destruction of the natural environment. It is inevitable to use alternative ways to control this disease that do not cause environmental pollution. Using beneficial micro-organisms such as bacteria is one of the best and most reasonable ways to control pathogens. this research was conducted with the aim of investigating the ability of Bacillus subtilis bacteria strains to control fusarium stem and root rot of greenhouse cucumber in laboratory and greenhouse conditions. For this purpose, fifty indigenous Bacillus antagonists were isolated from the soil of pastures, deserts, and pristine highlands in different geographical regions of Yazd province. From these, during morphological (colony shape and gram staining) and molecular (specific primer and 16S rRNA) studies, seven Bacillus subtilis isolates were selected and their effect on Fusarium fungus in laboratory conditions using the cross-culture method (simultaneous culture Fungi and bacteria in SDA in culture medium) were investigated. Laboratory investigations showed that three isolates had a high antifungal effect and significantly reduced the growth of pathogenic fungi in vitro. In the next stage, the effect of three selected isolates (BS-T1, BS-T3, BS-T4) in greenhouse conditions on the control of stem and root rot disease of greenhouse cucumber plants during a factorial experimental design with three factors, treatment (selected isolates, fungus Commercial biological, carbendazim chemical fungicide application times (0, 96 and 192 hours) and concentrations (0, 0.1, 0.3 and 0.5%) were evaluated in 5 replicates, meanwhile, the soil of the pots with Wheat infected with the fungus was mixed and irrigated with different concentrations of isolated strains at the same time as seed cultivation. During the greenhouse tests between the treatments, the BS-T4 isolate compared to the other two isolates had the highest rate of inhibiting the growth of fungi in laboratory conditions and in greenhouse conditions. The findings of this study strongly suggest that it is possible to control Fusarium root and stem rot of greenhouse cucumber by using Bacillus subtilis antagonist bacteria.