کنترل زیستی پژمردگی فوزاریومی سیکلامن با استفاده از Bacillus subtilis

Cyclamen (Cyclamen persicum) is one of the potted ornamental plants that is especially popular in winter. Fusarium wilt caused by Fusarium oxysporum f. sp. cyclaminis is the most common disease of cyclamen in greenhouses. Most cyclamen varieties are highly susceptible to Fusarium wilt and the use of chemical fungicides to control the disease has not been successful. In the present study, bacterial isolates were isolated from the cyclamen rhizosphere and the ability of them to inhibit the growth of Fusarium was investigated on PDA medium. Then, the superior isolates that corresponded to the Bacillus subtillis species were selected and investigated for the control of cyclamen Fusarium wilt disease under greenhouse conditions. In this study, cyclamen (26-week-old plants) tubers and roots were immersed in a 1% solution of carboxymethylcellulose containing B. subtillis isolates (1×109 CFU per mL) and planted in pot. Then, 1 gram of the pathogen's inoculum (rice seeds colonized with the fusarium) was added around the tuber and roots of each plant. The pots were placed in greenhouse conditions at 22 ° C/ 17 ° C (day/night) and grew for 8 weeks. Five isolates of bacteria and fungicide (Equation pro) were evaluated in this study. The results of disease control (plants at week 34) showed that isolate G5 with 62.5% control, exhibited the strongest activity to reduce fusarium wilt. Isolates M12, G8, G1 with 56.25, 56.25 and 50% control, respectively, placed in the next group and did not show a significant difference with fungicide treatment. There was no significant difference between M4 isolate and infection control. In vitro results showed that the antibiosis (9 mm inhibition zone against F. oxysporum) and competition (colonization of the environment) are the main mechanisms of G5 isolate to control the Fusarium wilt of Cyclamen. Finally, the identification of the secondary metabolites of B. subtilis G5 that involved in the disease control and the feasibility study of commercial production of B. subtilis G5 are suggested for future studies.