بررسی کارآیی برخی از جدایه‌‌های تجاری وبومی Bacillus subtilisدرممانعت از رشدFusarium oxysporum f.sp. tuberosiعامل پژمردگی آوندی سیب‌زمینی

Vascular wilt is one of the most important diseases of potato in Iran which associated with a high financial losses for farmers every year. The biologica control can employ in integrated disease management system for reducing pesticide content of soils and developing sustainable agriculture as well. In this study, the efficiency of various commercial and native strains of Bacillussubtilis on suppressing Fusarium oxysporum f.sp. tuberosi(Fot) mycelial growth. The studied strains included four commercial strains (NB4, NB3, NB2, and NB1) and four native strains.Native strains was obtained from potato rhizosphere of Khorasan-Razavi fields (BS1, PB2, BS2, and PB1). Iprodione- Carbendazim applied at three doses (2, 3 and 6 ppm) as control treatment. The antagonistic activity of Bacillussubtilis against Fot was screened. The bioassay of data showed that the inhibitory effect of BS1, PB2, BS2, PB1, NB4, NB3, NB2 and NB1 was 93.8, 92.5, 72.5, 45.8, 45.8, 45.8, 45.8 and 44.5 respectively. The study of antagonistic effect of volatile compounds showed that the inhibitory effect of NB4, NB3, NB2, BS1, PB2, BS2 and PB1 was 79.16, 79.16, 65.83, 59.16, 90.75, 87, 85.75 and 54.52 respectively. At 6 ppm, Iprodione-Carbendazim limited mycelial growth by 85 percent. Results showed that the pathogen growth suppressed by all antagonistic strains of B. subtilis whereas various strains showed different inhibitory percent. There was no significant difference between inhibitory effect of some of B. subtilis strains and Iprodione- Carbendazim, in respect of mycelial growth inhibition which revealed the high efficiency of biologic control of vascular wilt of potato.