Abstract
Black cumin (Nigella sativa) is an important seed spices crop, Fusarium root rot is a serious fungal disease responsible for significant losses worldwide, the present work was planned to study the used of some strains of Pseudomonas spp. to reduce the root rot disease of black cumin caused by Fusarium solani. Three isolates of Pseudomonas spp. were recovered from rhizosphere of black cumin plants and they were identified as Psedomonas fluorescens (PF1, PF2) and P. aeruginosa (PF3). They were tested as formulation and suspension under greenhouse and field conditions against root rot disease to reduce the disease severity. The results show that P. fluorescens (PF1) as a suspension and formulation gave the highest effect in reducing the disease severity (7.70 and 7.73%) also reduce the number of pathogenic fungi than control. All tested bacteria increased seed production than infected control. The laboratory results show that PF1 gave highest amount of siderophores followed by PF3, while P. fluorescens (PF2) show a weak production. Also, all tested bacteria have ability to phosphate solubilization with different degree among them, PF3 has highly ablitity to phosphate solubiization followed by other isolates. It could be control of F. solani the causal of root rot under greenhouse and field condition with this bioagents and could recommend using these isolates to control of root rot diseases of N. sativa under Assiut conditions.