Essai de lutte biologique contre le Fusarium oxysporum f. sp. ciceris à l'aide des microorganismes de la rhizosphère de la culture du pois chiche

Abstract

Chickpea is one of the most important legumes in Algeria. Surveys have shown the appearance of vascular wilt of chickpeas in northwestern of Algeria. This disease is caused by the plant pathogenic fungus Fusarium oxysporum f. sp. ciceris (FOC). Surveys were conducted during the 2008 crop year in four regions of northwestern Algeria that allowed us to detect the presence of wilt symptoms in all fields surveyed. The involvement of the FOC in the manifestation of wilt has been demonstrated and isolates carried testified to the colonization of the stem. FOC isolates showed variable pathogenicity. The use of antagonistic microorganisms is considered as promising method to ensure a successful protection against FOC. Furthermore 29 antagonistic rhizobacteria were selected among 131 isolated from the chickpea rhizosphere grown in nine regions of the northwest and northeast of Algeria: Mascara, Sidi Bel-Abbes, Tlemcen, Tiaret, Mostaganem, Relizane, Chlef, Guelma and Constantine. In vitro comparison tests between two isolates of FOC (FOC1 and FOC2) and 29 rhizobacteria separately showed inhibitory activity of the mycelial growth of the two pathogens of 25.63% to 71.11% by direct confrontation and 14.11% to 45.74% b indirect confrontation. All the isolates have the ability to solubilize phosphate, as well as the production of HCN, AIA and chitinase. These characteristics as they are called PGPR. Five performing species were identified as B. subtilis (Rb29), B. amyloliquefaciens (Rb4), B. megaterium (RB6), B. lentus (RB12), B. mycoides (RB15) and selected for control testing in vivo biological. These species have significantly reduced the incidence of vascular wilt after a bacterial inoculation of susceptible cultivar ILC 482 seeds of 60-99% in pot and 57.20 to 98% in the field. This study revealed that the rhizospheric species of chickpea belonging to the genus Bacillus can be used as biological control agents.