ETUDE COMPARATIVE DES ACTINOBACTERIES DE LA RHIZOSPHERE DE DEUX CULTIVARS DE PALMIER DATTIER SENSIBLE ET RESISTANT AU BAYOUD

Abstract

This report deals with the qualitative and quantitative distribution of the actinobacteria in the rhizosphere of two date-palm cultivars, one sensitive and one resistant to fusariosis, and with the antagonistic capacity of these microorganisms against the fungal pathogen Fusarium oxysporum f. sp. albedinis. The highest actinobacterial densities are noticed in the rhizospheric soils of the susceptible cultivar. However, we observed that the dominant species are present in the roots of resistant cultivar, and some strains tested were very effective against F. o. albedinis. Differences in the composition of genera and species are found between cultivars. Actinobacteria are mainly represented by the genera Streptomyces and Nocardioides with a net decrease in the percentage of Streptomyces, especially from endorhizosphere, going from resistant cultivar to healthy susceptible cultivar or mainly sick.Numerically, the most important species are related to Streptomyces chartreusis, Streptomyces gannmycicus and Nocardioides albus.