Selection of a rhizospheric microbial consortium to improve drought stress tolerance in maize

摘要

The response to abiotic stresses in plants is mediated by rhizospheric microorganisms by several ways. Mycorrizal fungi and plant growth promoting rhizobacteria (PGPR) can improve plant health under drought stress. In our work we isolated under osmotic stress selective pressure two bacterial strains and mycorrhizal fungi from a sahelian rhizospheric soil in the Lougha region of Senegal. We used these strains in consortium to inoculate maize plants under controlled conditions: seed were sowed in a glasshouse in mesocosms and different water regimes were tested, providing water at seven to fourteen days interval, and at different depth: at surface or at 65 cm. The aim was to check if the inoculum of specifically selected rhizospheric microorganisms could be useful to improve water uptake also from layer of soil that are not directly in contact with plant roots. The assays were carried out in comparison with uninoculted plants and with plants inoculated with a commercial, not specific inoculum of rhizospheric microorganisms. The biomass yield and physiological parameters were checked. Several beneficial effects coming from specifically selected rhizospheric consortium inoculation were detected, supporting the hypothesis of a positive effect of inoculation on the gas exchange parameters, on the photosynthetic activity and on the uptake of water from deep layers of soil. Tensiometric analysis of soil also revealed an effect of microbial inoculum on soil structure.