Improvement of drought tolerance in maize (Zea mays L.) by selected rhizospheric microorganisms

Several beneficial rhizospheric microorganisms, such as arbuscular mycorrhizal fungi (AMF) and Plant Growth Promoting Rhizobacteria (PGPR), can improve the tolerance of plants to water deficiency and other environmental stresses. In this work the addition to soil of selected rhizospheric microbial consortia was tested in order to increase tolerance to drought stress of maize crops. One consortium was a mixture of AMF fungi and PGPR isolated from an arid soil of Senegal and selected under osmotic stress conditions (M1); the other consortium was an unspecific commercial product (M2). The soil microbial populations and the root infection by AMF were affected by the inoculation with both consortia. Plant gas exchange parameters were positively affected by inoculation, with different responses depending on the consortium. A higher tolerance of plants to water deficiency stress was reached with consortium M1. Improvement of the mineral nutrients content of leaves and of the biomass yield was also recorded. It is concluded that the use of microbial inocula of rhizospheric microorganisms specifically selected for drought tolerance can be suitable for agronomical applications, aimed at improving the crop growth and yielding performances under low water availability.