BIOPROSPECÇÃO E POTENCIAL DE MITIGAÇÃO DO DÉFICIT HÍDRICO NA SOJA POR BACTÉRIAS PROMOTORAS DE CRESCIMENTO DE PLANTAS

Abstract

Soybean (Glycine max) is one of the most important agricultural commodities for global food supply; however, it frequently experiences yield losses due to environmental stresses, particularly drought. In addition, the crop has high nutritional requirements to achieve productivity levels that meet the growing global demand for food. This study investigated the potential of plant growth–promoting rhizobacteria (PGPR) to mitigate the drought effects in G. max and to enhance plant development. Initially, in vitro assays were carried out to identify functional traits of the bacteria, followed by genetic characterization. Based on this screening, 11 bacterial isolates, identified as belonging to the genus Bradyrhizobium spp., were selected according to the evaluated functional traits. Subsequently, two greenhouse experiments were carried out to simulate field conditions. The first experiment aimed to select bacteria with the greatest potential to promote the growth of inoculated plants, while the second evaluated the ability of these bacteria to enhance plant tolerance to water deficit. In both experiments, gas exchange, chlorophyll a fluorescence, photosynthetic pigments, and plant growth were assessed under well-watered and water-stress conditions, with and without inoculation using native or commercial bacteria, in addition to morphological evaluations of shoot and root systems. The results indicated that plant growth–promoting bacterial strains improved photosynthetic rates, electron transport efficiency, and root growth under both well-watered and drought stress conditions.