Enhancing drought resilience in common bean (Phaseolus vulgaris) through Lysinibacillus sphaericus inoculation

Phaseolus vulgaris L. is a key food crop in tropical regions, where climate change is expected to increase the frequency and intensity of drought events. The use of plant growth-promoting bacteria (PGPB) offers a sustainable alternative to chemical fertilizers and may enhance crop resilience under water-limited conditions. We evaluated whether inoculation with Lysinibacillus sphaericus improves drought tolerance in P. vulgaris. Plants were assigned to four treatments: inoculated/non-inoculated × control/ drought, exposed to 14 days without irrigation, and monitored for leaf water potential (ΨL), stomatal conductance (gs), photosynthetic rate (Amass) and transpiration rate (E) every seven days, followed by seven days of recovery. Inoculated plants maintained higher ΨL, lower E and higher Amass under drought, resulting in greater total plant biomass primarily through increased leaf production. After rewatering, all inoculated plants fully recovered, whereas only one non-inoculated plant did. These results demonstrate that L. sphaericus enhances drought resilience in P. vulgaris, highlighting its potential as a biological tool for sustainable bean production with reduced chemical fertilizers under future climate scenarios. Further studies should investigate the specific physiological and biochemical mechanisms underlying this response–such as shifts in root architecture, osmolyte accumulation, and nutrient uptake–and evaluate impacts on yield and pod production under field conditions.