Effects of PGP Bacteria on Holding Water at Pot Scale

Inoculating plants with selected beneficial bacteria can significantly enhance agricultural sustainability, providing vital solutions for regions facing drought conditions. In this study, a greenhouse experiment was conducted; wherein thirty potted tomato plantlets were inoculated with five Plant Growth-Promoting Bacteria (PGPB) strains: Micrococcus yunnanensis M1, Bacillus simplex RP26, Pseudomonas stutzeri SR7-77, Arthrobacter nitroguajacolicus 2-50, and Arthrobacter aurescens 2-T30, —previously isolated from the endosphere or rhizosphere of drought-adapted plants. Ten plants per strain were subjected to three different watering regimes: full irrigation (100%) matching the plant’s water requirement (PWR), moderate (75% PWR) and severe (50% PWR) irrigation. Soil moisture content was monitored using Time Domain Reflectometry (TDR) to assess the impact of bacterial inoculation on soil water storage and its influence on plant growth, as adequate moisture is necessary for nutrient uptake and photosynthesis. Results indicated that all inoculated strains improved plant performance, particularly under water stress conditions induced by reduced irrigation. Among the strains, Pseudomonas stutzeri SR7-77 demonstrated a significantly positive impact on soil water holding at pot scale, even under full irrigation, largely observed during the active growth stage. These results suggest that selected PGPB strains can enhance soil water availability and plant resilience, providing a viable strategy for improving tomato production in drought-affected regions.

Keywords:Plant Growth Promoting Bacteria (PGPB); Soil water fluxes; Time Domain Reflectometry (TDR); Greenhouse experiment; Air temperature