Use of plant growth promoting rhizobacteria (PGPRs) in the mitigation o water deficiency of tomato plants (Solanum lycopersicum L.)

Plant growth promoting rhizobacteria (PGPR) can improve the growth, productivity and tolerance of plants under stress conditions. The aim of this study was to investigate the effect of PGPRs on the physiological traits related to photosynthesis, canopy temperature (CT) and yield of tomato hybrids under water scarcity in open field conditions. Seedlings of H-1015 and UG 812J F, tomato hybrids were treated by B1, B2, B3 bacteria strains before planting, then they were grown under regularly irrigated (RI=ET100%), deficit irrigated (DI=ET50%) and non-irrigated (10) conditions in the field experiments. During flowering period, a higher chlorophyll fluorescence (Fv/Fm), canopy temperature and lower chlorophyll content (SPAD) were measured for plants treated by B2 and B3 treatments than for untreated plants. From flowering to ripening of tomato fruit, PGPRs influenced negatively the Fv/Fm, positively the SPAD value and canopy temperature, which resulted in a 47.8 to 75.4% increase in the green healthy fruit yield compared to the control. Under severe dry, non-irrigated conditions, B3 treatment increased the green fruits yield by 28.9%, the Brix by 16% and the vitamin C content by 13.6% in comparison with the untreated plants. Under moderate water deficiency using deficit irrigation the plants treated by B3 produced the same marketable yield and 33% lower diseased yield than untreated plants and they produced 9.5% higher Brix and 12.7% higher vitamin C content.