Role of some rhizospheric Pseudomonas on the growth and physiology of broad bean (Vicia faba) under salt stress conditions

Salt stress affects the development and growth of plants in various ways as a result of its effect on water relationships, photosynthesis, and nutrient absorption by physiological and biochemical processes. Consequently, several researchers have increasingly studied the effect of plant growth promoting bacteria (PGPR) as promoters and enhancers under saline environment. The main goals of this study were to examine the manifested response of the broad bean plant under saline conditions and to evaluate the role of some Pseudomonas isolates in improving plant tolerance to salt stress. Three Pseudomonas strains were isolated (P1 and P7 from a saline soil and P15 from a vineyard soil). These isolates were screened by salinity and used as inoculums in Vicia faba plants (OTONO variety) irrigated with two saline solutions (NaCl; 100 and 150 mM L-1) and one without salinity. The results show that salinity decreased the fresh weight, total chlorophyll content, and the Na+/K+ ratio, but it increased proline accumulation in inoculated and noninoculated plants. The inoculation of V. faba plants with P1, P7, and P15 strains significantly increased the production of fresh biomass in the presence and absence of salt stress, and positively affected the accumulation of proline and the Na+/K+ ratio. The inoculation with bacterial strains increased the total chlorophyll content in plants at all salt treatment levels, especially the P 1 strain that showed a significant effect.