Plant Growth-Promoting Characteristics of Salt Tolerant Enterobacter cloacae Strain KBPD and Its Efficacy in Amelioration of Salt Stress in Vigna radiata L.

Plant growth-promoting salt-tolerant bacteria can increase plant resistance to salt stress and correspond to an environmentally friendly approach to alleviate salt stress. With this approach, forty different bacterial species were isolated from salt-affected soil of Kolhapur, Maharashtra, India. Isolates were investigated for the expression of plant growth-promoting traits at five salt stress levels (0, 20, 40, 60, 80 g L−1 NaCl). Among these forty isolates, AA-P11 was the potent strain for maintaining ACC deaminase activity, phosphate solubilization, indole acetic acid, siderophore, ammonia, hydrogen cyanide and exopolysaccharide production under salt stress. Isolate AA-P11 was identified as Enterobacter cloacae strain KBPD. In the pot study, maximum shoot length, root length, fresh and dry weights were recorded in Vigna radiata L. when supplemented with KBPD in the presence of 0, 50, 100 and 150 mM of NaCl after 14 days. Proline content was high in salt-stressed plants but inoculation with E. cloacae KBPD reduced the concentration of proline. Similarly, total chlorophyll content was also high in bacterized salt-stressed plants compared to non-KBPD salt-stressed plants. AA-P11 also showed good rhizospheric competence under salt stress. Hence, the present study suggested that the Enterobacter cloacae strain KBPD has promising potential for alleviating salinity stress and promoting growth of Vigna radiata L. under salt stress conditions.