Plant Growth-Promoting Bacteria Associated With Some Salt-Tolerant Plants.

Abstract

Given the benefits of bacteria associated with the rhizosphere and phytoplane of halophytes, this research focused on examining the plant growth-promoting characteristics of bacteria isolated from Cressa cretica, Suaeda aegyptiaca, and Alhagi graecorum. From the 33 isolates tested, 9 exhibited plant growth-promoting traits. Bacillus rugosus strain CS5 and Bacillus sp. strain SS4 exhibited the notable growth inhibition of the pathogenic fungus Fusarium oxysporum, with values of 47% and 45%, respectively. Bacillus sp. strains SS4 and CS1 demonstrated impressive results in solubilizing phosphorus and zinc, respectively, achieving concentrations of 259 and 271 mg L^-1. Additionally, Staphylococcus xylosus strain SR2, Bacillus sp. strain SS4, and Bacillus paralicheniformis strain CR1 thrived in nitrogen-free media. The Priestia filamentosa strain AL4 showed the greatest HCN production, whereas B. paralicheniformis strain CR1 was notable for higher auxin production. The Bacillus sp. strains SS4 and CS1 exhibited greater tolerance than other isolates in a medium containing 600 mM of NaCl. Additionally, inoculating these isolates into soil significantly alleviated the salinity and drought stress on Zea mays seedlings. These findings suggest that further investigation into these strains as microbial inoculants could be beneficial for mitigating salt and drought stress in plants.