Quantitative Estimation of Auxin, Siderophore, and Hydrogen Cyanide Production in Halo and Drought-Tolerant Bacterial Isolates for Cucumber Growth.

Salt-tolerant bacteria can enhance plant growth through various mechanisms, including the production of auxin, siderophores, hydrogen cyanide, and the solubilization of insoluble phosphate. This study investigated the production of these growth-stimulating factors by salt- and drought-tolerant bacteria isolated from the arid and saline farmlands of Jiroft. Initially, we screened for bacterial strains that exhibited the highest levels of these factors. We then evaluated their effects on improving the growth indices of cucumber seedlings. Additionally, we optimized the protocols for isolating auxin, siderophores, hydrogen cyanide, and phosphate solubilization, which can also be applied to other host rhizobacteria to assess their growth-promoting compounds. Key features • The most resistant bacterial isolates to salinity and drought are identified by adding salt and polyethylene glycol to the culture medium in laboratory conditions. • This protocol can be used to evaluate the production levels of IAA, siderophore, hydrogen cyanide, and phosphate solubilization by salt- and drought-tolerant bacteria. • This protocol can also be used to evaluating the plant growth-promoting ability of salt- and drought-tolerant bacteria under greenhouse conditions. • This protocol can be applied to other host rhizobacteria to assess their growth-promoting compounds.