Mitigating salt stress in maize: A multifaceted role for a halotolerant Paenibacillus sp. isolate from arid saline Sebkha

Abstract

Soil salinity severely limits crop productivity in arid regions. This study investigates a halotolerant Paenibacillus sp. isolate for mitigating salt stress in maize (Zea mays L.). The bacterium was characterized for key plant growth-promoting rhizobacteria (PGPR) traits, indole-3-acetic acid (IAA) production, phosphate solubilization, siderophore secretion, and ammonia release, under NaCl concentrations up to 900 mM. Its efficacy was tested in maize seed germination and seedling growth assays under four salinity levels (0-150 mM NaCl). The isolate maintained high IAA production and phosphate solubilization up to 600 mM NaCl and exhibited enhanced siderophore secretion with increasing salinity. Inoculation did not affect final germination percentages but alleviated germination delays under 100 mM NaCl. Crucially, bacterial inoculation significantly improved seedling growth under all salt stresses, with shoot length showing up to a fourfold increase at 150 mM NaCl compared to uninoculated controls. These results demonstrate that this Paenibacillus sp. confers substantial salt tolerance to maize during early development, highlighting its strong potential as a bioinoculant for sustainable agriculture in saline environments.