Effect of combined treatment with Bacillus amyloliquefaciens H-2-5 and illite on mitigating salt stress in Panicum miliaceum

Soil salinity is a significant environmental challenge that negatively affects crop yield. Growth-promoting bacteria (GPB), such as Bacillus amyloliquefaciens H-2-5, offer a promising biological approach to enhance plant tolerance under saline conditions. This study investigates the beneficial role of B. amyloliquefaciens H-2-5, in combination with the clay mineral illite, in alleviating salt stress in Panicum miliaceum. Under 150 mM NaCl stress, the combined treatment significantly improved plant growth, increasing shoot and root lengths by 44.3% and 40.9%, respectively, compared to untreated stressed plants. The treatment enhanced relative water content (RWC) (18.8%) and chlorophyll concentration (36.3%), indicating improved water status and photosynthetic capacity. Moreover, elevated levels of flavonoids (57.1%) and polyphenols (27.3%) reflected the stimulation of antioxidant responses, while reduced superoxide dismutase (SOD) and DPPH activities suggested lowered oxidative damage. Elemental analysis revealed reduced sodium uptake (35.7%) and increased potassium accumulation (20.6%), resulting in a more favorable Na⁺/K⁺ ratio. These findings highlight the significant contribution of B. amyloliquefaciens H-2-5 as a GPB that not only promotes plant growth but also strengthens physiological and biochemical mechanisms against salt-induced stress, supporting its potential as a sustainable tool for improving crop resilience in saline environments.