Biofertilizer-mediated salt tolerance in sunflower: synergistic effects of Glomus mosseae and Pseudomonas fluorescens

Soil salinization poses a significant challenge to agriculture by hindering crop growth and yield. The present study aimed to examine the potential of two biofertilizers to mitigate the adverse effects of salt stress on sunflower plants.

Sunflower seedlings were inoculated with Glomus mosseae (arbuscular mycorrhizal fungi) and Pseudomonas fluorescens (plant growth-promoting rhizobacteria) individually, as well as in combination and exposed to salinity (150 mM) for 60 days.

Salt stress led to nutrient imbalance, promoted oxidative damage, reduced photosynthetic efficiency, and induced accumulation of compatible solutes and antioxidants in sunflower leaves. Biofertilizer treatments effectively alleviated the detrimental effects imposed by salinity. Inoculated plants exhibited promoted growth, and higher nutrient and photosynthetic pigment content under salinity stress. In inoculated plants, the adverse effects of stress on photosynthetic quantum yields were significantly attenuated. Antioxidant activity and flavonoid content increased in inoculated plants followed by a reduction in H₂O₂ and MDA, and electrolyte leakage. A higher accumulation of compatible solutes was stimulated in salt-stressed sunflower plants by the biofertilizer treatments.

Our results demonstrated that the combined application of G. mosseae and P. fluorescens was the most efficient treatment in diminishing the harmful impacts of salt stress on sunflower seedlings. Based on these results, the use of G. mosseae and P. fluorescens as biofertilizers offers a sustainable and eco-friendly strategy to increase crop tolerance against the deleterious impact of salinity.