Enhancing Salt Stress Tolerance in Sorghum bicolor, Sesbania sesban, and Cassia tora Through Arbuscular Mycorrhizal Fungal Symbiosis

Soil salinity is a major abiotic stressor that inhibits plant growth. Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with plants that can enhance their tolerance to such stresses. This study evaluated the efficacy of AMF in mitigating salt stress in three plant species. Sorghum bicolor, Sesbania sesban, and Cassia tora were cultivated under greenhouse conditions for five months. Plants were subjected to four salinity levels (0, 2.5, 5.0, and 7.5 dS m^-1) with or without AMF inoculation. Growth parameters (plant height, leaf number, fresh and dry weight of shoots and roots, relative growth rate (RGR), and root-to-shoot ratio (RSR)) were measured. The percentage of root colonization by AMF structures (mycelium, vesicles, arbuscules) was also assessed. AMF colonization rates were highest at the lowest salinity level (2.5 dS m^-1) and declined significantly at 7.5 dS m^-1. Sesbania sesban showed the highest colonization rate (90%), followed by Sorghum bicolor and Cassia tora. Inoculation with AMF significantly improved all growth parameters under salt stress, particularly at 2.5 dS m^-1. Sorghum bicolor demonstrated the highest tolerance, with AMF-inoculated plants showing remarkable improvements in RGR and biomass even at 7.5 dS m^-1. AMF symbiosis significantly enhances salt stress tolerance in the studied species, with the effectiveness being species-dependent and inversely correlated with salinity levels. Sorghum bicolor exhibited the greatest potential for AMF-assisted cultivation in saline soils.