Arbuscular Mycorrhizal Fungi: An Eco-Friendly Technology for Alleviation of Salinity Stress and Nutrient Acquisition in Sustainable Agriculture

Recent climate changes, low precipitation and high evaporation, and other abiotic stresses are some of the constraints limiting the crop production. Irrigation of crops with saline water has increased the salinity of soil and about 33% of the irrigated agricultural lands are currently afflicted by salinity worldwide. Thus, increase in salinity, together with the negative impact of environmental pollution from agro-chemicals, constitutes a significant current threat to both world food security and agricultural sustainability. The escalating salinity levels detrimentally impact the physico-chemical properties of the soil and the diversity of its microbial composition, resulting in compromised soil health and diminished crop yields. Hence, the convergence of environmental challenges and agricultural production issues has emphasized the pressing need to investigate sustainable and eco-friendly technologies capable of alleviating the adverse impacts of salt stress. In this context, some beneficial microorganisms isolated from extreme environments or halophytic plant roots, showed enormous potential to protect the plants against salinity stress. Among these beneficial microorganisms, arbuscular mycorrhizal fungi (AMF) were found to establish symbiotic associations with roots of different crop plants and alleviated abiotic stresses, thereby increased plant development, nutrient uptake, water relations and above-ground crop productivity. Thus, plant responses to colonization by mycorrhizal fungi include effective exploitation of soil mineral resources and their defensive role against abiotic and biotic stresses; providing competitive advantage over non-mycorrhizal plants leading to improved plant growth in diverse agro-ecosystems. Various mechanisms employed by AM fungi in alleviation of salinity stress and nutrient acquisition are discussed in this review. The application of AMF as bioinoculants in the field has surfaced as an advantageous agri-technology for enhancing or restoring soil fertility and increasing crop productivity under saline conditions. Effective management of AMF and their biofertilization holds the potential to address challenges in crop production, contribute to economic stability in agriculture, alleviate food shortages, and reduce reliance on chemical fertilizers, promoting sustainable agricultural practices.