Soil-Plant-Microbe Interactions in Salt-affected Soils

Soil salinization is a major abiotic constraint which causes loss of productivity of cultivated soils. Salinity affects plant growth by reduction in osmotic potential, imbalance of nutrients, and ion toxicity. Microorganisms have the ability to tolerate or adapt stresses; like under salt stress conditions, they synthesize osmolytes which help them to maintain cell turgor and metabolism. Halophilic plant growth-promoting microbes have been considered to mitigate such environmental stress. These have the multiple mechanisms, such as production of indoleacetic acid, ACC (1-Aminocyclopropane-1-Carboxylate) deaminase, exo-polysaccaride, and siderophore, phosphate solubilization, and nitrogen fixation and have antifungal activity, which makes them play important role in plant growth promotion under salt stress. Mycorrhizal fungi demonstrate several plant growth promotion properties by several mechanisms. These mechanisms include production of several plant growth-promoting metabolites like amino acids, vitamins, and phytohormones. Mycorrhiza also has the nutrient solubilizing and mineralizing potential, thus, can enhance plant tolerance against salinity and other environmental stresses. Many halophilic plant growth-promoting microbes and their consortia have recently been used for the promotion of plant growth under salt stress conditions and their bio-formulations acts as eco-friendly and cheap strategy for amelioration of salt-affected soils.