Emerging Roles of Plant Growth Promoting Rhizobacteria in Salt Stress Alleviation: Applications in Sustainable Agriculture

Abstract

Increase in soil salinity is a serious concern as it adversely impacts the growth, development and yield of agricultural crops. The disruption in the ionic composition thereby affecting the fertility of the soil is observed in salt-affected soils warranting the development of technologies for improved crop growth under salinity conditions. Whilst generation of transgenic plants harbouring genes important for imparting tolerance to salinity stress conditions is considered a feasible biotechnological approach, the usage of transgenic crops for human consumption is not well received. Further, breeding approaches for generation of salt tolerant varieties is time consuming. In this context, the usage of halotolerant Plant Growth Promoting Rhizobacteria (PGPR) for improvement of salinity tolerance in crop plants is considered as an eco-friendly and cost-effective approach. This approach will also maintain the soil microbial diversity thereby protecting it from salinity-induced degradation. Few PGPR such as Pseudomonas and Bacillus species although have been effectively used for imparting plant growth promotion under control conditions, isolation of halotolerant PGPR, their effective utilization and optimization for agronomical application in salt-affected soils are key factors for improvement of salinity tolerance in crop plants. Further, whilst many of the isolated halotolerant PGPR show plant-growth promoting traits under laboratory conditions, their efficiency is questionable under field conditions. In the current chapter, the methodologies employed for inoculation of isolated halotolerant PGPR either singly or as a consortium to agricultural crops and the changes observed in the plants towards improvement in salinity tolerance will be discussed. The efficient delivery methods with carriers like nanoparticles, biopolymers and organic carriers along with preparation of formulations, the route of administration for improvement of salinity tolerance in crop plants and their survival in saline soil will be elaborately discussed.