Salt-Tolerant Plant Growth Promoting Rhizobacteria for Enhancing Crop Productivity of Saline Soils

Abstract

Soil salinity has emerged as a serious issue for global food security. It is estimated that currently about 62 million hectares or 20 percent of the world's irrigated land is affected by salinity. The deposition of an excess amount of soluble salt in cultivable land directly affects crop yields. The uptake of high amount of salt inhibits diverse physiological and metabolic processes of plants even impacting their survival. The conventional methods of reclamation of saline soil which involve scraping, flushing, leaching or adding an amendment (e.g., gypsum, CaCl 2 , etc.) are of limited success and also adversely affect the agro-ecosystems. In this context, developing sustainable methods which increase the productivity of saline soil without harming the environment are necessary. Since long, breeding of salt-tolerant plants and development of salt-resistant crop varieties have also been tried, but these and aforesaid conventional approaches are not able to solve the problem. Salt tolerance and dependence are the characteristics of some microbes. Salt-tolerant microbes can survive in osmotic and ionic stress. Various genera of salt-tolerant plant growth promoting rhizobacteria (ST-PGPR) have been isolated from extreme alkaline, saline, and sodic soils. Many of them are also known to mitigate various biotic and abiotic stresses in plants. In the last few years, potential PGPR enhancing the productivity of plants facing salt-stress have been researched upon suggesting that ST-PGPR can be exploited for the reclamation of saline agro-ecosystems. In this review, ST-PGPR and their potential in enhancing the productivity of saline agro-ecosystems will be discussed. Apart from this, PGPR mediated mechanisms of salt tolerance in different crop plants and future research trends of using ST-PGPR for reclamation of saline soils will also be highlighted.

Halo-tolerant plant growth promoting rhizobacteria for improving productivity and remediation of saline soils

“…In the last few decades, anthropogenic activities have exacerbated the rate of soil salinization [1] , [2] . Saline soils are high in electrical conductivity (EC), low in water potential and excessive in amounts of ionic salts making survival of plant and other life forms difficult [3] , [4] . It is estimated that salinity has affected over 800 million hectares of agricultural land around the globe [5] .…”

“…Physical methods of treatment of saline soils, that include flushing, leaching, scraping and chemical amendments e.g. addition of gypsum and lime, are not sustainable [4] . Soil flushing and scraping has achieved only a little success and has limited practical significance as the salt accumulation tends to resurface due to lowering of water table and the problem intensifies with course of time.…”

Trichoderma Enhances Net Photosynthesis, Water Use Efficiency, and Growth of Wheat (Triticum aestivum L.) under Salt Stress

“…Several reports have shown that seed inoculation with microbes capable of indole-3-acetic acid (IAA) secretion efficiently improved plant tolerance to salt stress [ 30 , 31 , 32 ]. In addition, many cultivable salt-tolerant microbial strains isolated from saline environments survive under osmotic and ionic stresses and are known to mitigate the detrimental effects induced by a variety of abiotic stresses [ 33 , 34 ].…”

Novel Bioformulations Developed from Pseudomonas putida BSP9 and Its Biosurfactant for Growth Promotion of Brassica juncea (L.)

“…The role of plant growth promoting rhizobacteria (PGPR) has been widely exploited in the context of sustainable agricultural productivity [ 4 ]. Among various beneficial roles that PGPR confer to their host plant including production of growth enhancers, phytohormones, nutrient assimilation, metal chelation, they are also well known for their synthesis of surface-active compounds known as biosurfactants [ 5 , 6 , 7 ]. Biosurfactants are biomolecules that are amphiphilic in nature and include a large category of glycolipids, lipopeptides phospholipids, fatty acids and polymeric macromolecules [ 8 , 9 ].…”