Root-microbe interactions influencing water and nutrient acquisition efficiency

Drought and nutrient deficiency are considered the major constraints for agricultural productivity worldwide. Root uptake of water and nutrients is a complex process controlled by the physico-chemical characteristics of the soil, the plant, resident microorganisms, and environmental factors, all of which are strongly interconnected. Root system traits, such as length, surface area, and branching, play a key role in water and nutrient acquisition, although microbial associations also have a fundamental role in plant growth and nutrient availability and acquisition. Plant growth-promoting rhizobacteria (PGPR), a varied group of beneficial soil bacteria, are involved in several rhizosphere processes at the root–soil interface. PGPR populations improve plant growth via nitrogen fixation, solubilizing nutrients, and producing phytohormones and other compounds, thereby positively interacting with root and shoot growth. In recent years, research has focused on the role of bacteria that enhance abiotic stress tolerance (which is discussed comprehensively in this chapter) as a means to improve sustainability and increase yields in organic agriculture and degraded soils.