Exploiting plant growth promoting rhizomicroorganisms for enhanced crop productivity

Abstract

The increasing pressure on land resources has made it imperative for vertical growth through enhanced crop intensity and productivity. To meet this challenge, appropriate integrated nutrient and pest management packages must be configured for different agro-ecological conditions. By 2050, the crop nitrogen demand is expected to reach 40-45 million tonnes. To meet such enormous nitrogen requirements through chemical fertilizers, would not only be expensive but also could severely degrade soil health. Similar is the situation with other macro- and micro-nutrients. The rhizosphere environment, at the interface between root and soil, is a major habitat for soil processes. Rhizosphere biology is approaching a century of investigations, wherein growth-promoting rhizomicroorganisms such as Rhizobium, Azotobacter, Pseudomonas, Bacillus, Azospirillum, Frankia and mycorrhizal fungi have attracted special attention on account of their beneficial activities. Plant growth promoting rhizomicroorganisms (PGPR) include diverse microbes that influence plant health by colonizing roots, enhancing plant growth, reducing plant pathogen populations and activating plant defenses against biotic stresses. PGPRs promote plant growth in different ways such as influencing plant hormonal balance, antagonistic to pathogens through various modes, stimulation of plant resistance/defense mechanisms, effects nutrient uptake by secretion of organic acids or protons to solubilize nutrients, atmospheric N2 fixation and by modifying rhizospheric soil environment by exo-polysaccharides production. Though research was going on in isolation in the above areas, with the advent of a core group for PGPR research, the pace in this direction has significantly increased. The primary emphasis on exploiting the vast biodiversity of microorganisms to identify the beneficial strains has yielded very good results. However, most of the research is yet to reach the end-users. For effective transfer of these technologies, there is a need for functional networking of research, industry and extension systems. In this paper, we describe the recent advances in PGPR research and the future needs to strengthen PGPR research and development that will transfer the benefits to the end-users for enhanced and sustainable farm productivity hence contributing towards food security challenges.