Impact of Rhizosphere Ecology on Nitrogen Fixation in Millets

Abstract

Millets are prime underutilized nutraceutical crops that have potential to substitute staple crops. The agro ecological characteristics and nutritional qualities of millets are superior to those of major cereals, which make them efficient crops to meet immediate food security needs. A plant’s normal functioning is dependent on the condition of the soil, as it is a reservoir of water and nutrients. The rhizosphere is the area around a plant's roots, and there are complex relationships among the biotic and abiotic communities in this region. Microorganisms that comprise the rhizosphere microbiome include archaea, viruses, fungi, bacteria, and eukaryotic organisms which occupy a compact region of soil near the roots of plants. Symbiosis between plants and microbes has long been recognized as a helpful and important part of sustainable agriculture. Rhizospheric zones contain a wide variety of microbial populations. It is not just that different microbes interact, but they also have an impact on the host. The rhizosphere of millet is an important habitat for beneficial microbes, providing nutrition to plants and maintaining soil health. Rhizobacteria, nitrogen-fixing bacteria, arbuscular mycorrhizal fungi, and phosphate solubilizers and other micro- and macro-organisms make up the microbial community of millet crops. The rhizosphere of millets was dominated by Actinobacteria, Proteobacteria, Acidobacteria, Enterobacter, Pantoea, Klebsiella, and Arthrobacter. Among them species such as Chloroflexi Pseudomonas Pseudomonas fluorescens, Enterobacter hormaechei, and Pseudomonas migulae were mostly present. Certain microorganisms are involved in the biological nitrogen fixation, using nitrogenase enzyme, these organisms convert atmospheric nitrogen into ammonia. A plant’s rhizosphere harbors microorganisms that are capable of reducing atmospheric nitrogen to ammonia. In root zones, beneficial microbes are found to aid in the formation of root hairs, the increase of biomass, and a better growth rate. In this chapter, we will have a look at millets and the role of rhizospheric microbes associated with them.