Potential of Rhizobia in Improving Nitrogen Fixation and Yields of Legumes

Abstract

Strong demand for food requires specific efforts by researchers involved in the agricultural sector to develop means for sufficient production. While, agriculture today faces challenges such as soil fertility loss, climate change and increased attacks of pathogens and pests. The production of sufficient quantities in a sustainable and healthy farming system is based on environmentally friendly approaches such as the use of biofertilizers, biopesticides and the return of crop residues. The multiplicity of beneficial effects of soil microorganisms, particularly plant growth promotion (PGP), highlights the need to further strengthen the research and its use in modern agriculture. Rhizobia are considered as PGP comes in symbiosis with legumes taking advantage of nutrients from plant root exudates. When interacting with legumes, rhizobia help in increased plant growth through enriching nutrients by nitrogen fixation, solubilizing phosphates and producing phytohormones, and rhizobia can increase plants' protection by influencing the production of metabolites, improve plant defense by triggering systemic resistance induced against pests and pathogens. In addition, rhizobia contain useful variations to tolerate abiotic stresses such as extreme temperatures, pH, salinity and drought. The search for rhizobium tolerant strains is expected to improve plant growth and yield, even under a combination of constraints. This chapter summarizes the use of rhizobia in agriculture and its benefits.

Potential of Native Rhizobia to Improve Cowpea Growth and Production in Semiarid Regions of Kenya

“…The increased shoot DW on legumes following inoculation with native rhizobia could be attributed to the fact that rhizobia enhanced plant growth leading to increased biomass production (Kawaka et al, 2014;Jalloh et al, 2020;Matse et al, 2020). The high root DW and high shoot DW of native treated plants could be due to the production of plant-growth-promoting hormones such as 3-indoleacetic acid (IAA) by the native isolates (Mabrouk et al, 2018). In KNO 3 -treated plants and the negative controls, no nodules were formed, which confirmed the absence of any contamination.…”

Endophytic Bacteria From the Roots of the Medicinal Plant Alkanna tinctoria Tausch (Boraginaceae): Exploration of Plant Growth Promoting Properties and Potential Role in the Production of Plant Secondary Metabolites

“…Several bacteria including those from the genera Pseudomonas , Pantoea , and Bacillus have the ability to solubilize and therefore make accessible insoluble phosphate to plants ( Ghyselinck et al, 2013 ). Similarly, rhizobia can provide plants with combined nitrogen via biological nitrogen fixation ( Mabrouk et al, 2018 ). Soil microorganisms can also influence plant growth through the secretion of growth hormones such as indole acetic acid (IAA) or ethylene.…”

Microbes as Biofertilizers, a Potential Approach for Sustainable Crop Production

“…Rhizobium, Bradyshzodium, Sinorhizobium, Azorhizobium, and Mesorhizobium are collectively called rhizobia. They can act directly by fixing nitrogen or influencing plant hormones or indirectly by decreasing the inhibitory effects of pathogens [32]. Rhizobium is commonly used in agronomic practices to ensure adequate nitrogen (approximately 80% of biologically fixed N comes from symbiosis) and have potential to replace chemical N fertilizers [33].…”