What is the role of rhizosphere microorganisms in soil fertility and roles of soil bacteria in the nitrogen nutrition of plants?
The direct effect of these bacteria on the plant comes either by providing the plant with growth-stimulating substances produced by the bacteria, or by facilitating the absorption of some nutrients from the soil. As for the indirect effect of growth, it appears by preventing pathogens present in the soil from multiplying and attacking the plant and causing harm to it. This is done by colonizing the rhizosphere with a large population density, thus competing with pathogens for space, producing antibiotics, producing and changing the concentration of growth regulators such as indole acetic acid, gibberellins, cytokinins, and ethylene gas, fixing nitrogen gas, dissolving the mineral phosphorus, making potash available, and producing siderophores, which help in making the element Iron and other nutrients are available to the plant and make them easily absorbed by plant roots
Rhizosphere-associated microbes have an extensive variety of metabolic abilities and play an important role in the rhizosphere environment, such as organic matter breakdown and nutrient cycling, both of which benefit plant growth and health.In addition to pathogen attacks, plants can also encounter environmental stresses such as drought, heat, cold, salinity, and soil pollution. Rhizosphere microbes can play a critical role in helping plants alleviate these “abiotic” stresses. The rhizosphere conditions have a direct impact on crop growth and yield. Nutrient-rich rhizosphere environments stimulate plant growth and yield and vice versa. Extensive cultivation exhaust most of the soils which need to be nurtured before or during the next crop. Many soil bacteria process nitrogen in organic substrates, but only nitrogen fixing bacteria can process the nitrogen in the atmosphere into a form (fixed nitrogen) that plants can use. Nitrogen fixation occurs because these specific bacteria produce the nitrogenase enzyme. Soil bacteria are responsible for cycling carbon, influencing nutrient availability, bolstering plant health, and many other factors. Soil bacterial populations are influenced by residue type, moisture, temperature, and soil pH. The rhizosphere is an intense hub of activity in the soil. In this root zone around plants, plant roots feed nearby soil microbes in exchange for plant nutrients. In this way, the rhizosphere is the “bridge” where unavailable minerals are turned into plant nutrients. The rhizosphere harbors diverse microbial groups that perform various functions and exert numerous effects on plant growth. They are involved in nutrient cycling, protecting from phytopathogens as well as under biotic and abiotic stress conditions, and some may act as plant pathogens. Rhizosphere organisms that have been well studied for their beneficial effects on plant growth and health are the nitrogen-fixing bacteria, mycorrhizal fungi, plant growth-promoting rhizobacteria (PGPR), biocontrol microorganisms, mycoparasitic fungi, and protozoa. Rhizosphere organisms that have been well studied for their beneficial effects on plant growth and health are the nitrogen-fixing bacteria, mycorrhizal fungi, plant growth-promoting rhizobacteria (PGPR), biocontrol microorganisms, mycoparasitic fungi, and protozoa. Beneficial soil microbes perform fundamental functions such as nutrient cycling, breaking down crop residues, and stimulating plant growth. Microorganisms play a crucial role in nutrient cycling in soil. The composition and activity of microbiota impact the soil quality status, health, and nutrient enrichment. Microbes are essential for nutrient mobility and absorption. Through their varied functions, they stimulate plant growth and reduce diseases.
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