Explain the role of microbes as Bio-fertilizers
Bio fertilizers are organisms that enrich the nutrient quality of soil. The main sources of bio-fertilizers are as given below :
BACTERIA - Nitrogen fixing bacteria fix atmospheric N2 into organic form, which is used by the plant. e.g., Rhizobium is a symbiotic bacterium that lives in root nodules of legumes and fix atmospheric N2. Azotobacter and Azospirillum are free living bacteria which does the same.
FUNGI - They also form symbiotic association with plants, i.e., micorrhiza, which absorb phosphorus from the soil and passes it to the plants. Many members of the geus Glomus form mycorrhiza. Plants with mycorrhizal association show other benefits also such as : resistance to root-borne pathogens, tolerance to salinity and drought, increase in overall growth and development.
CYANOBACTERIA - These are autotrophic microbes found in aquatic and terrestial environments. Most of them fix atmospheric N2, e.g., Anabaena, Nostac, Oscillatoria, etc. In paddy fields cyanobacteria serve as important bio-fertilizer. Blue-Green algae also add organic matter to the soil. Thus, increasing its fertility.
BACTERIA - Nitrogen fixing bacteria fix atmospheric N2 into organic form, which is used by the plant. e.g., Rhizobium is a symbiotic bacterium that lives in root nodules of legumes and fix atmospheric N2. Azotobacter and Azospirillum are free living bacteria which does the same.
FUNGI - They also form symbiotic association with plants, i.e., micorrhiza, which absorb phosphorus from the soil and passes it to the plants. Many members of the geus Glomus form mycorrhiza. Plants with mycorrhizal association show other benefits also such as : resistance to root-borne pathogens, tolerance to salinity and drought, increase in overall growth and development.
CYANOBACTERIA - These are autotrophic microbes found in aquatic and terrestial environments. Most of them fix atmospheric N2, e.g., Anabaena, Nostac, Oscillatoria, etc. In paddy fields cyanobacteria serve as important bio-fertilizer. Blue-Green algae also add organic matter to the soil. Thus, increasing its fertility.