Question

Types of Biofertilizers

Symbiotic Nitrogen-Fixing Bacteria: Rhizobium is a vital symbiotic nitrogen-fixing bacteria that form a mutually beneficial relationship with plants, providing fixed nitrogen to them.

Loose Association of Nitrogen-Fixing Bacteria: Azospirillum is a type of nitrogen-fixing bacteria that live around the roots of higher plants without forming an intimate relationship with the plants. They collect plant exudates for food in a process known as associative mutualism.

Symbiotic Nitrogen-Fixing Cyanobacteria: Blue-Green algae or Cyanobacteria form symbiotic associations with various plants like liverworts, cycad roots, ferns, and lichens. Anabaena, found in fern leaf cavities, is responsible for nitrogen fixation.

Free-Living Nitrogen-Fixing Bacteria: These are free-living soil bacteria that perform nitrogen fixation independently. Examples include Clostridium beijerinckii and Azotobacter.

Among these types, Rhizobium and Azospirillum are the most widely used biofertilizers.

Answer 1

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Phosphate-Solubilizing Bacteria: These bacteria help in converting insoluble phosphorus into a soluble form that can be easily absorbed by plants. Examples include Bacillus megaterium and Pseudomonas striata.

Silicate Solubilizing Bacteria: These bacteria help in releasing silicon from insoluble silicates in the soil, making it available to plants. Examples include Bacillus spp. and Pseudomonas spp.

Potassium-Solubilizing Bacteria: These bacteria help in solubilizing potassium from insoluble minerals in the soil, making it available to plants. Examples include Bacillus fastidiosus and Bacillus mucilaginosus.

Zinc-Solubilizing Bacteria: These bacteria help in solubilizing zinc from insoluble sources in the soil, making it easily available to plants. Examples include Bacillus spp. and Pseudomonas spp.

Microbial Inoculants: These are mixed cultures of beneficial microorganisms that help in enhancing plant growth and improving soil health. Examples include Trichoderma spp. and Bacillus spp.

Plant Growth-Promoting Rhizobacteria (PGPR): These bacteria help in promoting plant growth by various mechanisms like nitrogen fixation, phosphorus solubilization, and production of plant growth hormones. Examples include Pseudomonas spp. and Bacillus spp.