Tag: microbes in human welfare

Fertilizers provide three main macronutrients: potassium, nitrogen and phosphorous which are consumed in larger quantities and are present in plant tissue, in quantities from 0.15% to 6.0% of a dry matter (DM) (0% moisture) basis. Iron is a micronutrient for plant growth which is not available in fertilizers.

The apogeotropic or positively geotropic roots appear in Cycas sporophyte are called Corolloid roots or Corollorhiza. These roots looks like anthozoans or coelenterates. They contain Blue green algae or cyanobacteria like Nostoc and Anabaena, and perform symbiotic nitrogen fixation. They show mutual association with plant body.

So, the correct option is ‘Cyanobacteria’.

The kingdom monera is comprised of the prokaryotic organisms. The blue-green algae are included under the kingdom monera. These are the primitive form of prokaryotic organisms. They are unicellular or multicellular forming filamentous structures. They do not have well-developed cellular components such as a nuclear membrane, nucleus, mitochondria, etc. 

The cyanobacteria (also referred to as blue-green algae) have chlorophyll a similar to green plants and are photosynthetic autotrophs. The cyanobacteria are unicellular, colonial or filamentous, fresh-water marine or terrestrial algae. The colonies are generally surrounded by a gelatinous sheath. They often form blooms in polluted water bodies. Some of these organisms can fix atmospheric nitrogen in specialized cells called heterocysts, e.g, Nostoc and Anabaena.

BGA and Azolla have known to be used for the rice cultivation and they are very good for increasing the crop yield and productivity as they supply the soil and the plant with enough nitrogen. They are known used together as the biofertilizers.

Cyanobacteria also known as Cyanophyta, are a phylum of bacteria that obtain their energy through photosynthesis, and are the only photosynthetic prokaryotes able to produce oxygen. The name "cyanobacteria" comes from the color of the bacteria. Cyanobacteria, which are prokaryotes, are also called "blue-green algae", though the term "algae" in modern usage is restricted to eukaryotes. Phototrophic eukaryotes perform photosynthesis by plastids that may have their ancestry in cyanobacteria, acquired long ago via a process called endosymbiosis. These endosymbiotic cyanobacteria in eukaryotes may have evolved or differentiated into specialized organelles such as chloroplasts, etioplasts and leucoplasts. By producing and releasing oxygen (as a byproduct of photosynthesis), cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere into an oxidizing one, causing the Great Oxygenation Event and the "rusting of the Earth", which dramatically changed the composition of the Earth's life forms and led to the near-extinction of anaerobic organisms.

Nostoc belongs to cyanobacteria genus, and it can be used as biofertilizer. It is also called the blue-green algae. Nostoc converts atmospheric nitrogen into ammonia, which can be further converted to a suitable form for plant growth. Biofertilizers enhance the quality of plants and soil.