Question

Write down the application of biofertilizers. Explain the role of cyanobacteria as a biofertilizer.

Answer 1

Biofertilizers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilizers are bacteria, fungi, and cyanobacteria (blue-green algae). The application of biofertilizers are as follows:

• There is increased mineral and water uptake.
• Due to the presence of the minerals, there is root development and vegetative growth.
• These organisms help in the growth of the plant by nitrogen fixation.
• These organisms produce growth hormones and products like vitamin-B complex, Indole acetic acid (IAA) and Gibberellic acids etc.
• They increase the soil fertility and productivity.

Blue-green algae or cyanobacteria such as Nostoc, Anabaena, possess specialized cells. These cells are called as heterocysts. These are modified cells which are formed from the vegetative cells. These are the sites for N${}_2$ fixation as it contains nitrogenase enzyme which helps in nitrogen fixation. Anabaena is an algae are present in the Azolla plant and are used in the paddy fields for increasing the nitrogen content of the soil and increasing the yield of rice crops.