Question

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

Answer 1

Hint: Biofertilizers are non-toxic alternatives of chemical and toxic fertilizers.

Complete answer: Biofertilizers are organisms that enrich the nutritional quality of the soil.
The major examples of biofertilizers are bacteria, fungi, and cyanobacteria (blue-green algae).
The application of biofertilizers are as follows:
1. There are an increased mineral and water uptake by the plants
2. Due to the presence of the minerals (from the biofertilizer), there is excessive and desirable root development and vegetative growth.
3. These organisms help in the growth of the plant by nitrogen fixation.
For example, Rhizobium is seen as the roots of leguminous plants.
They form root nodules that have a specialized protein known as leg-hemoglobin which helps in absorbing nitrogen compounds from the soil.
4. These organisms produce various growth hormones (products of metabolism of the biofertilizer) and other essential products like vitamin-B complex, Indole-3 acetic acid (IAA), gibberellic acids, etc.
5. They increase the fertility of the soil and also its productivity.

Additional information: Blue-green algae also known as cyanobacteria such as Nostoc, Anabaena, possess specialized cells known as heterocysts. These modified cells are formed from the vegetative cells, they are the sites for nitrogen fixation as it contains the enzyme nitrogenase. This enzyme helps in the process of nitrogen fixation.
Anabaena is an alga that is present in the Azolla plant.
They are used in paddy fields for increasing the nitrogen content of the soil and increasing the yield/ harvest of the rice crops There are specific modes of application of biofertilizers.
Some of them are seedling root dip, self-inoculation, tuber inoculation, seed inoculation, etc.

Note: The nitrogen-fixing biofertilizers contain several microorganisms such as Rhizobium, Actinobacteria, Azotobacter, and Azospirillum. They help in transforming atmospheric nitrogen into compounds absorbable by plants