What is importance of use of blue-green algae as Biofertilizers? Explain.

Blue-Green Algae or Cyanobacteria:

• Cyanobacteria such as Anabaena, Nostoc, Plectonema, and other non-symbiotic prokaryotes perform nitrogen fixation.
• Cyanobacteria have special cells called heterocyst. The Nif gene present in these cells does nitrogen fixation.
• Rice fields are ideal for the growth of blue-green algae, hence the use of blue-green algae in paddy fields increases the production of rice. Nowadays, one aquatic pteridophyte called Azolla is also used along with blue-green algae as algal biofertilizer in Southern and South-East Asia.
• The Azolla is a floating aquatic fern. Leaves of Azolla contain blue-green algae Anabaena azollae which fixes atmospheric Nitrogen. Anabaena pinata is also a good biofertilizer. When it is used in combination with Azolla, it can increase rice production by 50%.
• Anabaena azollae is commercially produced at Central Rice Research Institute, Cuttack.