Question

Azolla increases rice productivity, due to its association with

• A. Rhizobium
• B. Nostoc
• C. Anabaena
• D. None of the above

Answer 1

Answer: (C)

Anabaena

Blue-green algae belonging to Cyanobacteria genus, Nostoc or Anabaena, fix atmospheric nitrogen and are used as inoculations for paddy crop grown both, under upland and lowland conditions.

Anabaena in association with water fern Azolla contributes nitrogen up to 60 kg/ha/season and also enriches soils with organic matter. Azolla is a floating pteridophyte, which contains as endosymbiont the nitrogen-fixing cyanobacteria, Anabaena azollae. Widely cultivated in the Asian regions, Azolla is either incorporated into the soil before rice transplanting or grown as a dual crop along with rice.

So, the correct answer is option C.