Eduprobe
Question:
Which one of the following is regarded as a biofertilizer?
An association between gymnosperms and Nostoc
An association between legume and Rhizobium
An association between pteridophytes and cyanobacteria Anabaena
All of the above
Solution:
Cyanobacteria, either free-living or symbiotic, are considered biofertilizers because they fix atmospheric nitrogen into nitrates and nitrites through a biological process like that of Rhizobium. Blue-green algae belonging to the Cyanobacteria genus, such as Nostoc or Anabaena, fix atmospheric nitrogen and are used as inoculations for paddy crops grown under both upland and lowland conditions. So, the correct answer is option D.