Question

Which one as used/regarded as biofertiliser?

• A. A association between pteridophytes and cyanobacteria Anabaena
• B. A association between gymnosperms and Nostoc
• C. A association between legume and Rhizobium
• D. All of the above

Answer 1

Answer: (D)

All of the above

Answer 2

Cyanobacteria either free living of symbiotic are considered as biofertiliser because the fix atmospheric nitrogen in form of nitrates and nitrites by biological process. They leaves of Azolla pteridophytes has as many as $80,000$ BGA and fix atmospheric $N _{2}$ in field of rice. Nostoc with corrolloid roots of Cycas also fix atmospheric nitrogen. Soil nitrogen is maintained by association between Rhizobium and root nodule of legume.