Question

Which of the following acts as biofertiliser

• A. Mycorrhiza
  
• B. $Rhizobium$
• C. All of the above
• D. $Nostoc$

Answer 1

The correct option is C All of the above

Definition of biofertiliser
Biofertilisers consist of microorganisms that act to increase the soil fertility. They are widely used in organic farming.

Role of Nostoc as biofertiliser
Cyanobacteria like $Anabaena$ and $Nostoc$ have been used as biofertilisers as they contain specialised cells called heterocysts that can fix atmospheric nitrogen into absorbable compounds like nitrates.

Role of $Rhizobium$ as biofertiliser
$Rhizobium$ lives inside the nodules formed in the roots of leguminous plants. This symbiotic association helps in fixing atmospheric nitrogen by $Rhizobium$, helping in increasing the nitrogen content in the soil. As the soil fertility increases, $Rhizobium$ can be used as a biofertiliser.

Role of Mycorrhiza as biofertiliser
Mycorrhiza is an association of fungi with the roots of higher plants. This association helps in the solubilisation of phosphates and other nutrients for the plants.

Final answer
(D) All of the above