Question

Aquatic fern which is an excellent biofertilizer is
A) Salvinia
B) Azolla
C) Marsilea
D) Pteridium

Answer 1

Hint: Aquatic fern commonly grows in water they do not require soil . It has a symbiotic relationship with a cyanobacterium (blue –green algae) and it has the ability to get nitrogen fertilizer from the atmosphere that means it has the ability to produce biofertilizer ,livestock feed ,food and biofuel. As it is able to fix the nitrogen which increases the fertility of the soil and in turn to increase the production yield.

Complete answer:
To answer this question you must know about Azolla. Azolla is a pteridophyte or aquatic plant ,flot on the surface of water and used as a biofertilizer because it has association with nitrogen – fixing cyanobacteria anabaena azollae. Azolla – anabaena symbiotic system is the main biofertilizer inoculated in the rice fields in south-estern asia to increase yield upto 50%.

- Pteridium is a species of fern found in temperate and subtropical regions in both hemispheres. It is also known as eagle fern and it is not used as a biofertilizer.
- Marsilea ,a genus of approximately 65 species of aquatic fern of the family marsileaceae and it is not used as a biofertilizer.
- Salvinia is a genus in the family salviniaceae ,it is a floating fern named anton maria salvini . It is also not used as a biofertilizer.

From the above explanation it is clear that Azolla is used as the biofertilizer therefore the correct option of the given question is (B) i.e, Azolla.

Note: Azolla captures 6 tons of atmospheric carbon per acre per year and could reduce global co2 levels ,which provides high protein livestock feed for nitrogen rich fertilizers. Green plants have long been recognized as the cheapest and most abundant potential source of proteins because of their ability to synthesize amino acids.