Azolla possesses symbiotic association with
Anabaena
Nostoc
Azospirillum
Rhizobium
Mycorrhiza represents
Azotobacter and Bacillus polymyxa are
Bacteria found in root nodules of legumes are
Azolla enriches rice fields with nitrogen due to its association with
Give scientific reasons : The pressure on use of organic farming and biotic fertiliser has been increased.