The common nitrogenfixer in paddy fields is
Rhizobium
Azospirillum
Oscillatoria
Frankia.
The best fertilizer for paddy is
Azolla is used as a biofertiliser because it
Root nodules for nitrogen fixation of a non-leguminous tree possess
Farmers have reported $50\%$ higher yield of rice by using biofertilizer
Which of the following is used as biofertiliser?
$I.$ Cyanobacteria
$II.$ Yeast
$III.$ Symbiotic bacteria
$IV.$ Free living bacteria
Choose the correct option