Question

Farmers have reported over 50% higher yields of rice by using which of the following biofertilizers?
A Mycorrhiza
B Azolla pinnata
C Clostridium
D Rhizobium

Answer 1

Hint A biofertilizer is a chemical that contains living microorganisms that colonise the rhizosphere or the interior of the plant when applied to seeds, plant surfaces, or soil, and encourage growth by increasing the supply or availability of primary nutrients to the host plant.

Complete step by step answer:
Biofertilizers supply nutrients to plants through natural processes such as nitrogen fixation, phosphorus solubilization, and the creation of growth-promoting chemicals. Biofertilizers use microorganisms to restore the soil's natural nutrient cycle and increase soil organic matter.
Healthy plants can be developed with the application of biofertilizers while also improving the soil's sustainability and health. Biofertilizers will likely minimise the need of synthetic fertilisers and pesticides, but they will not be able to completely replace them. Plant-growth promoting rhizobacteria (PGPR) is a favoured scientific term for these helpful bacteria because they serve multiple roles.
Farmers have reported increased rice yields of more than 50% when using Azolla pinnata as a biofertilizer. In collaboration with the nitrogen-fixing blue green alga Anabaena azollae, Azolla is a free-floating water fern that floats in water and fixes atmospheric nitrogen. Azolla fronds are made up of a sporophyte with a floating rhizome and little bi-lobed leaves and roots that overlap.
Rice-growing regions in Southeast Asia and other third-world countries have recently shown significant interest in using the symbiotic N2 fixing water fern Azolla as a nitrogen supply alternative or supplement to conventional nitrogen fertilisers. Azolla is a biofertilizer for wetland rice that contributes 40-60 kg nitrogen per hectare each rice crop.

So, the correct answer is option B.

Note: Azolla is a genus of seven water ferns of the Salviniaceae family. They are exceedingly specialised and reduced in appearance, resembling duckweed or some mosses rather than other ferns. Azolla filiculoides is one of just two fern species with a published reference genome.