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Q77
(UPPCS/2023)
Economy › Agriculture & Rural Economy
The aquatic plant commonly used as bio fertilizer in the water-logged rice field is -
Result
Your answer:
—
·
Correct:
C
Explanation
Azolla is a free-floating aquatic fern widely used as a bio-fertilizer in water-logged rice cultivation. Its utility arises from a symbiotic relationship with the nitrogen-fixing blue-green algae (cyanobacterium) Anabaena azollae, which lives in its leaf cavities.
- Nitrogen Fixation: The Anabaena fixes atmospheric nitrogen (N2), making it available to the rice crop. When the Azolla dies and decomposes, it releases this nitrogen into the soil.
- Benefits: It can contribute significant amounts of nitrogen (approx. 30-40 kg N/ha), improves soil organic matter, and helps suppress weed growth in paddy fields.
- Other Options: Wolffia and Lemna are types of duckweed often used for animal feed or bioremediation, while Trapa (water caltrop) is cultivated for its edible starchy seeds.
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