Which of the following are nitrogen-fixing plants ? 1. Alfalfa 2. Amaranth 3. Chickpea 4. Clover 5. Purslane (Kulfa) 6. Spinach Select the correct answer using the code given below :

(a) 1, 3 and 4 only ✓ UPSC's answer
(b) 1, 3, 5 and 6 only
(c) 2, 4, 5 and 6 only
(d) 1, 2, 4, 5 and 6

Why the answer is (a)

• Nitrogen-fixing plants are legumes (family Fabaceae) that host Rhizobium bacteria in root nodules, converting atmospheric nitrogen into usable compounds.

• Alfalfa (lucerne), chickpea (gram) and clover are all legumes and fix nitrogen — items 1, 3 and 4.

• Amaranth, purslane (kulfa) and spinach are leafy vegetables of the amaranth and purslane families; they do not form nodules or fix nitrogen.

• Legumes are used as green manure and in crop rotation to restore soil fertility.

• Hence 1, 3 and 4 only, option (a).

Why the other options are wrong

(b) 1, 3, 5 and 6 only: Purslane and spinach are not legumes.
(c) 2, 4, 5 and 6 only: Amaranth, purslane and spinach do not fix nitrogen; alfalfa and chickpea do.
(d) 1, 2, 4, 5 and 6: Amaranth, purslane and spinach are not nitrogen fixers.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.