UPSC Prelims 2022 Question:

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:

Explanation:

• Symbiotic nitrogen fixation by alfalfa provides substantial amounts of nitrogen (N) to livestock operations, subsequent crops, and soil organic matter. So, point 1 is correct.
  
  

• Chickpeas form root nodules that support biological N fixation (BNF) and host symbiotic N-fixing bacteria. So, point 3 is correct
  
  

• Nitrogen is "fixed" in clovers through a symbiotic relationship with Rhizobium bacteria that infects the plant's roots. The plant provides energy for the bacteria, and bacteria provide the "machinery" necessary to convert atmospheric nitrogen into a form available to plants. So, point 4 is correct.
  
  

• Amaranth, Purslane (Kulfa), Spinach are not are nitrogen-fixing plants. So, points 2, 5 and 6 are not correct.
  
  

 Therefore, option (1) is the correct answer.

Subject: Environment|Terrestrial and Aquatic Ecosystem