Question

Given below are two statements: 
• [Statement (I):] Sesbania is used as green manure crop. 
• [Statement (II):] In Sesbania, nodules are formed only on the roots. 
In light of the above statements, choose the most appropriate answer from the options given below. 
 

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Sesbania rostrata is a classic example of a stem-nodulating legume.
It forms symbiosis with Azorhizobium caulinodans, allowing it to fix nitrogen under flooded, anaerobic conditions.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Green manuring is the practice of growing leafy crops (mostly legumes) and plowing them into the soil to improve organic matter and nutrient content.
Many leguminous plants form symbioses with nitrogen-fixing Rhizobium bacteria, which produce nodules on the plant.

Step 3: Detailed Explanation:
Let us evaluate both statements:
- Statement (I) is correct: Species of the genus Sesbania (such as Sesbania aculeata, commonly known as Dhaincha) are widely used as green manure crops in agriculture.
They grow rapidly, produce high biomass, and fix significant amounts of atmospheric nitrogen, which improves soil fertility when plowed under.
- Statement (II) is incorrect: While most leguminous plants form nodules only on their roots, some species of Sesbania are exceptions.
Specifically, Sesbania rostrata is a stem-nodulating legume.
It forms nitrogen-fixing nodules on both its roots and its stems.
These stem nodules are induced by the bacterium Azorhizobium caulinodans and allow the plant to fix nitrogen even in waterlogged or flooded soils where root nodulation is suppressed.
Therefore, nodules are not formed *only* on the roots in all Sesbania species.
Thus, Statement (I) is correct, but Statement (II) is incorrect.

Step 4: Final Answer:
Statement (I) is correct but Statement (II) is incorrect, matching Option (C).