*Sesbania rostrata* can fix up to 150-200 kg N/ha in 45-50 days.
This high fixation rate makes it an exceptionally powerful green manure crop for flooded rice soils.
Step 1: Understanding the Concept:
Green manuring is the practice of growing and plowing under fresh, green plant tissues to improve soil organic matter and nutrient content.
While most green manure crops (legumes) form nitrogen-fixing nodules only on their roots, a few unique species can form nodules on both their roots and stems. Step 2: Detailed Explanation:
Let us examine the nodulation characteristics of the given green manure crops:
1.Sunhemp (Crotalaria juncea) (A): This is an important quick-growing green manure crop, but it only forms nodules on its roots.
2.Sesbania aculeata (Dhaincha) (B): This is a widely used green manure crop in wet and saline soils, but its nodulation is restricted to the root system.
3.Sesbania rostrata (C): This is a tropical legume native to West Africa.
Unlike standard legumes, it forms nitrogen-fixing nodules on both its roots and its aerial stems in response to infection by *Azorhizobium caulinodans*.
These stem nodules contain chlorophyll and can fix atmospheric nitrogen under waterlogged conditions where root respiration is limited.
This unique dual-nodulating ability allows *Sesbania rostrata* to fix significantly more nitrogen per hectare than traditional root-nodulated legumes. Step 2: Final Answer:
The stem nodulating green manure crop is Sesbania rostrata.
