Common Nitrogen-Fixer in Paddy Fields
The correct answer to the question regarding the common nitrogen-fixer in paddy fields is Oscillatoria.
Overview of Nitrogen Fixation
Nitrogen fixation is the process of converting atmospheric nitrogen (N2) into a form that plants can absorb and utilize. In paddy fields, certain microorganisms contribute significantly to this process.
Role of Oscillatoria
- Cyanobacteria: Oscillatoria is a genus of cyanobacteria, often referred to as blue-green algae, which are crucial in aquatic ecosystems, including rice paddies.
- Nitrogen Fixation: These organisms have specialized cells called heterocysts that allow them to fix atmospheric nitrogen, making it available to plants in the soil.
- Benefits to Paddy Fields: By fixing nitrogen, Oscillatoria enhances soil fertility, promotes plant growth, and reduces the need for chemical fertilizers. This symbiotic relationship is particularly beneficial in the nutrient-deficient conditions often found in paddy fields.
Comparison with Other Options
- Azospirillum: While it is a nitrogen-fixing bacterium, it primarily associates with the roots of grasses and is not as prevalent in aquatic environments like rice paddies.
- Frankia: This bacterium forms symbiotic relationships with actinorhizal plants and is not commonly associated with paddy fields.
- Rhizobium: Known for its symbiotic relationship with legumes, Rhizobium is not a primary nitrogen-fixer in rice cultivation.
Conclusion
In summary, Oscillatoria plays a crucial role in nitrogen fixation in paddy fields, making it the most common nitrogen-fixing organism in this specific ecosystem. Its ability to thrive in aquatic conditions and enhance soil fertility is vital for sustainable rice farming practices.