Question

An organism used as a biofertilizer for raising soyabean crop is

• A. Rhizobium
• B. Nostoc
• C. Azotobacter
• D. Azospirillum

Answer 1

The Correct Option is A

To effectively determine the biofertilizer used in raising a soybean crop, understanding the role of certain microorganisms in agriculture is crucial. Biofertilizers are increasingly important in enhancing soil fertility and plant growth through natural processes.

Let’s evaluate the options given:

1. Rhizobium: Rhizobium is a well-known symbiotic nitrogen-fixing bacterium associated specifically with leguminous plants such as soybeans. It forms root nodules on the plant where it converts atmospheric nitrogen into a form the plant can absorb and use. This process enhances soil fertility naturally. Thus, Rhizobium is the most appropriate biofertilizer for soybeans, specifically due to its relationship with legume crops.
2. Nostoc: Nostoc is a genus of cyanobacteria that can also fix nitrogen. However, it is more commonly associated with non-leguminous partners and doesn't form specific nodules like Rhizobium does with legumes. It is not typically used as a biofertilizer for soybeans.
3. Azotobacter: Azotobacter is a free-living nitrogen-fixing bacterium. It enriches the soil but does not form a symbiotic relationship with soybean plants; hence, it is less efficient compared to Rhizobium for soybean cultivation.
4. Azospirillum: Azospirillum is known to enhance the growth of cereals and grasses, promoting better yield but is not specifically related to legumes like soybean.

From the analysis above, Rhizobium is the correct answer as it has a symbiotic relationship with soybean plants, making it an effective biofertilizer for this crop.

In conclusion, Rhizobium's ability to fix atmospheric nitrogen in conjunction with soybean plants enhances the plant's growth and soil fertility, thereby making it the best choice for the soybean crop.