Inoculating clover seeds with rhizobial bacteria primarily targets which process?

• A. Direct nitrogen fixation by the bacteria in the soil.
• B. Establishing effective nitrogen-fixing nodules on roots.
• C. Increasing photosynthesis rate.
• D. Preventing root diseases.

Answer: (B)

The inoculation targets establishing effective nitrogen-fixing nodules on the roots. When clover seeds are treated with rhizobia, the bacteria colonize developing root hairs and trigger the formation of nodules on the roots. Inside these nodules, the bacteria convert atmospheric nitrogen into ammonia that the plant can use, providing a meaningful nitrogen source for growth. Without nodulation, the nitrogen fixation that benefits the plant wouldn’t occur, even if rhizobia are present in the soil. So the primary purpose is to promote the symbiotic nodulation process that enables nitrogen fixation, rather than fixing nitrogen directly in the soil, increasing photosynthesis directly, or preventing root diseases.