Question

A leguminous plant grown in an autoclaved, sterilized soil fails to produce root nodules because

• A. Autoclaved soil is not good for root growth.
• B. Autoclaved soil is devoid of bacteria.
• C. Autoclaving reduces N${}_2$ content of soil.
• D. Plants cannot form root hairs in such soil.

Answer 1

Answer: (B)

Autoclaved soil is devoid of bacteria.

The process of autoclaving is performed at a temperature of about 121${}^o$ C. The high temperature kills all the bacteria and other organisms which are present in the soil. The root nodules of the leguminous plants are formed due to the association with the bacteria (Rhizobium). The absence of bacteria in the soil results in the failure to form the nodules.

Thus, the correct answer is option B.