Explant is required to be disinfected before placing in culture. This is done by

Options

A. autoclaving
B. ultra-violet rays
C. clorax or hypochlorite
D. X-rays

Explanation

### Step-by-Step Solution:

1. **Understanding Explant**:
- An explant is any part of a plant that is used for tissue culture. It can be a leaf, stem, root, or any other part of the plant from which a new plant can be developed.

2. **Importance of Disinfection**:
- Before placing the explant in culture, it is crucial to disinfect it. This is to ensure that the explant is free from pathogens or contaminants that could interfere with the growth of the new plant.

3. **Methods of Disinfection**:
- There are several methods for disinfecting explants, including autoclaving, ultraviolet rays, and chemical treatments. However, not all methods are suitable for explants due to their sensitivity.

4. **Evaluating Options**:
- **Autoclaving**: This method uses high temperatures (around 120°C) and is typically used for sterilizing nutrient media, not explants, as it can denature proteins in the plant tissue.
- **Ultraviolet Rays**: While UV rays can disinfect surfaces, they can also cause damage to the explant by denaturing proteins, making them unsuitable for direct application on explants.
- **Clorox or Hypochlorite**: These are chemical disinfectants that are commonly used to treat explants. They effectively kill pathogens without causing significant damage to the plant tissues.
- **X-rays**: Similar to UV rays, x-rays can cause damage to the plant tissues and are not suitable for disinfecting explants.

5. **Conclusion**:
- The most appropriate method for disinfecting explants before placing them in culture is by using a solution of Clorox or hypochlorite.

### Final Answer:
Disinfection of explants is done by treating them with Clorox or hypochlorite solution.

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