The stimulus of cold treatment (vernalisation) is perceived by

Options

A. fruits
B. shoot apex
C. axillary buds
D. flowers

Answer

### Step-by-Step Solution:

1. **Understanding Vernalization**: Vernalization is the process by which plants require a period of cold temperatures to trigger flowering. This is crucial for certain species to ensure that they flower at the right time of year.

2. **Identifying the Stimulus**: The stimulus in vernalization is the cold treatment that plants experience. This cold exposure is necessary for the transition from vegetative growth to flowering.

3. **Perception of Cold Stimulus**: Plants perceive environmental stimuli through various organs. In the case of cold treatment, the perception primarily occurs at specific growth points.

4. **Key Organs Involved**: The primary organ involved in perceiving the cold stimulus for vernalization is the shoot apex. This is where the flowering development is initiated.

5. **Conclusion**: Therefore, the correct answer to the question is that the stimulus of cold treatment (vernalization) is perceived by the **shoot apex**.