Differentiation of shoot is promoted by

Options

A. high auxin : cytokinin ratio
B. high cytokinin : auxin ratio
C. high gibberellin : auxin ratio
D. high gibberellin : cytokinin ratio

Answer

To answer the question "Differentiation of shoot is promoted by," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Plant Growth Regulators**:
- Plant growth regulators (PGRs) are crucial in regulating various aspects of plant growth and development, including differentiation of shoots and roots.

2. **Identifying Key Regulators**:
- The two main types of plant growth regulators involved in shoot and root differentiation are auxins and cytokinins.

3. **Role of Cytokinins and Auxins**:
- Cytokinins promote cell division and shoot formation, while auxins are primarily involved in root development.

4. **Cytokinin to Auxin Ratio**:
- The differentiation of shoots is specifically promoted by a high ratio of cytokinins to auxins. This means that when the concentration of cytokinins is greater than that of auxins, shoot differentiation occurs.

5. **Conclusion**:
- Therefore, to promote shoot differentiation, the environment must have a high cytokinin to auxin ratio.

### Final Answer:
Differentiation of the shoot is promoted by a high cytokinin to auxin ratio.

---