By which of the following method cytokinins leads to delay in leaf senescence ?

Options

A. Nutrient Immobilisation
B. Nutrient Mobilisation
C. By Preventing ABA synthesis
D. By promoting Auxin synthesis

Answer

**Step-by-Step Solution:**

1. **Understanding Cytokinins**: Cytokinins are plant hormones that play a crucial role in promoting cell division (cytokinesis) and are involved in various plant growth processes.

2. **Role in Leaf Senescence**: Leaf senescence refers to the aging process of leaves, which often leads to their eventual death. Cytokinins are known to delay this process.

3. **Mechanism of Action**: Cytokinins delay leaf senescence primarily by promoting nutrient mobilization. This means that they help in the movement of nutrients from other parts of the plant to the leaves, thus maintaining their health and vitality.

4. **Nutrient Mobilization vs. Immobilization**: During senescence, there is typically a process of nutrient immobilization, where nutrients are not effectively transported to the leaves. Cytokinins counteract this by ensuring that nutrients remain mobile, which helps delay aging.

5. **Conclusion**: Therefore, the method by which cytokinins lead to the delay in leaf senescence is through promoting nutrient mobilization.

**Final Answer**: Cytokinins delay leaf senescence by promoting nutrient mobilization.

---