First natural cytokinin was obtained from ________.

Options

A. Rice plants
B. Tobacco callus
C. Maize grains
D. Human urine

Answer

**Step-by-Step Solution:**

1. **Understanding Cytokinins**: Cytokinins are a class of plant hormones that promote cell division (cytokinesis) in plant roots and shoots. They play a crucial role in various plant growth and development processes.

2. **Identifying the First Natural Cytokinin**: The question asks about the first natural cytokinin. The first cytokinin discovered was Kinetin, but it was not found naturally in plants.

3. **Source of Natural Cytokinins**: The first natural cytokinin that was identified is called Zeatin. It was isolated from corn (maize) grains.

4. **Conclusion**: Therefore, the answer to the question "First natural cytokinin was obtained from ________." is **maize grains**.

**Final Answer**: Maize Grains

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