Name the chemical which is used by plant breeders to induce polypoidy.
(a)What is its other significance?(b)What is the source of the above mentioned chemical?

Answer

### Step-by-Step Solution:

1. **Identify the Chemical Used to Induce Polyploidy:**
The chemical used by plant breeders to induce polyploidy is **colchicine**.

2. **Explain the Other Significance of Colchicine:**
Colchicine has another significant role; it is used to **stop cell division**. By halting cell division at a specific stage, particularly during **metaphase**, it allows for the observation of **condensed chromosomes**. This property is valuable for morphological studies, which involve examining the structure and form of chromosomes.

3. **Identify the Source of Colchicine:**
Colchicine is derived from the **corms of the plant** known as **Crocus autumnalis** (commonly referred to as the autumn crocus). This plant is where the alkaloid colchicine is extracted.

### Summary of Answers:
- **Chemical:** Colchicine
- **Other Significance:** Stops cell division and aids in the morphological study of chromosomes.
- **Source:** Obtained from the corms of the plant Crocus autumnalis.