Find odd one (w.r.t. cause of seed dormancy)
(a) Amaranthus
(b) Capsella
(c) Ginkgo
(d) Trigonella

Options

A. Amaranthus
B. Capsella
C. Ginkgo
D. Trigonella

Answer

To solve the question of finding the odd one out with respect to the cause of seed dormancy among the given options, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Analyze Amaranthus:**
- The cause of seed dormancy in Amaranthus is internal, primarily due to its tissue and embryo development.
- Dormancy can be inhibited by exposure to light.
- Seeds do not germinate optimally at temperatures between 25 to 30 degrees Celsius.

2. **Analyze Capsella (Shepherd's Purse):**
- Similar to Amaranthus, the cause of seed dormancy in Capsella is also internal, due to tissue and embryo development.
- Dormancy can also be inhibited by exposure to light.
- Seeds do not germinate at the optimal temperature of 25 to 30 degrees Celsius.

3. **Analyze Ginkgo:**
- Ginkgo's seed dormancy is also internal, linked to tissue and embryo development.
- Like the previous two, dormancy can be inhibited by light exposure.
- Seeds do not germinate at the temperature of 25 to 30 degrees Celsius.

4. **Analyze Trigonella:**
- In contrast, the cause of seed dormancy in Trigonella is external, specifically due to a blocked testa pore.
- The dormancy can be released through a process called impaction, which involves vigorous shaking.
- Unlike the other three, Trigonella seeds can germinate at the temperature of 25 to 30 degrees Celsius.

5. **Identify the Odd One Out:**
- The first three options (Amaranthus, Capsella, and Ginkgo) share a commonality: their seed dormancy is internal and can be released by light exposure.
- Trigonella is different as its dormancy is external and requires a physical process (impaction) to be released, and it can germinate at the same temperature range.

### Conclusion:
Thus, the odd one out with respect to the cause of seed dormancy is **(d) Trigonella**.

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