Heterosis cannot be maintained in sexually reproducing plants as it disappears on

Options

A. Outbreeding
B. Inbreeding
C. Cross breeding
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Heterosis:**
- Heterosis, also known as hybrid vigor, refers to the phenomenon where the offspring of two different varieties or species exhibit improved or superior qualities compared to their parents. This can include traits such as growth rate, yield, and resistance to disease.

2. **Sexual Reproduction in Plants:**
- In sexually reproducing plants, offspring are produced through the combination of genetic material from two parent plants. This process can lead to genetic variation.

3. **Impact of Inbreeding:**
- Inbreeding occurs when closely related individuals breed with each other. This can lead to a decrease in genetic diversity and can result in the expression of deleterious alleles, which can diminish the advantages of heterosis.

4. **Why Heterosis Disappears:**
- When inbreeding occurs, the genetic variation that contributes to heterosis is reduced. As a result, the hybrid vigor that was initially present in the offspring diminishes, leading to a decline in the overall fitness of the plants.

5. **Evaluating Options:**
- The question provides several options regarding the condition under which heterosis cannot be maintained:
- **Outbreeding:** Incorrect, as outbreeding can maintain or enhance heterosis.
- **Inbreeding:** Correct, as it leads to the disappearance of heterosis.
- **Crossbreeding:** Incorrect, as crossbreeding also tends to maintain heterosis.
- **None of the above:** Incorrect, as inbreeding is indeed the correct answer.

6. **Conclusion:**
- Therefore, the correct answer is that heterosis cannot be maintained in sexually reproducing plants as it disappears on **inbreeding**.

---