Haploids are of great importance in crop improvement because they

Options

A. Are useful in study of meiosis
B. Grow better in acidic condition
C. Do not express mutation
D. Give homozygous lines after colchicine treatment

Answer

**Step-by-Step Solution:**

1. **Understanding Haploids**: Haploids are organisms or cells that contain a single set of chromosomes. In plants, haploids can be produced through various methods, including tissue culture and anther culture.

2. **Importance in Crop Improvement**: The significance of haploids in crop improvement lies in their ability to produce homozygous lines. A homozygous line is a genetic line where the alleles at a given locus are identical. This uniformity is crucial for breeding programs.

3. **Homozygous Lines**: When haploids undergo a process called "double fertilization" or "callus culture," they can be converted into diploids, resulting in homozygous plants. These plants are genetically stable and can be reliably reproduced.

4. **Benefits of Homozygous Lines**:
- **Increased Yield**: Homozygous lines tend to have consistent traits, which can lead to improved crop yields.
- **Disease Resistance**: Breeding homozygous lines can also enhance resistance to diseases and pests.
- **Uniformity**: Crops that are uniform in size, shape, and maturity are easier to harvest and process.

5. **Conclusion**: Therefore, the primary reason haploids are important in crop improvement is that they can give rise to homozygous lines after callus treatment. This is beneficial for farmers as it enhances crop yield and stability.

**Final Answer**: D. They give homozygous lines after callus treatment.

---