(GPB-507) Heterosis Breeding

Q1. Define the following (5 Marks)

1. Stability

2. Hybrid vigour

3. Stable restorer

4. Test cross

5. Bridge species

6. Luxuriance

7. Correlation

8. Stable Maintainer

9. Apomixis

10. Inbred line

---

Q2. Write a short note on the following (8 Marks)

1. Practices for hybrid rice seed production

2. Purification of two-line hybrids

3. General and specific combining ability

4. Development of apomictic hybrid if apomixis is controlled by a recessive gene

5. Development of synthetic varieties and composite varieties

---

Q3. Explain the following (5 Marks)

1. Apomixis in fixing of heterosis a concept of single line

2. Methods of inbred line development

3. Shift from double cross to three-way to single in maize

4. Commercial significance of heterosis

5. Two-line approach in heterosis breeding

---

Q4. Answer the following (15 Marks)

1. How do you exploit heterosis in rice? Explain.

2. Explain chemically induced male sterility in rice.

3. What are the male sterility systems available in wheat? Explain.

---

Q5. Give the classification of male sterility in rice along with suitable environmental conditions for hybrid seed production (2 Marks)