Which of the following statements about synthetic varieties are correct?
• [(A).] Unlike hybrids, the farmers can save the seeds of synthetic varieties.
• [(B).] Synthetic varieties have wider adaptability.
• [(C).] No need to make fresh crosses every year.
• [(D).] Synthetic varieties are higher yielding than the hybrids.
Choose the correct answer from the options given below:
Which of the following statements about synthetic varieties are correct?
• [(A).] Unlike hybrids, the farmers can save the seeds of synthetic varieties.
• [(B).] Synthetic varieties have wider adaptability.
• [(C).] No need to make fresh crosses every year.
• [(D).] Synthetic varieties are higher yielding than the hybrids.
Choose the correct answer from the options given below:
Show Hint
- Hybrids = Highest yield, narrow adaptability, seeds must be bought every year.
- Synthetics = Moderate-high yield, wide adaptability, seeds can be saved by farmers.
- (A), (B) and (C) only.
- (A), (B) and (D) only.
- (A), (C) and (D) only.
(D) (B), (C) and (D) only.
The Correct Option is A
Solution and Explanation
A synthetic variety is a population developed by intermating a set of inbred lines or clones that have been tested for their general combining ability (GCA).
Once developed, synthetic varieties are maintained by open pollination and are widely used in cross-pollinated crops.
Step 3: Detailed Explanation:
Let us analyze each of the statements to determine their accuracy:
- Statement (A) is correct: Unlike single-cross hybrids, which suffer a major reduction in yield (due to inbreeding depression) if seeds are saved and replanted, synthetic varieties maintain their yield performance over several generations.
This allows farmers to save and replant their own seed for several seasons, reducing seed costs.
- Statement (B) is correct: Synthetic varieties are genetically heterogeneous because they are composed of multiple parent lines.
This high genetic diversity gives them broader ecological buffering, resulting in wider adaptability to varying climates, soils, and disease pressures compared to genetically uniform hybrids.
- Statement (C) is correct: Because the variety is maintained through open pollination in isolation, breeders do not need to make fresh crosses or produce parent lines from scratch every year.
- Statement (D) is incorrect: Synthetic varieties generally produce lower yields than the best \(F_1\) hybrids.
Hybrids fully exploit specific combining ability (SCA) and maximize heterosis, whereas synthetics only exploit general combining ability (GCA).
Therefore, statements (A), (B), and (C) are correct, while (D) is incorrect.
Step 4: Final Answer:
The correct combination is (A), (B) and (C) only, matching Option (A).
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• [(A).] Seeds of synthetic varieties need to be replaced every year.
• [(B).] Hybrid crops need intensive care and more inputs.
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• [(B).] The male parents of the final crosses are heterozygous and hence heterogametic.
• [(C).] Each zygotic seed is a product of a separate, independent fertilization event.
• [(D).] Gametic selection is an effective method to isolate an inbred for hybrid breeding.
Choose the correct answer from the options given below:
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