The main similarities between the synthetics and composite varieties of crops are:
(A). Both are relevant to allogamous species
(B). Both can be reconstituted exactly and easily
(C). Both have a broad genetic base
(D). Both are mixtures of several homozygotes and heterozygotes
Choose the correct answer from the options given below:
(A). Both are relevant to allogamous species
(B). Both can be reconstituted exactly and easily
(C). Both have a broad genetic base
(D). Both are mixtures of several homozygotes and heterozygotes
Choose the correct answer from the options given below:
Show Hint
Synthetic varieties can be reconstituted exactly because their parents are maintained as pure inbreds or clones.
Composite varieties cannot be reconstituted exactly because they are created by mixing open-pollinated germplasms.
- (A), (B) and (C) only.
- (A), (B) and (D) only.
- (A), (C) and (D) only.
- (B), (C) and (D) only.
The Correct Option is C
Solution and Explanation
In plant breeding, synthetic and composite varieties are open-pollinated populations used primarily in cross-pollinated (allogamous) crops.
Both are designed to exploit heterosis (hybrid vigor) while providing farmers with seed that can be saved and replanted for several seasons without experiencing severe inbreeding depression.
Step 2: Detailed Explanation:
Let us analyze each statement to compare synthetics and composites:
1. Statement (A) is correct: Both synthetic and composite breeding schemes are developed for allogamous (cross-pollinated) species like maize, pearl millet, and alfalfa.
These species possess high levels of heterozygosity and are adapted to outcrossing.
2. Statement (B) is incorrect: A synthetic variety is developed by crossing a specific set of parent lines (usually inbred lines or clones) that have been tested for general combining ability (GCA).
Because these parental lines are maintained, a synthetic variety can be reconstituted exactly at any time by repeating the original crosses.
In contrast, a composite variety is developed by mixing several open-pollinated varieties, germplasm lines, or synthetics without testing their GCA.
Because the exact parental lines are not maintained as pure inbreds, a composite variety cannot be reconstituted exactly.
3. Statement (C) is correct: Both synthetic and composite varieties have a very broad genetic base.
They consist of many different genotypes, which provides them with excellent buffering capacity and stability across diverse environments and stressful conditions.
4. Statement (D) is correct: Because both are open-pollinated, highly heterogeneous populations, they are represented by a mixture of diverse homozygotes and heterozygotes at various loci.
Therefore, statements (A), (C), and (D) are correct, whereas (B) is incorrect.
Step 3: Final Answer:
The correct option is (C), which contains (A), (C) and (D) only.
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Select the correct statements about origin of the tetraploid and hexaploid wheat:
• [A.] The tetraploid species Triticum turgidum is an allopolyploid.
• [B.] The hexaploid species Triticum aestivum is an allopolyploid.
• [C.] Triticum turgidum arose from a combination of Triticum monococcum and Triticum timopheevii genomes.
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• [(A).] Fertilizer requirement.
• [(B).] Vernalization requirement.
• [(C).] Winter hardiness (cold tolerance)
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Male sterile cytoplasm in crop plants usually arises from-
• [(A).] Inter-specific hybridization
• [(B).] Self-incompatibility
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Which of the following statements is NOT correct?
• [(A).] Seeds of synthetic varieties need to be replaced every year.
• [(B).] Hybrid crops need intensive care and more inputs.
• [(C).] Open pollinated progeny test is used in Maize and Pearl millet.
• [(D).] Composite varieties exploit both GCA and SCA. Choose the correct answer from the options given below:
Which of the following combinations of the premises of 'Gamete Selection' in plant breeding is the correct one?
• [(A).] Multiparent crosses are required for simultaneous improvements of multiple traits.
• [(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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