Genetic homeostasis, which confers a population wider adaptability is, however, NOT exploited by -
Show Hint
- Varietal mixtures and multiline varieties
- Hybrids
- Synthetic varieties
- Composite varieties
The Correct Option is A
Solution and Explanation
In plant breeding and population genetics, buffering capacity describes a population's ability to maintain stable growth and yields across different environmental conditions.
According to Allard and Bradshaw (1964), this stability can be achieved through two distinct mechanisms: individual buffering and populational buffering.
Step 2: Detailed Explanation:
Let us analyze the differences between these two mechanisms:
1. Individual Buffering (Genetic Homeostasis): This is the capacity of an individual plant to adjust its physiological and developmental pathways to buffer against environmental stress.
This stability is highly characteristic of heterozygous genotypes, such as $F_1$ hybrids, synthetic varieties, and composite varieties.
The presence of different alleles at many loci provides these heterozygous individuals with biochemical versatility, allowing them to adapt to environmental fluctuations.
2. Populational Buffering: This is a property of heterogeneous populations composed of a mixture of different genotypes (such as different homozygous lines).
When the environment changes, some genotypes in the mixture may perform poorly, but others will thrive and compensate for the loss, stabilizing the overall population yield.
This populational buffering is exploited by heterogeneous but homozygous populations, such as varietal mixtures and multiline varieties.
These mixtures do not exploit individual genetic homeostasis because they are composed of homozygous lines that have low individual buffering capacity.
Therefore, varietal mixtures and multiline varieties do not exploit genetic homeostasis.
Step 3: Final Answer:
Genetic homeostasis is not exploited by varietal mixtures and multiline varieties, corresponding to option (A).
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• [B.] The hexaploid species Triticum aestivum is an allopolyploid.
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• [(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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