Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: In reciprocal recurrent selection, the two populations so developed can be used as synthetic variety.
Reason R: In reciprocal recurrent selection, the GCA of both the population is improved simultaneously.
In light of the above statements, choose the correct answer from the options given below.

• A. Both A and R are true and R is the correct explanation of A.
• B. Both A and R are true but R is NOT the correct explanation of A.
• C. A is true but R is false.
• D. A is false but R is true.

Hint:

Remember that reciprocal recurrent selection involves two populations and reciprocal testing.
Each population is used as a tester for the other population, allowing selection for improved combining ability.
The key point to remember is that reciprocal recurrent selection improves the GCA of both populations simultaneously.
Do not confuse this method with the direct development of a synthetic variety.
For examination questions, associate reciprocal recurrent selection primarily with improvement of two populations for their combining ability and subsequent hybrid performance.

Answer 1

The Correct Option is D

•

Step 1: Understanding the Question:
This is an Assertion--Reason question based on reciprocal recurrent selection, an important breeding method used particularly for improving the combining ability of two populations.
The method involves selecting superior individuals from two populations on the basis of their performance when crossed with individuals from the opposite population.
The question asks whether the improved populations can be used directly as synthetic varieties and whether reciprocal recurrent selection improves the general combining ability of both populations simultaneously.

•

Step 2: Key Formula or Approach:
No numerical formula is required for this question.
The concept can be evaluated by remembering the principal objective of reciprocal recurrent selection:
\[ \text{Reciprocal Recurrent Selection} \longrightarrow \text{Improvement of GCA in both populations} \] The two populations are selected and improved reciprocally so that their ability to produce superior progeny when crossed with the opposite population is increased.

• Detailed Explanation:

• Reciprocal recurrent selection is a recurrent selection method involving two genetically distinct populations.

• Individuals from each population are evaluated by crossing them with a tester derived from the opposite population.

• The superior individuals are selected on the basis of their testcross performance.

• Selected individuals from each population are then intermated within their respective populations to form the next generation.

• This process is repeated for several cycles, resulting in gradual improvement in the combining ability of both populations.

• General combining ability, or GCA, refers mainly to the average performance of a genotype in hybrid combinations and is largely associated with additive genetic effects.

• In reciprocal recurrent selection, the selection procedure is reciprocal because each population serves as a tester for the other population.

• Consequently, selection is directed toward improving the performance of both populations in crosses with the opposite population.

• Therefore, Reason R is true: the GCA of both populations is improved simultaneously through the reciprocal selection process.

• However, the Assertion states that the two improved populations can be used as a synthetic variety.

• A synthetic variety is generally developed by intercrossing selected genotypes or lines that possess good combining ability and then maintaining the resulting population through controlled or appropriate pollination.

• Reciprocal recurrent selection primarily aims at improving two populations for their performance when crossed with each other, rather than producing a synthetic variety directly.

• The improved populations obtained through reciprocal recurrent selection are particularly valuable for developing superior hybrids because their combining ability with the opposite population has been enhanced.

• Therefore, the statement that the two populations developed through reciprocal recurrent selection can themselves be used as a synthetic variety is not correct in the context of the objective of this breeding method.

• Hence, Assertion A is false, whereas Reason R is true.

• Final Answer:
Reciprocal recurrent selection is specifically designed to improve the combining ability of two populations simultaneously by reciprocal testing and selection.
Thus, the GCA of both populations is improved, making Reason R true.
However, the primary purpose of reciprocal recurrent selection is not to develop the two populations as synthetic varieties; rather, the improved populations are intended to have superior combining ability for hybrid development.
Therefore, Assertion A is false but Reason R is true.
\[ \boxed{\text{(D) A is false but R is true}} \]