The development of a composite variety consists of the following important steps. Arrange them in order from the first to the last -
(A) Evaluation of $F_1$s
(B) Mixing in equal quantities the parental seeds of superior crosses
(C) Intermating among selected genotypes to develop $F_1$s
(D) Selection of heterozygous base materials
Choose the correct answer from the options given below:
(A) Evaluation of $F_1$s
(B) Mixing in equal quantities the parental seeds of superior crosses
(C) Intermating among selected genotypes to develop $F_1$s
(D) Selection of heterozygous base materials
Choose the correct answer from the options given below:
Show Hint
- (A), (C), (B), (D).
- (D), (C), (A), (B).
- (B), (A), (D), (C).
- (C), (B), (D), (A).
The Correct Option is B
Solution and Explanation
A composite variety is developed in cross-pollinated crops by mixing seeds of outstanding, pre-tested open-pollinated varieties, synthetics, or inbred lines.
The development follows a systematic plant breeding sequence to maximize heterozygosity and performance.
Step 2: Detailed Explanation:
Let us arrange the breeding steps of a composite variety chronologically:
-
Step 1: (D) Selection of heterozygous base materials:
The breeding program begins by selecting diverse, heterozygous base materials (such as open-pollinated varieties, germplasm accessions, or populations) with desirable agronomic traits.
- (C) Intermating among selected genotypes to develop $F_1$s:
The selected parental lines or genotypes are intermated in all possible combinations (diallel cross) to produce a set of $F_1$ hybrid crosses.
-
Step 2: (A) Evaluation of $F_1$s:
These generated $F_1$ crosses are grown and evaluated in comparative yield trials over multiple locations to assess their general combining ability and yield performance.
-
Step 3: (B) Mixing in equal quantities the parental seeds of superior crosses:
The parental seeds of only the outstanding, high-performing $F_1$ crosses are mixed together in equal quantities.
This seed mixture is subsequently multiplied in isolation via open pollination to produce the foundation seed of the composite variety.
Thus, the correct chronological sequence of steps is: (D) $\rightarrow$ (C) $\rightarrow$ (A) $\rightarrow$ (B).
Step 3: Final Answer:
The correct chronological sequence of steps is (D), (C), (A), (B).
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• [(B).] The male parents of the final crosses are heterozygous and hence heterogametic.
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Choose the correct answer from the options given below:
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