Question

A top cross test is done to evaluate the performance of:

• A. Inbred line
• B. Single cross hybrid
• C. Pure line
• D. Double cross hybrid

Hint:

Top cross test:
- Evaluates GCA of inbred lines.
- Inbred line crossed with a common tester.
- Used in maize and other cross-pollinated crops.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
This question tests knowledge of plant breeding methods and testing of inbred lines.

Step 2: Detailed Explanation:
A top cross test is used to evaluate the general combining ability (GCA) of inbred lines.
In this test, an inbred line is crossed with a common tester (or a heterozygous variety).
The performance of the resulting progeny indicates the combining ability of the inbred line.
Single cross hybrid (B): Already a hybrid, not evaluated by top cross.
Pure line (C): A homozygous line, not evaluated by top cross.
Double cross hybrid (D): A hybrid of two single crosses.
Thus, top cross test is done to evaluate the performance of inbred lines.

Step 3: Final Answer:
Thus, a top cross test is done to evaluate inbred lines, which corresponds to option (A).
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