Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Minimum germination standard (%) for the seeds of maize inbred lines is 80%.
Reason R: Maize hybrid seed should have a minimum of 90% germination.
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:

Always remember that inbred lines are weaker than hybrids due to inbreeding depression. Therefore, inbred lines consistently have lower minimum germination standards than their corresponding hybrid seed classes.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Indian Minimum Seed Certification Standards (IMSCS) define specific physical and physiological seed standards for different classes and types of seeds, including germination percentage.
Hybrids and inbred lines have different germination standards due to differences in genetic vigor.

Step 2: Detailed Explanation:
Let us analyze both statements:
Assertion A: In maize (Zea mays), inbred lines are produced through continuous self-pollination.
Selfing leads to inbreeding depression, which reduces plant vigor, seed size, and overall physiological strength.
Consequently, the seeds of maize inbred lines naturally exhibit lower germination capacity and vigor compared to hybrids.
Therefore, the minimum germination standard for maize inbred lines is set lower, at 80%.
Thus, Assertion A is true.
Reason R: Maize hybrid and composite seeds are produced by crossing genetically distinct parent lines.
Due to heterosis (hybrid vigor), hybrid seeds are highly vigorous, robust, and have excellent germination potential.
Therefore, the minimum germination standard for maize hybrids and composites is set high, at 90%.
Thus, Reason R is true.
Relationship between A and R: Both statements are individually true, representing established seed standards.
However, the high germination standard of hybrid seeds (90%) is not the biological reason or explanation for why the inbred lines have an 80% standard.
The lower standard of inbred lines is a direct biological consequence of inbreeding depression.
Therefore, R is NOT the correct explanation of A.

Step 3: Final Answer:
Both Assertion A and Reason R are true, but R is not the correct explanation of A.
Therefore, the correct option is (B).