Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Flag leaf clipping in hybrid seed production in rice promotes higher seed setting.
Reason R: Flag leaf of rice intercepts more sunlight and facilitates accumulation of more photosynthates in the seeds as it is nearer to the panicle.
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:

In Assertion--Reason questions, never assume that a true Reason automatically explains a true Assertion.
First verify the truth of both statements independently and then check the logical relationship between them.
For rice, remember that the flag leaf is an important photosynthetic source because it is positioned close to the panicle and contributes photosynthates to developing grains.
However, when the question asks about flag leaf clipping in hybrid seed production, focus on its role in improving panicle exposure and facilitating effective pollination and seed setting.
A useful examination strategy is to distinguish between the physiological function of the flag leaf and the agronomic purpose of flag leaf clipping.
This distinction helps identify why both statements can be true while the Reason is not the correct explanation of the Assertion.

Answer 1

The Correct Option is B

•

Step 1: Understanding the Question:
This is an Assertion--Reason type question related to hybrid seed production in rice and the physiological role of the flag leaf.
The flag leaf is the uppermost fully developed leaf of the rice plant and is positioned very close to the panicle.
It is an important photosynthetic source because it receives sunlight and produces photosynthates that contribute to the development and filling of grains.
The question requires us to determine whether the Assertion and Reason are individually correct and whether the Reason provides the correct explanation for the Assertion.

•

Step 2: Key Formula or Approach:
No numerical formula is required for this question.
The appropriate approach is to evaluate the Assertion and Reason separately and then determine whether the Reason directly explains the Assertion.
For an Assertion--Reason question, the following sequence should be followed:

• First, determine whether Assertion A is true or false.

• Second, determine whether Reason R is true or false.

• Third, if both are true, determine whether R gives the direct and logical explanation for A.

• Detailed Explanation:

• The flag leaf occupies a strategic position immediately below the panicle in rice.

• Because of its position, it has a major contribution to the photosynthetic supply available to the developing reproductive structures and grains.

• The flag leaf intercepts sunlight and performs active photosynthesis.

• The photosynthates produced through photosynthesis are transported towards developing grains and contribute to grain filling.

• Therefore, the statement that the flag leaf intercepts sunlight and facilitates the accumulation of photosynthates in seeds because of its proximity to the panicle is biologically correct.

• Hence, Reason R is true.

• In hybrid seed production of rice, flag leaf clipping is a crop management practice used around the reproductive stage.

• Appropriate clipping of the flag leaf can improve the exposure of the panicle and facilitate better conditions for pollination.

• In hybrid seed production, effective pollination between the male and female parental lines is essential for obtaining higher seed setting.

• Flag leaf clipping can reduce obstruction around the panicle and improve the accessibility and exposure of the reproductive structures during pollination.

• Therefore, the Assertion that flag leaf clipping in hybrid seed production can promote higher seed setting is considered true.

• Hence, Assertion A is true.

• However, the Reason explains the beneficial photosynthetic role of an intact flag leaf rather than explaining why clipping the flag leaf promotes higher seed setting.

• The fact that the flag leaf receives sunlight and supplies photosynthates to developing grains does not directly explain the improvement in seed setting caused by clipping.

• Seed setting in hybrid seed production is primarily associated with successful pollination and fertilisation, and flag leaf management can influence the exposure and pollination environment of the panicle.

• Thus, although the Reason is a true statement about the physiological importance of the flag leaf, it does not provide the correct explanation for the Assertion.

• Therefore, both Assertion A and Reason R are true, but Reason R is not the correct explanation of Assertion A.

• Final Answer:
Assertion A is true because appropriate flag leaf clipping can promote better panicle exposure and facilitate conditions favourable for pollination and seed setting in hybrid rice seed production.
Reason R is also true because the flag leaf is an important photosynthetic source and contributes photosynthates to the developing grains due to its proximity to the panicle.
However, this physiological role of the flag leaf does not explain why clipping it promotes higher seed setting.
Therefore, the correct answer is:
\[ \boxed{\text{(B) Both A and R are true but R is NOT the correct explanation of A}} \]