Question

Given below are two statements :
Statement (I) : Erect and flat flag leaves interrupt pollen dispersal leading to poor seed set in the rice hybrid seed production program.
Statement (II) : The use of a 'flag leafless male sterile line' (lines without flag leaves) would increase the yield of hybrid seed production.

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

In hybrid rice seed production, any physical barrier to wind-pollination reduces seed set. The large, erect flag leaf of the maternal line acts as a shield blocking incoming pollen. Removing or genetically eliminating this leaf improves pollen flow and hybrid seed yield.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Hybrid rice seed production relies entirely on cross-pollination from the pollen parent (restorer line, R-line) to the male-sterile maternal parent (cytoplasmic male sterile, CMS line).
Since rice is normally a highly self-pollinated plant with limited natural outcrossing, morphological barriers that block pollen movement must be minimized.

Step 2: Detailed Explanation:
Let us evaluate both statements:
- Statement (I) is correct: The flag leaf is the topmost leaf of the rice tiller, located adjacent to the emerging panicle.
In many standard maternal parent lines, the flag leaves are large, erect, and broad.
Because they stand tall next to the panicles, they physically block and intercept the wind-borne pollen grains shed by the neighboring restorer lines, preventing the pollen from reaching the receptive stigmas of the CMS lines, which leads to poor outcrossing and low hybrid seed set.
- Statement (II) is correct: To overcome this physical barrier, seed producers often clip the flag leaves manually (which is labor-intensive).
Consequently, breeders have worked to develop genetic "flag leafless" CMS lines (where the flag leaf is genetically absent or highly reduced).
The use of these flag leafless male-sterile maternal lines completely removes the physical barrier, allowing unrestricted pollen flow to the stigmas, which significantly increases the outcrossing rate and the overall yield of hybrid seed production.
Therefore, both Statement (I) and Statement (II) are correct.

Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct.