Question:
Which one of the following is an unfavourable factor for self pollination?
Which one of the following is an unfavourable factor for self pollination?
Show Hint
Dichogamy = Timing difference.
Protogyny (G for Girl/Gynoecium first) and Protandry (A for Anther first) are both cross-pollination mechanisms.
Protogyny (G for Girl/Gynoecium first) and Protandry (A for Anther first) are both cross-pollination mechanisms.
Updated On: Aug 13, 2026
- Cleistogamy
- Geitonogamy
- Monoecy
- Protogyny
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Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
Self-pollination (autogamy) is the transfer of pollen from the anther to the stigma of the same flower. Plants have evolved various mechanisms to either promote selfing or ensure outcrossing (cross-pollination). Factors that separate the male and female organs in either space or time are unfavourable for self-pollination.
Step 2: Detailed Explanation:
1. Cleistogamy: This refers to flowers that never open. Since the reproductive organs are enclosed, self-pollination is mandatory. Thus, it is a highly favourable factor for selfing.
2. Geitonogamy: This is the transfer of pollen from an anther of one flower to the stigma of another flower on the same plant. While it involves different flowers, it is genetically equivalent to self-pollination and is favourable for maintaining the plant's genotype.
3. Monoecy: The presence of separate male and female flowers on the same plant. While it encourages cross-pollination between flowers, it does not strictly prevent self-pollination on the same plant (geitonogamy).
4. Protogyny: This is a form of dichogamy where the female reproductive part (gynoecium) matures and becomes receptive before the male part (androecium) sheds pollen. Because of this temporal separation, the pollen of a flower is not available when its own stigma is receptive. This is a powerful evolutionary strategy to prevent self-pollination and ensure cross-pollination. Therefore, it is an unfavourable factor for selfing.
Other factors unfavorable for selfing include Protandry (male matures first), Herkogamy (physical barriers), and Self-incompatibility.
Step 3: Final Answer:
Protogyny is the mechanism among the options that actively discourages self-pollination.
Self-pollination (autogamy) is the transfer of pollen from the anther to the stigma of the same flower. Plants have evolved various mechanisms to either promote selfing or ensure outcrossing (cross-pollination). Factors that separate the male and female organs in either space or time are unfavourable for self-pollination.
Step 2: Detailed Explanation:
1. Cleistogamy: This refers to flowers that never open. Since the reproductive organs are enclosed, self-pollination is mandatory. Thus, it is a highly favourable factor for selfing.
2. Geitonogamy: This is the transfer of pollen from an anther of one flower to the stigma of another flower on the same plant. While it involves different flowers, it is genetically equivalent to self-pollination and is favourable for maintaining the plant's genotype.
3. Monoecy: The presence of separate male and female flowers on the same plant. While it encourages cross-pollination between flowers, it does not strictly prevent self-pollination on the same plant (geitonogamy).
4. Protogyny: This is a form of dichogamy where the female reproductive part (gynoecium) matures and becomes receptive before the male part (androecium) sheds pollen. Because of this temporal separation, the pollen of a flower is not available when its own stigma is receptive. This is a powerful evolutionary strategy to prevent self-pollination and ensure cross-pollination. Therefore, it is an unfavourable factor for selfing.
Other factors unfavorable for selfing include Protandry (male matures first), Herkogamy (physical barriers), and Self-incompatibility.
Step 3: Final Answer:
Protogyny is the mechanism among the options that actively discourages self-pollination.
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