113. ‘Dichogamy’ refers to a phenomenon in which anther dehiscence and stigma receptivity are:
(1) temporally separated
(2) spatially separated
(3) temporally coinciding
(4) spatially coinciding

Detailed Explanation:

Question:
‘Dichogamy’ refers to a phenomenon in which anther dehiscence and stigma receptivity are:

✅ Correct Answer: (1) Temporally separated

What is Dichogamy?

Dichogamy is a reproductive strategy in plants where anther dehiscence (the release of pollen from the anthers) and stigma receptivity (the ability of the stigma to receive pollen) are temporally separated, either in time or during different phases of the plant’s flowering process. This separation helps prevent self-pollination and promotes cross-pollination, which enhances genetic diversity within plant populations.

There are two main types of dichogamy:

• Protandry: This is when the male (anther dehiscence) phase occurs before the female (stigma receptivity) phase. In this case, the plant releases pollen before its stigma is capable of receiving it, forcing cross-pollination with other plants.

• Protogyny: In this case, the female (stigma receptivity) phase occurs before the male (anther dehiscence) phase. The stigma is receptive before pollen is released, again promoting cross-pollination.

Why is Dichogamy Important?

Dichogamy plays a crucial role in preventing self-pollination, ensuring that plants engage in genetic recombination by cross-pollination, which is essential for the health and diversity of a species. By temporally separating these events, plants increase the likelihood of mating with another individual of the same species, thus enhancing genetic variability in the population.

Why Other Options Are Incorrect:

• (2) Spatially separated: This refers to a situation where the male and female reproductive parts are physically separated in space, which is a different concept than temporal separation.

• (3) Temporally coinciding: This would suggest that both anther dehiscence and stigma receptivity occur at the same time, which would facilitate self-pollination rather than cross-pollination.

• (4) Spatially coinciding: Again, this would imply physical proximity of male and female reproductive parts, which does not align with the concept of dichogamy.

Examples of Dichogamy in Plants:

• Many plants, such as members of the genus Salix (willows) and some species of Petunia, exhibit dichogamy. These species have evolved this mechanism as a way to maximize cross-pollination opportunities and increase genetic diversity within their populations.

Conclusion:

Dichogamy is a fascinating reproductive mechanism in plants where anther dehiscence and stigma receptivity are temporally separated. This strategy helps prevent self-pollination, ensuring that plants reproduce through cross-pollination, which is essential for maintaining genetic diversity and adaptability in nature.

✅ Correct Answer: (1) Temporally separated