Question

What is self-pollination? Mention its merits and demerits.

Answer 1

Hint: Pollination is the process of transferring pollen grains from the male part of the stamen which is the stamen to the female part of the plant which is the ovule. There are various ways to transfer the pollen, such as, through animals, air, water, etc. There are various modes of pollination depending on whether the pollen is getting transferred between the male and female parts of the same plant or different plants - self-pollination and cross-pollination.

Complete answer:
Self-pollination is associated with the pollination in the same flower. The transfer is happening within the stamen and ovule of the same flower. Therefore, self-pollination is the transfer of pollen grains from the stamen of the same plant to the stigma of the same plant. There are different types of self-pollination-
-Autogamy- It is a type of self-pollination in which the pollen grains get transferred from the anther of a flower to the stigma of the same flower. Everything happens within the same plant but there are conditions to autogamy-
Both the anther and the stigma of the same flower is open.
The stigma should be prepared to receive the pollen when released from the anther.
The anther and stigma should be close enough.

-Geitonogamy- Another type of self-pollination in which pollen grains get transferred from the stamen of one flower to the stigma of another flower but of the same plant.

The merits of self-pollination are-
-It keeps the genetic composition constant.
-It reduces the loss of pollen grains while transferring.
-Meiosis is followed by self-pollination which is the process of reproduction.
-Hermaphrodite flowers can go for self-pollination as a process of reproduction.

The demerits of self-pollination are-
-The biggest demerit is no variation.
-This way of pollination may lead to inbreeding depression.
-If there are any genetic defects in the plant genome then they cannot be removed.
-It reduces the ability of the plant to adapt to the environment.

Note: The concept of self-pollination comes with the bisexual plants which contain both male and female parts. A distinctive feature of Geitonogamy is that it resembles cross-pollination a lot whether it be the requirements of pollinating agents or pollination in different flowers of the same plant. The only feature which makes it an applicable candidate for grouping under the self-pollination category is that pollination occurs in the same plant even if the flowers are different.