Definition of Pollination
“The process of transfer of pollen grains from the male anther of a flower to the female stigma of the same flower or another flower is called pollination.”
There are two types of pollination-
Self Pollination involves only one type of flower. When pollen grains from the anther fall onto the stigma of the same flower, self-pollination takes place. Although this method of pollination is simple and fast, it reduces genetic diversity as sperm and egg cells from the same flower share hereditary data.
Advantages of Self Pollination-
- Self-pollination confirms the extraction of recessive traits.
- Pollen grains are less wasted in self-pollination than in cross-pollination.
- The purity of race is preserved because there is no diversity in the genes.
- There are no elements such as wind or water in self-pollination.
- Self-pollination demonstrates that even a small amount of pollen grains produced by plants is a productive pollination process.
The major drawback of self-pollination is that gene blending does not occur here as-
- The race's vigor and strength are rapidly declining.
- There is also a decrease in disease immunity among many of the offspring.
It is a difficult form of pollination that involves the transfer of pollen from one flower's anther to the stigma of another flower. Because the different flowers share genetic information to make unique offspring, this type of pollination increases genetic diversity.
Advantages and disadvantages of Cross-pollination-
- The virtues of seeds are good in terms of vigor and imperativeness here.
- Non-binary plants can reproduce through the method of cross-pollination.
- Recessive traits are eliminated as a result of genetic hybridization.
- The baby plant's protection level rises as a result of this process.
- Cross-Pollination results in the creation of new genes because it is primarily the result of fertilization between genetically dissimilar gametes.
- Pollen grains are being thrown away in large quantities.
- When genetic recombination occurs, there is a chance that good qualities will be lost and unwanted characteristics will be added to future generations.
Types of Cross-Pollination - Different pollinators are involved in pollination. It could be caused by the wind, an animal, or human beings.
- Wind Pollination
In wind pollination, the wind carries pollen from one flower to another.
- Animal Pollination
These are pathogens that move from flower to flower, transferring pollen to each one.
- Artificial Pollination
Humans are responsible for artificial pollination. This is also known as Hand pollination. If biotic and abiotic agents fail to pollinate the female flowers, the artificial pollination process is used, which involves spreading pollen grains over the female flowers. Genetic recombination techniques are used in this process.
Key Point - Some plants do not produce flowers. Plants like mosses and ferns reproduce through spores. Cone-bearing plants, such as pine and spruce trees, reproduce through pollen, which is produced by a male cone and travels by wind to a female cone of the same species. The seeds are then formed in the female cone.
Process of Pollination
Definition of Pollen Germination: “The physiological and developmental changes that occur in a heterosporous plant pollen grain, beginning with hydration and terminating with the emergence of the pollen tube through the aperture.”
Pollen germination takes place in three stages. These are pollen tube formation, activation, and hydration. The pollen grain is dehydrated to ensure that it can be easily transported from one flower to another. Germination occurs after rehydration. The pollen grain's plasma membrane reforms into an effective osmotic membrane as a result of hydration. Activation promotes the formation of filaments throughout the cytoplasm of cells.
As hydration and activation spread, the pollen tube grows. Microspores are produced by meiosis in the anthers of flowering plants. Mitosis is triggered, resulting in male gametophytes. Megaspores, on the other hand, are produced by meiosis in the ovules. When a pollen grain adheres to the stigma, it germinates and evolves into a pollen tube that grows through the style's tissues. When the tube reaches the egg sac, two sperm cells enter the female gametophyte and fertilization occurs.
Learning Outcomes -
- You can learn about the definition and process of pollination from this article.
- It can help you understand the advantages and disadvantages of self-pollination and cross-pollination in detail.
- The article also draws attention to the different types of cross-pollination.
- It will also teach you about the importance of plant-animal and human interaction in maintaining biodiversity balance.
Class 12 (PCB)