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Pollination refers to the fertilization and development of seeds. Pollination is the transfer of pollen grains from anther to the stigma of a flower. The transfer can take place within the flower or between two flowers. Anther is the male part of a plant and stigma is the female part of a plant. Agents that carry pollen grains are wind, water, insects, animals, etc. Some plants can self-pollinate. They don’t require any agents.
What is Pollination?
Pollination is defined as the transfer of pollen grains from the male part of a flower, stigma to the female part, anther of the same or on different flowers. It results in fertilization as well as the production of seeds. Pollination is successful only if pollen grains are transferred from the same species of flower.
These pollen grains are carried out by biotic or abiotic agents such as wind, water, insects, animals, birds, etc. These agents are known as Pollinators.
Process of Pollination
- The first step of Pollination is the transfer of pollen grains to the stigma of a plant.
- A pollen tube with style length is formed, connecting the stigma and ovary.
- After the formation of a pollen tube, pollen grains transmit sperm to the ovary.
- The fertilisation process will start when the sperm cell reaches the ovary.
- The parent will release a seed and will grow into a plant.
- This reproductive cycle will be continued by using pollination methods.
Types of Pollination
Pollination are of two types:
- Self Pollination
- Cross-Pollination
Self Pollination
Self Pollination is a primary pollination as a single flower is required in this. Self-pollination takes place when pollen grains are transferred from anther to the stigma of the same flower.
This method is smooth. Self-pollination decreases genetic diversity as both sperm and egg cells share genetic information.
Advantages of Self-Pollination
- In Self Pollination, pollen grains are wasted less in comparison to Cross-Pollination.
- Purity is maintained in Self-pollination as there is no diversity in genes.
- No external factors are involved in Self-pollination.
- In Self Pollination, the quantity of pollen grains becomes less, resulting in a successful Pollination process.
- This Pollination confirms that recessive characters are extracted.
Disadvantages of Self Pollination
- There is a reduction of vigour and vitality of the race.
- There is a reduction of immunity to disease among the resultant offspring.
Cross-Pollination
The process of transfer of pollen grains from the anther of the flower to the stigma of another flower is known as Cross-Pollination. In Cross Pollination, different flowers combine and share genetic information and unique offspring are made. Therefore, genetic diversity is increased.
Types of Cross-Pollination
Cross Pollination requires help of biotic and abiotic agents like animal, birds, wind and many other agents.
- Pollination by Animals – Zoophily
Animals play an important role in reproduction of plants as they help in seed dispersal. Animals move to different places to eat fruits of plants. This movement helps in dispersal of seeds from one place to another to create new plants.
- Pollination by Wind: Anemophily
This Pollination is carried by those flowers only if plants lack flowers with nectar. In anemophilous flowers, male parts produce a very large quantity of pollen grains and the female part is very large, sticky and feathery. Palm, maize, coconut are some examples of wind pollinated plants.
- Artificial Pollination: Anthropophily
This Pollination is done by humans. Artificial Pollination is done, if there are problems in Pollination by biotic and abiotic agents. In this process, pollen grains are spread over the female flowers. Hybridization method is used in Artificial Pollination.
Advantages and disadvantages of Cross Pollination
Advantages
- With the help of Cross Pollination, reproduction can be done by unisexual plants.
- Cross Pollination increases the immunity level of baby plants.
- Quality of seeds are good in vigour and vitality.
- New genes are generated by cross pollination as the fertilization is between genetically different gametes.
Disadvantages
- Pollen grains are wasted in large quantities.
- During genetic recombination, good qualities may be removed and unwanted features may be added to the new generation.
Difference between Self Pollination and Cross Pollination
| Self Pollination | Cross Pollination |
| Self-pollination is the transfer of pollen grains from the anther to the stigma of the same flower. | Cross Pollination is the transfer of pollen grains from the anther to the stigma of different flowers. |
| Self-pollination takes place in the same flower or different flower of the same plant. | Cross Pollination takes place between two flowers of different plants. |
| Pollen grains are directly transferred to stigma. | Pollen grains are carried by wind, insects, animals etc. |
| In self-pollination, a limited number of pollen are transferred. | In cross pollination, large numbers of pollen are transferred. |
| Genetic uniformity is increased in self pollination. | Genetic uniformity is decreased in cross pollination. |
| Genetic variation is decreased. | Genetic variation is increased. |
| Self Pollination can occur even in the closed flower. | Cross Pollination occurs only when the flower is open. |
| Self Pollination takes place in sunflowers, peas, peanuts etc. | Cross Pollination takes place in plums, tulips, strawberries etc. |
Similarities between Self Pollination and Cross Pollination
- The germination takes place in stigma in both the pollinations.
- Pollen grains are transferred from anther to stigma in both pollinations.
- In Self Pollination and Cross Pollination, male nuclei of the germ cell fertilise female ovules and develop into embryos.
FAQs on Pollination
Define pollinators?
Agents that move pollen grains from one plant to another are called pollinators. These can be wind, air, animals, water etc.
Write any two advantages of Self-pollination?
There is no wastage of pollen grains in self-pollination. Purity is retained in self-pollination.
What are the two main types of Pollination?
Self Pollination and Cross Pollination
