TYPES OF POLLINATION: CHARACTERISTICS, ADVANTAGES AND DISADVANTAGES - BIOLOGY - 2024

There are two types of pollination, taking into account the source of the pollen: self pollination and cross pollination. Additionally, self pollination can be subdivided into autogamy and geitogamy.

Pollination is the process by which pollen grains from an anther - the male portion of a flower - are transferred to the female part of the flower, known as the stigma.

For pollination to be successful, the transferred pollen grains must be from a flower of the same species.

Self pollination is the kind of pollination in which pollen from the anthers of a flower is transferred to the stigmas of the same flower.

Cross pollination involves the transfer of pollen grains from the flower of one plant to the flower stigma of another plant. This is the only type of pollination that brings different genetic types of pollen grains to the stigma during pollination.

Depending on the pollination agent, cross pollination can be classified into abiotic pollination and biotic pollination.

Pollination types

1- Self pollination

It is the most basic type of pollination because it only involves a single flower. This type of pollination occurs when pollen grains from the anther fall directly on the stigma of the same flower.

Although this type of pollination is simple and fast, it results in a reduction in genetic diversity, because sperm and eggs from the same flower share genetic information.

This self-pollinating mechanism can be observed in some legumes, such as peanuts and soybeans. Most self-pollinated plants have small, inconspicuous flowers.

These flowers shed pollen directly onto the stigma, even before the bud buds.

Plants that follow self-pollination processes often have the same number of stamens and carpels. Plants pollinate themselves and can produce offspring that are self-fertile.

Some plants that exhibit this type of pollination include peaches, figs, roses, tomatoes, orchids, and violets, among others.

Self pollination can be divided into autogamy and geitogamy.

- Autogamy

It refers to the fusion of two gametes that come from the same individual. Autogamy is predominantly observed in the form of self pollination.

It occurs when sperm from pollen from the stamen of a plant reaches the carpels of that same plant and fertilizes the ovum present. In this type of self pollination, the sperm and ovaries that came together came from the same flower.

- Geitogamy

In flowering plants, pollen is transferred from one flower to another flower on the same plant. In animal pollinator systems, this is accomplished when a pollinator visits multiple flowers of the same plant.

This process is also possible in species that are pollinated by air, and can be a common source of self-fertilizing seeds in self-compatible species.

Although geitogamy is functionally cross-pollinating involving a pollinating agent, it is genetically similar to autogamy, since the pollen grains come from the same plant.

Corn is a plant that shows geitogamy.

Advantages of self pollination

- Plants that pollinate themselves use less energy to produce pollinating attractants.

- They can grow in areas where organisms that could help pollination, such as insects and other animals, are absent or scarce. This includes arctic regions and regions with very high elevations.

- This process allows plants to spread beyond the range of available pollinators, or to produce offspring in regions where there is a reduction in the pollinator population.

- There is less chance of pollination failure and, therefore, they help maintain the purity of their species.

Disadvantages of self pollination

- There is no possibility of producing new species.

- The descendants show less vigor.

- Unwanted features cannot be removed.

- The ability to resist diseases is decreased.

- It does not help evolution.

- New features are not introduced.

2- Cross pollination

It occurs when pollen grains are transferred to the flower of a different plant. Plants that go through this process often have stamens longer than their carpels.

These plants use mechanisms to ensure that pollen grains are spread to other plant flowers.

The cross-pollination process requires the help of biotic or abiotic agents such as air, water, insects, birds, and other animals that act as pollinators.

- Abiotic pollination

Pollination is carried out without the intervention of other organisms. The most common form is pollination by the wind; Pollination by water exists in aquatic plants.

- Biotic pollination

This pollination requires pollinators to transfer pollen grains from an anther to the receptive part or stigma of the carpels or pistils.

There are many forms of biotic pollination. Pollination by insects, pollination by birds or bats, and pollination by humans are the most common variations.

Plants that use this type of pollination generally have characteristics in their smell, color and shape to attract pollinators.

Insect pollination occurs in plants that have colored petals and strong odors to attract insects; plants that pollinate aerial vertebrates generally have white petals and striking scents. Bird-pollinated flowers have brightly colored tubular corollas.

Advantages of cross pollination

- The descendants are stronger, more viable and resistant.

- There is the possibility of obtaining new desirable characters.

- Help in evolution.

- Unwanted plant characters can be eliminated.

Disadvantages of cross pollination

- Pollination may fail due to a distance barrier.

- The flowers must totally depend on external agents for pollination.

- Unwanted characters can be entered.

- There is more waste of pollen.

References

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2. Pollination. Recovered from wikipedia.org
3. Pollination: types and agents. Recovered from biologydiscussion.com
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5. Types of pollination. Recovered from biology.tutorvista.com
6. Disadvantages of cross pollination. Recovered from biology.lifeeasy.org
7. Geitonogamy. Recovered from wikipedia.org
8. Advantages of cross pollination. Recovered from biology.lifeeasy.org