Difference between Pollination and Fertilization

Every organism depends on the plants either directly or indirectly. So, for the continuation of life would not have been possible without the presence of plants. Flowering plants also reproduce by sexual reproduction like other organisms. Plants mainly reproduce in two ways to forward their characters to the next generations and to increase their population size.

Pollination is a process of transferring pollens from one flower to another flower, whereas fertilization is the process that takes place after successful transfer pollens to the flowers and involves the fusion of male and female gametes of plants. Both pollination and fertilization are natural processes. But only angiosperms undergo the process of pollination, whereas fertilization is the reproduction process of almost all living things. The method of pollination was discovered by Christian Sprengel in the 18^th century whereas the process of fertilization was found by the Oscar Hertwig.

Pollination gives rise to the fertilization process in flowering plants. In fertilization, egg cells and sperm cells combine to produce a zygote, which matures into seeds and grows the next generation. Female egg cells are provided in the ovary whereas male sperm cells are produced in the pollen grains.

Comparison Chart

What is Pollination?

Pollination is the process of germinating pollen on the stigma. In this process, pollens are transferred from the male organ to the female organ of the same or different flower. The male organ of the flower reproductive system is called anther in which pollen grains with genetic materials are produced. Anthers are present on the tip of a stalk known as the stamen. The female reproductive part of the flower is called the stigma which receives the pollen grains. Stigma is located at the tip of the female organ, pistil. This helps in sending the sperm cell from the stigma to the ovary which has the eggs or ovules.

Pollination can occur within a flower (self-pollination) or within different flowers of the same plant or different plants (cross-pollination).  Almost 25% of flowering plants produce two different flowers; staminate and pistillate flowers on the same plant. For example, maize plants have staminate and pistillate flowers on the same plant. Such species of plants are called monoecious. The remaining 4% of the species produce staminate and pistillate flowers on the separate plants, so these are termed as dioecious.

Types of Pollination

There are two types of pollination; self-pollination and cross-pollination.

Self-Pollination: In this type of pollination, the female part of the flower, stigma receives the pollen from the flower of the same plant. Self-pollination develops genetically identical offspring of the parent. It occurs mostly in Capsella rubella, Arabidopsis thaliana, and Bulbophyllum bicoloratum. This can also be further divided into two types; autogamy and geitonogamy. In autogamy self-pollination, pollen is transferred from the same flower to the stigma whereas in the geitonogamy self-pollination, pollen is transferred from the one flower to the flower of another plant.

Cross-Pollination: In this type of pollination, stigma receives the pollen from the other plant of the same species. Cross-pollination is also called allogamy. The genetic material of the two different plants is combined in cross-pollination which results in genetically varied offspring to parents. This type of pollination is used in increasing the variety of plants especially fruits, vegetables and flowering plants. External factors play a role in the transfer of pollen from the anther to the stigma such as butterflies, insects, moths, winds, animals and birds.

What is Fertilization?

In fertilization, there is the union of sperm and egg which is the mechanism for pollination. Each sperm and egg has half of the hereditary material which unite to develop a new plant. When a pollen grain come in contact, a small tube is generated along with the sperm. This pollen tube gets fit into another pipe-like structure known as the style of the female pistil. This pollen tube expands from the style to the opening of the ovary where the sperms get collected. When the sperm and egg get united completely, the egg fertilizes and develops into a plant seed, which is a zygote. This process of fertilization takes place inside the flowering plants.

Double fertilization is a very distinct process that occurs in the flowering plants also known as angiosperm. In this type of fertilization, out of two sperms, one fertilizes the egg to form the zygote while other sperm combines with the secondary nucleus to form a triploid nucleus. This is also known as the primary endosperm nucleus. Hence in this process, the fusion of the two male gametes with different nuclei of the embryo sac is called double fertilization. The fertilized egg becomes the zygote which develops into an embryo.

Types of Fertilization

There are two types of fertilization; external fertilization and internal fertilization.

• External fertilization: It is a mode of reproduction in which sperm fertilizes the egg outside the female body.
• Internal Fertilization: It is a mode of fertilization in which sperms are introduced through insemination and then combines with an egg inside the female body.

Key Differences between Pollination and Fertilization

1. Pollination is an external process, whereas fertilization is usually an internal process.
2. Pollination is a physical process, whereas fertilization is a genetic and biochemical process.
3. Pollination lacks the formation of the pollen tube, whereas fertilization involves the formation of the pollen tube.
4. Pollination happens before fertilization, whereas fertilization occurs after the pollination.
5. Pollination requires external factors, whereas fertilization does not require external factors.
6. Pollination happens only in flowering plants, whereas fertilization occurs in all living things.
7. Pollination requires pollinating agents, whereas fertilization requires male and female gametes.
8. Pollination leads to fertilization, whereas fertilization leads to the formation of seeds.

Key Similarities

• Both pollination and fertilization are responsible for the production of the next generation.

Conclusion

In conclusion, Pollination and fertilization are reproduction processes in the flowering plants. Both are entirely different processes.