Reproduction is one of the most fundamental processes carried out by living organisms. However, there are differences in the way living organisms exhibit the process.
Modes Of Reproduction In Plants
In plants, reproduction is carried out via two modes:
- Asexual Mode – New plants are obtained without producing seeds
- Sexual Mode – New plants are obtained from seeds.
Asexual Reproduction In Plants
In asexual reproduction in plants, plants are reproduced without the formation of seeds. Following are a few ways in which plants reproduce asexually.
As the name suggests, reproduction occurs through the vegetative parts of a plant such as stems, leaves, buds, and roots. These plants take less time to grow and are exact replicas of their parents as they are reproduced from a single parent.
Small bulb-like projections arise from yeast cells, eventually detaching itself from the parent cell. This then matures to grow into a new yeast cell. These, in turn, produce more buds and the chain continues forming a number of new yeast cells within a short period of time.
Some organisms have the ability to break into two or more fragments, with the new fragment becoming a new, independent individual. They multiply rapidly in a short period of time.
Spores are present in the air and are covered by a hard protective coat to bear low humidity and high-temperature conditions. Spores germinate and develop into new organisms under favourable conditions.
An explant is taken from a plant and allowed to grow in a nutrient medium under controlled conditions in the laboratory. The cells divided rapidly and form an unorganised mass of cells. This unorganised mass of cells is known as a callus. The callus is transferred to another nutrient medium to facilitate the differentiation of different parts of the plant. The plantlets are then transferred to the fields.
Advantages of Asexual Reproduction in Plants
- A large number of plants can be produced within a short period.
- The exact copies of the parent plant are produced.
- Many seedless varieties are obtained through the vegetative method.
- Less attention is required by the plants grown through asexual means than through seeds.
Sexual Reproduction In Plants
The reproductive parts of plants are flowers, Stamen being male reproductive part and pistil being the female reproductive part. If one of these reproductive parts are present in a flower, it is said to be a unisexual flower. Example: papaya. If both Stamen and Pistil are present in flowers they are called bisexual flowers. Example: rose.
Pollen grains produce male gametes. The pistil consists of style, stigma, and the Ovary. The ovary consists of one or more ovules. Ovules are where female gametes or the egg is formed. Female and male gametes fuse to form a zygote.
When pollen is transferred from the anther to the stigma of a flower through carriers such as insects it is called pollination. It can be a case of self-pollination if pollen lands on the stigma of the same flower or another flower of the same plant. If pollen grains land on the stigma of a flower of a different plant but of the same kind, it is called cross-pollination.
A zygote is formed as a result of the fusion of gametes which later develops into the embryo. Fruits and seeds are formed post-fertilization. Ripened ovary goes on to become a fruit. Ovules give rise to seeds which contain the embryo in a protective covering.
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