A project report on "SEXUAL and ASEXUAL" reproduction in plants

Definition : "Reproduction is the process by which living organisms produce new individuals of their own kind. For any living thing to continue the survival of its kind on earth,  it needs to reproduce. Plants reproduce through seeds , roots ,leaves or stem."

In plants there are two modes of reproduction, 

• Sexual and 
• Asexual

Sexual reproduction in plants 

In sexual reproduction,  two parents  (male and female ) are involved in producing a new individual. Male and female reproductive cells (called gametes ) combine  to form a single cell called Zygote. The zygote divides to form a multicellular structure called Embryo. Embryo develops into a new individual. In plants, embryo formed as a result of sexual reproduction is present inside the seed.

Stamen is the male reproductive part of a flower. Anther in a stamen produces pollen grains. Pollens contain male reproductive cells.

Pistil is the female reproductive part of a flower. Stigma is at the tip of a pistil. It is sticky and receives the pollen grains during pollination.

Fertilisation 

Pollen grains land on stigma and produce a tube called pollen tube. This tube carries the male gamete through the style to the ovule.

Ovule contains the female gamete. The male gamete combines with the female gamete to form a new cell called Zygote. The process of combining of male and female gametes is called Fertilisation.

Formation of Fruit and seeds

After fertilisation, the sepals, petals and other parts , except the ovary, dry and fall off.
Once the zygote is formed,  it divides rapidly to form an embryo.
When the zygote begins to divide and grow , the ovary begins to develop as fruit. The ovules start  developing as seeds.
The embryo,  thus formed, has two leaf- like cotyledons and is surrounded by the protective seed coat ( seed coat develops from the ovule wall). 
The embryo contains the cells which later develop into a plant.

Asexual Reproduction In Plants

“Asexual reproduction is the mode of reproduction that does not involve the fusion of male and female gametes and produces individuals that are genetically identical to the parent.”

Asexual reproduction in plants occurs through budding, fragmentation, vegetative propagation, and spore formation. No flowers are required for this method. The plants produced by asexual reproduction thrive well in stable environments.

Types Of Asexual Reproduction In Plants

Asexual reproduction in plants takes place in two ways:

• Naturally
• Artificially

Natural Methods

Natural methods of asexual reproduction include self-propagation.

The different ways in which a plant self propagates are mentioned below:

Budding :

Budding is the mode of asexual reproduction wherein a new plant is developed from an outgrowth known as the bud. A bud is generally formed due to cell division at one particular site.

For example, if you keep a potato for a long time, you can notice a number of small outgrowths, which are commonly referred to as ‘eyes’. Each of them can be planted which will grow up like a clone of an original potato plant.

Vegetative Propagation :

It is a form of asexual reproduction occurring in plants, in which new plants are produced from the vegetative parts of the plants, i.e. roots, stems or buds.

 Vegetative propagation in plants can occur both by naturally or also can be artificially induced 

by horticulturists.

Fragmentation:

This is a mode of asexual reproduction in which a new plant is produced from a portion of the parent plant. Each section or a part of the plants develop into a mature, fully grown individual. Some plants possess specialized structures for reproduction through fragmentation.  This type of reproduction happens naturally where the small part of the plant fall off onto soil and then begin to grow up into a new plant.

Spore Formation:

Many plants and algae form spores in their life cycle. A spore is an asexual reproductive body, surrounded by a hard protective cover to withstand unfavourable conditions such as high temperature and low humidity. Under favourable conditions, the spores germinate and grow into new plants. Plants like moss and ferns use this mode of reproduction.

Artificial Methods

Following are the artificial methods of asexual reproduction in plants:

Cutting:

In this method, a part of a plant is cut along with the node and is buried in the soil.

The cutting is watered regularly.

this is the cheapest method of vegetative propagation in plants.

Grafting :

In this method, the parts of two different plants are joined together such that they continue to grow as a single plant.

The rooted plant is known as the stock. The other plant is known as the graft.

Layering :

It is the method in which a stem attached to a plant is lowered in the ground and covered with soil. The stem grows roots while attached to the parent plant and then detaches as an independent plant.

Micropropagation:

This is the method of  producing a large number of plants from an explant under laboratory conditions within a short time interval. This facilitates the growth of rare and endangered plant species that are difficult to grow under natural conditions.

Germination :

The process by which a seed develops into a seedling or a young plant is called germination.

The seed needs favourable conditions like right soil, water, sunlight and air to grow into a plant.

In favourable conditions,   the seed coat becomes soft and spongy.

At this stage, the seedling breaks the seed coat and comes out of the seed. It obtains its food firstly from the cotyledons and then from the soil.

The seedling develops root and shoot. Roots grow underground and help in absorbing water and nutrients from the soil.

The shoot grows above the ground. It develops leaves and branches , and finally grows into a plant.