VEGETATIVE PROPAGATION AND ITS TYPES

VEGETATIVE PROPAGATION AND ITS TYPES

VEGETATIVE PROPAGATION:

      Vegetative is a type of asexual reproduction in which vegetative parts such as roots, stems and leaves grows into new plants.

       Artificial as well as natural vegetative reproduction takes place by the following methods.

a) Vegetative propagation through leaves:

       In some plants like Bryophyllum, the margin of leaf bears tiny shoot buds. When break off from the plant, they fall on the ground and their shoot buds develop roots. Thus new plants grow on the ground independently.

b) Vegetative propagation through stem:

          Common methods of stem vegetative propagation occur by runners and suckers. Grasses and strawberry are runners while mint (podina) and banana are suckers. The suckers grow underground up to some distance and then turns up, producing new plants.

i) The shoots of blackberry and many other plants form arches that touch the soil. The rubbing of stem on the soil cause to produced auxin. This plant hormone helps in the formation of roots. The developing roots then produce cytokinins. This hormone causes shoots formation.

ii) Bulbs are short underground stem. It is surrounded by fleshy leaves that contain stored food. Onion, tulips and lilies reproduce by bulbs. Adventitious roots arise from the base of the bulb and shoot from its top.

iii)Garlic reproduces by corms. Corms are short, swollen underground stem containing stored food. Buds are present at the top of the corm. Shoot grows from the bud, forming a new plant.

iv)Rhizomes are horizontal underground stems with scale leaves. Buds are produced at nodes. The upper buds give rise to shoot while lower buds form Ginger, ferns and water lilies reproduce by rhizome.

c) Vegetative propagation through root:

         Red raspberries and most shrubs produce root sprouts. Cytokinins in the roots help sh0ot formation. Near the base of the shrub, a new shoot called 'sucker begins to grow. This sucker grows into a new plant.

Artificial vegetative propagation

Cutting and grafting.

Artificial vegetative propagation:

       Gardeners and farmers use artificial methods of vegetative propagation. These methods are more economical and useful to increase the stock of the plant.

1. Cutting:

       It is the most popular, convenient and short cut method used by the gardeners and farmers. A short piece of stem with 2 or 3 nodes and buds are cut. The cutting is embedded in the soil with at least one bud above and one bud below the soil. A shoot grows from the above bud and adventitious roots from the below bud. Koses, ivy, sweet potato and grapevines are propagated by stem cuttings. This method is very useful in sugarcane plantation and blackberries. The plants that grow from stem cutting are identical to the parent plant.

2.Grafting:

       The method is used to get better quality and quantity of fruits. The shoot of desired variety of fruit plant is grafted on to a stem of ordinary healthy called 'scion'. The stem on which Scion is grafted 1S called stock. The scion grows and bears fruits of better quality. The two plants are normally of the same species. Variety of oranges, lemon and mango are obtained by the method of grafting. Grafting of apple on wild apple is very common.

Parthenocarpic fruits:

      These are seedless fruits which are produced without fertilization. Banana, pineapple and some varieties of grapes are the examples of seedless fruits. In such cases auxins (hormone) are produced in the ovary, which make the fruit.

APOMIXES:

      Apomixes is an asexual reproduction process in which no nuclear fusion of male and female gametes occur. It is the development of embryo or seeds without fertilization and meiosis cell division. It occurs in one of the following methods:

1. A body cell develops into diploid embryo.

2. The megaspore or embryo sac develops into embryo directly without meiosis.

3. Embryo is formed either from an egg cell or synergid (guard cell) or from antipodal cell. These cells are found in the ovule. The embryo develops into a new plan having haploid number of chromosomes, thus the plane produced is sterile.

CLONING:

       A group of genetically identical organisms are called clones. Cloning is an asexual method of reproduction. In this process, genetically identical individuals are produced from a single parent's cell. In this case, the vegetative cell of the parent is grown under proper conditions.

       In cloning. asexual reproduction occurs by means of mitosis. Such an organism is called a clone. By cloning method good characteristics of parent are passed to a large number of clones. This is a very useful method to preserve the quality of the animals. The disadvantages of cloning are rapid aging and low resistance to diseases. Human cloning is not acceptable socially, morally and the process is against the religion.