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The following points highlight the two main methods of vegetative propagation. The methods are: 1. Vegetative Propagation by Leaves 2. Vegetative Propagation by Stem Cuttings.
Method # 1. Vegetative Propagation by Leaves:
1. Take a pot, fill it with suitable amount of garden soil and put some water on the soil.
2. Pluck 2-3 leaves from the plants of Bryophyllum and Begonia and place them well in touch with the soil in the pot. Wait for 3-4 days and keep them watered daily during this period.
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3. Small plantlets develop along the leaf margins (Fig. 205) in Bryophyllum which on detachment produce independent plants.
4. In Begonia (Fig. 206), leaf buds are produced from petiole and veins throughout the leaf surface.
Method # 2. Vegetative Propagation by Stem Cuttings:
Vegetative propagation by stem cuttings can be seen in cuttings of plants like rose, salix, money plant, sugarcane and Bougainvillea.
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Take the cuttings of 15-20 cm of any or all of these plants and put the lower part of each cutting inside the soil in separate pots. Make the pot soil sufficiently watered and wait for a few days.
Roots will develop inside and buds on the nodes of the cuttings will start sprouting. If the roots do not develop easily, treat the cuttings with some IAA (indole acetic acid) which is a growth hormone.
Different parts of the several plants are modified for vegetative propagation. Some of the modified stems (e.g., bulbs, runners, rhizome, corm and tuber) are the common sources of vegetative propagation.
These are briefly discussed here:
(1) Bulbs:
These are the underground stems made up of a short axis with many overlapping thick leaves which store food, e.g., onion (Allium cepa, Fig. 207).
(2) Runners:
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Runners are stems which grow along the ground and produce roots and a new plant at its apex, e.g., doob grass (Cynodon dactylon, Fig. 208).
(3) Rhizome:
It is a stem which grows along under the ground, bearing buds which produce shoots which grow into whole new plants, e.g., ginger (Zingiber officinale, Fig. 209).
(4) Corm:
Corm is usually a thickened stem base with buds in its axils of dead leaf bases, as in taro (Colocasia, Fig 210).
(5) Tuber:
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Tuber is a thick underground stem in which food is stored as in potato (Solarium tuberosum, Fig. 211). Tubers have buds in modified leaf axils, from which new plants can grow.
Grafting:
Grafting is a method of vegetative propagation in which a segment (called scion) of a plant to be propagated is inserted onto another plant (called stock) in such a way that their vascular tissues combine (Fig. 212). Combination of vascular tissues of scion and stock allows growth of the grafted segment, i.e., scion.
The grafting ends of both scion and stock are cut obliquely and then placed over one another in a very close contact. Both are tied tightly by tape or rubber tube. The cambia of both scion and stock fuse and form a new continuous vascular column. The stock supplies all the desired nutrients to the scion in this technique.
Grafting is successful only in closely related species. It is commonly practised for obtaining desired quality of plants and fruits in several plants including apple, pear, mango, citrus and rubber.
Layering:
In this artificial method of vegetative propagation, runners or stolons or a branch of a plant is bent towards the ground and covered with moist soil. After some time, adventitious roots develop where a node touches the soil and shoot or new plantlets develop from the lateral meristem (Fig. 213).
These new plantlets eventually establish themselves in the soil. They can be separated from the parent plant and can be grown as independent plants. Layering in jasmine plant or Chameli is shown in Fig. 213.
