Plant propagation is the increase in number of the species by reproduction. Plants reproduce by sexual and asexual methods. Sexual propagation is the reproduction of plants by means of their seeds or spares.
Asexual propagation is the duplication of the plant from any of its part or organ. Plants are asexually propagated for different reasons: some plants reproduce true to type; other plants produce no seeds; there are seeds that are difficult to germinate.
Methods of Asexual Propagation
Cuttings are detached vegetative plant parts which can develop into a complete plant with characteristics identical to the parent plant.
Types of cuttings
a. Stem cutting
Parts of shoots with lateral or terminal buds are taken to produce an independent plant. The type of wood, the stage of growth, and the time of year in which the cutting is done are important considerations in rooting the plants.
b. Leaf cutting
The entire leaves with or without the petioles are used in making leaf cuttings. Leaves are cut into sections and laid flat on the propagating medium. With high humidity, a new plant will form where each vein is cut. (Ex. African violets, perperonia)
c. Leaf-bud cutting
To make a leaf-bud cutting, a leaf blade, a petiole and a short piece of the stem with the attached auxiliary bud are placed in the medium and covered enough to support the leaf.
d. Root cutting
Plants develop shoot from the root system. Root cuttings are made from root sections 5 to 15 cm. long. These cuttings may be planted in either vertical or horizontal position.
Layering is a vegetative method of propagation by producing roots from unusual parts of the plant before it grows from the parent plant.
Types of layering
a. Tip layering
The rooting takes place near the tip of the current shoot that naturally falls to the ground. The tip begins to grow downward into the soil, and after a period of time the tip curves upward with the roots developing from the part that touches the ground.
b. Simple layering
It is almost the same as tip layering except that the stem behind the end of the branch is covered with soil and the tip remains above the ground.
c. Trench layering
The base and the middle part of a young stem are placed in a shallow trench. The node is notched to increase the root formation, then covered with 5 to 10 cm of moist soil. Expose the tip to ensure continued growth.
d. Mound or stool layering
Soil is mounded at the base of the newly developed shoots to enhance root formation. The soil is removed at the end of the dormant season and new plants are detached. In this method the parent plants can be used year after year.
e. Air layering or Marcotting
This can be done with foliage plants such as ficus. The process of making this is the same as that of marcotting.
b. Approach grafting
Two plants are joined at their own rootstock. A piece of bark 2.5 to 5 cm long is removed from both plants, and the wounded area is pressed and held tightly together.
Grafting is the joining of two separate plants like root and stem or two stems to form a union and grow as one plant. The upper part of the union is the scion and the lower part is the stock.
Types of Grafting
a. Whip and tongue grafting:
Scion and stock must be 0.6
to 1.2 cm in diameter.
c. Cleft grafting
Scion should be one year old wood. The stock is usually 5 to 7 cm in diameter.
d. Bark grafting
This can be adapted to stock of any size or if the bark can already be separated from the wood. The scion shaped like a wedge is inserted between the bark and wood of the stock. You may use several scion to ensure selection.
e. Notch grafting
This can be used for top working trees with branches of large diameter.