Artificial Method of Reproduction
Stems are capable of giving adventitious roots and this principle is used by the gardeners, planters and horticulturists in artificial method of vegetative propagation.
The vegetative propagation by artificial means may be of the following types:
Small pieces of stems, bearing one or more buds at the nodes, are cut and placed in the soil. The cut end gives off adventitious roots and the buds grow up into new shoots, e.g., rose, sugarcane, etc. Poplars and apple trees frequently send up shoots from the roots when injured and thus root-cutting may also be used.
The shoot of a stem is bent and embedded in the soil for some time. The embedded portion is called layer. They give off roots under favourable conditions and become capable of independent existence, e.g., grapes, jasmine, etc.
In this process, two pieces of cut tissues are fixed together firmly, till they grow together to form one piece. The grafting involves bringing together the cut surfaces of two different plants so that their growing tissues, i.e., cambium come in contact with each other, e.g., an apple tree can be grafted to another apple tree of a different variety.
In this process, a bud is removed from the stem and inserted under the bark of the stem of another plant. The wound is bandaged and tied and the two fuse together. After about three weeks, the bud will grow out and produce a branch of its own type.
This is done in the case of tall plants which cannot be bent down. Only the terminal portions of upright branches are chosen for this process. The stem is cut halfway like a tongue and the exposed part is covered with the soil and then bandaged tightly. The cut end gives off adventitious roots after some time and the part of the shoot just below it is detached from the parent plant and is transplanted in the soil.