Write short notes on the following —

(a) Micropropagation

(b) Bryophyllum

(c) Vegetative reproduction

(d) Grafting

(a) Micropropagation — Micropropagation is the propagation of plants by tissue culture techniques. If vegetative propagation is not possible in a plant, then tissue of vegetative buds, shoot apex or any other suitable part of the plant can be used as explant for micropropagation. The explants are treated with sterilisation chemicals to prevent microbial growth, and then cultured in a particular nutrient medium. Cells grow and divide to form a cell mass called callus. Some growth regulators (plant hormones) are added. The callus differentiates into plant parts looking like a tiny plant called plantlet. After 4-6 weeks the plantlets are transferred to the soil.

(b) Bryophyllum — Bryophyllum is the plant whose leaves produce adventitious buds in their margin. When such leaves with adventitious buds fall in moist soil, their buds in the margins begin to grow as young tiny plants.

(c) Vegetative reproduction — New plants can be produced by certain parts of a plant such as the leaf, stem and root. These vegetative parts of a plant that are capable of giving rise to new plants are called propagules and the process is known as vegetative propagation. It can be either natural or artificial.

(d) Grafting — In Grafting, a small shoot or bud of a desired variety of plant is intimately fixed on the stem of another plant of the same or related species. The plant receiving the bud or the shoot is called the stock and the shoot fixed on it is called the scion.
For a successful graft, it is important that the cambium layers of the stock and the scion must come into very close contact so that growth may continue. The grafted points are bound with tape and the joint is covered with wax to prevent dehydration and protect against bacterial infection.