The horticultural technique of joining a scion to a rootstock is called grafting.
In grafting, the scion is the upper plant part selected for desirable stems, leaves, flowers, or fruit, while the rootstock supplies the established root system and lower stem. The two parts are cut and joined so that their vascular tissues, especially the cambium layers beneath the bark, can grow together and form a functioning graft union.
Growers use grafting to combine useful traits in one plant. A rootstock may provide resistance to soil diseases, drought tolerance, cold hardiness, or controlled vigor, while the scion preserves the desired cultivar’s fruit or ornamental qualities. Commercial apples, pears, grapes, and many other fruit crops are commonly grafted. Vegetable grafting is also used for crops such as tomatoes, eggplants, cucumbers, and watermelons.
Grafting is a form of asexual propagation, but it is not the same as budding. Budding joins a single bud to a rootstock, whereas grafting usually joins a shoot or stem section containing multiple buds. Layering instead roots a stem while it remains attached to the parent plant.