All tree fruits, including citrus, are propagated onto the root system of another plant. This root system is commonly referred to as the understock or rootstock . The upper part of the grafted or budded plant that bears fruit is referred to as the scion variety. Rootstock varieties are not as plentiful as scion varieties, so selecting the proper rootstocks to use with fruit types grown in a particular area is easier. However, growers should become familiar with the rootstocks of choice for their particular needs.
Rootstocks allow faster fruiting.
Fruit trees grown from seed require 3 to 8 years to begin bearing. Rootstocks influence cold hardiness, overall fruit quality, yields, and disease and insect resistance. The only highly effective dwarfing rootstocks available are for apples. Except for apple, the home gardener should purchase tree fruits on standard rootstocks and control tree size through judicious pruning and balanced fertilization. Dwarfing rootstocks for other tree fruits are either mediocre performers or are still being researched.