Dwarfism in fruits crops: A way to produce new canopy architecture

Abstract

Dwarfing is an alteration in the normal growth pattern. A dwarf plant is that which is smaller than normal size at full maturity and possess other characteristics like precocity, canopy architecture and time of flowering and altered fruit size. As fruit trees generally have a large size, the production of small or even dwarf trees are of great interest for most of fruit crops. In this review, some of the main tropical, subtropical and temperate fruit trees that have small or even dwarfing cultivars are approached. The causes of dwarfism, although the use of dwarfing rootstocks, is the main theme of this review. The factors that affect the size of the fruit trees are also approached, as well the dwarf cultivars of banana, papaya and cashew, and the dwarf rootstocks for guava, mango, anonaceae, loquat etc. The principle is to make the best use of vertical and horizontal space per unit time and to harness maximum possible returns per unit of inputs and natural resources. The mechanisms underlying involves anatomical, physiological and biochemical changes. The various methods to induce dwarfism include: use of dwarfing root stock/ interstock or use of dwarfing scion; Use of bio regulators; Use of incompatible root stock; Induction of; viral infection; Pruning and training; Nutrients; Phenols; In vitro techniques; Genetic engineering; Ringing or girdling and Others. Some important dwarfing rootstocks of fruit crops include: Apple: - M27, M9, EMLA 26; Pear: - Quince C; Peach: - Siberian C, St. Julien X, P. besseyi and Rubira; Plum: - St. Julien A, St. Julien K, Pixy; Cherry: - Giesela series, Stockton Morello, Oppenheim, Charger; Mango: - Olour, Vellaikolumban; Citrus: - Trifoliate Orange, Flying Dragon; Guava: - Pusa Srijan, P. friedrichesthalianum; Ber: - Jhar ber. Dwarfing in fruit crops can be achieved through various approaches like use of dwarfing rootstock, root pruning, training, use of growth retardants, control of nutrient elements etc.