Kiwifruit

Abstract

Kiwifruit are still a relatively minor crop making up perhaps 0.2% of total world annual production of fruit. The kiwifruit of commerce are large-fruited selections of two closely related species Actinidia chinensis and A deliciosa. Most current kiwifruit cultivars are selections from the wild or from seedling populations and only a few result from planned hybridizations. The main emphasis in the breeding programs underway is on fruit novelty, flavor, size, time of harvest, flesh color, length of storage life, environmental adaptation and vine productivity. Until recently, nearly all the kiwifruit grown commercially outside China were of one green-fruited cultivar of A.deliciosa; now yellow-fleshed, sweeter flavored kiwifruit are becoming important in international trade. To take advantage of the considerable diversity within the genus requires good germplasm resources and a better knowledge of the reproductive biology of kiwifruit. The main constraints to breeding include dioecy, the long generation time and the complexity of some key traits as well as the need for support structures, the exuberant vegetative growth and the need to control growth to ensure fruiting. Many of the traits associated with fruit quality are quantitatively inherited. Use of molecular biological and biotechnological techniques should facilitate improvement programs.