Horticultural Classification of Citrus Cultivars

Globally, citrus fruits are grown over an area of 11.42 million ha with 179.0 million tons production. China with 82.7 m tons production is the major producer of citrus fruits followed by Brazil (18.14 m tons) and India (10.53 m tons) (FAOSTAT, 2019). All commercially used scion and rootstock cultivars belong to the genus Citrus, except kumquats, Fortunella spp., and Poncirus trifoliata, which are used as rootstock only all over the world. Worldwide citrus cultivars divided into four, reasonably-well-defined horticultural groups: the Sweet oranges, the mandarins, the grapefruits and the pummelos and the common acid members. The true or ‘biological’ citrus, including species of Citrus (C. reticulata, C. maxima and C. medica), share certain characteristics, however, these are clearly differentiated according to the morpho- taxonomic traits. Hundreds of different citrus cultivars are available. Many varieties were chance finds from natural populations, and not the product of intentional breeding efforts. Other varieties in common use have originated from planned citrus hybridization and breeding efforts from worldwide. Most of the readers will be well acquainted with the cultivated types of Citrus scion and rootstocks. This chapter provides ripening season information for worldwide, farmers/gardeners have had success with citrus in many different regions of world where tropical/subtropical climatic conditions occur.