New mandarin varieties

One of the major issues occurring during the last three decades was the increase of the fresh fruit marketof mandarins. For clementines and satsumas, new cultivars have only been selected from spontaneous orinduced mutations while both mutant selection and breeding programs have allowed varietal progress inother type of mandarins. In relation with specific market demands and environmental conditions (biotic and abiotic constraints), the maingoal of breeding may vary strongly between the production areas. Expanding the harvesting period with highquality seedless fruits is currently the main objective of new mandarin varieties for the fresh fruit market. Thismarket promotes organoleptic qualities (aroma, taste, acidity, sugar) and pomological qualities (easy to peel,seedlessness, external appearance). The definition of organoleptic quality can vary according to the consumers. Citrus breeders must therefore endeavour to develop a wide range of varieties likely to meet these diverse needs. Nutritional quality based on vitamin C, carotenoid and polyphenol contents are now considered as breedingcriteria in some projects. Some diseases cause considerable damages in orchards. Huanglongbing in Asia, SouthAfrica and recently in Brazil and Florida, citrus canker in most tropical and subtropical areas, cercosporiosisin Africa, citrus variegated chlorosis and Sudden death in Brazil. Alternaria also becomes a problem for somemandarin cultivars such as `Fortune? in Spain. Ranges of varietal susceptibility have been established for most ofthese diseases and tolerant parents are selected in some breeding programs. Conventional breeding in citrus has important limitations due to the complex reproductive biology of thesespecies. Most genotypes are apomictic and adventitious embryos develop directly from nucellar cells limitingor precluding the development of zygotic embryos. This limits the recovery of large sexual populations and inpractice apomictic genotypes are avoided as fema