Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 52

MAJOR BREEDING OBJECTIVES. Mango production is affected by different environmental and biotic factors in various regions. The most important breeding objectives include: (i) regular bearing, particularly in the north Indian cultivars; (ii) dwarfness or compact tree size; (iii) precocity of bearing; (iv) attractive fruit, with appealing skin and flesh colour, good taste and flavour, free of fibre and of moderate size (300–500 g); (v) resistance to major diseases, particularly anthracnose, which is caused by Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. In Penz.; (vi) resistance to insect pests; (vii) freedom from physiological disorders, such as internal breakdown (jelly seed and soft nose); and (viii) good shipping quality and extended shelf life (Iyer and Degani, 1998).

BREEDING ACCOMPLISHMENTS. Many of the scion cultivar breeding objectives can be achieved within conventional breeding programmes involving either controlled or open pollinations between superior selections followed by selection among the offspring. Open pollination has been effective as demonstrated by the identification and naming of superior ‘Florida’ cultivars (Knight, 1998). These cultivars produce fruit with a highly attractive blush and are regular bearers. Some of the ‘Florida’ mangoes, such as ‘Keitt’ and ‘Tommy Atkins’, are also considered to be moderately resistant to anthracnose.

The main breeding goals have been to overcome the problems of alternate bearing and internal fruit breakdown, which are inherent in many of the traditional monoembryonic cultivars of India. Large-scale evaluations of seedling trees following controlled crosses between monoembryonic ‘Florida’ cultivars, i.e. ‘Irwin’, ‘Sensation’ and ‘Tommy Atkins’, as female parents with ‘Kensington Pride’ (polyembryonic) are underway at various locations in Queensland, Australia (Whiley et al., 1993). The goal of the Australian programme is to develop new cultivars with greater disease resistance, skin colour, flavour and postharvest performance; the ‘Calypso’® mango is a noteworthy release.