Annona Species Monograph.pdf - Crops for the Future

Chapter 9. Genetic Improvement
crosses, were planted. Since attractiveness is a key factor in selling fruits, the
exciting possibility exists to develop new cultivars with external and internal
pink-red colours. Crossing of newly introduced red and pink-skinned
atemoya x cherimoya selections to red-skinned sugar apple types selected in
Queensland, Australia, is currently in progress (George et al., 1999).
Spain is more focused on germplasm collection and ex situ evaluation of
numerous accessions (Farré Massip and Hermoso González, 1987, cited by
Scheldeman, 2002). Pérez de Oteyza and Farré (1999) reported that the
selection of a superior cultivar of cherimoya at the Experimental Station of
La Mayora, Spain, is based on the following characters: a) regarding
agronomic and commercial parameters - size, format and pilosity on leaves,
length and colour of flowers, floral density (number of flowers per one metre
of mature stem), susceptibility to fruit fly, season of maturation and harvest,
defects on the skin and in the pulp, resistance to fungal attack and seed
colour; and b) regarding fruit transport and consumption - type of skin, pulp
firmness, taste (sugar content and acidity) and seed index (number of seeds
per 100 g of fruit).
In Chile, introduction and selection of cherimoya showed that the new
cultivars from Spain were superior, with longer harvest periods and better
fruit quality than Chilean cultivars (Gardiazabal and Cano, 1999). Ten
cultivars from Spain were evaluated for fruit weight, shape and colour, skin
type, number of days post-harvest to reach appropriate ripeness for eating,
resistance of pulp to pressure, percentage by weight of fruit components,
seed type, number of seeds per 100 g of pulp, sugar and acidity, and taste.
The Spanish cultivar ‘Cholan’ showed the highest general rating.
In Mexico, genetic improvement of cherimoya started in 1991, with
evaluation of seedlings of local cultivars and evaluation of introduced
cultivars from Spain, Chile and New Zealand (Román and Damián, 1999).
Characterisation and selection of cherimoya fruits from trees collected in
three regions of Michoacán State, Mexico, was done by Agustín (1999).
While studying such characteristics as fruit weight, percentage of pulp and
seed, fruit soundness, type of skin and earliness, he found great genetic
variability among native fruits and proposed this as the basis for developing
germplasm for commercial plantations. A very similar strategy has been used
in Italy and Portugal (Madeira), with selection and evaluation of promising
local types and introduced cultivars (Monastra, 1997; Nunes, 1997).
The methods and strategies used in Madeira to develop superior cultivars of
cherimoya were somewhat different. First, the agricultural service surveyed
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