Agriculture Reference
In-Depth Information
The skin colour of the ripe fruit ranges from several shades of green to yellow-
green, from reddish to maroon and from light to dark purple. The buttery fl esh
(mesocarp) is greenish-yellow to bright yellow to cream when ripe. Oil content
ranges from 7.8 to 40.7% on a fresh-weight basis (Kawano et al. , 1976). Size
varies from the small fruit of some Mexican types, about 225 g or less, to the
large Guatemalan types, 1.4-2 kg or more (Table 7.1). In shape, the fruit is
usually pyriform to oval and round.
In West Indian and Mexican cultivars, the fruit matures 150-240 days
after anthesis, while Guatemalan cultivars take more than 250 days (Fig. 7.5).
All show a typical sigmoid growth curve (Fig. 7.6). There is little delay before
growth occurs in fruit, seed and pericarp thickness.
CULTIVAR DEVELOPMENT
Cytogenetics and genetics
Persea species generally have a diploid number of 24 chromosomes. Among P.
americana materials examined, Garcia (1975) found one triploid (2n = 36) and
600
Waldin
West Indian
500
Taylor
Guatemalan
400
300
200
Capac
Mexican
100
0
0
70
140
Days from full bloom
210
280
Fig. 7.5. Increase in fruit mass of three cultivars from different ecological races,
showing the difference in time for fruit to reach maturity and fi nal fruit size relative
to the ecological race (redrawn from Valmayor, 1967).
 
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