MANGO - Tropical Fruits - page 259

absence of an ovary. Petals are pinkish-white, with several yellow ridges on the
inner surface. The percentage of perfect fl owers on a panicle ranges from 1.25
to 81%, with a strong varietal dif erence in fl ower-sex expression (Table 10.1).
The percentage of perfect fl owers is higher in the apical zone of the panicle
than in the basal and central portions; climate can also af ect the percentage,
as can the position of the panicle in the canopy. Late-season panicles and
those formed in the interior of the tree usually have a larger number of perfect
fl owers (Adlan, 1965). Flower and infl orescence colour and fl ower scent vary
among cultivars.
A good crop of fruit is obtained when only a small percentage of the
fl owers are pollinated. Lack of fruit set is attributed to: (i) lack of fertile pollen;
(ii) poor pollen-tube growth; (iii) failure of ovule fertilization; (iv) failure of
pistil or ovules to develop; (v) abortions of embryo sac, embryo or endosperm;
(vi) anthracnose disease of the fl owers; and (vii) other physical factors
(Schaf er et al. , 1994). Anthracnose disease is a major problem and is more
prevalent if rainfall occurs during fl owering. The disease will eventually af ect
the whole panicle, leading to fl ower and young fruit shed.

Pollination and fruit set

Natural pollination
About 65% of the fl owers open before 6 a.m. and the rest open during the day.
Anther dehiscence occurs within an hour after anthesis, with a maximum
between 9 a.m. and noon. Eighty per cent of the pollen is viable (Fig. 10.3).
Stigmas are receptive from 1 day before anthesis until 2 days after, with the
day of anthesis being the optimum. Mango cultivars are considered to be self-
fertile, but self-incompatibility has been reported. Self-pollination produces
0-1.68% set, while cross-pollination produces 6.2-23.4%, but there are clear
cultivar dif erences. The pollen grains fall on the base of the ovary and the
nectary discs rather than the stigma; hence pollination agents are required.
Insects, including bees, wasps and fl ies, are the principal pollinating agents, as
indicated by the sticky pollen, secretion of nectar, colourful corolla and fl ower

Table 10.1. Percentage of hermaphroditic and male fl owers on three cultivars
grown in Hawaii (Adlan, 1965).
Sex

Cultivar

Fairchild Zill No. 9 Total

Hermaphrodite 396 787 556 1739

Male 1660 1153 104 2917

Total 2056 1940 660 4656

% hermaphrodite 19.20 40.50 84.24