PAPAYA - Tropical Fruits - page 301

Fig. 11.6. Stamen carpellody induced by environmental conditions (temperature,
water stress, fertilization) on young hermaphrodite trees signi fi cantly alters fruit
shape. The mild forms are sometimes referred to as 'cat face'.
The fl oral primordia of 'Solo' is laid down 50-70 days prior to anthesis,
at a rate of about one new fl ower in each leaf every 2-3 days along with
new leaves. Ovaries dif erentiation begins 42-50 days prior to anthesis and
is completed within 28 days before anthesis. Stamen dif erentiation begins
50-56 days before anthesis and is completed by 35 days prior to anthesis.
Female fl ower bud emergence to anthesis ranges from ~46 days in Hawaii to
80 days in India, with the wide discrepancy being due to temperature.
Pollination and fruit set
In hermaphrodite populations, wind pollination is minimal as the stamens
are packed inside the corolla tube and seldom protrude prominently out of
the fl ower (Fig. 11.3b). The hermaphrodite fl owers are cleistogamous, i.e. the
anthers dehisce and release the pollen prior to anthesis of the fl ower, leading
to self-pollination. Varieties such as 'Sunrise', 'Kapoho' and 'Eksotika' are
enforced self-pollinators, and seeds gathered from hermaphrodite fruit will
usually breed true to type. Self-incompatibility in cultivars is relatively rare,
though there are isolated cases when controlled self-pollinations are made.
Self-pollination in papaya also does not appear to result in any loss of vigour.
In mixed planting of pistillate and hermaphroditic trees or in purely
hermaphroditic stands, no pollination problems are experienced. Problem
occurs when dioecious cultivars are planted with an inadequate number
of male trees. In Australia, the recommended ratio of female to male is