Agriculture Reference
In-Depth Information
Fig. 11.4.
The growth rate of papaya root and stem in the fi eld, showing root growth
rate reduction at the start of fl owering and shoot growth as fruits start to develop
(after Marler and Discekici, 1997).
two unisexual fl ower types and exhibits numerous deviations. The basic fl ower
on a short peduncle is characterized by an elongated pistil with fi ve stigmatic
rays and fi ve petals that are fused to about two-thirds of their length, forming
a corolla tube. There are ten stamens in two series of fi ve attached to the
throat of the corolla tube. The pistil is normally fi ve-carpellate and elongated,
oval or pyriform.
Taking into account the numerous deviations, Storey (1941b) classifi ed
papaya fl owers into fi ve basic types (Table 11.1). Type I: pistillate or female
fl ower devoid of stamens, with a distinct ovoid ovary terminating in a fi ve-
lobed stigma (Fig. 11.3a). Type II: hermaphrodite (pentandria) fl ower having
fi ve functional stamens and a globose fi ve-furrowed ovary (Fig. 11.3b).
Type III: hermaphrodite (carpelloid) fl ower having six to nine functional
stamens and an irregularly ridged ovary. Type IV: hermaphrodite (elongata)
fl ower having ten functional stamens and an elongate, smooth ovary. Type
IV+: hermaphrodite (barren) fl ower having ten functional stamens but
the pistil aborts, becomes vestigial and lacks a stigma (Fig. 11.3c). Type V:
staminate fl ower having ten functional stamens only. The ovary is completely
absent and fl owers are bunched in an infl orescence. Although fi ve basic
