Botany and Improvement 19
one set of flowers on a pistillate tree was bagged before anthesis and another set was
pollinated before anthesis and then bagged. Both pollinated and unpollinated flow-
ers produced fruits devoid of seeds. In still another case, bagged flowers produced
seedless fruits, while unbagged flowers produced seeded fruits. Rodriquez-Pastor
et al. (1990) have observed parthenocarpy at a rate of 35% in Sunrise and 5% in an
advanced line 298F5. The parthenocarpic fruits are of adequate quality. Purohit (1980)
also noted a tenfold increase in seed number of unbagged flowers from female trees
with supplemental pollination. Under subtropical north Indian climate, controlled pol-
lination done in August–September produces highest seed yield (Ram and Ray 1992).
2.2.6 Self-Incompatibility
Self-incompatibility in cultivars of Carica papaya seems to be rare as indicated by
the lack of literature on this subject. However, Nakasone (1986) observed a hermaph-
rodite papaya strain to be partially self-incompatible as about 50% of the self-polli-
nated flowers dropped without fruit set. Some degree of self-incompatibility in the
variety, Maradol from Cuba has also been reported as many self-pollinated flowers
failed to set fruits. It is apparent that there are isolated cases exhibiting some degree
of self-incompatibility. These cases are not the same as the anther/stigma–position
relationship mentioned earlier (Ray 2002).
2.3 Genetics
C. papaya with a somatic chromosome number, 2n = 2x = 18, is the sole species of
the genus Carica of Caricaceae, a family that includes six genera with at least 35
species (Storey 1976; Ram 1996; da Silva et al. 2007; Carvalho and Renner 2013).
Caricaceae, consisting of four genera: (1) Carica with 22 species, (2) Jacaratia with
six species, (3) Jarilla with one species and (4) Cylicomorpha with two species.
The first three are indigenous to tropical America and the last one to equitorial
Africa (Badillo 1971). Species having edible fruits are found only in Carica. Besides
C. papaya, they are C. chilensis, C. goudotiana, C. monoica and C. pubescens. The
fruit of C. papaya L. is generally eaten fresh. The fruits of other three species are
eaten cooked as a vegetable or candied by cooking in syrup. In Peru, the leaves of
C. monoica are cooked and eaten for greens.
2.3.1 Species
Among 22 Carica spp., following species are utilised in breeding programmes to
induce resistance to diseases, waterlogged condition and frost.
C. candamarcensis Hook: It is the mountainous papaya and is small tree with
cordate, palmately 5-lobed leaves and small yellow 5-angled 7.5–12.5 cm long fruit.
The fruits are too acid to be used but can be stewed or made into jam.
C. erythrocarpa Linden and Andre: This is similar to C. papaya Linn. but the
fruit has thin red flesh.
C. quercifolia Bant and Hook: The plant height reaches up to 2 m maximum
and has oak-like leaves and cluster of small ellipsoid fruit 2.5–5 cm long with