134 Papaya
forms or sex reversal is possible. These variations of the hermaphrodite flower,
classified as floral abnormalities, reduce crop yields and increase seasonality in
fruit yield, leading to supply oscillations and consequently to price variations of
papaya on the market. Carpelloid fruits occur due to the transformation of stamens
into carpel-like structures, producing fruit with varying degrees of malformation,
while pentandrya is the transformation of hermaphrodite into a typically female
flower, with a reduced number of stamens and an ovary with five deep grooves.
These variations occur mainly at mild or low temperatures and high moisture and
soil nitrogen levels (Awada 1958; Arkle Junior and Nakasone 1984) and are unde-
sirable in plantations, since their fruit has no market value, decreasing yields. Sex
reversal, however, is a result of abortion or ovarian atrophy, producing no fruit.
This phenomenon occurs related to high temperatures, water stress and low soil
nitrogen (Awada 1958; Arkle Junior and Nakasone 1984).
12.2 Environmental Influences
Papaya flourishes in the frost-free and humid areas of the tropics and subtropics with
an average temperature of 25°C and rainfall between 1500 and 2000 mm, which
spread throughout the year. Due to its soft wood and flat root system, the papaya
is very susceptible to wind break, especially in a monoculture. Soil must be well
drained because papayas are susceptible to stagnant water. Dry periods longer than
two months may lead to the necessity of irrigation. It reacts very sensitively to cul-
tivation mistakes (Naturlande 2000). Even under optimum sites, plantations have
encountered several problems that have brought low production due to poor varieties,
weediness, pollination, abiotic and biotic stress, etc., as given below:
12.2.1 Choice of Variety
Heavy or shy bearing is a genetical character in papaya. But some acclimatised
varieties give good yield in a specific zone. The cultivar Ranchi is acclimatised
to Jharkhand conditions and has a wide adaptability under North Indian condi-
tions. Coorg Honey performs well in South India, especially in Karnataka but a
poor yielder in North India. Similarly, Barwani in Central Zone, Washington in
Western Zone and Co varieties in a good part of Southern zone perform well.
Exotic varieties like, Solo, Sunrise Solo, Waimanalo, Taiwan and Thailand per-
form well in Southern and Western India but give poor performance under North
Indian conditions. Homesteads from Nigeria show good potential in yield all over
the country. Pusa varieties have also shown good performance under most parts
of the country. Therefore, only tested varieties suitable for a specific zone should
be grown.
In the dioecious condition, the male and female plants are separate, so out-cross-
ing is requisite to fertilisation. In a dioecious variety (Washington), anther dehis-
cence was completed 36–18 h before anthesis and stigmas became receptive a day
before anthesis (Khuspe and Ugale 1977). In gynodioecious varieties, self-fertilisa-
tion is possible in hermaphrodite flowers. Anthers dehisce before anthesis, facilitat-
ing cleistogamy (Chan et al. 1999). Maximum stigma receptivity has been found to