Unfruitfulness 135
occur on the day of anthesis (Dhaliwal and Gill 1991). A hermaphrodite flower’s
pollen may be released before its stigmas’ are receptive (protandrous dichogamy),
with the stigmas becoming receptive only at anthesis (Pares et al. 2002). There may
be genotype differences in variety lines, and seasonal changes in flower receptivity
affecting pollination (Pares-Martinez et al. 2004). In gynodioecious plants, seed set
was 10 times greater when Coorg Honey Dew plants in India were hand-pollinated
after being open-pollinated (Purohit 1980), but hand pollination did not increase
papaya fruit set. These results depend upon the pollinators available as well as the
papaya variety (Rodriguez-Pastor et al. 1990).
12.2.2 Planting Season
Papaya is a tropical fruit and it requires warm and humid season. Winter season
retards the growth and fruiting of this crop. Most parts of our country are subtropi-
cal. The papaya starts flowering and fruiting after about 6 months under normal
condition. Therefore, planting should be manipulated in such a way that fruiting
may continue for a longer period. The optimum period has been found to be August–
September for sowing seeds in the nursery and October–December for planting. This
provides an extended long range of warm and humid condition for fruiting (Ram and
Ray 1992). Planting done in other season either takes a longer time for fruiting or
leads to sparse fruiting in the first season.
Under commercial conditions, papaya has exacting climate requirement for
vigourous growth and fruit production. It must have warmth throughout the year
and will be damaged by light frost (O’Hare 1993), even brief exposure to 0°C is
damaging and prolonged cold without overhead sprinkling will kill the plants
(California Rare fruit Growers Inc 1997). Temperatures below 12–14°C strongly
retard fruit maturation and adversely affect fruit production (Nakasone and Paull
1998) but hotter temperatures, if accompanied by dry conditions, can also adversely
affect fruit set (Elder et al. 2000). Similarly, soil temperatures below 15°C limit
growth (O’Hare 1993). An ambient temperature range between 21°C and 33°C is
ideal (OECD 2005).
12.2.3 Organic Manuring
Basal dose of organic manure should be applied in pits and not flat beds. In a
field trial, cv., Pusa Delicious was transplanted in (a) pits dug 90 days and filled
with manures 60 days ahead of the transplanting date, (b) pits dug and filled with
manures 2–3 days ahead of the transplanting and (c) in flat lands (beds) prepared
2–3 days ahead by deep ploughing after broadcasting the manures in a metre-
wide band running along the planting row. Plants getting treatment (a) flowered
quite earlier than those under treatment (c) and produced the highest fruit yield,
36.40 kg/plant. The result with (b) was statistically comparable to that of 34.50 kg/
plant (a). Transplanting in flat land (c) brought about significant reduction in the
plant productivity (9.1 kg). These observations give strong support for transplant-
ing papaya in pits dug and manured either recently or in advance in heavy soil
(Ram and Ray 1992).