15114
Fruiting, Harvesting
and Post-Harvest
Papaya flowers are borne on inflorescences that appear in the axils of the leaves.
Female flowers are held close against the stem as single flowers or in clusters of
2–3 (Chay-Prove et al. 2000). Male flowers are smaller, numerous and are borne on
60–90 cm long pendulous inflorescences (Nakasone and Paull 1998). Bisexual flow-
ers are intermediate between the two unisexual forms (Nakasone and Paull 1998).
Male flowers have no ovary and do not produce a fruit. They contain stamens bear-
ing pollen that can pollinate a papaya flower with an ovary, making it to produce a
fruit. It is known as polycarpic fruit crop. Flowering and fruiting continue through-
out lifespan of plant but economic life is only for 1–3 years. Fruit shows a double sig-
moid type growth pattern during development. A range of variation of 4–6 months
for first flowering date, 8.5–11 months to first harvest and 1–7 kg for fruit weight
were recorded (Ocampo et al. 2006).
In modern cultivars, one papaya leaf can sustain the development of three to four
fruits. However, there are indications of poor adjustment capacity of source to sink
ratios in fruiting papaya plants, presumably because the fruits have low capacity to
attract assimilates (Zhou et al. 2000). In most of the crops, biomass allocation to the
harvested organ is the yield component, and most susceptible to selection and breed-
ing (Bugbee and Monje 1992).
Soil type, mulching, irrigation and fertilisation influence the water and nutrient
supply to the plant, which in turn affect the nutritional quality of fruit harvested. The
effects of mineral and elemental uptake from fertilisers by plants are variable. High
calcium uptake by fruit has been reported to reduce respiration rates and ethylene
production delays ripening, increases firmness, reduces incidence of physiological
disorders, decays and ultimately increases shelf-life. High nitrogen content is often
associated with reduced shelf-life and decay (Kader and Rolle 2004). Over feeding
of nitrogenous fertilisers results in softening of papaya fruit (Desai and Wagh 1995).
There is a progressive increase in total sugars, vitamins (A and C), minerals
(P, K, Ca), xanthophylls and carotene pigments as the fruit matures. The nutritional
composition of the fruit at harvest varies widely depending on cultivar, maturity,
climate, soil type and fertility. Ascorbic acid and carotenoid contents increase with
maturation and ripening of papaya fruit (Lee and Kader 2000). Also, ascorbic acid
levels in fruit are influenced by the availability of light to the crop and to individual
fruits. In general, the lower the light intensity, the lower the ascorbic acid content
of plant tissues; best quality of papaya fruit is determined largely by sugar content,
development under full sunlight in the final 4–5 days to full ripening on the tree
(Samson 1986). Lower temperature (<10°C) decreases fruit growth, sweetness and
fruit size of papaya (Desai and Wagh 1995). Rainfall may influence the composition
of the harvested plant part and its susceptibility to mechanical damage and decay