The leaves grow from the top part of the stem in a spiral. They have long, horizontal stalks measuring 35-105 cm long. The leaves are large, and divided into 5-9 irregular segments. They have prominent yellow ribs and veins.
The papaya fruit range from oval to round, measuring 15-50 cm long and 10-20 cm wide. The largest may weigh up to 9 kg. Unripe fruit are green and hard with white latex. Ripe fruit have light to deep yellow skins with yellow, orange, salmon or red succulent flesh. The flesh is juicy, sweet with an aromatic to musky flavour. The seeds, found in the centre of the fruit, are usually black and surrounded by a transparent, fleshy coating.
Papaya is a short-lived, fast growing, soft wooded perennial It has an extensive root system, erect growth and does not branch. How pollination takes place in papayas is not known with certainty. Wind is probably the main agent, as the pollen is light and abundant, but thrips and moths may assist. Hand pollination is sometimes necessary to get a proper fruit set.
A high initial growth rate leads to early flowering (within 6 months from sowing) and fruiting (fruit maturing 4-5 months after flowering). The fruit moderates the growth rate, but a steady and relatively fast pace should be maintained to produce fruit throughout the year and in large quantities.
After transplanting, shoot growth is initially slow, though considerable root growth is taking place. Growth rate peaks at flowering then declines as the tree starts bearing. The rate of stem growth is influenced by nitrogen and phosphorus supply, irrigation, and temperature. Root growth declines dramatically as flower initiation occurs, continuing at a very low rate during flowering and fruiting.New leaves are constantly formed at the apex and old leaves senesce and fall. Usually there are up to 15 mature leaves per plant. New flower buds are formed at leaf axils every two to three days. The time from bud initiation to flower anthesis ranges from 46 to 80 days, the wide discrepancy due to effect of temperature.
Fruit growth shows two major phases. The first phase of rapid growth lasts about 80 days after flower opening, while the second phase is apparent just before fruit maturity. Sugars begin to accumulate only during the last 28 to 42 days of fruit development. Fruit development usually takes 190 to 270 days in the cooler subtropics.
Papaya grows best in light, well-drained soils rich in organic matter with soil pH of 6.0-6.5. It can tolerate any kind of soil provided it is well-drained and not too dry. On rich, organic soils the papaya grows well and bears heavily but produces fruits of low quality. The roots are very sensitive, even short periods of water logging can kill the plants.
Optimum temperature for growth is between 21’C to 33’C. Hermaphroditic cultivars grown with minimum temperature less than 17’C may have 100% of the flowers reverting to femaleness. At higher temperatures (>35’C), there is a tendency of hermaphrodite cultivars to form functional male flowers with poorly developed and non-functional female parts.