|
Climate
and soil
Papaya thrives well in tropical climate. . The occurrence of low temperature and
frost limits its cultivation. The optimum temperature for the growth and development
of papaya is 22-26°C. In Kerala, the limiting factors for commercial cultivation
are high rainfall and severe drought in summer. However, this is best suited as
a homestead fruit crop. The papaya prefers a rich, well drained soil. It will not
tolerate water logging around the trunk.
Top
Varieties
Washington, Honey Dew, Coorg Honey Dew, Solo, Pusa Dwarf Surya, Co-7, Pusa Nanha,
Pusa Giant, Co-2 and Co-5 are suitable for papain extraction.
Top
Propagation
and planting
Papaya is propagated almost entirely by seeds. . The best time for raising papaya
seedlings is from February to March. The seeds are sown in raised seedbeds of 2
x 1m made 15cm above the ground level or in polythene bags. A mixture of sand, leaf
mould and dried FYM is spread over the seedbed. The seeds are sown 2-3 cm deep at
a distance of 5cm in rows 15 cm apart. To raise seedlings for planting in a hectare,
250g seeds are required. Seedbeds should be watered daily, if there is no rain.
Papaya seedlings raised in polythene bags can stand transplanting better than that
raised in seedbeds. Polythene bags of 20 x 15cm size and 150 gauge thickness are
used as containers. They are filled with a mixture of FYM, soil and sand in equal
proportions. Two seeds are sown in each bag and after germination, only one seedling
is retained. Vegetative propagation by mound layering is also possible.
Planting
Two month old seedlings are transplanted in the main field in May-June at a spacing
of 2 x 2 m. Pits of size 50 x 50 x 50cm are taken and filled with topsoil. Male
plants are removed as soon as they flower and the female and hermaphrodite plants
are retained. In pure female plantations, one male plant is retained for every 10
female plants. Seedlings are shaded to protect them from excessive sunlight until
they establish. In hermaphrodite or monoecious types male plants may not be required.
Top
Intercultural
operations
Manuring
Organic manure may be applied at the rate of 10 to 25 kg / plant / year at the onset
of southwest monsoon in basins around the plant. Each papaya plant should also be
supplied with 40 g N, 40 g P2O5, and 80 g K2O at
every two month interval.
Weeding and intercropping
Keep the papaya plot free of weeds. Two hand-diggings, one in the beginning of the
rainy season and another in January - February are necessary. When papaya is grown
as the main crop, vegetables can be profitably cultivated as intercrop for about
six months from planting of papaya seedlings.
Irrigation
The crop should be irrigated in summer. The ring system of irrigation is better
for papaya than the basin system because the ring system prevents irrigation water
coming into contact with the stem, thus preventing collar rot.
Top
Plant
protection
Diseases
- Damping off
It causes rotting of seedlings in the nursery. This can be prevented by sterilizing
the soil of the seedbed with 2.5% formaldehyde solution and covering it for 48 hours
with newspapers or polythene sheets. This treatment is given 15 days before sowing.
- Collar rot or stem rot
Water logging and bad drainage are the chief contributing factors. Application of
Bordeaux paste on the stem and soil drenching with Bordeaux mixture are control
measures.
- Anthracnose
It causes premature fruit fall and leaf fall. To control, spray Bordeaux mixture
1%.
Papaya mosaic and papaya leaf curl are two serious
virus diseases of papaya. Remove the affected plants and burn them immediately.
Top
Harvesting
The seedlings flower and set fruit within 3-5 months after transplanting. The number
of fruits harvested per tree per year varies from 25 to 30. Fruits showing streaks
of yellow colour are harvested. Although papaya trees bear flowers and fruits continuously
for many years, it is not economical to retain the trees after 2.5 to 3 yrs.
Top
Extraction
of papain
Papain is an active enzyme present in the latex or milky secretion of papaya plants
and immature fruits. Half to three-fourth matured fruits (about 70 to 100 days from
fruit set) are preferred for papain extraction. Tapping of fruits can be done early
in the morning by giving longitudinal skin-depth incisions (0.3cm) on the surface
of the fruits from the stalk end to tip. Stainless steel blades or knives or bamboo
splinters are used for incising papaya fruits. The milky latex is collected in arecanut
spathes or aluminium or glass vessels.
The incisions are repeated in two or three subsequent occasions at 3 to 4 days intervals.
The latex collected in this way is dried in the sun or in an artificial drier at
50-55°C. A small quantity of potassium metabisulphite is added to the liquid latex
to extend the storage life of papain. The dried latex can be stored in airtight
polythene or glass containers for a period of six months. Tapped fruits are equally
tasty as untapped fruits, although impaired in appearance.
Top
|