Papaya
Papaya (Carica papaya) produces fruits throughout the year. It requires less area for tree, comes to fruiting in a year, is easy to cultivate and provides more income/ha next to banana. It has a high nutritive and medicinal value. Papain prepared from dried latex of its immature fruits is used in meat tenderising, manufacture of chewing gum, cosmetics, for degumming natural silk and to give shrink resistance to wool. Besides, it is also used in pharmaceutical industries, textile and garment cleaning paper and adhesive manufacture, sewage disposal, etc.
Climate and Soil :
Papaya is a tropical fruit. However, it also grows well in the mild subtropical regions of the country up to 1,000m above mean sea-level. Temperature is one of the most important climatic factors which determines the success of papaya cultivation. Night temperature below 12°–14°C for several hours during winter season affects its growth and production severely. It is very much sensitive to frost, strong winds and water stagnation.
It can grow in a wide variety of soils, provided these are well-drained and aerated. A rich, well-drained sandy loam soil is ideal for its cultivation. It grows well in deep, rich, alluvial soils on banks and deltas of big rivers of India. Papaya can also be grown in calcareous and stony soils provided with heavy dose of organic manures. Soils with high pH (8.0) and low pH (5.0) should be avoided.
Varieties :
A large number of varieties are cultivated. As a matter of fact many of these are not real varieties since these cannot be relied upon to reproduce the parental characters in all their progenies. However, well-known varieties with certain specific plant and fruit characters are described below.
Pusa Delicious :
It is a gynodioecious variety with 100% productive plants with good fruit yield and quality having excellent taste and good flavour.
Pusa Majesty :
This is also gynodioecious variety with high productivity and better keeping quality of fruits. This is also one of the highest papain yielders.
Pusa Giant :
This is a vigorous variety and is dioecious in nature. The plants are sturdy and tolerant to strong winds. The fruits are suitable for tooty-fruity and candies like petha.
Pusa Dwarf :
It is a dwarf-statured dioecious variety with good yield. Fruits are medium-sized with oval shape and are preferred by consumers.
Pusa Nanha :
An extremely dwarf variety, it is suitable for kitchen gardens, pot and roof-top cultivation. This is ideal for high-density orcharding.
Co 1 :
A dwarf and dioecious variety. Fruits are medium-sized with spherical shape.
Co 2 :
It is medium-tall, dioecious variety, having good fruit quality with high papain content. It is predominantly cultivated for papain production.
Co 3 :
It is a gynodioecious variety with tall, vigorous trees. The fruits are medium-sized, with high sugar content and red coloured flesh. This is preferred for dessert.
Co 4 :
It is a dioecious variety with medium-tall, vigorous trees. There are purple tinges on the stem, petiole and leaf. It is suitable for home-gardening.
Co 5 :
It is a selection from Washington variety, cultivated mainly for papain production. It yields 1,500–1,600kg/ha of dried papain.
Co 6 :
A selection from Pusa Majesty, it is dioecious having dwarf stature. It produces large-sized fruits. It is recommended both for papain and dessert purposes.
Coorg Honey Dew :
A selection from Honey Dew, it is a gynodioecious variety having excellent fruit quality under south Indian conditions.
Pink Flesh Sweet :
It is a selection with excellent-quality fruits. Fruits are medium-sized with pink flesh. The TSS is 12–14° Brix. It is a good dessert variety..
Pant 1 :
Its plants are dioecious providing medium-sized fruits. It is recommended for tarai area in Uttar Pradesh. Sunrise Solo This is a gynodioecious variety having pink flesh and good taste.
Taiwan :
This is also gynodioecious variety with blood-red coloured flesh and good taste.
Propagation :
Papaya is commercially propagated by seed. Gynodioecious varieties breed true-to-type and are preferred by commercial growers. Tissue culture or micropropa-gation are recent techniques for propagating papaya. These, however, need to be standardized.
Since papaya is commercially grown by seed, production of quality seed is most important for successful production and establishing papaya-based industries in the country.
Cultivation
Sowing :
About 250–300g seeds are sufficient for a hectare. The seedlings can be raised in nursery-beds 3m long, 1m wide and 10cm high as well as in pots or polythene bags. The seeds should be sown 1cm deep in rows 10cm apart and covered with fine compost or leaf-mould. Light watering should be done with watercan in the morning. The nursery-beds may be covered with polythene sheet or dry paddy straw to protect seedlings. Tender seedlings should also be protected from heavy rainfall. Dusting of insecticides to protect the seedlings against insect pests is also advised. Damping off is most serious disease. Treating seeds with 0.1% Monosan (phenyle mercury acetate), Ceresan, Agrosan or Thiram dust before sowing is the best preventive measure to check it. The nursery-beds should also be treated with 5% formaldehyde solution before sowing. If disease appears in the nursery, Bordeaux mixture (1%) or copper oxychloride (0.2%) should be sprayed.
The seedlings raised in polythene bags stand transplanting better than those raised in seed-beds. Perforated polythene bags of 20cm × 15cm size of 150–200 gauge can be used as a container. They are filled with a mixture of farmyard manure, soil and sand in equal proportion. Four to five seeds are sown in each bag. After germination only three seedlings are retained.
The seedlings may be transferred to nursery-beds or pots or polythene bags to avoid overcrowding and further check of growth of. This is also done when the field is not ready for planting. Generally 15–20cm tall seedlings become ready for planting in about two months.
Field preparation :
Since papaya does not withstand waterlogging, a well-drained upland should be selected for its cultivation. Its plants are also sensitive to strong winds. In open and high-lying areas, where plants are exposed to strong winds or storm, suitable windbreaks are essential to protect them. Such windbreaks also save the trees to a great extent from damage caused by cold winds or frost.
The seedlings are planted in pits of 60cm × 60cm × 60cm size. The pits are dug about 15 days before in summer and filled with top soil along with 20kg farmyard manure, 1kg neem or karanj cake and 1kg bone-meal or fish-meal. Tall and vigorous varieties are planted at greater spacing, while medium and dwarf ones at closer spacing.
Planting :
Papaya is planted during spring (February–March), monsoon (June–July) and autumn (October–November). Spring planting is done in areas where the climatic condition is mild throughout the year. Monsoon planting is preferred in the frost-prone areas, and autumn planting generally done in the regions where the rainfall is high and virus problem is acute in rainy season. Plants are protected against frost damage by covering them with a polythene-sheet.
Planting distance is determined by the integration of light interception, cultivar and economic consideration. A spacing of 1.8m × 1.8m is normally followed for most of the cultivars. A closer spacing of 1.33m × 1.33m (5,609 plants/ha) is optimum for variety Coorg Honey Dew. The spacing of 1.4m × 1.4m or 1.4m × 1.6m is best-suited for papaya Pusa Delicious under subtropical condition of Bihar. Spacing of 1.6m × 1.6m gives highest yield of fruits as well as papain in Tamil Nadu. A closer spacing of 1.2m × 1.2m for Pusa Nanha is adopted for high-density orcharding, accommodating 6,400 plants/ha.
Planting of papaya seedlings should be preferred in the evening. The seedlings from nursery-beds are lifted with a ball of earth and planted in the field. Plants raised in polythene bags are planted after removal of polythene. Three seedlings should be planted in each pit followed by light irrigation. Only one seedling may be planted with pure gynodioecious varieties. It is also important to keep some extra plants reserved in the nursery or in polythene bags for gap filling in the field.
Aftercare :
Proper care should be taken to save the seedlings in the field especially against insect pests and heavy rainfall in early stage. In frost-prone areas, they should be protected with small thatches or polythene structure. Some extra seedlings reserved in the nursery may be utilized for gap filling.
Since sufficient space is available between rows, papaya-based cropping systems (sequential and intercropping) are most remunerative. Papaya + tobacco intercropping in north Bihar is ideal. It is advised not to grow crops like chilli, tomato, brinjal and lady’s finger to avoid viruses as they act like hosts. No intercrop should be taken when flowering and fruiting start. A suitable crop rotation must be followed to maintain soil fertility and to avoid replant problem. Intercropping leguminous crops after non-leguminous ones, shallow-rooted crops after deep rooted ones are beneficial.
Weed control:
Weeds grow luxuriantly in papaya fields and exhaust most of the applied nutrients. In the beginning, they also compete for light, air and water, resulting in poor fruiting. Deep hoeing is recommended during first year to check weed growth. Hoeing should not be done in rainy season or after fruiting since its plants are shallow-rooted. Overgrowth of weeds also causes waterlogging condition and makes the plants vulnerable to root-rot and foot-rot in rainy season. Therefore weeding should be regularly done, especially around the plants. Application of Fluchloralin or Alachlorin or Butachlorine (2.0g/ha) as pre-emergence 2 months after transplanting can control all weeds for 4 months.
Removing unwanted male plants:
It is necessary to keep 10% male plants in papaya orchards for good pollination, where dioecious varieties are cultivated. As soon as the plants flower, extra male plants should be uprooted. The hermaphrodite plants produce good-quality fruits and should not be confused with male plants while removing them from the orchard. Weaker and diseased plants should be uprooted, after ensuring 1 plant/pit. Earthing-up should be done 30cm in radius around the plants on or before the onset of monsoon to avoid waterlogging. It also helps plants to stand erect.
Manuring and fertilization:
Papaya is a heavy feeder and needs heavy doses of manures and fertilizers. Apart from the basal dose of manures applied in the pits, 200–250g each of N, P2O5 and K2O are recommended for getting high yield. Application of 200g N is optimum for fruit yield but papain yield increases with increase in N up to 300g. A dose of 250g N, 250g P and 500g K/plant is recommended for papaya Coorg Honey Dew under Bangalore conditions, while 200g each of N, P and K in split doses in the first, third, fifth and seventh month is recommended for papaya Co 1 under Coimbatore conditions.
Deficiency of lime and B has often been observed in papaya orchards. Spraying of 0.5% zinc sulphate (twice) and one spray of Borax (0.1%) may be done depending upon the nutrient status of soil.
Irrigation:
Optimum soil moisture is essential for growth, yield and quality of fruits. Under low moisture conditions, floral sex shifts towards female sterility, resulting in low yield. At the same time, over-irrigations may cause root-rot disease. Thus efficient water management is required in papaya cultivation. Number of irrigations depend upon soil type and weather conditions of the region. Protective irrigation is required in the first year of planting. In the second year when its plants are ladden with fruits, irrigation at fortnightly interval in winter and at 10 days interval in summer is needed from October till May.
Generally basin system of irrigation is used but care is taken to avoid water stagnation around the plant. In low rainfall area, where the water is scarce, sprinkler or drip system can be adopted.
Papaya plants are very susceptible to waterlogging. Even 24hr stagnation with water may kill the well-established plants. Therefore it is most important to select upland for papaya plantation. It may further be shaped slopy in heavy rainfall areas to make a few furrows or trenches for quick and complete drainage of water during rainy season.
Pot cultivation :
Papaya can also be grown in big pots. Half cut iron drums and wooden crates can also be used for this purpose. The size of pot should not be less than 75cm × 40cm. Papaya seedlings can be raised in August–September. The polythene bags used for raising seedling should be filled with one-third part each of sand, compost and soil. The seeds should be sown 1cm deep with 5–6 seeds in each bag. It should be watered regularly with watering can. When seedlings are 10–15cm high they should be planted in pots already prepared during October–November. At least 4 plants in each pot should be planted. These are thinned down to one after removing male and other diseased or weaker plants.
Apart from the organic manures, a dose of chemical fertilizers containing N (50g), P (50g) and K (75g) should be applied as topdressing. Chemical fertilizers should be applied after flowering. The same quantity should be repeated in each month from July to October. Precaution should be taken that these fertilizers are applied at least 15cm away from the plant in a circular fashion. Water should be immediately applied after each topdressing.
Harvesting and Postharvest management
The fruits should be left on tree until they fully mature. Usually fruits are harvested when they are of full size, light green with tinge of yellow at epical end. On ripening, fruits of certain varieties turn yellow while some of them remain green. When the latex ceases to be milky and become watery, the fruits are suitable for harvesting.
While picking fruits from the tree, care must be taken that they are not scratched, and are free from any blemishes, otherwise these are attacked by fungus and start decaying during marketing. The fruit yield of papaya varies widely according to variety, soil, climate and management of the orchard. On an average each plant of improved varieties bears 30–45 fruits, weighing 40–75kg in one fruiting season. On an average, yield of 60–75 tonnes/ha may be expected in a season from an orchard of papaya.
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