Tuesday, June 1, 2010
Papaya, papaw or papita (Carica papaya L.) originated from tropical America, has become a popular fruit due to its fast growth, high yield, long fruiting period and high nutrient value as well.
papain production at immature stage. It can be a highly profitable crop now.
The papaya plant has male, female, hermaphrodite (bisexual flower) and some other complex forms.Male plants do not bear any fruit, Normally the fruit shape from female plant is shorter, but the fruit shape from hermaphrodite (bisexual flower) plant is longer.
CLIMATE AND SOIL CONDITION
Papaya is a tropical, plant, very sensitive to frost. Optimum temperature is 25 - 30° C and minimum 16° C. The suitable ph value is between 6 and 6.5. The well-drained or sandy loam soil with adequate organic matter is most important for the papaya cultivation. In high rainfall area, if drainage is poor and roots are continuously drenched for 24 to 48 hours, it may cause the death of the plants. Sticky and calcareous soils are not good as rain water may accumulate in the soil even only for a few hours. In this case, higher raised bed and drainage ditch are recommended.
The growing field should be irrigable and kept at suitable soil moisture which is necessary for the growth of papaya plants, although dry climate at the time of ripening is good for the fruit quality.
Continuous cropping in the same field may result to poor growth and cause disease problem of papaya trees. Papaya does not like strong, cool, hot, dry or salty wind. It is better to grow in sheltered but full sunshine place. Staking and/or windbreak can decrease the damage to plants under strong wind.
The seed must be from dependable source and sown as soon as possible. The remaining seeds must be sealed tightly and kept at cool (5 -10° C) and dry (under relative humidity 40%) place.
One gram contains about 50 - 80 seeds, mostly 65 -75 seeds. It needs 50 to 80 g seeds per hectare at one plant per hill average of 80 % seed germination and 80% successful seedlings.
The time of sowing depends upon the choice of fruiting season and danger of rain or frost.
The optimum temperature is 21 - 27° C, and of radical emergence is 19 - 29 °C. it take 1 - 4 weeks from sowing to emerge depending on the temperature. The seed may be treated with Thiram (TMTD) W.P. before sowing to control the fungus diseases at young stage.
It may be sown directly, but normally, it is better to be seeded to raise seedlings and transplanted.
1. Plastic bag or soft plastic pot sowing:
Transparent plastic bag in 8 - 9 cm wide and 8 cm wide and 8 cm high or black soft plastic pot is used for raising seedlings. Drainage hole is required. Then fill with the mixture of sandy loam virgin soil and sand at the ratio3: 1. Sow 1 or 2 seeds each bag (pot)and cover with well fermented compost, then water fully.
Cover the bags (pots) with plastic film or thatch such as straw sheets or used jute bags to keep warm and wet till emergence. Meanwhile, keep the air fresh and moist, and then remove the cover gradually for fitting the seedling under the sun shine.
2. Seedling Tray sowing:
The use of plastic seedling tray is new way of seedling culture to obtain the healthy seedlings which are easily for the transporting and transplanting. The Tray size may be 74 to 82 holes at 4.5 cm each in diameter. Fill the prepare media in the holes, sow 1 to 2 seeds in each hole, and cover the layer of media. Other procedures are similar to plastic bag (pot) sowing.
For purposes of controlling aphid, viral infection, rain and wing protection, and maintaining tolerable temperature during seedling stage, it is required to use screen house,greenhouse or tunnel covered with 0.07-0.10 mm plastic film or 32 - mesh net. Black plastic net is also usually used for shading. During the seedling stage, semi-humid environment is preferred. For better aeration, the film may be covered during the cool night or heavy rain period and opened in the warm day time. The site of the bag, pot or tray should be changed if the roots of seedling penetrate into the soil. In this way, it will induce more new roots and healthy seedlings.
A. Transplanting stage:
When the seedling is 10 -15 cm tall, it should be transplanted, but 30-40 cm is also all right if it is grown in a larger container.
A 40-60 cm high bed is required if the soil is not well drained. Normally, the distance between rows is about 2-2.5 m, and 2 m between plants (or 3m x 3m when grown at sloping land, or 2.7 m of distance between beds for the tractor practice).The total number of plants for each hectare is about 2,000 to 2, 5000. In case of eradication of undesirable sexual or virus infected plants later, the distance between plants at beginning of planting may be 1.2-1.5 m.
C. Pollinator Plants:
Minimum10-20% hermaphrodite plants are required for pollination.
D. Planting method:
(A) Black-and-white plastic mulching film on the beds can be used to:
(a) Reduce the loss of water and fertilizer nutrient
(b) Control weed
(c) Repel the winged aphids
(d) Decrease virus infection at young stage
(e) Decrease bed soil erosion.
(B) Drill the planting hole about 45 cm in diameter and 30 cm in depth.
The soil in the hole is mixed with compost for planting. Then transplant the Seedlings (seedlings should be fully watered one day before transplanting) On a cloudy day or late afternoon to minimize transplanting shock.Take care Not to plant too deep, otherwise collar-rot disease may affect the buried part Of the stem. Then water immediately after planting.
(C) Intercrop with the newly-planted long term fruit trees such as orange.
Short term crop such as corns or vegetables may also be considered but not Necessary.
(D) To retard growth, lower the fruit - setting site, resist the wind facilitate Management and harvesting, slant planting is considered as follows:
Plant the seedlings at the angel of 45° C between the stem and surface of Soil and then later cut the leaves, which touch the soil. Fix with rope at two thirds of the stem from the base and adjust the site up when the plant grows higher to prevent the stem from being upright.
Above procedures may be modified to fix the plant with plastic rope down to the side(s) of bed about 1-2 months after transplanting (about 36-40 cm height of the plant).
(E) Screen house cultivation: For reducing virus infection during growing Period, the following cultivation is recommended:
Use 3.0 - 3.6 m long of bamboo stems or concrete stakes as supporters at a distance of 4.5 - 5m, and connect with No.12 iron wire. Then tightly surround with 32- mesh white net, which contains anti-ultra violet material.
After the construction is completed, the protected healthy seedlings are planted and planted and the virus-infected plants destroyed and buried immediately once found. Note that hand pollination for female trees is required (the central flower of the cluster on the bisexual plants can be taken as pollen supplier) and control the powdery mildew and mites well. The net may be taken off before the fruit is mature.
The plant needs continuous fertilization, as fruiting is continuous upon maturity.
Apply 10 tons of fermented compost per hectare (or 1 kg per square meter) before planting or when forming beds. The same dose should be repeated every year for the adult plants.
Apply 0.25 - 0.5 kg borax per 100 plants right before dry season In which is boron-deficient. For the young trees, apply compound fertilizers in the trench (10 cm deep and 15 cm wide) around the outer of tree crown, then fill back the soil, or top dress at furrows after irrigation
V. Weed control
Weeds should be removed at the young stage frequently and lightly, but never do deep tillage to the soil since the plant has shallow roots. Growers may apply herbicide once before emergency with 43% lasso E.C. at 1:200 or 80% Kamex W.P. at at 1:400; or mulch the bed with the plastic film before transplanting or with rice / sugarcane straws before or within a few days after transplanting to control the weeds, soil erosion and water loss.
Normally, irrigate every 10 days in winter or every week in summer, but practise varies according to soil, climatic conditions, and irrigation methods. Ring method, furrow or drip irrigation can be done. However, be sure to prevent the water from coming in contact with the stem. Irrigation may prevent the plants from the damage of frost.
A. Remove the side shoots of the stem as soon as possible.
B. Cut the old, dry, or disease leaves and petioles.
C. Thin the fruits, which are poorly pollinated, malformed or pest- infected. Nevertheless, avoid transmitting the virus mechanically from infected plant to others through the above practices.
D. Support the plant with stakes, which should tide with the rope, especially when bearing
heavy fruits and during storm season.
E. Pollinate by hand to increase the fruit setting and the percentage of large and normal fruits,
especially when growing net house.
F. Management after storm
1. Drain the plantation well.
2. Apply the fungicide to control phytophthora blight.
3. Spray 0.5% urea or side dress the fertilizers.
4. Support the fallen trees to keep them from the surface of the soil.
5. Cover the fruits with paper to avoid the sun scald.
6. Thin the small fruits if the trees are severely damaged.
In general, papaya takes six months to flower and another five for harvesting; but it may vary according the climate conditions and management. For shipping to the distant markets the fruits should be harvested when the apical and starts turning yellow and the latex is no longer milky. During the cold months the fruits can be left on the tree to develop deeper color and obtain better flavor.
Step ladder or plumber ‘s helper with long bamboo pole is usually used by the small growers to pick the fruits if the trees grows too tall. The bin attached to the tractor is used for harvesting in large plantation. The fruits can matcher well by treatment of calcium carbide or ethylene gas.
Compiled by Harsh Saxena.
Posted by KRISHI MITRA at 10:03 PM