Eco- Friendly technologies for enhancing papaya production

Papaya (Carica papaya L.) is one of the few important tropical fruits. It belongs to the family Caricaceae has 4 genera, Carica with about 21 species, with a somatic chromosome number of 18. The plant of Carica papaya are small herbaceous, evergreen dicotylendonous fragile tree with a hollow, soft wooded 1 to 10 m high perennial which may produce fruits for more than 20 year but economically life is not more than 3 year,. It is diploid (2n=9), dicotyledonous plant with a small genome size of 372 Mbp. To obtain higher yield improved cultural method should be adopted as follows: Nursery management Seed rate: For one hectare planting, about 250-300 g papaya seed is sufficient. Raising of seedlings in nursery: Nursery bed should be prepared at least one month in advance of seed sowing and thorough weeding should be done before sowing the seeds. The seedlings can be raised in nursery bed measuring 3 m. long 1 m wide and 10 cm high. Seeds can also be germinated in seed pan tray made of hard black plastic measuring 53 cm x 27 cm containing 98 drainage cells available in the market. The seed should be sown 1 cm deep in rows of 10 cm apart and covered with fine compost or leaf mould to get highest germination.

The nursery bed may be covered with polythene sheet or dry paddy straw to protect the nursery against adverse weather conditions. Depth of sowing the seeds in nursery is an important aspect for higher germination. It may vary from soil to soil i.e. 2 cm deep in sandy soil, 1.5 cm in sandy loam and 1 cm deep in clay-loam soil. In an experiment conducted by the author, the highest germination was found in 1 cm deep sowing followed by 2 cm in semisandy soil. Light watering with the help of watering-can in the morning hour is preferred.Tender seedlings should be protected against heavy rainfall. Sprinkling of Fipronil per liter/acre insecticide should be done to protect the seedlings against insect pests. The most serious disease in the nursery is "damping off'.

Treating the seed with 0.1% Monosan (phenyle mercury acetate), Ceresan, Agrosan or Thiraum dust before sowing is the best preventive measure against this disease. Also the nursery bed should be treated with 5% formaldehyde solution before sowing. If the disease appears in the nursery, Bordeaux Mixture (1%) or copper oxychloride (0.2%) should be sprayed. The damaged plants by this disease should be burnt as a preventive measure for future spread of the disease. It is experienced that papaya seedlings raised in polythene bags stands better than those raised in seed beds. Perforated polythene bags of 20 cm x 15 cm size can be used as container. Polythene bags are filled with mixture containing farmyard manure, soil and sand in equal proportion. Four to 5 seeds are sow in each bag and after germination only 3 seedlings are retained. Seedlings in polythene bags are best suited for long distance transportation.

Transfer of seedlings

When the seedlings are growing densely, they can be transferred to next nursery bed or pots or plastic bags to avoid overcrowding and further check of growth of seedlings. This is also useful when the Mild is not ready for planting in time. Generally the seedlings become ready for transplanting in the field in about 2 months when it is 15-20 cm high. Watering in the nursery bed should be stopped one week prior to transplanting. This helps better stand population in the field.

Suitable land, field preparation, and provision of windbreak

Since papaya does not withstand water logging, a well drained upland should be selected for cultivation. Papaya plants are also sensitive to strong wind, lest the tree break down. In open and high lying area where the plants are exposed to strong winds or storm, suitable wind break are essential to protect them. Such windbreak also saves the trees to great extent from damage caused by cold wind or frost.

Jaint (Sesbaniaaegyptiaca) should be sown around the field on the onset of the monsoon to act as an effective wind-break. This windbreak is quick growing hedge commonly used in the eastern parts of the country. For better fruit yield, papaya is planted in pits (60 cm x 60 cm x 60 cm) which is opened for about 15 days earlier in summer and filled with the top soil along with 20 kg farmyard manure, 1 kg neem or Karanj cake and 1 kg bonemeal or fishmeal. Tall and vigorous varieties are planted at greater spacing while medium and dwarf varieties are planted at closer spacing. Accordingly pegging should be done to open the pits in the field and filled with organic manures on the onset of monsoon. If there is no rain, heavy flood irrigation should be done to settle down and decompose the organic manures in the pits prior to transplanting.

Planting Season

Planting of papaya is done in 3 distinct seasons for commercial purpose. They are Spring (February—March), Monsoon (June—July) and Autumn (October—November). Spring planting is done in area where the climatic condition is mild throughout the year. Monsoon planting is preferred in the frost prone area, as plants become hardy when the frost occurs. Plants are protected against frost damage by covering with polythene structure in the frost prone area. Autumn planting is generally done in the regions where the rainfall is high and virus problem is acute in rainy season. In an experiment the author has found the highest yield and least infection of virus when the seeds were sown in the nursery in 3rd week of August and planted in the field in the middle of October under sub-tropical condition of North Bihar. This finding is very suitable for North Eastern regions of India including West Bengal, Eastern Uttar Pradesh, Bihar and Orissa. It should be remembered that flowering and fruiting takes place after more than 5 months of transplanting and fruit sets in the monsoon season from July to October only. Hence in frost pronged area the seeds can be sown in the month of September and protected under plastic cover throughout the winter and planting can be done in Spring (February-March) to catch the ensuing monsoon season of flowering and fruiting.

Planting Space

Planting distance is determined by the integration of light interception, cultivar and economic consideration. The spacing of 1.8 m x 1.8 m is normally followed for the most of cultivars. A closer spacing of 1.33 m x 1.3 m (5609 plants/ha) was found to be optimum under Bangalore conditions for Coorg Honey papaya. The spacing of 1.4 m x 1.4 m or 1.4 m x 1.6 m is best suited for papaya cv. Pusa Delicious under sub-tropical conditions of Bihar while the spacing of 1.6 m x 1.6 m recorded highest yield of fruits as well as papaya in Tamil Nadu. A closer spacing of 1.2 m x 1.2 m for PusaNanha has been adopted for high density orcharding containing 6400 plants/hectare and yielded 103 tonnes of fruit. Since sufficient space is available in between two rows of papaya in the first year, a number of intercrops are taken for better economic return. Under such circumstances the distance from plant to plant and row to row may vary greatly. The number of plants per hectare has been shown according to different distances.

Operation of Planting

Planting of papaya seedlings in the field should be preferred in evening. The seedlings from nursery-bed are lifted with 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 variety. It is also important to keep some extra plants reserved in the nursery or in polythene bags for gap filling in the field. It is desirable to maintain full population in the field otherwise there will be economic loss at the rate of Rs 100 per gap at the minimum.

Careing and gap filling

Proper care should be taken to save the seedlings in the field especially against insect pests and heavy rainfall in the early stage. In frost prone area, these should be protected with small thatches or polythene structure. Some extra seedlings kept already reserved in the nursery for gap filling may be utilised for planting in the gaps as soon as possible. Mechanical damage of young seedling or plants is frequently observed which should be avoided during cultural operations in the field.

Intercropping and crop rotation

In the beginning sufficient space is available and therefore, some crops can be taken up with advantage. The papaya based cropping system (sequential and intercropping) are found most remunerative as they give high net returns in case of papaya + tobacco intercropping in North Bihar and growing of onion with papaya intercropping is easily.

When papaya is grown in tobacco, no digging of pits and basal dose of organic manure is required. This is because the farmers give heavy dose of manures and fertilizers in tobacco crop. Hence the cost of the cultivation is drastically reduced when both crops are combined together. It is advised not to grow crops like chillies, tomato, brinjal and lady's finger to avoid viruses as they act host. No intercrop should be taken when flowering and fruiting start. A suitable crop rotation must be followed up to maintain soil fertility and to avoid replant problem. Intercropping of leguminous crop after non-leguminous one, shallow-rooted crops after deep rooted ones are beneficial.

Standardised crop rotations are given below:

Weeding and hoeing

Grasses cause much damage to papaya plants in the early stage. The weeds grow luxuriantly in the papaya field and exhaust most of the applied nutrients. In the beginning, they also compete for light, air and water which result poor papaya fruiting. Deep hoeing is recommended in the first year to discourage weed growth. In no case hoeing should be done in rainy season after fruiting as the plant of papaya is a shallow rooted crop. Over-growth of weeds also causes the water logging conditions and makes the plants vulnerable to root rot and roof rot in rainy season. Therefore weeding should be regularly done specially around the plants. Gramoxone at 1.0 litre per/ha controlled weeds and gave maximum fruit yield in papaya (91. tonnes/ha) under west Bengal conditions, Paraquate (1.0 litre/ ha) applied twice at 90 and 180 days after transplantation caused maximum reduction of weeds, improved plants growth, advanced flowering and resulted in higher fruit yield. At IIHR Bangalore Diuron 2 kg/ha was found effective in controlling weeds without any adverse effect on papaya. With the increasing labour cost, chemical weed control appears to be suitable measure for operation. Application of fluchloralin or Alachlorin or Butachlorine at 2.0 kg/ha as pre-emergence application, two months after the transplanting papaya can control all the weeds for a period of 4 months.

Removal of male plants

It is necessary to keep 10% male plants in the orchard for good pollination where dioecious variety is cultivated. As soon as the plants flower, the extra male plants should be uprooted. The hermaphrodite plants produce good quality fruit which should not be confused with male plant while removing them from the orchard. While removing the extra plants, weaker and diseased plants should be uprooted.

Thinning of fruits

Healthy papaya trees can be expected to flower about 4-6 months from the time of transplanting in the field. Fruit thinning is an important practice that will regulate production and improve the percentage of uniform size marketable fruit. After fruit set, the initial stages of fruit development are very rapid. Therefore, any fruitlets that remain under-developed after a week or so from setting is unlikely to develop into marketable fruit. The poor development is normally due to poor pollination and fertilisation of the ovules. Such fruits are normally seed-less and very small and should be picked off by hand at the early stage. In some instances, particularly during very wet and cool conditions, the papaya develops carpelloid fruits. The malformation is evident even at the flower stage and detection and elimination of such fruitlets can be done very early. Other fruitlets which should be discarded are those that have apparent damage due to thrips, mites and disease. The improved varieties of papaya set a single fruit. It is also recommended that a single fruit per node should be retained. On occasions when some nodes carry two or more fruitlets, only the largest one should be retained. Fruit thinning will result in a high percentage of well formed, uniform size fruit because very early in their development all parasitic malformed fruit which do not have economic importance have been removed.

Nutrient and fertilizers

Papaya is a heavy feeder crop since it grows vigorously and continuously and give high yield of fruits. Adequate and efficient manuring of young and mature tree is essential to maintain the health of papaya and to obtain profitable yield. Manuring start from raising the seedlings in the nursery for the production of vigorous healthy plants. During preparation of nursery bed, 20 kg fine compost should be applied in each nursery bed measuring 3 x 1 m. After germination where the seedlings are one month old liquid solution of fertilizer of 10-10-10 if applied correctly produce healthy seedlings especially in poor soil. Manurial experiments in fruiting orchard carried out all over the world have indicated positive response to nitrogen, phosphate and potash and to several micronutrients in papaya. Both organic and inorganic manures are beneficial to the papaya plants. Organic manures like farmyard manure, sheep manure, neem cake wood ash and bonemeal improve yield and quality of papaya fruits. Hence manuring in papaya should be half from organic manures and half from chemical fertilizers.

Irrigation

Maintenance of optimum soil moisture is essential for plant growth, fruit yield and quality. Under low moisture conditions floral sex shifts towards female sterility resulting in low productivity. At the same time over irrigation may cause root rot disease. Thus efficient water management is required. Number of irrigation depends upon soil type and weather conditions of the region. Protective irrigation is required in the first year of planting. In the second year when the plants are ladden with fruits, irrigation at fortnightly interval in winter and at 10 days interval in summer is needed from October till May. Excessive moisture is more detrimental to plant than moisture stress necessitating the effective drainage system, especially in heavy soils under high rainfall conditions, to avoid plant mortality. Studies conducted at Coimbatore have also indicated that the papaya has high tolerance for heat and soil moisture and for higher productivity however moisture stress at fruit development stage should be avoided.

Total water requirement of Co2 papaya under tropics is estimated to be 1800-1900 mm and excessive depletion of moisture causes reduced growth and yield. However, intermittent moisture stress induces deep root penetration. Depletion of soil moisture also causes increase in N and Mg content while Ca content is reduced. Irrigation at 60-80% available soil moisture (ASM) depletion is found to be optimum for papaya. Generally basin system of irrigation is followed but care is taken to avoid water stagnation around the plant. In low rainfall area, where the water is scarce, sprinkler or drip system of irrigation can be adopted for higher production. These system save water from 60 to 80% according to method and region.

Drainage

It should be remembered that papaya plants are very susceptible to waterlogging. Even 24 hours stagnation with water may kill the well established orchard. It is therefore most important to select upland for papaya plantation. It may further be shaped sloppy in heavy rainfall area. It is essential to make furrow or trenches for quick and complete drainage of water during rainy season, Earthing up around the plant may be repeated according toneed during rainy season.

Protection against adverse weather conditions

The fruited plants should be covered with gunny bags against high temperature in summer and low temperature in winter. White polythene may also be used for this purpose. Covering of young plants against strong summer wind, frost and schorchy sun rays is also essential to protect them. Covering of young plants of papaya should be done in advance in frost pronged areas. While covering the young plants, care should be taken that the southern east -portion of plant is opened so that sufficient air and light is available to the growing plants .When there is forecast for frost in the ensuing night. Irrigation must be done in the plantation. Smudging around the field may also help to protect against frost-along with the irrigation. If the plantation is well managed with effective wind break, it also saves from such adverse conditions.

Protection technology against frost and Insect

Cultivation of papaya in Pot

The IARI Regional Station, Pusa Bihar has developed PusaNanha, an extremely dwarf variety of papaya. Since there is potential scope of papaya cultivation in urban area where land is a limiting factor, PusaNanha papaya can easily be grown in big pots. The following aspect should be taken care of while growing papaya in pots.

Papaya Cultivation in Pot

Pot Size

The size of pot should not be less than 75 cm x 40 cm. The following quantity of manures should be filled in each pot before planting papaya plants:

Raising techniques of seedlings

Papaya seedlings can be raised in August-September. The polythene bags used for raising seedling should be filled with 1/3 part sand. 1/3 part compost and 1/3 part soil. The seeds should be sown one cm deep with 5-6 seeds in each, bag. It should be watered regularly with watering can. When the seedlings are 10 to 15 cm high they should be planted in the pot (already prepared) in the month of October-November. Atleast 4 plants in each pot should be planted and finally thinned out to one after removing male and other diseased or weaker plants.

Nutrition Management in Papaya plant

Apart from the organic manures already given in the pot, the following dose of chemical fertilizers should be applied as top dressing:

These 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 15 cm away from the plant in a circular fashion. Water should be immediately applied after each top dressing.

Growing of papaya in kitchen garden and on roof tops

There is potential scope of papaya cultivation in kitchen garden and on roof tops by the amateur growers in big towns with dwarf varieties like Pusa Dwarf and PusaNanha. While growing papaya in the kitchen garden, the southern and western side of plot should be selected It should be grown in one line reducing distance to half from plant to plant. The border area can be better utilized. Other operations like planting, manuring, irrigation intercultural and insect and pest management should be same as in commercial plantation. For growing papaya on roof tops, soil up to 30 cm high should be put and maintained. The soil should be collected from the place where there is no weed or weed seeds. 20 kg farmyard manure 1 kg/ Neem cake or karanj cake and 1 kg bonemeal or SSP should be spread in 36 square feet. The number of plants can be kept according to family, need assuming 20 kg fruits per plant in variety PusaNanha and 35 kg fruits in Pusa Dwarf.

The planting distance, application of fertilizers and diseases and pest control should be same except irrigation. Frequent light irrigation is given and sprinkler system should be preferred. Staking of plants with bamboos should be done when the plants are ladden with fruits. This is essential to protect against strong winds. Drainage point should be blocked in other season, and opened in only rainy season for quick drainage of water.

Cropping system and mixed cropping

In the commercialised agriculture, mixed cropping in papaya needs more emphasis than growing papaya as monocrop. Besides taking more profit per unit area and per unit time, it is advantageous in maintaining and sustaining soil fertility, water conservation and availability in situ efficient utilization of sunlight and recycling of these resources for long time use in better production and productivity. This system will be proved as a boon for a poor and marginal land holding. The incidence of insect pests and diseases is also minimized. The papaya is a delicacies crop and its cultivation in the cropping system approach depends on the climatic condition, soil type and choice as well as marketable value of the crop. However, there are few tips which are of immense importance for papaya cultivation and higher production in cropping system.

1.The crop which have higher water requirement should not be grown with papayas as it affects the papaya crop adversely e.g. paddy in papaya.

2.Papaya is a tropical fruit which requires maximum sunlight. In such situation crops like bottlegourd, spongegourd, kheksa, tinda and squash should not be grown as catch crop, mixed or intercrop.

3.Papaya is highly susceptible to virus diseases. As such no crop should be grown with papaya which are not only affected by virus but also acts as an alternate host i.e. brinjal, tomato, lady finger and chillies etc. Some suitable mixed cropping system in papaya is given below:

(a) Papaya can be grown as filler crops in newly planted orchard of litchi, mango, sapota, citrus, guava, pomegranate and coconut etc. Some intercrops can also be taken like different types of vegetables, leguminous crop, covercrops, and spices in its inter and intra row space of plantation.

(b) Papaya and banana can be taken as companion crop. In the beginning, garlic, coriander, onion, legume, safflower, can also be taken in the little space of papaya and banana plantation.

(c) Some precrop can also be taken in papaya field such as short duration

crops like cucumber (June to September) in the pits filled with organic manures meant for papaya plantation (October planting).

(d) Some relay crops can be grown in papaya field and after planting papaya, some sequential crops can be grown in furrows. Some examples are potato (Sept.), papaya in furrows (Oct.) and mustard or coriander in scattered manner in wheat (Nov.) sown in the interspace of papaya plantation.

(e) Semi shade or shade loving crops can be grown in papaya plantation like turmeric, ginger, suran and calocasia as an intercrop.

(f) Multistoried or tier system of cropping scheme can be easily followed in the tropical or semitropical regions which comprises of coconut, areca nut, papaya, different spices, tapioca and sweet potato (underground crops).

Thus these papaya based crop production systems are not only capable of improving the economic condition of the farmer but also have substantial employment potential for rural poors and landless labourers, women and tribals in its cultivation as well as in processing, manufacturing, packing, marketing, transportation of end products or industrial produce manufactured based on these agri-cultural raw materials. Besides, there is a substantial scope for alternate uses of papaya through its commercial exploitation for industrial and pharmaceutical values as mentioned earlier.

Dr. RS Sengar
Sardar Vallabh Bhai Patel Agriculture University, Meerut
Email ID: sengarbiotech7@gmail.com

Alok Kumar Singh
Deptt. of agricultural biotechnology

D.K. Srivastava
Uttar Pradesh Council of agricultural research Lucknow