AN OVERVIEW OF TOMATO CULTIVATION IN NEPAL

Anusha Satyal

The most widely grown tomato ranks second to the potato in the world. The popularity of tomato is rising up due to the short cropping period and relatively high yield. The crop is economically attractive to the farmers across the globe so area under the cultivation is increasing daily.

Tomatoes are rich in vitamins, minerals, essential amino acids, sugar and dietary fibers that aid much in keeping the healthy balanced diet. Tomato contains Vitamin like Vitamin A, Vitamin C, Vitamin E and Vitamin K along with the minerals such as calcium, iron, magnesium, manganese, phosphorous and potassium. Tomato also has antioxidant property. Beneficial tomato can be consumed in multiple ways; as fresh salad, cooked with other vegetables, pickle, processed sauce, purees, ketchup and many more.

ORIGIN

Tomato is believed to be originated from tropical America (Thompson and Kelly, 1957) and spread all over the globe in 16th century. The vegetable has got its popularity more over six decades in Nepal.

BOTANY

 The scientific name of tomato was Solanum lycopersicon before Miller (1978) gave the name Lycopersicon esculentum to cultivated tomato and L. pimpinellifolium to wild anavar dosage for men varieties of tomato.

  • Tomato belongs to family ‘Solanaceae’.
  • It is a herbaceous annual herb, sexually propagated (occasionally asexually) and self-pollinated with bisexual flowers.
  • The fruit type is berry and root is tap root system.
  • Tomato can be differentiated into two types depending upon its growth habit; (i) Determinate and (ii) Indeterminate types. The plant terminates into flower bud in the former type and appropriately called “self topping” or “self pruning” so they are dwarf. In the other hand, the terminal portion of the stem grows and flower is produced in every third node thus, the later is tall and needs pruning.

VARIETIES

In Nepal there are several recommended as well as introduced varieties of tomato. Tomato varieties are classified into two category depending on the growth habit i.e.  determinate and indeterminate.

Determinate varieties:

The height of these type of variety is approximate 1.0 m with fruiting and flowering on same time.

  • Generally, determinate tomato is matures early.
  • The feature of fruiting and flowering in this variety is in the gap of every one leaf or one node, so that plants become dwarf.
  • Examples of dwarf variety of tomato (determinate or semi determinate) are BL 410, Pusa early, Durbarg, Surakshya, NS 2535, NS 815 etc. These are cultivated in Nepal.

 Indeterminate tomato plant

  • These plants are tall in height ranging from 1.2-1.5m.
  • Flowering and fruiting takes place in different time so, these are late at maturity but harvesting can be done throughout the life of the plant.
  • Plants require full support so staking should be done.
  • The cultivar that fall under this category are Srijana, Nabin-2000, Marina etc.

CLIMATE

Tomato is a day neutral crop so it can be grown throughout the year under suitable climatic condition. Temperature of 10-30 degree Celsius is good for tomato however it does well in the optimum temperature range of 21-15 degree Celsius. Flowering, fruit setting. fruit retention and pigmentation are greatly affected by temperature and light intensity. Being a warm season crop, it cannot withstand high temperature beyond 30 degree Celsius. Red color starts to disappear and fruit becomes yellowish red above 30 degree Celsius and above 40 degree Celsius, lycopene gets destroyed completely. Below 10 degree Celsius fruit cannot develop color.

 Day temperature of 25 degree Celsius and night temperature of 18 degree Celsius is best for the flowering and fruit setting in tomato. 21-23 degree Celsius is best for the pollen grain germination.

SOIL AND FIELD PREPARATION

Tomato can be grown in the variety of soil from light sandy to heavy clay however, well drained loamy soil with .rich in organic matter is best suited for the cultivation of tomato. The soil pH required is 6-7.

Land should be ploughed deeply, crush clods, weeding and till or dig for 2-3 times in order to make soil friable for cultivation.

MANURE AND FERTILIZERS

Well decomposed farm yard manure (FYM) 1500kg, 10kg of urea, 9 kg of DAP, 4 kg of MOP per ropani is to be applied in the field as per the recommendation of Government of Nepal. Full dose of FYM, phosphorus, potash and half dose of nitrogen should be applied during the field preparation. Remaining dose of nitrogen is applied in equal half dose after 25-30 days after of transplantation and 45-50 days after transplantation.

NURSERY MANAGEMENT

Nursery bed of 1 m width and 2 m length is required to grow seedlings for 1 ropani of land. Bed should be raised 15cm and seed should be sown in lines 10 cm apart. Before sowing seed in nursery, 3kg FYM per, 20gram nitrogen, 20 gram phosphorous and 20 gram potash needs to be incorporated per meter square 15 days earlier.

In order to grow healthy seedlings, the nursery bed should be solarized to terminate the growth of weeds and spread of the diseases and attack of insect pest. For solarisation, white plastic sheet should be used to cover the nursery bed for 10 days. It is the best non-chemical method to  control disease and pest.

SEED RATE AND SAPLING

10 gram of seed and 2,000–2,500 saplings is enough per ropani land. Good yield can be had by using good quality seeds.

PLANTION SEASON

Geographical areaSowing seed and transplanting seedlingHarvesting time
High hillsApril-MayJuly to September  
Mid hillsMarch to AprilJune to JulyJune to SetemberSetember to November
Lower hillsAugust to SeptemberJanuary to FebruaryOctober to FebruaryApril to July  
Time of planting and harvesting.

TRANSPLANTING AND SPACING

It would be appropriate to transplant the seedlings in 4–5 leaf stage or 4-5 weeks after sowing the seed.  Seedlings should always be transplanted in the evening. Before transplanting, the seedlings must be harden by withholding water for 4-5 days and watering at the uprooting. Seedlings are transplanted in flat or raised beds.

The spacing in tomato differs the growth habit and variety of tomato. In general spacing such as 60cm X 45cm, 60am X 60cm, 75cm X 60cm and 75cm X 75cm are practiced.

IRRIGRATION

Tomato though cannot tolerate waterlogged condition, frequent irrigation is required to maintain the adequate moisture in the field for the proper growth and development. Soon after the transplantation first irrigation is done. Frequent irrigation is needed in the root zone when the plant is small. Similarly, during the split application of urea, irrigation is important. Besides, in summer in the interval of 3-4 days and in winter in the interval of 10-15 days irrigating the soil is essential to keep soil moist. Provision of good drainage during rainy season should be done.

TRAINING AND PRUNING

Training and pruning is basically required in indeterminate tomato plant to prevent lodging and loss of fruit through the contact with the soil. Training in tomato is done using different support system like tying up in the sticks, fencing with sticks and ropes or by using the net. The use of support system makes easier in harvesting and performing intercultural operations like spraying pesticides, earthing up too.

Pruning is vital for the indeterminate type of tomato to improve light penetration and air circulation. Removal of side shoots is called nipping and removal of tops of stem is called heading. Nipped plants have only one main stem where all the nutrients are concentrated that enhances the quality and size of the fruits. Tip of the main stem is chipped when 3- 5 leaves are fully grown. Then two branches are allowed grow until 2 -4 buds are grown and again clipped. In this way four branches are allowed to grow.

Similarly, yellow and diseased leaf must be removed regularly to control disease. Water sucker and side branches should be also pinched off for better yield.

INTERCULTURE AND WEED CONTROL

Weeds compete with the tomato for different factors like water, nutrition and light and also they act as the host for different pest and voluntary crop for the disease. Thus, weed ultimately hampers the growth and development of the tomato resulting in low yield. Therefore, weed must be taken out of the crop field while performing intercultural operations. General practice includes hand hoeing in the first and third fortnight after transplanting and earthing up is done in second fortnight after transplanting. Some other measures to minimize the population of weed from the field are as follows:

  • Spraying of herbicide is most economical but unhealthy measure to control weeds.
  • Removal of crop residue from previous season.
  • Deep ploughing and exposing the soil in sun helps to kill the weed seeds.
  • Emerged weed of the field should be uprooted before flowering.
  • Hand weeding is effective to remove weeds in between plant rows.
  • Mulching also helps in reducing the weeds.

HARVESTING AND YIELD

The time of maturity of the tomato fruit varies with the type of tomato. In determinate cultivars, fruiting starts after 70 days while in indeterminate type, in between 70-100 days harvesting is done generally. Tomatoes should be harvested at the right stage in accordance with the purpose of the use.

  • Green stage: Physiologically developed fruits that are green in color and are suited for distant market.
  • Breaker stage: 10% of green color changes to yellow.
  • Turning stage: Only 10-30% of the fruit color changes to pink or red.
  • Pink stage: 30-60% is ripe and fruits are ready to ship to local markets.
  • Light red: 60-90% fruit peel turns red.
  • Red: >90% of fruit turns red and fruit is suitable for processing.

The average yield of open pollinated variety ranges from 20-25ton per hectare and that of hybrid variety is about 50ton per hectare on an average.

STORAGE AND MARKETING

Tomato fruit is highly perishable so shelf life is relatively short. Taking this into account, fully matured tomato can be kept in storage for 12-14 days in 12-14 degree Celsius and 90-95% relative humidity. Similarly, fully ripe tomato can be stored for 4-5 days in 8-10 degree Celsius and same humidity as mentioned above. To delay the ripening process in the tomato, harvested tomato can be dipped in Solution of calcium chloride (1.75 g/litre of water). In Nepal, plastic crate is used to ship tomatoes in local market.

INSECTS

Tomato fruit borer (Helicoverpa armigera)

Tomato fruit borer (Helicoverpa armigera)
  • One of the most destructive pest of tomato.
  • Larvae bore into tomato fruit and makes its unmarketable.
  • In severe case the fruit gets 80% damage.

Management:

  • Picking the infested fruit and destroying them.
  • Deep ploughing of field in summer to expose pupae in sun.
  • Planting African marigold as a trap crop.
  • Setting up the light trap and pheromone trap (10-12 trap per hectare to kill the adult moths.
  • Spraying of neem based pesticides at 5ml per litre to kill larvae.
  • For chemical management spray Thiodane 0.2% or Cypermmethrin 0.04-0.05% at 15 days interval.

Jassids (Empoasca devastans) in tomato

  • The insect suck sap from the leaves and the infested leaves curl upward gradually becoming yellow.
  • This inset also acts a vector to transmit a mycoplasmal disease, little leaf.

Management:

  • Enhancing the growth of the predatory insects like lady bird beetle and spider.
  • Avoiding excess use of nitrogenous fertilizer as it makes plant tastier to the insect.
  • Sprayinf of Eldrin, Parathon or Malathion (0.1%) to control the insects.

Whitefly (Bemisia tabaci)

Whitefly (Bemisia tabaci)
  • White flies feed to the tender parts and leaves of the plant.
  • The infected parts become yellow and curls up.
  • Bemisia species are the vector to transmit tomato yellow leaf curl virus.

Management:

  • Protecting the natural predators like lady bird beetle, lacewing etc
  • Uprooting alternate host.
  • Use of yellow sticky trap.
  • Spraying of dimethoate (0.05%) or Rogor (0.1%).

Tomato leaf minor (Tuta absoluta)

Tomato leaf minor (Tuta absoluta)
  • Larvae of the insects feed on the leaf and stem of the plant and makes tunnel.
  • This weakens the plant as a result of insufficient chlorophyll to make food that hampers yield of the crop.

Management:

  • Clean cultivation.
  • Pheromone traps at the site of production.
  • Destruction of affected leaves.
  • Application of chemical pesticide (rogor).

DISEASE

Bacterial Diseases

(i)Bacterial wilt (Pseudomonas solanacearum)

Bacterial wilt (Pseudomonas solanacearum)

Symptoms:

  • The early stage symptoms includes wilting, curling of leaflets, and browning of leaves, usually only on one side of the plant.
  •  After the leaf is dead, the petioles remain green and firmly attached to the stem. Yellowish brown discoloration of the vascular element comes out when stem is cut off.

Management:

  • It is soil borne so crop rotation should be done with non solanaceous crop.
  • Use tolerant varieties like Srijana,Amar,HRD-17, Gaurav-555 etc.
  • Destroy the infected plants.
  • Application of neem cake.
  • Seed treatment with Streptocycline @1g/liter of water for 30 minutes.
  • Fumigation of soil with 7% of formalin.

 (ii)Bacterial canker (Corynebacterium michiganese)

 (ii)Bacterial canker (Corynebacterium michiganese)
 Bacterial canker (Corynebacterium michiganese)

Symptoms:

  • The disease symptoms is characterized by  yellow or tan patches from between the veins and permanent or temporary wilting of the leaflets.
  • Affected fruits shows yellow to brown streaks.

Management:

  • Healthy and disease free seedlings should be used.
  • Crop rotation in long term excluding solanaceous crop.
  • Destroying the infected plants.
  • Seed treatment.

(b) Fungal Diseases:-

Damping off(Pythium ultimum, Rhizoctonia solani, Phytophthora parasitica)

Damping off(Pythium ultimum, Rhizoctonia solani, Phytophthora parasitica)

Symptoms:

  • The collar region of the stem decays and the seedlings topples down.
  • The disease is more serious when excess of water is supplied and temperature is high.

Management:

  • Drainage of excess water should be done.
  • Soil solarization.
  • Seed treatment with Captan,Thiram or Bavistin @3g/kg
  • Spray Captan, Bevistin or rodomil @1.5-2g/liter of water to control post emergence damping off.
  • Drenching of soil with formalin 50ml/10 liter of water and cover bed with plastic for two weeks.

Late blight (Phytophthora infestans)

Late blight or potato blight of Tomato

Symptoms:

  • Late blight first appears as a gray-green spots in the old lower leaves of the plant.
  • The maturity of the disease makes the spot even more dark and growth of fungal mass beneath the spot.
  • Brown spots are seen in the fruits that later becomes black.

Management:

  • Plantation of tolerant varieties like Srijana, HRG-17 etc.
  • Wider spacing during transplanting i.e.75cmX75cm.
  • Removal of volunteer plant from the field.
  • Destroy all tomato debris after harvesting the fruit.
  • Application of Diethane M-45 (0.2%), Rodomil(0.2%), Bavistin(0.1%) at 5-6 days interval at early stage of disease.

Fusarium wilt( Fusarium oxysporum f lycopersici)

Fusarium wilt( Fusarium oxysporum f lycopersici)

Symptoms:

  • Symptoms first appears in the older and lower leaves and consists of of clearing of veinlet, dropping of petiole, yellowing of leaves leading to death of plant at later stage.
  • Often only a branch or a side of the plant shows the symptoms.

Management:

  • Plant resistant varieties like Ureka, Marglobe, Pant Bahar,Rutgers, etc.
  • Crop rotation with non solanaceous crop.
  • Sterilization of farm equipments.
  • Seed treatment with fungicide.
  • Spray Dithane M-45 (0.25%) at 15 days interval.

Septoria leaf blight( Septoria lycopersici)

Septoria leaf blight( Septoria lycopersici)

Symptoms:

  • The symptoms contain water soaked spots,that turns out gray with darker margins in the surroundings.

Management:

  •  Clean cultivation (destruction of crop debris, uprooting the alternate host).
  •  Crop rotation.
  • Spraying or dusting with copper compounds.

Early blight (Alternaria solani)

Early blight (Alternaria solani)

Symptoms:

  • Lesions first seen in the lower leaves which slowly become wider about 2-5mm in diameter with concentric rings inside.
  • As the disease progresses, whole leaf becomes yellow and defoliation occurs.
  • Symptoms can be seen in leaves, Stem and fruit.

Management:

  • Crop rotation excluding solanaceous crop.
  • Seed treatment in hot water 50-55 degree Celsius for 15 minutes.
  • Removal of volunteer weeds.
  • Apply fungicide Diathane Z-78 or M-45 or Xined (0.2%).

Buckeye rot or fruit rot (Phytopthora nicotianae var. parasitica)

Buckeye rot or fruit rot (Phytopthora nicotianae var. parasitica)

Symptoms:

  • The first symptoms appears on the fruit that touches the soil with grayish green or broen water soaked spot.
  • Later the spot gets larger on the surface of infected fruit and the fruit have a pattern of alternating light and dark brown concentric rings that  resembles markings on a buckeye.

Management:

  • Use of disease free seed from recognized sources.
  • Practice crop rotation.
  • Proper drainage facility in the field abd avoid overhead irrigation method.
  • Mulching helps to avoid the contact of fruit and the soil.
  • Pick infected fruit and destroy them.
  • Seed treatment.
  • Application of fungicide at 8 days interval.

(c) Viral Diseases:-

Tomato mosaic virus

Symptoms of pepino mosaic virus on tomato leaves

Symptoms:

  • This diseases causes yellowing and mottling of the leaves along with stunting of the plants.
  • Fruits do not ripe evenly.

Management:

  • The virus can be alive for 2 years in soil and also in crop debris.
  • This disease can be controlled by use of resistant varieties, proper sanitation and avoiding mechanical contact from the infected crop.

Leaf curl virus

Leaf curl virus in tomato plant

Symptoms:

  •  The young leaves curl up and become hairy in touch whereas the old leaves become leathery that gradually turns brown and finally dries.
  •   The plant become stunted with small fruits.

Management:

  • The virus is spread by the vector white fly. Thus, white fly should be controlled to control the disease.

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