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How to Grow Eggplant

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Eggplant (Solanum melongena L.) originated from India and is generally grown as a vegetable throughout the tropical, sub-tropical and warm temperate areas of the world. It is an important vegetable in countries like India, China, Japan and Philippines. It is termed as aubergine and brinjal (English,) talong (Tagalog), tarong (Ilocano) or bringhinas (Bisaya). It is cultivated for the immature fruits which are roasted, fried or stuffed. Young fruits are also eaten as raw. It has much potential as raw material in pickle making and dehydration industries. It has also been reported to contain certain medicinal properties wherein white eggplants are good for diabetic patients; and can cure toothache. It has also been recommended as an excellent remedy for those suffering liver complaints.

Nutritional Value

Table1.  Nutrient content of eggplant per 100 g edible portion

PropertiesAmountPropertiesAmount
Water (g)92.00Sulphur (mg)44.0
Protein (g)1.60Chlorine (mg)52.0
Fat (g)0.20Vitamin A (I.U.)124.0
Fiber (g)1.00Thiamine0.04
Carbohydrates (g)4.00Riboflavin0.11
Calcium (g)22.00B-carotene (ug)0.7
Iron (mg)0.90Oxalic acid (mg)18.0
Vitamin B1 (mg)0.08Magnesium (mg)16.0
Vitamin B2 (mg)0.07Phosphorus (mg)47.0
Niacin (mg)0.7Sodium (mg)3.0
Vitamin C (mg)6Copper (mg)0.17
Energy Value (kj)100Potassium2.0
Calories24
Source: Siemonsma J.S. and Piluek, K. (Editors). 1994. PROSEA Handbook No. 8. Vegetables. Pudok, Wageningen. 1993/Prosea, Bogor and AVRDC

VARIETIES

Table 2. Eggplant varieties found in the PSIA Seed Catalogue.

Varieties of eggplants
OWNERVARIETYMATURITY (DAT)FRUIT TYPEFEATURES
ShapeLength (cm)ColorWeight (g)
Pine Valley Corp.Century Round Allgrow70Round7 cm length, 9 cm diameterGreen130-140Plant height is 16 inches upright. Fruit is glossy with green calyx. Adaptable in lowland and in relatively cold areas.
HavesonHybrid chhaya55-60Half Long20Shining blackish purple70-80Cluster bearing (2-3), resistant to bacterial wilt.
Pine Valley Corp.Hybrid Black Pride Allgrow65Cylindrical23-25Dark purple75-80With long shelf life. Abundant fruiting.
Pilipinas KanekoHybrid Eggplant Zam45Semi-pointed143High yielding, light green fruits.
Allied BotanicalJapanese type early Bird60Elongated Oval12Glossy purple-black with purple calyx90A Japanese eggplant hybrid that bears numerous fruits. Has long productive life. Very attractive color and firm flesh. Ideal for tempura and frying.
Allied BotanicalLong purple ABC select65Straight, long, slightly curved20Purple145Moderately vigorous and uniform plants.
Pine Valley corp.Long San Juan70Cylindrical22Purple90Good tolerance against bacterial wilt. Glossy fruit.
KeystoneMayumi60Long slender 12 inches log80High yielding (Pakbet type) moderately resistant to bacterial wilt.
KeystonePepito65Semi-round250Fresh market, bacterial wilt resistant.
Allied BotanicalSpitfire 25260-65Long, cylindrical20Deep purple145Fruits are glossy with attractive bright green calyx. A premium quality hybrid.

CULTURE AND MANAGEMENT

  • Soil Requirement. Eggplant production can be successful on any good agricultural soil by using appropriate management methods. A deep, fertile and well drained sandy loam or silt loam soils with pH of 5.5 to 6.8 and a high organic content are desirable for eggplant growth and development. Studies have indicated that lower or higher pH results in low yields because pH is closely related to the availability of soil nutrient content. A sandy loam soil is ideal especially when early yield is desired. Eggplant is susceptible to root rotting fungi, so saturated soil conditions and heavy clay loam soils should be avoided. Nematode problems are more likely to happen on very heavy soils.
  • Climatic Requirements. Eggplant can be grown from low to mid elevations throughout the year. A relatively long growing season of about 120 days is required for successful production. Eggplant is a warm weather plant, and the optimum temperature for growth and fruit development are 21°C to 29°C. It is intolerant of frost, and the growth of young plants will be retarded when night temperatures are below 16°C. On flowering plants, both cool temperature and low light intensity can cause pollen viability and failures of fruit set. Eggplant, though more resistant in drought and excessive rainfall than tomato, has relatively slow growth under high temperature. When both temperature and relative humidity are high, eggplant becomes vegetative.
  • Seedling Production. Eggplant is best grown when transplanted. Incorporate 1 kg of fully decomposed chicken manure and 300 g carbonized rice hull/m2. The optimum temperature for seed germination is 24° to 29°C. At this temperature, seedlings should emerge in 6-8 days. Wet the seedbeds and make shallow lines 5 inches apart. Sow thinly 200-250 g of seeds and cover lightly with soil, rice hull or chopped rice straws can be used as mulch. Provide partial shade during the dry season and rain shelter during the wet season. Regular watering is necessary.  Harden seedlings one week before transplanting by decreasing the frequency of watering and fully exposing to sunlight to minimize transplant shock. Transplant the seedlings four weeks after emergence. Seedlings grown in cells or containers are ideal because they allow field planting without disturbing the root system. Bare rooted seedlings could be successful if the field is irrigated and no drying of the young root system during the planting process. The most recent technique is the use of mechanical sowing. The seeds are mechanically dispersed into the cells or plugs of a PE tray by the seeder.  The plug seedlings are raised under greenhouse condition. Fertilize the plug seedlings weekly after two weeks, preferably with a water soluble fertilizer solution.  Plug seedlings will be ready to set in the field 4-5 weeks after sowing.
  • Land Preparation. Prepare land by plowing and harrowing twice. Make furrows 1m apart. Spread fully decomposed chicken manure along rows at 1 kg/linear meter or 2 kg of vermicompost/m2. Apply complete fertilizer (14-14-14) at 10-15 g/hill and cover tightly with soil.
  • Transplanting and Maintenance. A total of 13,500-16,000 seedlings are needed for transplanting for an area of 1 hectare, depending on spacing distances. A cloudy, cool weather condition and moist but not wet soil are ideal for transplanting. During sunny days, transplanting is best done in the late afternoon to allow the seedlings to recover at night. However, seedlings that are adequately hardened with slightly damaged roots could recover well when transplanted in a well-irrigated field, even on a hot day.

About 6-9 days before transplanting, seedlings are hardened by slightly withholding water and exposing them to strong sunlight by removing the netting. This will decrease the transplanting shock. The seedlings are thoroughly watered 12-14 hours before transplanting to the field. The ideal seedlings to be transplanted have 3-4 true leaves, stocky and diseased free. Generally, seedlings are ready to set in the field 4-6 weeks after sowing. Eggplant seedlings are transplanted by hand into a hole deep enough to bury a plant. After transplanting, press the soil firmly around the root, and irrigate furrows immediately. Plant 1 seedling/hill at a distance of 0.5-1.0 m depending on the variety. Provide 1m long stake to prevent lodging. Irrigate by furrow every 7-14 days depending on season and soil type.

Side dress the seedlings with 46-0-0 at 10 g/hill every two weeks during the vegetative stage. Use equal parts of 46-0-0 and 0-0-60 at the start of fruiting. Weed two-three times during the growing season, or as necessary. Weeds are controlled either by physical/mechanical methods. Mulching with black polyethylene will effectively control weeds and greatly lessen labors. Natural organic mulches (rice straw, rice hull) not only help conserve moisture, but also add organic matter to the soil.

  • Organic Fertilizer: Fertilizer should be bio-degradable materials of microbial, plant or animal origins produced on organic farms such as vermicompost and processed chicken manure. Basal applications of organic compost of 5-10 tons/ha are needed for vegetable crops. Supplementary application of Fermented Plant Juice (FPJ) of Fermented Fruit Juice (FFJ) should also be applied twice a week up to flowering stage.
  • Pest  Management. Timely protection of crops is essential. In the tropics, eggplant is attacked by several pests. Chemical sprays, botanical and biological pesticides are used to control pests. Insect infestation is one of the most limiting factors for accelerating yield potential of eggplant. The crop is prone to damage by various insects, although there is wide variability in the degree of infestation.

Several pests infest eggplants during its growth stages. Table 1 and Table 2 present pests that damage eggplant at different growth stages and their control, respectively.

Table 3.   Insect pests of eggplant and growth stage of infestation

Growth Stages Insects/Mites
0 Stage – SeedsAnts
Seedling Stage – LeavesAphids Whiteflies
Vegetative Stage – Leaves – StemAphids Colorado potato beetle Flea beetle Spider mites Stink bug Thrips Whiteflies Eggplant fruit and shoot borer
Reproductive /Flowering Stage – Flowers and foliage – StemAphids Colorado potato beetle Flea beetle Spider mites Stink bug Thrips Whiteflies Eggplant fruit and shoot borer
Maturation /Fruiting Stage – Fruits and stemsEggplant fruit and shoot borer

Insect pests of eggplant and their control measures

  • Ants. Ants tend to bring insect pests like aphids, scales, whiteflies, mealybugs, and other honeydew producing insects which  results in missing hills, loss of plant stand, uneven growth distribution in the field, and an increased incidence of diseases caused by the mentioned insect pests.
    • Control measure:
      • Increase seeding rate and thin the plants 3 weeks after sowing.
      • Control aphids, whitefly and other insects that excrete honeydew
      • Spray mixture of dishwashing soap, vegetable oil, table salt, vinegar and water
      • Cultivate and flood the field
      • Avoid using heavy doses of highly soluble nitrogen fertilizers
  • Aphids. Both the nymphs and the adults pierce the plant tissues to feed on plant sap. It causes severe distorted leaves. Defoliation and stunted growth of plant.
    • Control Measure
      • Place yellow sticky traps on planting area
    • Place yellow basin trap on the area
    • Use botanical pesticides such as ginger rhizome extract and custard apple leaf extract
    • Spray soap mixed with water (coconut-based soap)
    • Spray ammonia mixed with water
  • Colorado Potato Beetle. Adults and larvae feed on leaves and often consume the entire leaves starting with the young and soft ones.
    • Control Measure
      • Crop rotation (garlic and beans as rotation crops and coriander, marigold, and tansy are good trap crops).
      • Remove weeds.
      • Plow-under crop residues after harvest.
      • Crush eggs and collect adults manually. Place collected beetles in a pail of soapy water.
      • Use row covers.
      • Mulching encourages beneficial insects, by giving them a habitat.
  • Cutworm. Young caterpillars eat the soft leaves of the plant while fully grown caterpillars are capable of eating the entire plant. Newly hatched larvae will feed from the base toward the tip of the leaf. It causes discoloration and yellowing of plant leaves.
    • Control Measure
      • Removal of weeds in and around fields (at least 2-3 weeks before planting).
      • Plow and harrow fields properly before planting.
      • Interplant main crops with onion, garlic, peppermint, coriander, or garlic every 10-20 rows.
      • Sunflowers and cosmos can also be planted as a trap crop in or around fields.
      • Place protective collars made of plastic or paper cups, plastic drink bottles with ripped-out bottom, sturdy cardboard, and milk cartons around the young plant and push into the soil to prevent the cutworm from attacking the stem.
      • Place sticky substances such as molasses, saw dust, or crushed eggshells around the base of each plant.
  • Fruit and Shoot Borer. Wilted shoots are the initial feeding damage then the stems and fruits have small holes. It bores into the young fruit and feeds inside which makes the fruit unmarketable.
    • Control Measure
      •  Plow the field to expose larvae to predators and weather.
      • Plant resistant varieties.
      • Raise seedlings under row covers and/or nets to prevent the moths from directly laying eggs on them.
      • Practice crop rotation.
      • Proper field sanitation will also reduce the pest population.
      • Cut and/or prune immediately the larvae-infested shoots.
      • Do not drop the cut shoots in the field, burn or cut them into small pieces.
      • Uproot all old plants after harvest and burn them.
      • Use pheromone traps.
  • Spider Mite. Spider mites feeds on the undersides of leaves. The upper leaf surface has a speckled of mottled appearance while the underneath appears tan or yellow and has a crusty texture. Infested leaves may turn yellow, dry up and drop in a few weeks. Heavy infestation will result in a fine cobweb by appearance on the leaves. Plants die when infestation is so severe.
    • Control Measure. Spray botanical pesticides such as Coriander seed extracts.
  • Thrips. Will suck up the released plant fluid and will cause tiny scars on leaves and fruit, called stippling, which can cause stunted growth. Damaged leaves may become papery and distorted. Infested terminal lose their color, rolls, and drop leaves prematurely.
    • Control Measure. Spray botanical pesticides such as garlic bulb extracts.
  • Whiteflies. Both the larvae and adults will pierce and suck the sap of the leaves and will results to the weakening and early wilting of plant which result to reduced plant growth.
    • Control Measure.
      • Spray botanical pesticides such as garlic oil extracts, madre de cacao and neem extract or neem oil extracts.
      • Spray coconut-based soap.
      • Spray Potato flour mixed with water and drops of liquid soap.

Harvesting of Eggplant. The fruit of the eggplant can be harvested anytime after they have reached sufficient size for your intended market. In any case, be sure to harvest fruit before their flesh becomes tough and their seeds begin to harden. Harvest at least once per week, although two harvests per week would ensure harvesting most fruit at the optimal stage of maturity.

Cut the fruit off with a knife or pruning shears, be sure to leave the calyx (cap end) attached to the fruit. Because the fruit bruises easily, eggplant is not run across a grading line. Fruits are generally sorted by size, color and field-packed into bushel baskets or cartons, depending on the market.

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