Botanical and biological features
The eggplant (Solanum melongena) is an annual plant belonging to the Solanaceae family.
It features a cylindrical stem growing to a height of 40–150 cm, depending on the variety and growing conditions. The flowers are monoclinous. At harvest maturity, the fruit color varies from white to light purple to deep purple.
The seeds are small, flat, light brown and hairless. Under optimum growing conditions, germination occurs 8–10 days after sowing. Early in the growing season, the plants exhibit very low growth rates. The most vigorous growth is observed approximately a month after transplanting. The eggplant root system is well developed, most of the roots being located in the top soil layer at a depth of 20–40 cm. The absorbing capacity of the eggplant roots is lower than that of the tomato root.
The eggplant is one of the most demanding crops in terms of growing conditions. It is more sensitive to temperature conditions than sweet pepper or tomato. The eggplant is highly sensitive to variations in temperature: a drop or a sharp increase in temperature causes reproductive organs to fall off. The optimum growth temperature is 25–28˚Ñ. No germination occurs at temperatures below 15˚Ñ. Subzero temperatures or long periods of subnormal temperatures cause the plants to die.Light requirements of eggplants are also high. In cloudy weather or in highly crowded conditions, the growth is retarded, many reproductive organs fall off, small fruit are formed and a sharp drop in yield is observed.
The eggplant is a moisture-loving crop. Soil moisture deficit during fruiting causes buds, flowers and ovaries to fall off. Optimum soil humidity during fructification is 80 % of the field moisture capacity and early in the growing season it is about 70 % of the field moisture capacity.
The eggplant is particularly sensitive to soil fertility and structure. It absorbs large amounts of nutrients from the soil and gives low yields of fruit when there is a deficiency of available nutrients. Application of organic and mineral fertilizers is an effective measure for increasing the yield of this crop.
The best results in eggplant cultivation have been obtained on light soils with adequate fertilizer application. In crop rotation, the eggplant is normally preceded by winter wheat, cucumber, onion, legumes or cabbage.
The cultivation is generally by transplanting. Seedlings are transplanted when there is no longer any risk of spring frost and the soil has warmed up to 15°Ñ at a depth of 10–12 cm. The planting density is 1,5–2,5 pl/m2 (15,000–25,000 pl/ha). The planting pattern is 80–100 õ 45–60 cm. The seeding rate is 0,15–0,3 g per 10 m2 (0,15–0,3 kg/ha).
To achieve a yield of 6–8 kg/m2 (60–80 ton/ha), organic fertilizers are applied at a rate of 40–60 kg per 10 m2 (40–60 ton/ha) in combination with mineral fertilizers: 600 g of nitroammophoska per 10 m2 (N 100, Ð2Î5 100, Ê2Î 100 kg of active substance per hectare). During the growing season, 3 to 4 applications of ammonium nitrate at a rate of 300–400 g per 10 m2 (N 100–140 kg of active substance per hectare) are given to the crop. The fertilizer application rates are adjusted according to the nutrient status of the soil.
During the growing season, the crop is irrigated 10–12 times, the amount of water given being 350–400 l per 10 m2 (350–400 m3/ha) per irrigation. It is not recommended to irrigate with cold water and when the air temperature drops. Combining drip irrigation with application of water-soluble fertilizers through the drip irrigation system (fertigation) is a highly efficient technique resulting in a more uniform moisture and fertilizer distribution in the root zone, more efficient water use, less soil compaction, and no soil crust formed. Readily soluble mineral fertilizers are given with each water application.
Major pests: potato beetle and spider mite. Insecticides such as Actara, Zolone and Karate provide effective control of potato beetle and acaricides are used to control spider mite.
Major diseases: Verticillium wilt, Fusarium wilt, and Anthracnose.
Control measures: crop rotation, adequate soil and crop management practices, use of disease-resistant hybrids and fungicide sprays.