Botanical and biological features
The sweet corn (Zea mays saccharata Sturt.) is an annual plant belonging to the Poaceae family.
The roots are filamentous. The root system is well developed, aggressive, penetrating the soil to a depth of about 2,5 m. The stalk is upright, growing to a height of 2,5 m. Floral initiation is 45-90 days after emergence. Male flowers open earlier than female flowers, normally 3-5 days after tasselling (paniculation). The time from female flower opening to milky ripeness of kernels is 20 to 25 days.
Sweet corn is a warm-weather crop. It has particularly strong requirements for high temperatures during cobbing. Germination occurs at 10–12˚С, but the optimum growth temperature is 20-24˚С. High air temperatures (over 30˚С) during flowering/anthesis adversely affect the pollen viability and fertilization, resulting in lower yields and inferior quality cobs. Sweet corn is less drought-resistant as compared with fodder corn. Its requirements for soil moisture are the highest during cobbing, which commences a week before tasselling and lasts for a month.
Sweet corn is sensitive to light. It is a short-day plant.
Corn is an anemophilous (wind-pollinated) plant. Therefore, it should be sown as a continuous, unbroken stand rather than rows or strips (coulisse), so as to avoid incomplete pollination and the resultant partially filled ears. If corn cannot be sown as a continuous stand, individually growing plants are given additional, artificial pollination, by shaking the tassels, on a quiet morning. Sweet corn fields should not be close to fodder cornfields since cross-pollination can occur, resulting in lower quality kernels and in deterioration of sweet corn eating qualities.
The best preceding crops are grain legumes, early vegetable crops, cucumber, and onion.
Sowing takes place when the soil has warmed up to 8–10˚С at a depth of 8-10 cm. The depth of seeding is 6–8 cm. The planting pattern is 70 х 25 cm, resulting in a plant density of 5–6 pl/m2 (50,000–60,000 pl/ha). The seeding rate is 10–15 g per 10 m2 (10–15 kg/ha).
To prolong the sweet corn consumption period, varieties (hybrids) with different maturation time should be used. To ensure an uninterrupted supply of fresh market sweet corn from mid-July until late September (in the southern Ukraine and Moldova), it is wise to have several planting dates for high-yielding early hybrids (sowing performed every 7–12 days).
Sweet corn responds very well to fertigation (application of fertilizers through the drip irrigation system). With autumn soil cultivation, nitroammophoska is applied at a rate of 400 g per 10 m2 (N 65, P2O5 65, K2O 65 kg of active substance per hectare). During the growing season, fertilizers are applied at a rate of 100 g of potassium nitrate and 150 g of ammonium nitrate per 10 m2 (N 65, K2O 45 kg of active substance per hectare). The fertilizer application rates are adjusted according to the soil nutrient status data.During the growing season, 2–4 irrigations are given to the crop, the water application rate being 350–400 l per 10 m2 (350–400 m3/ha) per irrigation. 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.
Among the sweet corn diseases, the most damaging are boil or common smut and head smut. Control measures: adherence to the crop rotation program, good cultural practices, seed treatment, and use of tolerant varieties.
Corn is attacked by various cutworms, as well as by meadow moth, European corn borer, and thrips. Upon infestation (during mass flight and egg-laying period), insecticide sprays are made with Karate, Shtefesin or similar chemicals.