Sweet corn (lat. Zea mays saccharata) is a special type of corn, and it was created by mutation are genes from the subspecies of corn toothed (lat. Zea mays ssp. indentation) and hard corn (lat. Zea mays ssp. indurate). Like all other types of corn, sweet corn belongs to the family Poaceae. It is mostly grown and produced in the United States of America, where it originates from. It is the most popular type of corn, along with popcorn corn.
According to morphological characteristics, sweet corn does not differ much from other types of corn. Of course, there are certain minor specifics. The root is tough and develops through a large volume of soil. However, it is somewhat less developed and is usually shallower, i.e. it only penetrates to a depth of 1.5 – 2 m.
The stem is smooth and straight and is usually shorter than regular corn. It grows approximately from 1.5 – 2.5 m, depending on the hybrid. One leaf grows at each node on the stem. The leaf has a prominent central vein that can be as long as 60 cm. The buds develop from lateral buds located in the axils of the lower leaves. It is a heterozygous and monoecious plant that has separate male and female flowers.
On the one hand, the male flowers are collected in an inflorescence in a panicle, which is located at the very top of the stem. On the other hand, the female flowers are located on the cob located in the axils of the leaves, in the middle part of the stem. The flowering of the panicle begins a few days before the flowering of the female flowers. Depending on the weather conditions, flowering lasts from 6 to 10 days, during which the stamens are secreted and thus, with the help of the wind, the female flowers are pollinated.
Sweet corn has a sweet kernel that has a shriveled surface when ripe. It usually weighs 150 – 250 g and is planted in warm regions because it is a heliophilic plant.
Types of sweet corn
Sweet corn has early, mid-early and late hybrids. For early or very early hybrids, the vegetation period does not exceed 70 days, and for medium-early hybrids, the vegetation period lasts from 75 to 80 days. Later hybrids reach maturity approximately after 85 – 90 days. In relation to sugar accumulation, it is possible to distinguish three recessive genes according to which sweet corn hybrids differ. It’s about are, are and sh2 genes.
Hybrids are type are moderately sweet hybrids and are included in the standard type of sugarcane. They have a creamy texture, but are not good for storage due to the rapid conversion of sugar to starch. Hybrids are type are sweet hybrids and have a slightly higher sugar level compared to hybrids are type. The reason for this is the slower conversion of sugar into starch after harvesting. The grains are less creamy and quite tender.
Finally, sh2 type hybrids are super sweet hybrids that have a very high sugar content. Since such hybrids contain little starch, their grains are shriveled. Thanks to the high sugar content, these hybrids can be consumed fresh, i.e. without cooking. Their grains are not creamy, but crunchy.
In Croatia, there are domestic hybrids of sweet corn that were created in Osijek and Zagreb. In the Variety List of the Republic of Croatia, out of a total of nine hybrids, there are five domestic hybrids:
Super sweet FAO 300
It is a newer type of sweet corn that contains an increased amount of sugar. This hybrid is sown in several terms so that it can be harvested multiple times. The corn cob is harvested 20 – 30 days after fertilization. It requires spatial and temporal isolation in relation to other species.
Sundance F1
Sundance F1 is a sweet sweet corn hybrid. It has a cylindrical-conical piston shape, and it is most often yellow in color. The length of the cob is 17 – 19 cm, and the length of the vegetation is 68 – 70 days. This hybrid can grow up to 170 cm and is most often used fresh or for processing. It is very rewarding to produce and is not difficult to grow.
Spirit F1
Spirit F1 is a very early hybrid that is suitable for earlier sowing. It is a hybrid are type and standard sweet sugar. It tolerates the cold very well, and its vegetation length is approximately 70 days. It can be consumed fresh, and it can also be preserved or frozen.
Overland F1
Overland F1 is the flagship super sweet hybrid sh2 type whose vegetation lasts approximately 80 days. It is highly productive and has a stable yield.
GH2301
It is a hybrid are type and at the same time a mid-early hybrid. The growing season lasts approximately 72 days. It grows up to 210 cm, and the grains are approximately 12 – 13 mm. It is characterized by high fertility potential.
Elite F1
It is a late hybrid whose vegetation lasts approximately 85 days. It is of top quality and belongs to the group of plants with the largest stem, as much as 270 cm. The grains are golden-yellow in color and approximately 11 or 12 mm in size. The hybrid has a high yield and is suitable for freezing and canning.
Planting sweet corn
It is necessary to plant sweet corn in a specific period and to know the method of planting the seeds, the appropriate temperature and characteristics of the soil for planting and cultivation.
Planting time
Sweet corn can be planted in several periods, from the second half of April to the middle of July. However, the planting time also depends on the length of the hybrid’s vegetation. On larger areas, it is possible to carry out successive planting, with intervals of 10 – 20 days. Then it starts in April and lasts until the end of August.
Planting from seed
To plant sweet corn, it is first necessary to prepare the soil. Deep autumn-winter plowing should be carried out, which will ensure a good structure and moisture supply for later, spring planting. Sweet corn is sown from seed to a depth of 3-5 cm, depending on soil texture and humidity. Heavier soils will require planting to a depth of 2 – 2.5 cm, and on lighter soils it can be sown to a depth of 3.5 – 4 cm.
Planting itself is not too different from planting popcorn, but there are usually recommendations from the seed manufacturer in regards to adjusting the row spacing for each hybrid. When the planting distance, size and germination of the seeds are taken into account, 10 – 20 kg of seeds are needed per hectare. Usually, sweet corn is planted on large areas with an inter-row spacing of 70 cm. If it is to be grown in the garden, it can be sown in small houses at a distance of 60 – 70 cm.
Ground
Sweet corn can be grown on almost all types of soil, of course with well-adapted agricultural techniques. However, the best soils stand out as medium-heavy soils that have a good structure and a pH value of 5.5 to 7. In addition, sweet corn can tolerate slightly more acidic soils.
Climate
Sweet corn grows in extremely bright and sunny places because it is a heliophilic plant. This means that the lowest temperature for germination is 13°C, and the most favorable temperature for further germination ranges from 21 – 27°C. Sweet corn does not tolerate frost, and the plant’s vegetative growth will stop at a temperature of 10°C. On the other hand, temperatures above 32°C and dry winds do not suit sweet corn either, because then the pollen and silk are damaged. Consequently, this affects poorer fertilization, where the tips of the cobs usually remain unfertilized.
Cultivation of sweet corn
Sweet corn is not too demanding to grow. It will do well if the rules on stacking crops, watering, fertilizing and propagation are followed and applied.
Matching cultures
Corn is generally singled out as a monoculture, whereby sweet corn must not come to the same place for 2-3 years. It can also be grown as a second crop, and good pre-crops are early potatoes, canola and early brassicas such as cauliflower, cabbage, kale and broccoli.
Watering
Water needs are not the same during the entire cultivation of sweet corn, but they change depending on the stage of development. The need for water is great during the time of intensive vegetative growth, and they increase immediately before threshing and silking, during fertilization and at the beginning of grain pouring.
Sweet corn is sensitive to drought, so irrigation is recommended to ensure high and stable yields. The drip irrigation method is usually applied. A good yield requires from 3,000 to 6,000 m3 of water per hectare. Care should be taken that water does not accumulate because sugarcane does not tolerate stagnant water.
Fertilization
If it is a question of soil that is moderately supplied with nutrients, as determined by soil analysis, 100 – 250 kg/ha of nitrogen, 80 – 100 kg/ha of phosphorus and 100 – 150 kg/ha of potassium are usually added before planting. A third of the nitrogen is applied at seeding time, another third approximately 30 days after seeding, and a third approximately 50 days after seeding. At the time of cob development, sweet corn needs potassium supply the most.
Propagation
Sweet corn is propagated by seeds. Accordingly, it is necessary to adhere to all the previously mentioned rules and conditions for proper planting or sowing of seeds.
Maintenance and care
The maintenance and care of sweet corn implies certain agrotechnical measures from the beginning of planting to harvest. Maintenance and care measures are used to ensure the best possible conditions for plant growth and development.
Plantation maintenance
For the maintenance of plantations, inter-row cultivation is important, which prevents the appearance of scab or reduces its negative effects. In addition, inter-row cultivation thins the surface layer of the soil, destroys weeds and reduces water loss from the soil. It is done mechanically, usually two or three times during the growing season and at the same time as fertilizing.
The first inter-row cultivation of sweet corn is done when the corn develops 3-5 leaves, and the next one is done as needed. Also, for the cultivation of sweet corn, its spatial isolation from ordinary corn is important, because sweet corn interbreeds with other types of corn. Accordingly, sugarcane must be 75 – 100 m away from ordinary corn.
Along with inter-row cultivation, it is necessary to remove unwanted weeds, which are one of the great enemies of corn. This means that even before planting, it is necessary to work the soil several times in order to provoke the sprouting of weeds, which must then be removed.
Sweet corn harvest
Sweet corn is usually hand-harvested together with cob, where it is immediately cleaned of cob and silk or plucked at the base of the cob. In order to achieve the highest possible yield, it is good to harvest 2-3 times a year. If the sweet corn is intended for processing, mechanized harvesting is carried out, but then usually around 30% of the waste remains in the field. It can later be used for green fertilization.
Harvesting is usually done in the early morning to avoid high daytime temperatures. After harvesting, the cobs should be cooled to 0°C, as this slows down the conversion of sugar into starch and preserves the initial quality of the grain.
Storage
It is best to store sweet corn immediately after harvesting so that it does not lose its value. It can be stored and preserved for 6 – 8 days. It should be stored at a temperature of 0°C and at a relative humidity of 95%. A temperature of 5°C is sufficient for storage for 3 – 5 days, and 10°C is sufficient for storage for only 2 days.
Diseases
Sweet corn can be attacked by different diseases and different pests, but they usually do not cause significant damage. It is possible to fight against them with proper crop rotation, balanced plant fertilization and correct agrotechnical measures during the growing season.
In relation to planting sweet corn, it is first necessary to ensure healthy seeds, because many fungal diseases occur precisely on the seeds. The most common diseases of seeds and seedlings are seed mold, scutellum rot and sprout blight. Along with them, leaf diseases include gray leaf spot and blister blight.
Moldyness of seeds
Seed mold occurs after sowing when the seeds sprout and germinate very slowly. This fungal disease occurs more often on heavier and colder soils when the temperature of the sowing layer is below 10°C, and less often on warm and airy soils. Usually, there are several types of fungi that cause mold, such as fungi from the genus Penicillium, Aspergillus and Fusarium. Seed moldiness can be reduced by using quality and healthy seeds and proper agrotechnical measures.
Scutellum rot
Scutellum rot can also cause poor seed germination. The disease can only be diagnosed when the germ grows 1-2 cm. The disease causes root reduction, therefore the whole plant develops slowly. This rot usually occurs on seeds that are not yet ripe. Despite the fact that such seeds will have good germination, their germination energy will be weak. The disease occurs more often where there are bad weather conditions and if the seeds are not properly dried. As with moldiness of seeds, it is necessary to use healthy and high-quality seeds and to observe proper agrotechnical measures.
Germ burning
Germ blight can be recognized when newly emerged plants fail in terms of lodging and melting. The disease develops in the soil before the germs come to the surface. Then the roots are covered with watery spots and ring-shaped surrounding the root and the young plant. The disease occurs in conditions of high soil temperature, more precisely when the temperature exceeds 15ᵒC, and it can occur at any stage of plant development. As a protection measure, the preventive application of appropriate agrotechnical measures is highlighted in order to ensure the most favorable conditions for germination, emergence and growth of sweet corn.
Gray leaf spot
Gray leaf spot may appear during the growing season, but it will not cause significant economic damage. The disease is recognized by gray elongated spots on the leaves that have a dark brown edge. Spots are first formed on the lower leaves, and in the case of a stronger infection, the entire leaves dry up. The disease occurs during warm and humid summers, and the most effective fight against gray leaf spot is the cultivation of resistant varieties, i.e. hybrids.
Bubble gar
Blistering blight affects the above-ground parts of the plant, and is recognized by the blistering growths, which are actually a mixture of infected corn tissue and fungus. In the beginning, these growths are smooth and silver in color, and as they mature, their membrane bursts and a black dusty mass falls out of it. It is believed that the disease occurs more often in dry periods than in wet periods. The development of the disease is favored by a weak covering of the corn cob with compost, bad weather such as hail, various damage from birds, etc. This disease can cause the greatest damage, and the best protection and prevention measure is the selection and breeding of tolerant hybrids.
Pests
Pests can damage the grains, but also the entire sweet corn plant. They are usually combated by high-quality land preparation, proper selection of hybrids and sowing at the recommended depth. The cable cars and the corn flame stand out.
Cable cars
The most common wireworms are stork larvae Agriotes. They appear in the first phase of the plant’s development when they burrow into the germinated seed or the ground part of the young plant. They can cause great damage and consequently lead to the death of the plant. As a protection measure against wireworms, the application of appropriate agrotechnical measures stands out. This includes proper soil treatment, which causes the eggs and young larvae to decay, and chemical protection that is applied directly to the seed or to the soil.
Corn fritters
Corn borer develops one or two generations per year. As an adult caterpillar, it overwinters in the tree and corn cobs or, alternatively, in the soil. It mostly attacks the corn stalk, which becomes brittle and breaks easily after its attack. In addition, the corn borer damages the cob, cob and kernels of corn. Plants that have been attacked are no longer so resistant and strong. Shredding and plowing of crop residues to a greater soil depth, from 25 to 40 cm, stands out as the most effective protection measure. Also, ecological preparations based on bacteria can be used Bacillus thurigiensis.
Use of sweet corn
The use of corn is generally very broad. It is used in the nutrition of domestic animals, in human nutrition and in the food industry.
Sweet corn in medicine
Sweet corn has a similar nutritional value to peas, but slightly less protein. It is a very healthy ingredient in the human diet because it is very rich in energy and nutrition. For example, 100 g of sweet corn contains 86/360 kcl/kJ and approximately 76 g of water. It is also a good source of B vitamins, which are necessary for energy production, and folic acid. In addition to vitamins of the B group, it also contains vitamins C and A. In relation to mineral substances, it contains the most potassium, phosphorus and magnesium.
Sweet corn, like other types of corn, is rich in carbohydrates and does not have too much fat, so it is a good source for replenishing and improving energy. The fats it contains are not saturated. Thanks to fiber, it has a positive effect on cholesterol and blood sugar levels. As it contains starch, it is good for digestive problems.
Sweet corn in cooking
Sweet corn is most often consumed cooked, but it can be preserved and frozen. In the case of canning, whole cobs or parts of cobs are used. In relation to grain, whole grains or whole grains mixed with crushed grains can be used. The same applies to freezing sweet corn.
In its fresh state, it can be used as a boiled grain or a boiled cob. It is consumed in the same way as all grains or vegetables for cooking and baking. It can be combined in various stews, salads, desserts, soups, etc. Nevertheless, sweet corn is a common snack during the summer months when it is consumed cooked.
History
Corn originates from America, and it is believed that sweet corn began to be produced in the USA back in 1779. From that year, work also began on the creation of his first hybrid. It was not until 1924 that the white type of sweet corn, known as Redgreen.
Interesting things
The US leads the way in corn production in general. They are also the largest producer of sweet corn on approximately 250,000 ha. In addition, about 70% of the produced sweet corn is used for processing. The consumption of sweet corn in the USA is 12 kg per inhabitant.
In addition to the USA, France, Hungary, Canada and Thailand also stand out. In relation to the continents and the total world production of sweet corn, 63.8% of production takes place in North and South America, 23.3% in Europe and 10.7% in Asia.
The generally prevailing opinion is that raw vegetables are always healthier than cooked vegetables. However, this is not true for corn. On the contrary, when it is thermally processed – cooking or baking, its antioxidant effect is improved, i.e. molecules are released that have a positive effect on the body’s defense against harmful radicals. However, although heat treatment increases the antioxidant activity, the amount of vitamin C decreases.
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