Sunflower, also known as calom, jáquima, maravilla, mirasol, and tlapolote, is a plant whose botanical name is Helianthus annuus. It belongs to the Asteraceae family and is cultivated for ornamental, forage, and oilseed purposes. Native to the Americas, it has been cultivated since ancient times for its nutritional value. I invite you to learn more about sunflower cultivation in this article.
Sunflower cultivation
The cultivation of Helianthus annuus, which is the botanical name of the Sunflower, also called by different common names depending on the region where it grows, such as flower of shield, calom, jáquima, maravilla, mirasol, tlapololote, maíz de teja, acahual; dates back to about 3000 BC in its regions of origin North America and Central America, because it was cultivated by the indigenous tribes of the areas of New Mexico and Arizona as it was one of the main agricultural items used for food by the indigenous communities before the discovery of America.
When the New World was discovered, the colonizers took sunflower seeds to Spain and from there it spread to the rest of the European continent. Sunflower cultivation in Spain and the rest of the European countries was cultivated for more than two centuries for ornamental use only, due to its size and its beautiful inflorescences, which makes it very attractive. However, at the beginning of the industrial era in the XNUMXth century, sunflowers also began to be cultivated as an oleaginous plant, to extract sunflower oil for human consumption.
Siembra
The climatic characteristics of the region where a Sunflower Crop is going to be established are decisive to start its sowing, for this reason it is said that the Sunflower sowing time is variable. For example, the timing of Sunflower rainfed cultivation is conditioned by the latitude of the place where it is to be cultivated, beginning about 30 days after the start of the summer season. Likewise, the sowing projects of the spring and winter seasons have the particularity of taking advantage of the thermo-hydric conditions that are observed in the Sunflower Crop.
Crops in the winter season have the benefit of a high yield of achenes and fat production, however, the disadvantage is the possible frost that can ruin your harvest and also the proliferation of weeds that compete for the water and nutrients of the soil that have been provided to increase the yield of the Sunflower Crop.
The Sunflower Crop can be grown in different types of soils, although it responds better when it is planted in a clay-sandy soil with a large amount of organic matter. Sunflowers are demanding with soil drainage, which has to be good, and the water table must be found at a shallow depth.
In order for sunflower seeds to germinate, certain conditions of temperature and soil humidity must be met. The average temperature of the soil must be 5°C throughout the day, since these factors, together with the type of soil, determine the sowing depth.
- The sowing depth of Sunflower seeds will be between 5 to 6 centimeters, when it is grown in humid areas and spring days are warm, the texture of the soil is heavy and retains moisture.
- On the other hand, the depth of the Sunflower seeds will be 7 to 9 centimeters, in agricultural regions with dry days during the spring season, and it is being cultivated in light soils with little moisture retention.
Planting depth and soil texture influence the germination and flowering of sunflower plants. As a consequence, the plants that are cultivated at shallow depths germinate and flower early, unlike the Sunflowers cultivated at greater depths. By sowing in advance, the entire volume of water percolated or lost is reduced, because the period of use of rainwater by the crop in full development is increased.
In addition, the chosen sowing time is directly proportional to the amount of oil in the achenes, and the volume of oil is greater when sowing is early. Among the Sunflower varieties grown by farmers for use as fodder is a variety with a drooping head. Farmers like to grow the Sunflower variety due to drooping head, which helps to reduce losses caused by birds and by diseases of this plant.
Density
The planting density of sunflower plants is also determined by environmental variables such as rainfall, soil fertility, the distance between rows and the hybrids used. On average, the planting distance is about 70 centimeters between rows and its planting density must be four plants per linear meter.
In arid regions with high temperatures, solar radiation and little water, it is preferable to increase the distance between the rows between 80 centimeters to 1 meter, to increase the use of available irrigation water, at the time of flowering and maturation. achieving a yield of between 45.000 to 50.000 plants per hectare.
In Sunflower Crops, it is possible to increase plant yields per hectare depending on soil fertility and the agronomic management used, reaching around 80.000 to 100.000 plants per hectare. In case there is a potential risk of lodging, the distance between the ridges is increased and the distance between the plants is shortened.
Irrigation
Due to the ability of the roots of Sunflower plants to absorb water deep in the soil, which other plant species do not reach; It is a crop that can take advantage of irrigation water more effectively in periods of low rainfall and scarcity of irrigation water. This plant has the peculiarity of adapting the surfaces of its leaves to absorb water from the environment, as it is a dryland plant. Likewise, the Sunflower responds well when grown under irrigation conditions, increasing its yield at the time of harvest.
Carrying out agricultural practices such as deep subsoiling, with the aim of improving the distribution of water in the soil at different depths, consequently the drainage and aeration of the soil and in this way the plants take better advantage of the irrigation water. The Sunflower is a crop that does not require much water until about 10 days after the chapter emerges, and that is when about 50 to 60 liters/meter2 will be watered. From that moment the water requirements increase a lot and it maintains for about 25 to 30 days after its flowering and, at that moment, an irrigation of about 60 to 80 liters/meter2 is applied, at the same time of flowering.
Fertilization or subscriber
Because the Sunflower is a plant with a very well developed root system that has the peculiarity of absorbing water at different depths and also the different minerals from the soil, with which it is nourished. Due to this, it is not very demanding in terms of the application of fertilizers, the amount and frequency of fertilizer will be adjusted to the nutritional characteristics of the soil and the availability of water according to the rainfall regime and frequency of irrigation.
During the first days of plant development, the absorption of nutrients by the plant is greater. Due to its characteristic of absorbing minerals from the soil at greater depths, it is very sensitive to the toxicity of aluminum present in acid soils. This situation affects the development of its roots and due to this, symptoms of water stress or symptoms of deficiency of elements such as phosphorus or magnesium can be observed in the aerial organs.
Nitrogen Element
During the growth stage of Sunflower plants, the most important nutrient is nitrogen, a deficit of this mineral causes a decrease in the yield of the Sunflower Crop. Nitrogen is of importance during the growth, differentiation and formation of its organs, applying a dose of Nitrogen between 80 to 100 kg/ha favors an increase in the yield of the Sunflower Crop by 15% to 20%.
To find out if Sunflower plants may be suffering from a Nitrogen deficiency, observe if the plant suffers from a general chlorosis that is observed in both young and mature leaves and that can occur at any stage of its growth. On the other hand, if an excess of Nitrogen occurs, the significant reduction in the sunflower seed oil yield will be affected and, on the other hand, the amount of protein in them will increase.
phosphorous element
This phosphorus mineral is applied during the autumn season by fertilizing with superphosphate at a dose of 40 to 80 kg/ha. The requirements of phosphorus by Sunflower plants increase in the stage of flower formation and, in case of applying fertilizers to provide this element, this does not negatively affect the yield of oil in the seeds.
It can be detected that Sunflower plants have phosphorus deficiency by observing a decrease in their size and the lower leaves suffer from necrosis. The lack of phosphorus in the plant affects it in its first phases of the vegetative cycle, such as when the formation and filling of achenes begins, which, together with the seeds, are quite appetizing in the food industries and due to their oleaginous properties.
Potassium Element
This nutritional element for the Sunflower must be applied at a dose of 100 kg/ha in its k20 formula, as it is an element that this plant absorbs in large quantities between its vegetative phase and the formation of its flowers. This is because potassium influences the color of the flowers, the resistance of the plant to pests and diseases, and the growth of roots and fruits. That is, it contributes to the internal balance of the plant and resistance to drought. It can be determined if the plant may have a potassium deficiency when the lower leaves are observed to be yellow with necrotic spots.
Boron Element
Among the micronutrients, Boron is important for the Sunflower plant, because it is vital for the cell division of the apices of the roots of this plant, that is, a low supply of this micronutrient negatively impacts the development of the roots. . However, its deficiency will be observed at the time of flowering, seeing that the floral chapter is deformed and the highest leaves become brittle, deformed and necrotic, taking on a bronzed color. To correct its deficiency, boron must be supplied at a dose of 0,5 to 1 kg in 200 liters of water/ha, with a foliar sprinkler.
Molybdenum Element
The Sunflower Crop suffers from a deficiency of this micronutrient when it is observed during the early stages of its development that the older leaves suffer from chlorosis with a wrinkled appearance. To nourish the plant with Molybdenum, this micronutrient must be added by foliar spray in an amount of 50 grams of 50 grams of sodium molybdenum diluted in 100 liters of water.
Weed control
The control of weeds or weeds during the development of the Sunflower Crop, is carried out due to the competition of these unwanted plants that subtract water, nutrients and sunlight, negatively impacting the good growth and yield of the Sunflower Crop. For its control, agrocultural, mechanical and chemical practices are used.
Agrocultural practices
To avoid the proliferation of weed growth that competes for nutrients, water and light with Sunflower plants, crop rotation is suggested. Crop rotation is an agricultural practice that helps to decrease the growth of weeds or weeds, in case you also apply herbicide, you will also have to do crop rotation. Another practice that will help reduce weeds is to increase the planting density in the Sunflower Crop as much as possible, without affecting its optimal limits and, in this way, the appearance of weeds is avoided because the empty spaces in the land are reduced and It also increases the shading of the ground.
mechanical practices
One of the mechanical practices consists of carrying out a raking to eliminate a superficial crust of the soil and with it the weeds or weeds that have grown due to rainfall. These crusts and proliferation of weeds can increase when it starts to rain after planting and temperatures decrease, a situation that affects germination because it is delayed.
chemical practices
In large areas of cultivation, combating the appearance of weeds or weeds is more profitable by applying agrochemicals such as herbicides. Chemical herbicides must be applied taking precautions for sunflower and farmer plants. In the event of applying “phenoxyacetic” herbicides, it must be done under favorable weather conditions and very early in the day, providing for a protection zone.
Sunflower cultivation is quite sensitive to herbicide compounds such as "atrazine" and "simazine", for this reason you have to be careful to plant on land that has been treated a previous planting with high amounts of these products, because they are residual, and it will affect the Sunflower plants that you plant on that land a year later.
Depending on the moment of their application, the herbicides used during sunflower cultivation can be grouped as: Pre-sowing herbicides: these herbicides are applied in soil preparation before starting sowing. Pre-emergence herbicides, these herbicides are used in a complementary way to the herbicides applied in pre-sowing. As for the Post Emergence Herbicide, it is applied in a period comprised between the six weeks following the emergence of the Sunflower plants.
- Pre-sowing herbicides and their active ingredients and their dose in (liters/ha.). Trifuralin 1,2 to 2,4; Trialate 3; Ethalfluralin 3; Dinitramine 2.
- Pre-emergent herbicides and their active ingredients and their dose in (kg or lt/ha.). Alachlor 5 liters; Fluorochloridone 2-3 liters; Linuron + Pendimethalin 5 to 7 liters; Linuron 1 to 2,5 Kg; Metachlor 1 to 4 liters; Metachlor + Promethrin 4 to 7 liters; Pendimethalin 4 to 6 liters; Terbutryn 2 to 3 liters and Carbetamide 2,5 to 4 kg.
- Pre-emergent herbicides and their active ingredients and their dose in (lt/ha.). Fluazifop 1,2 to 2; Haloxyfop 1; sethoxydim 1,5 to 2,5.
Crop Varieties
As the Sunflower Crop is of great agricultural and agro-industrial importance, several intra-specific crosses have been made to obtain varieties to improve their yields, improve their oil content, improve their percentage of oleic acid, resistance to the attack of mildew and jopo fungi, as well as the duration of its cultivation cycle and the size of the plants.
Pest control
Sunflower crops are susceptible to infestations by various species of cutworms ( Agrotis segetum , A. exclamationis , and A. ypsilon ). These caterpillars, with green bodies and black heads, range in size from 10 to 50 millimeters and attack the base of the plant stems. They infest sunflower plants from germination until they reach about 15 centimeters in height. Damage occurs from the roots and the base of the herbaceous stem, which they cut, causing the plants to wilt and stop growing.
This can be controlled. Advance sowing to reduce the attacks of these gray worms. Place baits so that the worms eat them, these will be baits of 1 kg of Trichlorfon + 20 kg of bran + 500 g of sugar per hectare. Perform spray application on the entire field or just the planted area, with Trichlorfon, Pyrethroids or Lindane insecticides. In case the plague of these worms is very abundant, it is suggested to disinfect the soil with chlorinated and phosphoric insecticides.
Wireworms (Agriotes lineatus) . The female of these wireworms lays her eggs in the soil at the base of sunflower plants. When these eggs hatch, rigid, elongated, and cylindrical larvae emerge, yellow-orange in color and about 1,5 centimeters long. These larvae eat the sunflower seeds before the seedling emerges, consuming the contents and leaving only the husk.
Wireworm control consists of applying chemical insecticide with Lindane, at a rate of 1 to 1,5 kg/ha. As well as granulated insecticide applied on the planting line. Sprinkling with chlorinated and phosphorous insecticides is also suggested. Preventively it is good to disinfect the soil with Aldrin in a quantity of 3 to 4 kg/ha.
White grubs ( Melolontha ) . White grub ( Melolontha ) larvae are about 10 to 15 millimeters long and maintain a curled posture. It is during this larval stage that they cause the most damage to sunflower crops. The larvae are white caterpillars with black heads, feeding on the roots of sunflower plants. These larvae damage the plant from seed germination until two to three weeks after the seedlings emerge. When these caterpillars reach adulthood, they transform into beetles with antennae, which emerge during the month of May.
It is controlled with the practices of disinfection of the cultivation soil with insecticides and, also carrying out the same treatment for the control of the Wireworm. Lindane insecticide applied. Likewise, dusting with chlorinated and phosphorous insecticides is also suggested.
False wireworms (family Tenebrionidae) . These worms feed on the hypocotyl and cotyledons of the sunflower plant, destroying them. They can be controlled using the same methods as wireworms.
Sunflower leaf weevils (Tanymecus dilaticollis) . This is a brown beetle species that grows to about 7 millimeters in length. It is a polyphagous and thermophilic species. This pest appears in spring and hides in soil holes on the surface of cultivated land and near sunflower plants, which are its food source. The beetles feed on the leaves, starting at the edge and moving inwards, and also eat the cotyledons of the seeds. In their larval stage, they feed on the roots of sunflower seedlings.
This pest is controlled with organochlorine and organophosphate granular insecticides. If intercropping, it is recommended to avoid planting sunflowers after harvesting corn and sugar beets. When selecting the planting site, avoid soils infested with Cirsium arvense , as this weed is a host plant for the leaf weevil (Tanymecus dilaticollis). It is preferable to plant winter cereals or peas the previous year.
Sunflower moth ( Homoeosome nebulella ). This pest is a gray Lepidoptera larva with three purple stripes on its back and a yellowish head, measuring 1 cm in length. It feeds on sunflower flowers and seeds after destroying the flower head. As an adult, it is a moth with yellowish-gray wings. The problem arises when its flight coincides with the sunflower flowering period, as these moths lay their eggs in the sunflower inflorescences.
So far, this pest has been controlled through cultural practices, such as cultivating varieties resistant to this pest, the Sunflower Moth ( Homoeosome nebulella ), and as a preventive practice, it is suggested to destroy plants that grow spontaneously and belong to the Asteraceae family, the same family as the Sunflower.
Heliothis. This caterpillar is yellowish-green or black, with a brown head and long striations around its body. It destroys leaves, flower heads, and achenes. It can be controlled with the insecticides Methomyl, Trichlorfon, and Pyrethroids.
Sunflower diseases
Sunflower plants are highly susceptible to fungal diseases such as sunflower downy mildew ( Plasmopara helianthis). In sunflower crops where environmental conditions include high humidity (around 90-100%) and temperatures between 12° and 22°C, the fungal reproductive structures develop on the plant surface and then spread through the air and soil to infect other plants. Symptoms of the disease include stunted growth and pale green leaves, with the discoloration progressing from the base to the tip.
Sunflower mildew control is carried out with cultural practices, the use of certified hybrid seeds treated with anticryptogamics. Apply fungicide to control Mildew such as Metalaxil, this fungicide allows controlling infections that come from the soil, and that can originate from infected seeds.
Charcoal rot of the roots and stems ( Macrophomina phaseolina). This fungus thrives in sunflower plants under water stress, as it is polyphagous and thermophilic. Plants in their adult and mature stages are most affected, leading to premature death and organ damage. Currently, cultural practices are being used to control the fungus and prevent water stress in sunflower plants.
Verticillium wilt (Verticillium dahliae) . This fungus can remain in the soil for 4 to 9 years, living in crop residue or in the soil itself. Once in the soil, it begins to penetrate through the roots, reaching the stem and the rest of the plant, causing it to wilt. The severity of the infestation depends on the sunflower variety. It can be controlled by applying preventative agronomic measures and implementing crop rotation, such as alternating with resistant grasses and weed control.
Gray mold (Botrytis cinerea). This fungus poses a significant threat to sunflower crops due to its conidia shape. Its life cycle occurs in spring and begins on plant debris left in the cultivated soil. Symptoms of damage include discolored seedlings and leaves with poor turgor, causing them to curl, soften, and rot. When climatic conditions favor fungal growth, the plant becomes covered in a grayish powder due to the fungal conidiophores and conidia. Control is achieved through spraying with chemical fungicides such as diclofluanid or thiophanate-methyl maneb.
In addition, it is attacked by the mycelia of the fungus White rot (Sclerotinia sclerotiorum), Sunflower rust (Puccinia helianthi), White pustule (Albugo tragopogi, A. phylliodes), Sunflower black spot (Phoma oleracea), and Broomrape ( Orobanche cumana).
Use of Sunflower
Sunflower has been cultivated since ancient times, apparently it has been cultivated for more than 1.000 BC. However, studies have found records with information indicating that the sunflower was initially domesticated in Mexico about 2.600 to 3.000 BC. In addition to having been cultivated for consumption, different cultures such as the Aztecs and Otomi of Mexico and the Incas of Peru, considered it a symbol that represented the Sun god. In the Tahuantinsuyo countries (Peru, Bolivia and Ecuador), the image of the Sunflower was revered as symbol of their solar god.
From the introduction to Europe at the beginning of the XNUMXth century, the distribution of the Sunflower spread to many countries, where Sunflower Cultivation is carried out intensively for food and ornamental purposes. Currently there are different varieties of Sunflowers that are grown for oilseed purposes, for confectionery, due to their high content of oleic acid and for ornamental use.
The Sunflower fruit is composed of up to 58% of oil used for cooking, and also to produce biodiesel. Although virgin sunflower oil is obtained by pressing the pipes (seeds), they do not have the qualities of olive oil, although they are characterized by having four times more natural vitamin E than olive oil.
The "caterpillar" that remains as residue after the oil is extracted is used as feed for cattle. Its stems are very fibrous and can be used to make paper, and its leaves can also be used as fodder for livestock. If soy flour is compared with Sunflower flour, it will be observed that the lysine content is higher in Sunflower flour.
Sunflower fruit husks that remain as residue after oil extraction are ground and used as an ingredient in ruminant feeds. From these hulls, a high-protein fodder yeast for cattle and poultry is obtained. Likewise, the sunflower heads are used to feed sheep and cattle and, when the head is ground, this flour is used as part of the feed ration for adult cattle and poultry.
Composition and Properties
Sunflower flower contains quercemetrine (flavonoid glycoside), anthocyanins and histidine, the seeds contain 23 to 31% proteins, 20% carbohydrates and 35 to 55% fat; also albumins, choline, betaine, lecithin. The Sunflower plant is an excellent honey. Among its properties are known that it is hypocholesterolemic, febrifuge, expectorant, vulnerary, diuretic.
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