Sunflower (Helianthus annuus) is a yellow-flowered agricultural plant grown for the seeds and oil from the family of chamomile (Asteraceae). Although the homeland of sunflower is North and Central America, three species grow in South America. Because of its round heads, petals and color, it is named as sunflower because it looks like the sun. It is grown as food and ornamental crops for humans, cattle and poultry in temperate regions and in some tropical regions. It grows in summer and early autumn, the dense growing season is in the middle of summer.
Sunflower species are not common in garden use due to their tendency to spread rapidly and become invasive. They are perennial plants, they can grow 3 meters or more. They are located in forested areas adjacent to damp, rural-like areas, primarily streams. In the 16th century, the first crops were brought to Europe from America by explorers, and were first grown from Mexico to Southern Canada by Native American peoples.
Sunflowers have bright yellow ray florets outside and yellow or burgundy disc florets inside. Sunflowers can carry one or more terminal flower heads. During growth, the sunflower bends to look at the sun throughout the day, but stops after it begins to bloom. When ripe, sunflower often faces east. In wild varieties, the coarse and downy stem branches at the top, but in domesticated varieties, the stem is usually unbranched. A sunflower flower is arranged in a natural spiral. Most of the sunflowers have disk flowers that are entirely yellow, but a few have disk flowers with reddish lobes. One species, H. radula, lacks ray flowers altogether.
Sunflower is one of the most important oil plants in the world. The seeds on sunflower are processed and sold in factories. Sunflower requires a total temperature of around 2600-2850 ° C during the 100-150 year growing period. Due to its deep and pile root system, drought resistance is high. Although it grows in all types of soil, it likes more well-drained soils with a neutral PH (6.5 – 7.5) and high water retention. It does not like acidic soils with high ground water. It is moderate to withstand salinity.
At least the soil temperature should be 8-10 ° C for sunflower to germinate. Therefore, it is generally cultivated between the beginning of April and mid-May. Early planting significantly increases yield. Sunflower is resistant to cold and generally does not get damaged from the first frosts to 4-6 leaves. However, it is highly affected by the frost formed when the temperature drops below -4 ° C.
For optimum yields, 7-8 kg of pure nitrogen and the same amount of phosphorus are sufficient in the researches conducted in the region. However, these amounts should be increased in aqueous conditions. Fertilizer application is extremely important after soil analysis is done and the nutrient content of the field is specified. If there is enough phosphorus in the soil, 15-16 kg urea (46% N) or 25-30 kg ammonium nitrate (26% N) fertilizer containing 7–8 kg pure nitrogen is mixed by sprinkling and then sowing is done. Since the soil is generally rich in potassium, fertilizer containing this nutrient is not recommended. However, if the deficiency of this nutrient is stated as a result of the soil analysis, it is necessary to apply a sufficient amount of 15-15-15 fertilizers depending on the current situation in the soil. Because, the three numbers on composite fertilizers should be preferred according to N-P-K, namely Nitrogen – Phosphorus – Potassium nutrients, respectively.
After preparing a good seed bed, planting is done with pneumatic seeders in sunflower. As a result of the researches, it was determined as the most economical soil cultivation method by the version with the plow with stems in autumn, and the preparation of the seedbed with the crowbar in the spring and then the rake. Generally, drugs with trifluarin composition are applied before weeding for weed pesticides. However, after applying the medicine, it must be mixed with a rake or similar second class tillage tool. In addition, when the plants are 25 – 30 cm for weed control, intermediate hoeing is done with the hoeing machine.
Researches have revealed that a plant population of 4500-5000 decares, which is provided with a planting frequency of 70 cm between rows and 30-35 cm above the rows, gives the highest yield. Hybrid seeds have high yield potential, they bloom and ripen on the same days and give the same quality product. There are many hybrid sunflower varieties of different companies on the market. As the seed size increases, the amount of seed to be thrown increases. In fact, it does not have the advantage that the large seed has a slightly greater germination power, especially in unfavorable climatic and soil conditions. The amount of seed thrown per decare is around 400 gr / decare, depending on the seed size.
Sunflower removes a large amount of nutrients from the soil. Therefore, sunflower planting should be avoided. Therefore, wheat-sunflower crop rotation is generally applied.
The fact that the screed is slightly tilted, that is, looking towards the ground, reduces bird damage and scintillation from the sun. For this reason, such hybrid varieties should be preferred where bird damage is intensely felt.
The water requirement of the sunflower plant is approximately 700-800 mm during the growing period. It is around. For this reason, in order to obtain high and desired efficiency, the difference should be given with irrigation water in places suitable for irrigation in the years when precipitation is low. Water requirements of plants in the soil are measured by soil tension meter. The most sensitive circuit in sunflower is between the circuit where the plates begin to form before flowering and the milk forming phase. The stress in the water that occurs in this period causes losses that will not come back in efficiency. This need especially for water reaches the highest level at the time of flowering. Therefore, if there is no precipitation in these circuits, sunflower must be irrigated for high yield. Farmers in Turkey’s Denizli province, had tried that with 20 days interval and increase the efficiency of irrigation has seen. After 40 cm, irrigation should be done every 20 days.
If irrigation is to be carried out, the irrigation of plants 45-50 cm in length, milk in the circuit in which the table is formed, and watering to be done in the maturity phase will increase the efficiency by 100%. Increasing the number of plants per decare and the amount of fertilizer to be given, especially in irrigated areas, are other factors required for increase in yield.
The most important pest of sunflower is the orobanş parasite. However, these parasite-resistant hybrids are available on the market. In addition, other diseases are sunflower mildew, stalk, root and screed rot. Hybrid seeds against sunflower mildew are medicated, but they are not resistant to Slerotinia, especially in watery areas, and there is no medicinal struggle.
The sunflower reaches maturity when the back of the sunflower tray and 50% of the brakte leaves turn brown. However, in order to harvest, the table, stem and leaves should turn completely brown and the moisture content in the grain should decrease to 9-10%. Because sunflower has oily seeds, when it is stored in high humidity, the grains heat and spoil in a short time. For this reason, it is extremely important that grain moisture is below 10% at harvest. Sunflower harvest should not be delayed too much, as the harvest that is not made on time will cause some kinds of grains especially.
100-150 Kg / hectare product in dry conditions and 250-400 Kg / hectare in aqueous conditions can be obtained from sunflower. Sunflower harvesting is easily done with small changes in wheat harvesters and appropriate adjustment.