The sunflower is an annual plant in the family Asteraceae, with a large flower head (capitulum). The stem of the flower can grow up to 3 meters tall, with a flower head that can be 30 cm wide. Other types of sunflowers include the California Royal Sunflower, which has a burgundy (red + purple) flower head.
The flower head is actually an inflorescence made of hundreds or thousands of tiny flowers called florets. The central florets look like the center of a normal flower, and the outer florets look like yellow petals. All together they make up a “false flower” or pseudanthium. The benefit to the plant is that it is very easily seen by the insects and birds which pollinate it, and it produces thousands of seeds.
- Kingdom: Plantae
- Division: Magnoliophyta
- Class: Magnoliopsida
- Order: Asterales
- Family: Asteraceae
- Tribe: Heliantheae
- Genus: Helianthus
- Species: H. annuus
Sunflower (Helianthus annuus L.) is one of the few crop species that originated in North America (most originated in the fertile crescent, Asia or South or Central America). It was probably a “camp follower” of several of the western native American tribes who domesticated the crop (possibly 1000 BC) and then carried it eastward and southward of North America. The first Europeans observed sunflower cultivated in many places from southern Canada to Mexico.
Sunflower was probably first introduced to Europe through Spain, and spread through Europe as a curiosity until it reached Russia where it was readily adapted. Selection for high oil in Russia began in 1860 and was largely responsible for increasing oil content from 28% to almost 50%. The high-oil lines from Russia were reintroduced into the U.S. after World War II, which rekindled interest in the crop. However, it was the discovery of the male-sterile and restorer gene system that made hybrids feasible and increased commercial interest in the crop. Production of sunflowers subsequently rose dramatically in the Great Plains states as marketers found new niches for the seeds as an oil crop, a birdseed crop, and as a human snack food. Production in these regions in the 1980s has declined mostly because of low prices, but also due to disease, insect and bird problems. Sunflower acreage is now moving westward into dryer regions; however, 85% of the North American sunflower seed is still produced in North and South Dakota and Minnesota.
SUNFLOWER PLANTING SEASON
To plant in rows, space seeds about 6 inches apart in a shallow trench between 1 and 2 inches deep. In sandy soil, 2 inches deep is better. Cover and keep watered until seeds sprout in 7 to 10 days. When first true leaves appear (the second set of leaves); thin plants to about 2 feet apart. Depending on the variety, sunflowers will mature and develop seeds in 80 to 120 days. So a new row every 2 to 3 weeks to enjoy continuous blooms until the first frost.
For maximum seed production space rows 2 to 3 feet apart. Use traditional, tall, seed-producing varieties such as ‘Mammoth’ or ‘Paul Bunyan Hybrid’, ‘Aztec Gold Hybrid’, or ‘Super Snack Hybrid’.To grow smaller flowers for bouquets, space plants much closer together?about 6 inches apart in Maine, or as close as 2 inches in dry places like Arizona. Skip fertilizing. The plants will be much smaller, with fewer branches, but the stems will be longer and flower heads a good size for arrangements.
Sunflower is grown in many semi-arid regions of the world from Argentina to Canada and from central Africa into the Soviet Union. It is tolerant of both low and high temperatures but more tolerant to low temperatures. Sunflower seeds will germinate at 39°F, but temperatures of at least 46 to 50°F are required for satisfactory germination. Seeds are not affected by vernalization (cold) in the early germination stages. Seedlings in the cotyledon stage have survived temperatures down to 23°F. At later stages, freezing temperatures may injure the crop. Temperatures less than 28°F are required to kill maturing sunflower plants.
Optimum temperatures for growth are 70 to 78°F, but a wider range of temperatures (64 to 91°F) show little effect on productivity. Extremely high temperatures have been shown to lower oil percentage, seed fill and germination.
Sunflower is often classified as insensitive to daylength, and photoperiod seems to be unimportant in choosing a planting date or production area in the temperate regions of North America. Oil from northern regions tends to be higher in linoleic acid and has a higher ratio of polyunsaturated to saturated fatty acids than oil produced in southern latitudes.
Sunflower is an inefficient user of water, as measured by the amount of water transpired per gram of plant above-ground dry matter. Levels were 577 (g H2O/g DM) for sunflower, 349 for corn, 304 for sorghum in an Akron, Colorado study. It is similar to wheat, soybean, field bean, oat, and rape in that respect. Efficiency is measured at an optimum moisture level and is not a measure of drought resistance.
Sunflower is not considered highly drought tolerant but often produces satisfactory results when other crops are damaged during drought. It’s extensively branched taproot, penetrating to 6.5 ft, aids the plant during water stress. A critical time for water stress is the period 20 days before and 20 days after flowering. If stress is likely during this period, irrigation will increase yield, oil percentage and test weight, but decrease protein percentage.
Sunflower will grow in a wide range of soil types from sands to clays. The demands of a sunflower crop on soil macronutrients are not as great as corn, wheat or potato. As with other non-leguminous grain crops, nitrogen is usually the first limiting factor for yield. Medium to high levels of macronutrients are usually required for good plant growth. Sunflower stover contains a large proportion of these elements, which means sunflower is relatively inefficient in the use of these elements. However, most of these nutrients are returned to the soil with the stove.
Sunflower is low in salt tolerance but is somewhat better than field bean or soybean in this respect. Corn, wheat, and sorghum are rated medium, and sugarbeet and barley are high in salt tolerance.Good soil drainage is required for sunflower production, but this crop does not differ substantially from other field crops in flooding tolerance.
Sunflower seeds are an American original. Called either confection or non-oil, seeds are a delicious and nutritious snack or addition to your favorite food.
It is a native species to North America and was used by American Indians for an important, high-energy food source. Spanish explorers carried it with them to Europe. Russian agronomists were responsible for the first agricultural hybrids. These returned to the United States with Russian and German immigrants.Sunflower began as an important agronomic crop in the U.S. in the 1950’s, starting in North Dakota and Minnesota.
Seed means the seed is left intact with the “meat” of the seed still in the shell. It is normally roasted and seasoned. It is eaten as a snack by cracking the shell with one’s teeth, discarding the hull and eating the delicious morsel within. ‘Chew and spit’ is a great American pastime, especially at baseball games and other outdoor events.
Kernel means the processor has mechanically removed the hull. The resulting kernel is now in a convenient form to be sold raw or roasted for snacking or as an ingredient.
Commercially available sunflower varieties contain from 39 to 49% oil in the seed. In 1985-86, sunflower seed was the third largest source of vegetable oil worldwide, following soybean and palm. The growth of sunflower as an oilseed crop has rivaled that of soybean, with both increasing production over 6-fold since the 1930s. Sunflower accounts for about 14% of the world production of seed oils (6.9 million metric tons in 1985-86) and about 7% of the oil cake and meal produced from oilseeds. Europe and the USSR produce over 60% of the world’s sunflowers.
The oil accounts for 80% of the value of the sunflower crop, as contrasted with soybean which derives most of its value from the meal. Sunflower oil is generally considered a premium oil because of its light color, high level of unsaturated fatty acids and lack of linolenic acid, bland flavor, and high smoke points. The primary fatty acids in the oil are oleic and linoleic (typically 90% unsaturated fatty acids), with the remainder consisting of palmitic and stearic saturated fatty acids. The primary use is as a salad and cooking oil or in margarine. In the USA, sunflower oils account for 8% or less of these markets, but in many sunflower-producing countries, sunflower is the preferred and the most commonly used oil.
High oleic sunflower oil (over 80% oleic acid) was developed commercially in 1985 and has higher oxidated stability than conventional oil. It has expanded the application of sunflower oils for frying purposes, tends to enhance shelf, life of snacks and could be used as an ingredient of infant formulas requiring stability.
Non-dehulled or partly dehulled sunflower meal has been substituted successfully for soybean meal in isonitrogenous (equal protein) diets for ruminant animals, as well as for swine and poultry feeding. Sunflower meal is higher in fiber, has a lower energy value and is lower in lysine but higher in methionine than soybean meal. Protein percentage of sunflower meal ranges from 28% for non-dehulled seeds to 42% for completely dehulled seeds. The color of the meal ranges from gray to black, depending upon extraction processes and degree of dehulling.
The price of sunflower oil usually prohibits its widespread use in industry, but there are several applications that have been explored. It has been used in certain paints, varnishes and plastics because of good semi drying properties without color modification associated with oils high in linolenic acid. In Eastern Europe and the USSR where sunflower oil is plentiful, sunflower oil is used commonly in the manufacture of soaps and detergents. The use of sunflower oil (and other vegetable oils) as a pesticide carrier, and in the production of agrochemicals, surfactants, adhesives, plastics, fabric softeners, lubricants and coatings has been explored. The utility of these applications is usually contingent upon petrochemical feedstock prices.
Sunflower oil contains 93% of the energy of US Number 2 diesel fuel (octane rating of 37), and considerable work has been done to explore the potential of sunflower as an alternate fuel source in diesel engines. Blends of sunflower oil and diesel fuel are expected to have greater potential than the burning of pure vegetable oil.
The use of sunflower seed for bird feed or in human diets as a snack,has grown consistently over the past 15 years. Varieties used for non-oilseed purposes are characterized by a larger seed size and require slightly different management practices. During processing, seeds is divided into 1) larger seed for in-shell roasting, 2) medium for dehulling, and 3) small for birdseed. Standards for different uses vary.
Sunflower can also be used as a silage crop. It can be used as a double crop after early harvested small grains or vegetables, an emergency crop, or in areas with a season too short to produce mature corn for silage.
Forage yields of sunflower are generally less than corn when a full growing season is available. In one study, sunflower dry matter yields ranged from 2.0 to 3.0 ton/acre compared with 3.1 to 3.8 ton/acre for corn. Moisture content of sunflower at maturity is usually high (80 to 90%) and would require wilting before ensiling.
Nutritional quality of sunflower silage is often higher than corn but lower than alfalfa hay (Table 1). Crude protein level of sunflower silage is similar to grass hay and higher than corn silage. Generally, crude protein of sunflower decreases and lignin percentage increases after the flowering stage. High plant populations increases fiber and lignin percentage. Seed size does not seem to affect yield or quality.
SUNFLOWER HARVESTING TIME