The sunflower, Helianthus annuus L., is a member of the
Compositae, a large and successful family of flowering plants occurring
throughout the world. The genus Helianthus is named from the Greek hellos
meaning sun, and anthos flower.
Figure 6: Sunflower.
Source: KIT, 1979
Basically a temperate-zone plant, the main commercial production
of sunflower is in the warm-temperate regions but breeding and selection have
produced varieties adapted to a wide range of environments. Optimal conditions
are short, hot (around 27ºC) summers with not too much rain (around 250 mm)
during flowering and fructification. Greatest production is between latitudes of
200 to 500 north and 200 to 400 in the southern hemisphere, usually below
altitudes of 1 500 m.
Sunflower is the only crop of worldwide commercial importance
that originates from the area of the USA (probably south-western states to
Mexico). Earlier used for food by the Indians of that region, it was already
cultivated when the Europeans arrived in North America. The post-war
introduction of Russian varieties, which not only pushed the oil content of the
seeds to 50 % but were suitable for mechanized harvesting (90 to 150 cm high),
had an immense impact on the development of sunflower as a commercial crop in
Europe and the Americas.
Today, world production of sunflower ranks fifth among oil seeds
and third among the vegetable oils (see Tables 1 and 2). In world trade, it has
established an equally important position, although a significant portion of the
production in developing countries is for personal consumption and therefore not
registered. World production of sunflower seeds was dominated by the USSR which
used to account for 50 %, but has declined since the 1970's to roughly half that
share or 5 million tons in absolute terms. Other major producers are now
Argentina (3.4 million tons), China (1.9), France (1.5) and the USA (1.4).
Argentina has also become the leading exporter of sunflower oil and now accounts
for almost half the world trade.
The cultivated sunflower is a tall, erect, unbranched, coarse
annual, with a distinctive large, golden head. The plant grows rapidly, the stem
varying in height from I to 3m when full grown with individual plants of giant
varieties reaching 5m. New hybrids have a shorter stem and are remarkably even
in growth and final height (within 5 % deviation). The discshaped head is born
terminally on the main stem and branches where these occur and is commonly 10 to
30 cm in diameter.
- The fruit, or sunflower seed, ranges in colour from black
through to white, but brown, striped or mottled seed can also occur. Seed varies
greatly in size and weight, but is generally a compressed, flattish oblong.
Average seed yields are currently 1.3 tons per ha, but can reach up to 4
tons/ha. The oil content of sunflower seed is between 25 and 48 %, but can reach
65 % under experimental conditions. Important for developing countries is the
fact that high temperatures during seed development can reduce the total oil
content to below 25 %, which would make small-scale processing less rewarding.
Sunflower oil, which is pressed in a cold stage, is a very
highly valued salad oil; lower qualities are also used for technical purposes