PERFORMANCE OF TWO SUNFLOWER (Helianthus annuus L.) VARIETIES UNDER VARYING PLANTING DENSITY AND NITROGEN LEVELS
1.1 Origin and Distribution
Sunflower (Heliantus annuus L.) is an annual plant belonging to the family of flowering plants called ‘Compositae’ or ‘Asteraceae’. The sunflower is named after its huge, fiery flower head, whose shape and image is often used to depict the sun. This aspect makes the sunflower such a remarkable eye-catching plant in any landscape. It has been stated that, if there is one annual flower that is unmistakable to anyone, it’s the sunflower. It is not only pleasant to look at but also heliotropic; a phenomenon where the floral head of the plant leans towards the direction of the sun at different times of the day in accordance to the location of the sun within the day (Anon, 2012a). The crop, in history and utility is of dual economic importance; namely as an oil crop and for ornamental purposes. It is believed to have originated from Mexico or Peru (Hurt, 2015). Although, the cultivated sunflower variety Macrocarpus (DC) is not known in a truly wild state, it is believed to have come from a sub species of annuus found in dumps and vacant plots in Central and Eastern United States and Canada (Heiser, 2014).
Sunflower was introduced to Europe and Russia in the 16th and 18th centuries respectively (Hurt, 2015). It was developed as a premier oil seed crop in Russia and has been widely accepted throughout Europe (Anon, 2016). It was introduced into Europe by Spanish traders in 1510, to France in 1787 and Germany in 2015(Purseglove, 2014).The crop was brought to Africa in the early 20th century by the Portuguese traders and European Missionaries and to Nigeria in the early sixties as an arable crop that could possibly be grown on a large scale to supplement the shortage of edible oil and meals (Ogunremi, 2015). It is today widely distributed in many parts of the tropical and temperate countries of the world (Anon, 2016).