Abstract:
Experiments were conducted in south west Nigeria to evaluate the response of sunflower
{Helianthus annuus L.) to different plant population densities under rain fed conditions during
the late rainy season cropping o f 2002 and 2003. In both years, three open pollinated varieties
namely: Funtua ( a local adapted variety), Record and Isaanka (exotic varieties) were grown at
three spacings, 60 x 15,60 x 30 and 60 x 45cm, to achieve 37,500,55,000 and 111,000 plants/ha,
respectively. Funtua flowered and matured later and grew taller than Record and Isaanka in
2002 and 2003. Similarly, Funtua significantly out-yielded Record and Isaanka in both years.
Increase in population density significantly reduced stem girth and increased lodging in 2003. As
population density increased from the lowest (37,500 plants/ha) to the highest (111,000 plants
/ha), seed production efficiency significantly increased, whilst average head diameter, head
weight, achene weight/head, number o f achene/head and 100 seed weight significantly reduced
in 2002 and 2003, respectively. The highest plant population density produced significantly
higher seed yield than the intermediate (55,000 plants/ha) and the lowest by about 37 and 64%,
and 75 and 98% in 2002 and 2003, respectively. The overall yield response was highest at 111,000
plants/ha irrespective of variety in both years. It is therefore, concluded that sunflower could be
grown up to 111,000 plants/ha under rain fed conditions in the transition zone of south west
Nigeria.
