Abstract

Planting at appropriate time leads to good crop yield; hence the need for detailed investigation on optimum planting dates of sunflower (a vital oil seed crop). Experiments were therefore conducted to determine the appropriate planting time of two cultivars of sunflower in Ibadan. Two cultivars of sunflowers, “Funtua and Isanka”, as main plot were subjected to five weekly planting dates (WPD) as subplot between August 13 and September 10 in 2004 and seven WPD between July 21 and September 1 in 2005 arranged in split plot layout in randomised complete block design with three replications at the Teaching and Research Farms, University of Ibadan. Nitrogen, phosphorus and potassium were applied as basal treatment based on soil test results. Vegetative, reproductive and yield parameters were collected to assess the influence of the treatment combinations on productivity of sunflower. Data collected were analysed using ANOVA and means were separated with LSD_(0.05). Planting date significantly affected all the growth and yield parameters including oil yield. As planting was delayed, seed and oil yields declined (2,513 kg/ha and 1,077 L/ha, respectively when planted on August 13 as against 1,234 kg/ha and 528 L/ha, seed and oil yields respectively, at September 10 planting) in 2004. Similar trend was observed in 2005; but there was a significant reduction in yield (815 kg/ha and 349 L/ha, respectively when planted on July 21 as against 216 kg/ha and 92 L/ha seed and oil yields, respectively, at September 1 planting) due to change in rainfall distribution (climate) during growth period. The luxuriant growth of those planted late did not translate to seed yield because there was not enough water during the seed filling stage of growth. The two cultivars had similar agronomic qualities and consequently no significant influence on all the yield parameters. Late July till mid August is the best planting time for optimum sunflower seed and oil yields in Ibadan. However, for successful planting, farmers must rely heavily on meteorological weather forecast most especially that the world is experiencing climatic change phenomenon.

Key words: Sunflower, cultivar, planting date, oil yield, rainfall.