Effects of Planting Date and Early Termination of Irrigation on Yield and Yield Quality of Confection Sunflower.

A study was conducted at the University of Wyoming Research and Extension Center in Powell, WY during 2012 and 2013 growing seasons to determine the effects of planting date and early termination of irrigation on yield and yield quality of confection sunflower. The experiment was conducted in a RCBD in a split-plot arrangement with planting date as main treatment and different irrigation strategies as sub-treatment with three replications. Dahlgren D-9569, a confection sunflower hybrid, was planted on a furrow irrigated field. In 2012, seven planting dates from 1^st May through 29^th June at ten days interval were set while in 2013, planting dates were: 3^rd May, 9^th May, 23^rd May, 4^th June and 10^th June. In both years, the irrigation treatments were- irrigation till R5.5, R6 and R7 growth stages. Both planting date and irrigation had significant effect (p≤ 0.05) on yield in 2012 whereas there was no effect of irrigation in 2013. The highest yield (5683 kg ha^-1) in 2012 was from planting on 30^th of May while the highest yield (6012 kg ha^-1) in 2013 was from 10^th of June. The 7.94 mm sieve yield (seeds retained after screening on 7.94 mm sieve) was found affected by planting date only. No interaction effects of planting date and irrigation were observed except in total yield and 7.94 mm sieve yield of 2012 growing season. In both years, seed moisture at harvest was higher in late planting. Irrigation did not affect the number of seeds per head. In both years, 1000 seeds weight was significantly affected by planting date. Results from 2012 and 2013 show planting date as an important factor in determining yield and yield components of confection sunflower. Planting date from the last week of May to first week of June and irrigation till R5.5 growth stage are promising management practices for optimum sunflower production for conditions in Wyoming.