Agronomic Management Practices for Confection Sunflower Production in the Bighorn Basin, Wyoming.

Confection sunflower has become an increasingly important cash crop in Wyoming, especially in the Bighorn Basin region. However, several aspects of its cultivation are still lacking for the semi-arid growing conditions of the region. In order to develop sustainable management strategies, on-station studies and on-farm trials were conducted at the University of Wyoming Research and Extension Center located in Powell and at nearby producers’ fields, respectively. An experiment was conducted under furrow irrigation during three consecutive growing seasons (2012-2014) to determine the effects of planting dates (from May 1 to June 15) and early termination of irrigation (irrigation until R5.5, R6 and R7 stages) on yield and quality of confection sunflower. A second experiment was conducted under sprinkler irrigation during the 2014 growing season to evaluate the effects of deficit irrigation (50, 75 and 100 % replacement of ETc until R4 stage followed by full irrigation in all treatments until R7 stage) and seeding rates (from 39,300 to 61,400 plants ha^-1) on yield and quality of confection sunflower. Our results showed the last week of May as the suitable planting period. Planting date affected the yield by causing significant variations in head diameter and seed number per head. The study also showed that irrigation of confection sunflower grown on a clay-loam soil may be terminated as early as at R5.5 stage without significant yield reduction but to late stages if grown on coarse soils. The combination of 39,300 plants ha^-1 and the replacement of 75% ETc was found as the most profitable, reducing the water use by up to 14%. Increase in plant population tended to decrease yield and yield components. Our research indicates the potential of growing confection sunflower under limited irrigation for higher profits in the semi-arid region of Wyoming.