2017 ASHS Annual Conference

A recent study from the Midwest demonstrated that plant populations for maximum sweet corn yield vary greatly for different hybrid varieties, and suggested that yields could increase by planting most of the newer hybrids at higher populations than are currently used. The study was conducted under a rain-fed system with lower yield potential compared to the Columbia Basin region in Washington where sweet corn is irrigated. In this trial, we evaluated the yield and processing qualities of seven sweet corn hybrids grown in the Columbia Basin at varying plant populations in 2014 and 2015. The seven hybrids were Hardi, CSHYP10-104, Marvel, DMC 21-07, XTH1079, XTH1779, and XTH3174. They were planted at four seeding rates: 19,000, 23,200, 29,900, and 41,800 seeds per acre using a Latin Square design and four replications. The actual plant populations achieved in 2014 and 2015 differed; stands were about 80% and 70% of the seeded rate in 2014 and 2015 respectively. Plant growth differed greatly each year; the plants matured earlier, ears were larger, there were more ears per acre, and yields were higher in 2015 compared to 2014. In both years, total ear count and primary ear count increased as plant population increased, while unhusked ear weights decreased. Larger ears compensated for fewer ears as the plant population increased so that yields were not significantly different at each plant population in 2014. In 2015, the larger ears at lower plant populations did not make up for having fewer ears and the total yield increased significantly with each increase in plant population. Processing quality assessments including, tip fill, ear weight, ear diameter, and the weight of kernels recovered per ear significantly decreased as plant population increased both years. The yield of kernels recovered on a per acre basis, however, is also influenced by the number of ears produced and so the results differed each year. There were significant hybrid x population responses in this study for secondary ear count and secondary ear yield, ear weight, and all processing recovery measurements. Quadratic response curves for yield and cut kernel yield have been assembled for each of the hybrids we evaluated. All of the hybrids should be evaluated again at higher populations to round out the curves (most of their responses are nearly linear with populations under 33,000 plants per acre) and to account for seasonal differences. We plan to continue these trials in 2018.