Heterotic patterns among open-pollinated sweet corn cultivars

Abstract

Heterotic patterns in sweet corn are weakly defined. Most sweet corn inbreds are descended from three open-pollinated cultivars: 'Golden Bantam', Stowell's Evergreen', and 'Country Gentleman'. Heterotic and phylogenetic relationships among these three cultivars and others are not clearly known. This investigation was designed to investigate the heterotic patterns among some historically important open-pollinated sweet corn cultivars: 'Country Gentleman', 'Golden Bantam', 'Lindsey Meyer Blue', 'Stowell's Evergreen', 'Howling Mob', and 'Pease Crosby'. The 15 possible hybrids from the diallel cross plus the 6 parents were grown in midspring and late summer plantings. Heterosis and combining ability effects were estimated for 13 traits. Hybrid x planting date interactions were significant for most of the main traits, hence, planting dates were analyzed separately. Average midparent heterosis for grain yield was 29.17 % in the first planting date and 57.04% in the second planting. Midparent heterosis for yield and plant height were highest for hybrids with 'Country Gentleman' as a parent. 'Stowell's Evergreen' when crossed to 'Pease Crosby', 'Lindsey Meyer, and 'Golden Bantam' exhibited high heterosis. The two late-maturity cultivars 'Country Gentleman' and 'Stowell's Evergreen' had higher general combining ability than the four early-maturity cultivars for most traits. Specific combining ability was seldom significant. Yield of 'Country Gentleman' hybrids averaged over all crosses and planting dates was the highest. These data indicate a strong heterotic pattern-'Country Gentleman' x 'Pease Crosby'. 'Golden Bantam', and 'Lindsey Meyer Blue'- and a weaker one-'Stowell's Evergreen' x 'Pease Crosby', 'Golden Bantam', and 'Lindsey Meyer Blue'.