Cold Tolerance Evaluation in a Diallel among Open-pollinated Sweet Corn Cultivars

Abstract

Many sweet corn hybrids germinate poorly and have low seedling vigor in cold soils. Sources of cold tolerance and an understanding of its inheritance would benefit sweet corn production. Our objective was to determine the genetics of cold tolerance among open-pollinated progenitors of modern sweet corn. Six open-pollinated sweet corn cultivars were used as parents of a diallel. The 15 crosses plus reciprocals, parents, and checks were evaluated in cold chambers. Growing conditions were 14 hours with light at 14 °C, and 10 hours without light at 10 °C. Days to emergence, percent emergence, shoot dry weight, and root dry weight were recorded. The experiment was repeated in the greenhouse under warm conditions. Variation for cold tolerance was present among the crosses and cultivars. The variation was primarily due to general combining ability (GCA) effects, with specific combining ability (SCA) effects and reciprocal effects being significant for seedling dry mater. `Howling Mob' had significant favorable GCAs for all cold tolerance traits and resulted in the most cold-tolerant hybrids. `Country Gentleman' and `Stowell's Evergreen' were the slowest emerging parents. Days to emergence under cold conditions was not correlated to days to emergence under warm conditions. The correlations between root weight (cold) and root weight (warm) and shoot weight (cold) and shoot weight (warm) were significant, positive, and relatively large. In this material it appears that seedling vigor under warm conditions could be used to predict seedling size under cold conditions.