Recurrent Selection for Seedling Growth of Sweet Corn in Cool Temperatures

Abstract

ABSTRACTEarly spring sweet corn producers would benefit from supersweet cultivars with improved seedling cold tolerance. We performed recurrent selection for improved seedling vigor and germination rates at cool temperatures in three sweet corn populations. The original populations were formed by crossing temperate sweet corn and High‐altitude Mexican germplasm. A sugary1 (su1) and a shrunken2 (sh2) population derived from Cacahuacintle Dulce germplasm were evaluated, as well as a sh2 population derived from ‘Maíz Dulce’. The most uniformly vigorous seedling lots were chosen by replicated visual selection and then intermated to form the next cycle. The direct effects of selection were measured through growth chamber germination tests at 10°C. The indirect effects of selection were assessed through replicated field trials. A positive significant linear response to selection for seedling length was present in the two sh2 populations (R2 = 0.92, P < 0.001; R2 = 0.94, P < 0.001). There was a 71% increase in seedling length over four cycles of selection in one sh2 population, and a 116% increase in the other. Significant linear decreases in the average number of dead kernels were observed in both sh2 populations (R2 = 0.91, P < 0.05; R2 = 0.89, P < 0.05). There were no significant changes in kernel carbohydrate composition in either of the sh2 populations. No linear changes were observed as a direct response to selection in the su1 population. While germination under field conditions improved for both of the sh2 populations, selection had a negative effect on several agronomic traits, including plant height, ear height, and ear weight, suggesting the possibility of inbreeding during recurrent selection.