Identification of Field Corn Inbreds Adapted to Europe to Improve Agronomic Performance of Sweet Corn Hybrids

Elite American and European field corn inbreds (Zea mays L.) could improve the agronomic value of sweet corn for European conditions. The choice of field corn inbreds for improvings weet corn performance can be accomplished by a variety of methods. Our objectives were to identify American and European field corn inbreds adapted to European conditions as potential donors for improving yield and agronomic performance of sweet corn hybrids, and to provide additional information on the relationships among different estimators of favorable alleles when the donor lines show better performance than the inbred lines to be improved. Eleven field corn inbreds were crossed to seven sweet corn inbreds that were parents of seven sweet corn hybrids. The field × sweet corn hybrids and inbreds were evaluated separately in field trials at two locations in northwesternS paini n 1993 and 1994. Yield and four agronomic traits were recorded. Estimates of the relative number of alleles at six classes of loci (B, C, D, E, F, and G) were computed, and the methods for identifying field corn inbreds with favorable alleles were an estimate of favorable dominant alleles present in the donor but not in the hybrid (μG’), predicted threeway cross (PTC), minimum upper bound (UBND), net improvement (NI), probability of net gain of favorable alleles given complete dominance (PNGg)and given partial dominance or complementarye pistasis (PNGcₑg), and general combining ability (GCA). Correlations between μG’, UBND, PTC, NI, and GCA were very high for all traits. The field corn inbreds A632, EP42, and EP29 were identified as the best potential donors for improving yield and several yield components of sweet corn hybrids. European flint inbreds offer new possibilities for improving the agronomic value of sweet corn and its adaptation to cold areas with short growing seasons. Research supported by the Committee for Science and Technology of Spain (Project Cod. AGF92-0161) and Excma. Diputación Provincial Pontevedra, Spain.