Combining Abilities and Heterosis for Adaptation in Flint Maize Populations

Abstract

Breeding of maize (Zea mays L.) in the Atlantic coast of Europe has focused on developing hybrids to exploit heterosis between flint and dent germplasm. Flint x flint hybrids could have some advantages because of their earliness and early vigor that are important in short growing season areas. The objective of this work was to study the adaptation of a set of 10 flint varieties crossed to flint and dent testers and in a diallel design to check the feasibility of a breeding program to obtain flint hybrids well adapted to European Atlantic conditions. In the testcrosses, general combining ability (GCA) of the flint tester EP42 for kernel moisture at harvest and days to silking was lower than those of dent testers. Improvement of flint varieties for combining ability with inbred line EP42 could be done to obtain earlier flint x flint hybrids with a better dry-down rate than flint x dent hybrids. Diallel entries were analyzed following Analysis II of Gardner and Eberhart. Variety and heterosis effects were significant for all traits. Varieties Gallego and Norteño, besides having large variety effects, also showed intermediate variety heterosis for adaptive traits and they would be the best adapted varieties to include in breeding programs. The cross ‘Gallego x Basto/Enano levantino’ combined the best yield and good specific heterosis for adaptive traits. Thus, flint hybrids to be grown in short season areas could be obtained following this heterotic pattern.