Heterotic Patterns among Flint Maize Populations

Abstract

Most maize (Zea mays L.) hybrids cultivated in Europe follow the heterotic pattern European flint × Corn Belt dent. However, at present, no commercial hybrids have been obtained from European flint inbreds exclusively. A flint × flint heterotic pattern could be an alternative to use in breeding programs to obtain early maturity, high‐yielding hybrids, potentially useful for producing high quality flours. The objective of this work was to search for heterotic patterns within flint germplasm adapted to temperate conditions. Ten open‐pollinated flint maize cultivars were crossed in a diallel design without reciprocals and evaluated in four environments in northwestern Spain. Cultivar effects explained most of the sum of squares for traits analyzed, except for yield. Crosses yielded 30% more than parental cultivars. Yield of crosses ranged from 3.94 to 5.61 Mg ha−1 Midparent heterosis values ranged from 2.5 to 64.7%. The crosses ‘Gallego’ × ‘Basto/Enano Levantino’ and Basto/Enano Levantino × ‘Longfellow’ showed high heterosis and the best averages for grain yield. On the basis of these results, these crosses could be included in a recurrent reciprocal selection breeding program to increase heterosis among the cultivars and improve their hybrids. A cluster analysis made with midparent heterosis for grain yield as a measure of distance revealed that the flint germplasm probably had similar origins and were related to the ‘Northern Flint’ race. Some differences among these cultivars were detected. ‘Norteño Largo’ was closely related to Northern Flint, while Basto/Enano Levantino was different from the rest of the cultivars. It was concluded that the development of hybrids combining good yield and the typical agronomic characteristics of flint maize is feasible.