Recurrent Selection for Grain Yield in Two Spanish Maize Synthetic Populations

Abstract

The most common maize (Zea mays L.) heterotic pattern in Europe is European flint × U.S. dent. Northern Spain × southern Spain has been proposed as an alternative heterotic pattern. Three maize synthetic populations, namely EPS6 from northern Spain, EPS7 from southern Spain, and EPS10 formed by early American populations, were produced in Pontevedra, Spain. Because of their low yield, the two Spanish synthetic populations were subjected to three cycles of intrapopulation S1 recurrent selection for grain yield. Our objectives were to evaluate the effect of selection on grain yield and other agronomic traits, and to determine the changes in heterosis and general (GCA) and specific (SCA) combining ability brought about by selection. The three original synthetic populations, the three cycles of selection of the two Spanish synthetic populations, and the crosses among the original and the improved cycles were evaluated in two locations in northwest Spain in 1994 and 1995. Yield significantly increased with selection in both Spanish synthetic populations. The GCA improved with selection in both EPS6 and EPS7. Heterosis and SCA did not change significantly with selection. The third cycles of each Spanish synthetic would be the most appropriate maize populations to start a reciprocal recurrent selection to improve the heterotic pattern northern Spain × southern Spain.