Three Cycles of Full‐Sib Reciprocal Recurrent Selection in Two Spanish Maize Populations

Abstract

ABSTRACTSpanish maize (Zea mays L.) populations can be useful for enhancing adaptation and stress tolerance of commercial varieties. Two improved Spanish maize populations, one from the northwest and the other from the southeast of Spain, that represent an alternative heterotic pattern have been subjected to three cycles of full‐sib reciprocal recurrent selection to increase the performance of the population cross. The objectives of this study were to evaluate the effect of selection on grain yield and on the correlated responses in the populations and their crosses and to investigate changes in heterosis and inbreeding depression during selection. Ten populations per se (S0), selfed (S1), and intercrossed were evaluated at six environments. Yield significantly increased with selection in the population cross (4.1% per cycle) and in the northwestern population (6.7% per cycle). Yield of the southeastern population did not change with selection. Correlated responses in other important agronomic traits were also in the desired direction. Mid‐parent and high‐parent heterosis increased significantly with selection (2 and 1.5%, respectively). The third cycle of selection of both populations is an interesting source for new inbred lines that could be the foundation for new adapted hybrids. The cross between the improved cycles could be useful for sustainable or organic agriculture as population hybrids, but more importantly, the reciprocal recurrent selection program can continue improving the population cross.