Combining ability associated with S-1 recurrent selection in two maize synthetics

Abstract

S-1-progeny recurrent selection has proved effective improving the performance per se and the general combining ability (GCA) of maize (Zen mays L.) synthetic populations. Two maize synthetics, EZS1, a flint-type of Span ish origin, and EZS2, a dent population of North American origin, were produced al Zaragoza, Spain, and subjected to two cycles of S-1 recurrent selection for increased grain yield and reduced lodging and grain moisture. Our objectives were i) to assess the effect of S-1 recurrent selection on the heterotic behaviour of these synthetics, and) to evaluate the changes in combining ability after selection using as testers the populations themselves and three diverse inbred lines. The entries from a diallel mating design of the three cycles (0,1, and 2) of the two populations were tested in five environments. Testcrosses involving the three selection cycles of both synthetics and three diverse inbred testers were evaluated in three environments. Selection in both synthetics resulted in more productive populations, with less lodging, and no important negative responses in other agronomic trails. Improvements were less evident in the crosses of the populations, with significant GCA change only in EZS2 for lodging. Gains due to selection for grain yield in both synthetics and for lodging in EZS2 were significant, but the gains were not consistent across testers. Selection was effective in improving the populations per se. and the best testcrosses were not significantly different from the hybrid checks used for comparison.