AN EVALUATION OF MODIFIED EAR-TO-ROW SELECTION IN A POPULATION OF CORN (ZEA MAYS L)

Four cycles of modified ear-to-row selection were applied to the open-pollinated cultivar, ''Hays Golden.'' The objective of this research was to evaluate the effectiveness of combined selection for yield of grain. The method entails selection among and within half-sib families. The family selection was based on the average performance in 3 replications, 1 at each of 3 locations. The selection of individuals within selected families was based upon phenotypic performance in a natural crossing block isolation. The mean yield increased an averageof 99.44% per cycle relative to the parental variety. The predicted gain from selection based upon estimates of genetic and genetic-environmental variances in the original ''Hays Golden'' cultivar was in good agreement with the observed response for grain yield. The modified ear-to-row procedure is more effective than mass selection alone in improving yield in the Hays Golden varietal population. Modified ear-to-row selection may be used to obtain a more rapid increase in the frequency of favorable genes prior to the extraction of inbred lines. The method can be used to advantage after some reduction in the additive genetic variance has resulted as a consequence of effective mass selection and a more precise measure of the genotypic effect is needed.