RELATIVE PERFORMANCE OF SINGLE CROSS, THREE-WAY CROSS, AND DOUBLE CROSS CORN HYBRIDS RECOMMENDED IN ONTARIO, 1968–72

Abstract

Yield performance was determined for all single cross (SC), three-way cross (3W), and double cross (DC) corn (Zea mays L.) hybrids recommended by the Ontario Corn Committee between 1968 and 1972. The SC hybrids yielded 3.8 q/ha more than 3W and 6.3 q/ha more than DC. The yield advantage of the SC was apparent over all heat unit areas and years. The SC outyielded 3W and DC in both high- and low-yielding environments. This yield advantage was proportionately greater at the high-yielding environments. Yield stability of the three groups is discussed. Stability is described by two parameters, a regression coefficient and the standard error of this regression. The regression coefficient is calculated by regressing over locations the mean yield of each group of hybrids, at each location on the mean yield of all hybrids at that location. There were no differences in yield stability between the three types of hybrids.