The nature of genotype × environment interactions for wheat yield in Western Australia

Abstract

The object of this study was to examine genotype × environment interaction (GE) for wheat yield in Western Australia and to consider its breeding implications. One hundred lines were grown in 28 environments in each of 2 years, 1978 and 1979. Linear regression techniques explained only a small fraction of the GE variance. Analyses of variance indicated that years interacted strongly with lines and also with lines × locations. The importance of the year interaction was further highlighted by the multidimensional technique of pattern analysis which revealed a distinct separation of the 1978 and 1979 environments. Environmental groupings with years showed no regional basis other than that associated with successive sowing dates at a location. Groupings of locations were not repeatable between years. Additional Western Australia wheat yield trial data were examined. The major of variation was environmentally determined and interactions of lines with locations, with years, and with location-years were generally highly significant. All results indicate a selection problem for wheat breeders in Western Australia and the necessity for wide testing over several seasons.