Genetic Control of Grain Yield and Grain Physical Characteristics in a Bread Wheat Population Grown Under a Range of Environmental Conditions

Environmental conditions such as moisture deficit and high temperatures during the growing period affect the grain yield and grain characteristics of bread wheat (Triticum aestivum L.). The aim of this study was to map quantitative trait loci (QTL) for grain yield and grain quality traits using a Drysdale/Gladius bread wheat mapping population grown under a range of environmental conditions in Australia and Mexico. Despite large effects of known photoperiod-sensitivity loci (Ppd-B1 and Ppd-D1) on crop development, grain yield and grain quality traits, it was possible to detect QTL elsewhere in the genome and to examine the variation of these effects across environments subject to water limitation and/or heat stress. The TaGW2 region on chromosome 6A was associated with grain width, thickness and roundness. The Ha locus on chromosome 5D was associated with particle size index and flour extraction and a region on chromosome 3B was associated with grain width, thickness, thousand grain weight and yield. The genetic control of grain length appeared to be largely independent of the genetic control of the other grain dimensions. As expected, effects on grain yield were detected at loci that also affected yield components. On chromosome 2D, QTL for aspect ratio, grain thickness and width co-located within a 9-cM region that is not closely linked with phenology loci. Some QTL displayed QTL-by-environment interactions.