Genotype-by-management interactions for grain yield and grain protein concentration of wheat

The magnitude of genotype-by-management (G x M) interactions for grain yiel d and grain protein concentration was examined in a multi-environment trial (MET) involving a diverse set of 272 advanced breeding lines from the Quee nsland wheat breeding program. The MET was structured as a series of manage ment-regimes imposed at 3 sites for 2 years. The management-regimes were ge nerated at each site-year as separate trials in which planting time, N fert iliser application rate, cropping history, and irrigation were manipulated. irrigation was used to simulate different rainfall regimes. From the combi ned analysis of variance, the G x M interaction variance components were fo und to be the largest source of G x E interaction variation for both grain yield (0.117 +/- 0.005 t(2) ha(-2); 49% of total G x E 0.238 +/- 0.028 t(2) ha(-2)) and grain protein concentration (0.445 +/- 0.020%(2); 82% of total G x E 0.546 +/- 0.057%(2)), and in both cases this source of variation was larger than the genotypic variance component (grain yield 0.068 +/- 0.014 t(2) ha(-2) and grain protein 0.203 +/- 0.026%(2)). The genotypic correlati on between the traits varied considerably with management-regime, ranging f rom -0.98 to -0.31, with an estimate of 0.0 for one trial. Pattern analysis identified advanced breeding lines with improved grain yield and grain pro tein concentration relative to the cultivars Hartog, Sunco and Meteor. It i s likely that a large component of the previously documented G x E interact ions for grain yield of wheat in the northern grains region are in part a r esult of G x M interactions. The implications of the strong influence of G x M interactions for the conduct of wheat breeding METs in the northern reg ion are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.