Identification of Factors Affecting Trait Stability via Factorial Regression and Environmental Variance: II. Application to End-Use Quality of Bread Wheat

The stability basis in bread wheat still remains to be understood. Our objective was to determine factors affecting the stability of end-use quality in wheat, using a method developed in a companion paper that combined environmental variance and factorial regression. Kernel protein percentage (% protein), strength (W), tenacity (P) and extensibility (L) of dough were studied. Twenty-five environmental covariates characterized grain formation and nitrogen yields, dry matter and nitrogen quantities at anthesis, grain-filling, and post-anthesis temperatures. Earliness was a genotypic covariate. For each trait, the factorial regression, introducing the two environmental covariates that best discriminated for stability and best explained the interaction, was selected. The best factorial regressions explained 31.5%, 53.3%, 49%, and 46.3% of the interaction sum of squares for the % protein, W, P, and L, respectively. The selected covariates indicated that nitrogen availability at anthesis, nitrogen grain-filling rate, and duration were involved in the quality stability. The stable varieties appeared to use poorly environments favorable to nitrogen accumulation, and to behave well in unfavorable ones. Such information will be helpful in future breeding programs. (C) 2007 by The Haworth Press, Inc. All rights reserved.