CHROMOSOMAL LOCATION OF WHEAT QUANTITATIVE TRAIT LOCI AFFECTING STABILITY OF 6 TRAITS, USING RECIPROCAL CHROMOSOME SUBSTITUTIONS

A major limitation to the genetic improvement of wheat (Triticum aestivum L.) is lack of information about the effects of quantitative trait loci (QTLs) on stability of agronomic traits across environments. Our objective was to determine the chromosomal locations of QTLs controlling stability of grain yield and yield components, grain test weight, and plant height. Reciprocal sets of chromosome substitution lines in duplicate between two hard red winter wheat cultivars, Cheyenne and Wichita, were used to identify chromosomes that carried QTLs affecting stability. Data from the two parental cultivars, 40 Wichita chromosome substitutions in Cheyenne, and 34 Cheyenne chromosome substitutions in Wichita, grown in six environments in Nebraska, were used to compute the regression coefficient on the environmental index (b(i)), the mean square of the deviation from regression (s(d)2), and the coefficient of variation (CV). Little variation existed among the substitution lines for s(d)2 and CV, so b(i) was the primary stability parameter used to describe the lines. Wichita had one or more major QTLs on chromosomes 3A, 6A, 2B, and 3D that increased b(i) of grain yield in Cheyenne. Cheyenne had one or more major QTLs on chromosome ID that decreased b(i) of grain yield in Wichita. We identified one Wichita and two Cheyenne chromosomes with QTLs affecting stability of seeds per culm, one Wichita and three Cheyemme chromosomes with QTLs affecting stability of seed weight, nine Wichita and eight Cheyenne chromosomes with QTLs affecting stability of culm per square meter, and seven Wichita and four Cheyenne chromosomes with QTLs affecting stability of grain test weight.