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Abstract
A major limitation to the genetic improvement of wheat is the lack of information on genes that affect agronomic performance and environmental stability of quantitative traits. This study had two objectives: (1) to determine which chromosomes carry quantitative trait loci (QTLs) affecting agronomic traits in wheat, including grain yield (Mg ha$\sp{-1}$), seeds tiller$\sp{-1}$, 1000 seed weight (g), tillers m$\sp{-2}$, grain test weight (kg m$\sp{-3})$, plant height (cm), and anthesis date; and (2) to determine which chromosomes have QTLs affecting the environmental stability of these traits.
The materials for this study were reciprocal sets of chromosome substitution lines developed in duplicate at the University of Nebraska between two hard red winter wheat cultivars, Cheyenne and Wichita. The lines were evaluated in field trials conducted in 1987 at Lincoln (Typic Argiudoll soil), in 1988 at Lincoln, Mead, (Typic Argiudoll soil), and Alliance (Aridic Argiustoll soil), and in 1989 at Lincoln, Mead, Alliance, and North Platte, NE (Typic Argiustoll soil), using a randomized complete block design with three replications at each site.
We detected QTLs on Wichita chromosomes 3A and 6A that significantly increased grain yield in Cheyenne, and on Cheyenne chromosomes 3A and 6A that significantly decreased grain yield in Wichita. We detected QTLs that affected each of the other traits on one or more chromosomes. Homoeologous group 3 chromosomes carried proportionately more QTLs than other homoeologous groups.
Data from 74 substitution lines and the two parents grown in six environments were used to compute stability parameters (b$\sb{\rm i}$, s$\sp2\sb{\rm d}$, C.V.). We detected QTLs on Wichita chromosomes 3A, 6A, 2B, and 3D that decreased the environmental stability of grain yield in Cheyenne, and on Cheyenne chromosome 1D that increased the environmental stability of grain yield in Wichita. We detected QTLs on one or more chromosomes that affected environmental stability of each of the other traits except plant height. No homoeologous group of chromosomes carried proportionately more QTLs affecting environmental stability of these traits.
