CHROMOSOMAL LOCATION OF WHEAT QUANTITATIVE TRAIT LOCI AFFECTING AGRONOMIC PERFORMANCE OF 7 TRAITS, USING RECIPROCAL CHROMOSOME SUBSTITUTIONS

A major limitation to the genetic improvement of wheat (Triticum aestivum L.) is the lack of information about quantitative trait loci (QTLs). The objective of this study was to determine the chromosomal locations of QTLs controlling grain yield and yield components, grain test weight, plant height, and anthesis date. Reciprocal sets of chromosome substitution lines in duplicate between two hard red winter wheat cultivars, Cheyenne (CNN) and Wichita (WI), were used to identify the chromosomes bearing QTLs. Field trials were conducted in Nebraska at Lincoln in 1987, at Lincoln, Mead, and Alliance in 1988, and at Lincoln, Mead, Alliance, and North Platte in 1989. Wichita had major QTLs on chromosomes 3A and 6A that increased grain yield in Cheyenne and major QTLs on chromosome 3B that decreased grain yield in Cheyenne, while Cheyenne had major QTLs on chromosomes 3A and 6A that decreased grain yield in Wichita. The increase in grain yield by WI 3A and WI 6A was due to a significant increase in seed weight. The decrease in grain yield by CNN 3A and CNN 6A was due to a significant decrease in culms per square meter. The decrease in grain yield by WI 3B was due to a significant decrease in winterhardiness, resulting in decreased seed weight and culms per square meter. We identified one Wichita and seven Cheyenne chromOsomes with QTLs affecting seeds per culm, seven Wichita and five Cheyenne chromosomes with QTLs affecting seed weight, one Wichita and three Cheyenne chromosomes with QTLs affecting culms per square meter, and one or more chromosomes with QTLs affecting each of the other agronomic traits.