Previously, quantitative trait loci (QTLs) for grain yield (GYLD) and yield-related traits were identified by using a population of recombinant inbred chronnosome lines (RICLs) developed from the wheat {Triticum aestivum L.) eultivar Cheyenne (CNN) and its substitution line CNN(WI3A), in which the 3A chromosome of eultivar Wichita (Wl) was substituted for CNN chromosome 3A. Our objectives were to identify and validate the QTL previously identified in CNN(RICLs3A), using the mirror population WI(RICLs3A). A population of 90 WI(RICLs3A) was used to evaluate GYLD, 1000-kernel weight (TKW), kernels per spike (KPS), kernels per square meter (KPSM), spikes per square meter (SPSM), grain volume weight (GVW), plant height (PHT), and anthesis date (AD). Data were collected from replicated trials grown in six Nebraska environments from 2008 to 2009. Twelve QTL for GYLD, TKW, KPS, SPSM, GVW, AD, and PHT were detected. The phenotypic variance explained by these QTL ranged from 12% for SPSM to 53% for GVWT Most of the QTLs were co-localized in one or two regions of chromosome 3A. The major grain yield QTL {QGyld.neb.3A.1) detected in the combined analysis explained 19% of the phenotypic variance and the substitution of CNN alíeles for Wl alíeles decreased grain yield. Using a different genetic background, this study confirmed most of the GYLD and yield-related QTL reported in previous RICLs3A mapping studies on chromosome 3A of winter wheat evaluated in Nebraska. N. Mengistu, Pioneer Hi-Bred

In diverse growing environments, cultivar blends of hard winter wheat (Triticum aestivum L.) are considered as an option over pure cultivars for maintaining grain yield and reducing risk to producers. The objectives of this research were to evaluate the grain yield between blends and their component cultivars over several locations in Nebraska and to compare blend grain yield stability. Two separate experiments of six three‐cultivar blends and their component cultivars tested in a total of 30 environments and three two‐cultivar blends and their component cultivars tested in a total of 20 environments were grown in replicated randomized block designs. All component cultivars and cultivar blends (referred to as lines, hereafter) were evaluated for mean grain yield performance and stability. ‘Pronghorn’‐‘Goodstreak’‐‘Buckskin’ was the sole cultivar blend that significantly increased grain yield when compared with the average of its component cultivars. The grain yield advantage for the mean average cultivar blends varied from 2.2% lower to 1.9% higher with overall advantage of 0.4% yield increase for all the nine cultivar blends. Cultivar blends of ‘Millennium’‐‘Wesley’‐‘Wahoo’, Millennium‐‘Halt’‐Wahoo, and Millennium‐‘Alliance’‐Wahoo were the most stable lines using regression estimates for stability. When compared with the average of component cultivars, cultivar blends were more stable over different environments with little or no reduction in grain yield.

Abstract:Approximately 20 years ago, we began our efforts to understand grain yield in winter wheat using chromosome substitution lines between Cheyenne (CNN) and Wichita (WI). We found that two chromosome substitutions, 3A and 6A, greatly affected grain yield. CNN(WI3A) and CNN(WI6A) had 15 to 20% higher grain yield than CNN, whereas WI(CNN3A) and WI(CNN6A) had 15 to 20% lower grain yield than WI. The differences in grain yield are mainly expressed in higher yielding environments (e.g. eastern Nebraska) indicating genotype by environment interactions (G × E). In studies using hybrid wheat, the gene action for grain yield on these chromosomes was found to be mainly controlled by additive gene action. In subsequent studies, we developed recombinant inbred chromosome lines (RICLs) using monosomics or doubled haploids. In extensive studies we found that two regions on 3A affect grain yield in the CNN(RICLs-3A) with the positive QTLs coming from WI. In WI(RICLs-3A), we found a main region on 3A that affected grain yield with the negative QTL coming from CNN. The 3A region identified using WI(RICLs-3A) coincided with one of the regions previously identified in CNN(RICLs-3A). As expected the QTLs have their greatest effect in higher-yielding environments and also exhibit QTL × E. Using molecular markers on chromosomes 3A and 6A, the favorable alleles on 3A in Wichita may be from Turkey Red, the original hard red winter wheat in the Great Plains and presumably the original source of the favorable alleles. Cheyenne, a selection from Crimea, did not have the favorable alleles. In studying modern cultivars, many high yielding cultivars adapted to eastern Nebraska have the WI-allele indicating that it was selected for in breeding higher yielding cultivars. However, some modern cultivars adapted to western Nebraska where the QTL has less effect retain the CNN-allele, presumably because the allele has less effect (is less important in improving grain yield). In addition many modern cultivars have neither the WI-allele, nor the CNN-allele indicating we have diversified our germplasm and new alleles have been brought into the breeding program in this region.

Fusarium head blight (FHB) is a devastating disease of wheat (Triticum aestivum L.). Fhb1, a major gene that confers resistance to FHB, has been incorporated into spring wheat cultivars but not into hard winter wheat cultivars in the northern Great Plains of the United States. Our objective was to determine if the Fhb1 gene itself has or genes linked to Fhb1 have deleterious effects on agronomic or end‐use quality traits in winter wheat. Forty‐two F3:7 entries from a three‐way cross (‘Alsen’/‘NE00403’//‘NE02584’) and three check cultivars were divided into five genotypic classes: (i) 20 Fhb1 lines, (ii) one Fhb1 blend (a physical mixture of equal proportion of the 20 Fhb1 lines), (iii) 20 fhb1 lines, (iv) one fhb1 blend, and (v) three adapted checks. The entries were evaluated for agronomic and end‐use quality traits in replicated trials at five locations in Nebraska. Contrasts of Fhb1 lines vs. fhb1 lines showed that Fhb1 lines were significantly more winter hardy, earlier, and higher in grain yield but were lower in protein content as compared to fhb1 lines. However, there were no differences in any measured trait between Fhb1 and fhb1 blends. No significant differences were observed among the genotypic classes with and without the Fhb1 gene for grain volume weight, kernels per spike, 1000‐kernel weight, flour yield, and mixograph mixing time and mixing tolerance. Hence, Fhb1 did not have deleterious effects on agronomic and end‐use quality traits and should be deployed in winter wheat cultivars.