The wheat stem sawfly (WSS) (Cephus cinctus Nort.) is an important pest of wheat (Triticum aestivum L. em. Thell.) in the Northern Great Plains. This paper reports the genetic analysis of antixenosis for egg‐laying WSS females in recombinant inbred lines (RIL) of hard red spring wheat. Female WSS preferentially choose certain wheat genotypes for egg‐laying, with the cultivar Reeder being preferred and Conan being less preferred. We measured percent stem infestation and percent stem cutting for 91 RIL from a Reeder–Conan cross in four sawfly‐infested locations in Montana. Heritability based on means over environments was h2 = 0.86 for infestation and h2 = 0.75 for cutting. Percent infestation was negatively correlated with heading date (r = −0.57, P < 0.001) and degree of stem solidness (r = −0.31, P < 0.01). A molecular map was created with 431 markers. Quantitative trait loci (QTL) for infestation and cutting were identified as cosegregating with QTL for heading date (controlled by Ppd‐D1 on chromosome 2D) and stem solidness (controlled by Qss.msub.3BL). Additionally, significant QTL for infestation and cutting on chromosomes 2D and 4A were present in several environments, and did not cosegregate with heading date, plant height, or solid stems. These QTL may complement the use of solid stems for host plant resistance by developing wheat lines that vary for attractiveness to the wheat stem sawfly.

Increasing temperatures are a threat to hard red spring wheat (Triticum aestivum L.) production in the northern Great Plains and may impact objectives for breeding programs. Weather data and agronomic performance of experimental lines and a check cultivar ‘Thatcher’ were compiled for six sites in Montana for 1950 to 2007. Mean annual temperature increased significantly at five sites. March temperature increased significantly at all sites, and planting date has become significantly earlier at a rate of 0.24 d yr−1. Grain yield of Thatcher increased significantly at a rate of 23.5 kg ha−1 yr−1. July temperatures increased significantly at two sites. July temperatures showed a significant negative correlation with grain yield at three sites and with grain volume weight at three sites. Nursery means over years as adjusted for Thatcher was used as a measure of genetic change and showed significantly increased grain yield and significantly earlier heading date. Our results suggest that earlier planting due to warmer spring temperatures has helped to alleviate negative effects of high temperatures during grain filling periods. Genetic changes in breeding materials have also contributed to increased yield potential, partially due to earlier heading and avoidance of July heat. Projection of increasing temperatures suggests the need for management and breeding strategies to insure productivity of hard red spring wheat in the northern Great Plains.

Modern spring wheat (Triticum aestivum L.) cultivars are typically of semidwarf growth habit and have higher yield potential than their predecessors. Since the introduction of reduced height alleles, breeders have selected for higher grain yield and improvements in other traits. The objective of this project was to determine the genetic basis for differences between a modern spring wheat cultivar ‘McNeal’ with Rht‐D1b for semidwarf habit and a historically important standard height cultivar ‘Thatcher’. A recombinant inbred line (RIL) population with 160 lines, including 80 in each height class, was tested in five environments in Montana. The Rht‐D1 locus explained 90% of the height variation. The Rht‐D1b allele had positive pleiotropic effects on grain yield and productive tiller number, explaining 73 and 33% of the respective variation. Negative pleiotropic effects occurred for grain protein, seed weight, and test weight, as Rht‐D1 explained 42, 24, and 7% of the variation within the RIL. Favorable alleles at quantitative trait loci (QTLs) of lesser effect than Rht‐D1 were more often contributed by McNeal for seed size and test weight than by Thatcher. A total of 17 epistatic interactions were observed, of which nine involved Rht‐D1. Our results indicate that alleles for semidwarf habit explain most of the improvement in grain yield. Selection of favorable alleles at other loci has helped to mitigate negative pleiotropic effects of Rht‐D1b. Our results provide insight into the genetic basis of wheat improvement through breeding.

Endosperm texture has a tremendous impact on the end-use quality of wheat (Triticum aestivum L.). Cultivars of barley (Hordeum vulgare L.), a close relative of wheat, also vary measurably in grain hardness. However, in contrast to wheat, little is known about the genetic control of barley grain hardness. Puroindolines are endosperm-specific proteins found in wheat and its relatives. In wheat, puroindoline sequence variation controls the majority of wheat grain texture variation. Hordoindolines, the puroindoline homologs of barley, have been identified and mapped. Recently, substantial allelic variation was found for hordoindolines among commercial barley cultivars. Our objective was to determine the influence of hordoindoline allelic variation upon grain hardness and dry matter digestibility in the 'Steptoe' x 'Morex' mapping population. This population is segregating for hordoindoline allele type, which was measured by a HinA/HinB/Gsp composite marker. One-hundred and fifty lines of the 'Steptoe' x 'Morex' population were grown in a replicated field trial. Grain hardness was estimated by near-infrared reflectance (NIR) and measured using the single kernel characterization system (SKCS). Variation attributable to the HinA/HinB/Gsp locus averaged 5.7 SKCS hardness units (SKCS U). QTL analysis revealed the presence of several areas of the genome associated with grain hardness. The largest QTL mapped to the HinA/HinB/Gsp region on the short arm of chomosome 7 (5H). This QTL explains 22% of the SKCS hardness difference observed in this study. The results indicate that the Hardness locus is present in barley and implicates the hordoindolines in endosperm texture control.