Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein.)], also known as scab, is a destructive disease of wheat (Triticum aestivum L; T. turgidum L. var durum) and barley (Hordeum vulgare L.). Host resistance has long been considered the most practical and effective means of control, but breeding has been hindered by a lack of effective resistance genes and by the complexity of the resistance in identified sources. This paper will provide an overview of progress in developing host plant resistance for FHB, primarily in the USA, by review of the sources of resistance in wheat and barley, and their utilization in breeding programs. Although there are no reported sources of immunity, considerable genetic variability exists for resistance in both wheat and barley. Sources of resistance in durum, however, are limited. The strategy of breeding programs is to recombine different types and sources of resistance steadily through traditional breeding strategies. To facilitate selection, artificial inoculation techniques are used in both the field and greenhouse. This enables breeders to select simultaneously for resistance and desirable agronomic characteristics. Incremental increases in resistance are being reported in hexaploid wheat and to a lesser extent in barley and durum wheat. It is anticipated that the development of molecular markers will improve the efficiency of developing FHB wheat and barley cultivars.

ten, 1982a). Barley forage was highest in digestible DM and lowest in acid detergent fiber (ADF) concentra-Oat (Avena spp.) is a popular cereal forage in cool semiarid regions. tions. Crude protein concentration was 16 g kg Ϫ1 greater Barley (Hordeum vulgare L.) has produced equal or greater amounts of superior quality forage in subhumid regions. The importance of in barley forage than in oat forage. cereal crop, cultivar, and plant part on forage production was deter-The superior quality of barley forage compared with mined in low-soil-N environments in southwestern North Dakota. oat and other cereal forages may result from a greater Barley and oat cultivars, along with intercrops of pea (Pisum sativum proportion of DM occurring as inflorescence in barley. L. subsp. sativum) with barley and oat, were compared for forage More than 25% of barley forage DM consisted of infloyield and quality over 2 yr. Forage dry matter (DM) yield averaged rescence compared with 20% for oat, triticale, and wheat 3.84 Mg ha Ϫ1 for oat compared with 2.91 Mg ha Ϫ1 for barley while forage across six maturity stages in subhumid regions crude protein (CP) concentration of oat forage averaged 61 g kg Ϫ1 (Cherney and Marten, 1982b). The inflorescence was compared with 90 g kg Ϫ1 for barley (P Ͻ 0.05). No difference in forage more digestible and nutritious than other plant compo-N yield occurred between barley and oat. Acid detergent fiber and nents. The leaf blade and sheath of barley also had less neutral detergent fiber concentrations averaged 39 and 41 g kg Ϫ1 lower, respectively, for barley compared with oat forage while Ca lignified area than oat. Similar compositional data are and P concentrations were higher for barley forage. Cultivar selection not available for barley and oat cultivars grown in the within each crop species generally did not affect forage yield or quality.Northern Great Plains. The relative contributions of stem, inflorescence, leaf blade, and leafThe CP concentrations of barley and barley-pea forsheath to forage yield were similar between cereal species and average were superior to those of oat and oat-pea forage in aged 20, 44, 14, and 22%, respectively. Intercropping with pea ina study at Dickinson, ND (Carr et al., 1998). Additional creased forage and N yield. These results suggest that forage yield is cereal forage quality data have been compared in subreduced but quality is enhanced when oat is replaced with barley in humid regions (Cherney and Marten, 1982b) but not in low-soil-N, unfertilized environments. Furthermore, the results indithe Northern Great Plains. Factors in addition to CP cate that forage yield and quality can be enhanced by intercropping concentration are important in determining the nutritive barley or oat with pea.

Recent advances in high-throughput genotyping have made it easier to combine information from different mapping populations into consensus genetic maps, which provide increased marker density and genome coverage compared to individual maps. Previously, a single nucleotide polymorphism (SNP)-based genotyping platform was developed and used to genotype 373 individuals in four barley (Hordeum vulgare L.) mapping populations. This led to a 2943 SNP consensus genetic map with 975 unique positions. In this work, we add data from six additional populations and more individuals from one of the original populations to develop an improved consensus map from 1133 individuals. A stringent and systematic analysis of each of the 10 populations was performed to achieve uniformity. This involved reexamination of the four populations included in the previous map. As a consequence, we present a robust consensus genetic map that contains 2994 SNP loci mapped to 1163 unique positions. The map spans 1137.3 cM with an average density of one marker bin per 0.99 cM. A novel application of the genotyping platform for gene detection allowed the assignment of 2930 genes to fl ow-sorted chromosomes or arms, confi rmed the position of 2545 SNP-mapped loci, added chromosome or arm allocations to an additional 370 SNP loci, and delineated pericentromeric regions for chromosomes 2H to 7H. Marker order has been improved and map resolution has been increased by almost 20%. These increased precision outcomes enable more optimized SNP selection for markerassisted breeding and support association genetic analysis and map-based cloning. It will also improve the anchoring of DNA sequence scaffolds and the barley physical map to the genetic map.

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Previous studies have shown that there is considerable population structure in cultivated barley (Hordeum vulgare L.), with the strongest structure corresponding to differences in row number and growth habit. U.S. barley breeding programs include six‐row and two‐row types and winter and spring types in all combinations. To facilitate mapping of complex traits in breeding germplasm, 1816 barley lines from 10 U.S. breeding programs were scored with 1536 single nucleotide polymorphism (SNP) genotyping assays. The number of SNPs segregating within breeding programs varied from 854 to 1398. Model‐based analysis of population structure showed the expected clustering by row type and growth habit; however, there was additional structure, some of which corresponded to the breeding programs. The model that fit the data best had seven populations: three two‐row spring, two six‐row spring, and two six‐row winter. Average linkage disequilibrium (LD) within populations decayed over a distance of 20 to 30 cM, but some populations showed long‐range LD suggestive of admixture. Genetic distance (allele‐sharing) between populations varied from 0.11 (six‐row spring vs. six‐row spring) to 0.45 (two‐row spring vs. six‐row spring). Analyses of pairwise LD revealed that the phase of allelic associations was not well correlated between populations, particularly when their allele‐sharing distance was >0.2. These results suggest that pooling divergent barley populations for purposes of association mapping may be inadvisable.

crop residue at the soil surface and subsequently cool spring soil temperatures, both of which contribute to Tillage is declining in wheat production systems in the Great Plains.immobilization of soil N (Westfall et al., 1996). How-Our objective was to determine if a tillage ϫ cultivar interaction ever, following an adjustment period, greater amounts occurred for grain yield, protein concentration, kernel weight, and test weight for hard red spring wheat (Triticum aestivum L. emend. P.M. Carr and W.W. Poland, North Dakota State Univ., Dickinson Cultivar differences across and even within studies may Res. Ext. Ctr., 1089 State Ave., Dickinson, ND 58601; R.D. Horsley, have contributed to the inconsistency in yield response Dep. Plant Sci., North Dakota State Univ., Fargo, ND 58105. This to changes in tillage. paper is a contribution of the North Dakota State Univ. Agric. Exp. Stn.

Fusarium head blight (FHB) in barley and wheat, caused by Fusarium graminearum, is a continual problem worldwide. Primarily, FHB reduces yield and quality, and results in the production of the toxin deoxynivalenol (DON), which can affect food safety. Identification of QTLs for FHB severity, DON level and related traits heading-date (HD) and plant-height (HT) with consistent effects across a set of environments, would provide the basis for marker-assisted selection (MAS) and potentially increase the efficiency of selection for resistance. A segregating population of 75 double-haploid lines, developed from the three-way cross Zhedar 2/ND9712//Foster, was used for genome mapping and FHB severity evaluation. A linkage map of 214 RFLP, SSR and AFLP markers was constructed. Phenotypic data were collected in replicated field trials from five environments in two growing seasons. The data were analyzed using MQTL software to detect quantitative trait locus (QTL) x environment (E) interactions. Because of the presence of QTL x E, the MQM procedure in MAPQTL was applied to identify QTLs in single environments. We identified nine QTLs for FHB severity and five for low DON. Many of the disease-related QTLs identified were coincident with FHB QTLs identified in previous studies. Only two of the QTLs identified in this study were consistent across all five environments, and both were Zhedar 2 specific. Five of the FHB QTLs were associated with HD, and two were associated with HT. Regions that appear to be promising candidates for MAS and further genetic analysis include the two FHB QTLs on chromosome 2H and one on 6H, which were also associated with low DON and later heading-date in multiple environments. This study provides a starting point for manipulating Zhedar 2-derived resistance by MAS in barley to develop cultivars that will show effective resistance under disease pressure.

Grain protein of barley (Hordeum vulgare L.) produced for malting often is greater than the industry's acceptable standards of 135 and 130 g kg−1 for six‐rowed and two‐rowed barley, respectively. Environmental conditions such as low rainfall and high temperatures after anthesis often cause increased grain protein. This study was conducted at four dryland environments in North Dakota over 2 yr to compare the effects of N fertilization and planting date on agronomic and malt quality traits of two experimental barley genotypes inherently low in grain protein with two barley cultivars currently grown in the U.S. Midwest. Agronomic traits evaluated were grain protein, grain yield, kernel weight, and kernel plumpness. Malt quality traits evaluated were fine‐grind extract, soluble wort protein, diastatic power (DP), and ɑ‐amylase activity. Nitrogen rates ranged from 0 to 200 kg ha−1. Nitrogen significantly increased grain protein, grain yield, soluble wort N, DP, and ɑ‐amylase activity, and decreased kernel weight, kernel plumpness, and fine‐grind malt extract. Significant genotypes differences were observed for all traits. The N × genotype interaction was significant for all agronomic traits, soluble wort N, and DP. The standard cultivars had greater than the acceptable grain protein when fertilized with 150 or 200 kg N ha−1. Delaying planting significantly decreased grain yield and fine‐grind malt extract. Grain protein of the low‐protein genotypes was within the limit desired by the malting and brewing industry at all N rates and planting dates. Thus, protein levels acceptable to maltsters can be obtained for low‐protein barley genotypes when excessive N is available and growing conditions are unfavorable.