US Wheat Research Articles

STEEP: Impact of long-term conservation farming research and education in Pacific Northwest wheatlands

Erosion took a serious toll of prime topsoil from wheat fields in the Pacific Northwest United States since farming began in the 1870s. By the mid-1900s, it had become a serious environmental and economic threat to the region that produces world-record rain- fed grain yields and almost 13% of the US wheat crop. Of significance is that 80% of the nation's specialty soft white wheat is grown here for food grain, of which 90% is exported. To combat the severe erosion, wheat growers, the experiment stations, and the USDA in Idaho, Oregon, and Washington joined forces in 1975 to develop a multidisciplinary program named Solutions to Environmental and Economic Problems (STEEP). For more than 30 years, it has proved itself a national landmark in effective conservation farming research and education. The basic strategy was a systems approach that addressed all facets of farming from planting to harvesting in multi-year rotations. Its primary goal was to reduce soil erosion from the region's 3.3 × 10 6 ha (8.2 × 10 6 ac), consisting of highly productive but considerably steep cropland. Through the successful development and implementation of improved conserva- tion technology and farming systems by the tri-state STEEP effort, regional soil loss rates averaging 45 Mg ha -1 y -1 (20 tn ac -1 yr -1 ) were reduced over the 30 years to a tolerable 11 Mg ha -1 y -1 (5 tn ac -1 yr -1 ) or less. In addition, financial returns to wheat growers using the conservation systems are equal or have increased, and long-term benefits to soil, water, and air quality have improved. A conservative estimate shows that the investment cost of saving soil and improving water quality was less than $0.50 ha -1 y -1 ($0.20 ac -1 yr -1 ) over the life of STEEP. Though STEEP can boast success, much more is needed to preserve and protect the Northwest environment, natural resources, and productivity to ensure that agriculture is fully sustainable for the future. Ongoing solutions are needed to resolve emerging issues relating to greenhouse gas emissions, carbon storage, energy costs, and other farm inputs that can affect agricultural health. Its proven success provides strong assurance that STEEP can deal with future challenges relating to changes in farm policy, economics, technology, and sociologi- cal issues. This paper documents the extent that program goals were achieved and qualitative estimates of return from money invested.

Structural Conservation Practices in US Wheat Production: A Cost-Function Technology Adoption Approach

Abstract Based on 2004 CEAP-ARMS Phase II data, higher-sales farms not participating in a conservation programme adopted farmland conservation structures much more intensively on wheat fields than did any other farm-size type among conservation programme participants or non-participants. Survey results suggest that wheat farms not participating in a conservation programme more frequently adopted infield conservation structures, while conservation programme participants more often installed field perimeter conservation structures. Wheat producers, particularly those not participating in a conservation programme, recognize productivity and profitability benefits of infield structures as sufficient to promote their adoption without programme incentives. However, for field perimeter structures, programme incentives may be needed to encourage their adoption because benefits are more commonly off-site. To supplement univariate comparisons between conservation programme participants and non-participants, we used a cost-function based acreage allocation model to examine adoption of structural conservation practices, including such practices as strip cropping, terraces, grassed waterways, field borders, and stream-side herbaceous buffers. To accurately assess the potential environmental impacts of conservation programmes, it is important to account for the variability in on-site field, farm, and environmental conditions influencing producer adoption decisions. Econometric models suggest that not accounting for factors such as field, farm, operator, and environmental attributes will likely under- or overestimate adoption of conservation structures with respect to input and commodity prices, regardless of programme participation status.

Does Plant Variety Protection Contribute to Crop Productivity? Lessons for Developing Countries from US Wheat Breeding

The application of intellectual property rights (IP) in developing countries is and remains highly controversial, particularly as regards applications to food/agriculture, and pharmaceuticals, which have direct ramifications for large numbers of peoples. One dimension complicating a reasoned dialogue on the public benefits of IP, particularly when many developing countries are implementing the Agreement on Trade‐Related Aspects of Intellectual Property Rights (TRIPS) as mandated by membership in the World Trade Organization, is a dearth of information on their actual operation and effects. In this study, we address one particular aspect of the limited documentation on the effects of IP systems, the effect of plant variety protection (PVP) on the genetic productivity potential of varieties. Specifically, we examine wheat varieties in Washington State, United States, which are produced by both public and private sector breeders. Results from the study show that implementation of PVP attracted private investment in open pollinated crops such as wheat in the United States and provided greater numbers of varieties of these crops, which are high yielding from both the public and private sectors. These results may provide some insights for policy makers from developing countries on the effects of IP for plants as their TRIPS commitments are being implemented.

Integrated strategies for Fusarium head blight management in the United States

Optimum management of Fusarium head blight in wheat and barley is best achieved with multiple strategies; a single strategy generally fails during epidemic conditions. Members of the management group of the US Wheat and Barley Scab Initiative established integrated management studies in 2007, across multiple regions and grain classes, to quantify the value of additive strategies for Fusarium head blight and deoxynivalenol reduction. Strategies studied were a combination of two or three of the following approaches: variety resistance, fungicides, and crop rotation. Results in the northern plains state of North Dakota indicated that the lowest field severity of Fusarium head blight and the lowest deoxynivalenol, and the highest yields and test weights were achieved with multiple, rather than single management strategies.

Analysis of gene-derived SNP marker polymorphism in US wheat (Triticum aestivum L.) cultivars

In this study, we developed 359 detection primers for single nucleotide polymorphisms (SNPs) previously discovered within intron sequences of wheat genes and used them to evaluate SNP polymorphism in common wheat (Triticum aestivum L.). These SNPs showed an average polymorphism information content (PIC) of 0.18 among 20 US elite wheat cultivars, representing seven market classes. This value increased to 0.23 when SNPs were pre-selected for polymorphisms among a diverse set of 13 hexaploid wheat accessions (excluding synthetic wheats) used in the wheat SNP discovery project (http://wheat.pw.usda.gov/SNP). PIC values for SNP markers in the D genome were approximately half of those for the A and B genomes. D genome SNPs also showed a larger PIC reduction relative to the other genomes (P < 0.05) when US cultivars were compared with the more diverse set of 13 wheat accessions. Within those accessions, D genome SNPs show a higher proportion of alleles with low minor allele frequencies (<0.125) than found in the other two genomes. These data suggest that the reduction of PIC values in the D genome was caused by differential loss of low frequency alleles during the population size bottleneck that accompanied the development of modern commercial cultivars. Additional SNP discovery efforts targeted to the D genome in elite wheat germplasm will likely be required to offset the lower diversity of this genome. With increasing SNP discovery projects and the development of high-throughput SNP assay technologies, it is anticipated that SNP markers will play an increasingly important role in wheat genetics and breeding applications.

The genetic diversity of UK, US and Australian cultivars of Triticum aestivum measured by DArT markers and considered by genome

The genetic diversity of UK, US and Australian wheat varieties over the period of modern plant breeding is estimated using diversity array technology markers. Diversity is assessed by both genetic distance between varieties, by AMOVA and as the volumes of multi-dimensional convex hulls estimated from principal co-ordinate analysis. At the whole genome level the three populations are genetically distinct; this is also true of the B genome. However, the US and Australian D genomes are found to occupy the same region of diversity space and the A genomes for these countries are partially overlapping. The use of high-density genotyping with a common marker set allows an unprecedented direct comparison between the diversities of the national populations, between individual genomes and the fluctuation of diversity over time. The highest genetic diversity amongst varieties is reported in the Australian population followed by the US, which in turn is more diverse than the UK. However the average diversity of loci is higher in the US set than in the Australian. Non-random fluctuations in genetic diversity over time are observed.

Structural Change and Long‐run Relationships between US and EU Wheat Export Prices

AbstractThis paper analyses the nature of the long‐run relationship between US and EU wheat export prices over the period 1981–2000. We employ a novel approach of testing for cointegration with structural change developed by Barassi and Taylor (A Test for Change in the Cointegrating Rank, University of Birmingham, Birmingham, 2004). The method enables us to determine the breakpoint, which is found to occur after the 1992 CAP reforms were implemented. On analysing the two separate subperiods, we find no evidence of a long‐run relationship prior to the 1992 CAP reform. However, clear evidence of a long‐run relationship is found after the CAP reforms were implemented. Further analysis reveals that, in the post‐CAP reform period, the EU wheat prices follow then US soft wheat prices, consistent with the EU export subsidy regime over this period, albeit that export subsidies by the EU have been relatively small.

Molar fractions of high-molecular-weight glutenin subunits are stable when wheat is grown under various mineral nutrition and temperature regimens

Molar fractions of the high-molecular-weight glutenin subunits (HMW-GS) were determined for flour from bread wheat ( Triticum aestivum L. cv Butte86) produced under 13 different combinations of temperature, water and mineral nutrition. Albumins, globulins and gliadins were removed from the flour by extraction with 0.3 M NaI in 7.5% 1-propanol. Total HMW-GS were recovered by extracting the remaining protein with 2% SDS and 25 mM DTT. Individual HMW-GS were then separated and quantified by RP-HPLC. Constant molar fractions for the five HMW-GS were maintained under all environmental conditions, despite large differences in duration of grain fill, total protein per grain, flour protein percentage, and total HMW-GS per grain. Similar molar fractions were found for five other US wheat varieties. The Bx7 subunit accumulated to the highest level at 30% of total HMW-GS. The Dx and Dy subunits were present in smaller but nearly equal proportions, 22% and 23%, respectively, and the Ax and By subunits were the least abundant, 14% and 12%, respectively. Although the amounts of HMW-GS per unit of flour are strongly affected by environment, the different subunits respond so similarly to external conditions that their final proportions appear to be determined mainly by genetic factors.

Flour Characteristics and End-Use Quality of Korean Wheats with 1Dx2.2+1Dy12 Subunits in High Molecular Weight Glutenin

White salted noodles and pan bread were prepared from Korean wheats with 1Dx2.2+1Dy12 subunits in high molecular weight glutenin subunits (HMW-GS) to evaluate the suitability for end-use products through the comparison with US wheats with various classes and commercial wheat flours. Korean wheat flours with 1Dx2.2+1Dy12 subunits showed higher SDS sedimentation volume than US wheat flours with similar protein content. Compared to wheat flours with similar protein content and SDS sedimentation volume, water absorption percent of Korean wheat flours using a mixograph was higher than that of US wheat flours, but similar to commercial wheat flours. Mixograph mixing time was similar to hard wheat flours and commercial noodle flours. Optimum water absorption percent of noodle dough from Korean wheat flours was higher than that of US wheat flours. Noodle sheets from Korean wheat flours with 1Dx2.2+1Dy12 subunits showed lower L values, higher a values and similar b values compared to commercial noodle flours. Hardness of cooked noodles from Korean wheat flours 1Dx2.2+1Dy12 subunits correlated positively with protein content, NIRS hardness, mixograph water absorption and gluten yield of flours. Korean wheat flours with 1Dx2.2+1Dy12 subunits showed lower loaf volume and harder crumb firmness than hard wheat flours and commercial bread wheat flours in spite of similar protein quantity and quality to hard wheat flours.

Use of a large-scale Triticeae expressed sequence tag resource to reveal gene expression profiles in hexaploid wheat (Triticum aestivumL.)

The US Wheat Genome Project, funded by the National Science Foundation, developed the first large public Triticeae expressed sequence tag (EST) resource. Altogether, 116,272 ESTs were produced, comprising 100,674 5' ESTs and 15 598 3' ESTs. These ESTs were derived from 42 cDNA libraries, which were created from hexaploid bread wheat (Triticum aestivum L.) and its close relatives, including diploid wheat (T. monococcum L. and Aegilops speltoides L.), tetraploid wheat (T. turgidum L.), and rye (Secale cereale L.), using tissues collected from various stages of plant growth and development and under diverse regimes of abiotic and biotic stress treatments. ESTs were assembled into 18,876 contigs and 23,034 singletons, or 41,910 wheat unigenes. Over 90% of the contigs contained fewer than 10 EST members, implying that the ESTs represented a diverse selection of genes and that genes expressed at low and moderate to high levels were well sampled. Statistical methods were used to study the correlation of gene expression patterns, based on the ESTs clustered in the 1536 contigs that contained at least 10 5' EST members and thus representing the most abundant genes expressed in wheat. Analysis further identified genes in wheat that were significantly upregulated (p < 0.05) in tissues under various abiotic stresses when compared with control tissues. Though the function annotation cannot be assigned for many of these genes, it is likely that they play a role associated with the stress response. This study predicted the possible functionality for 4% of total wheat unigenes, which leaves the remaining 96% with their functional roles and expression patterns largely unknown. Nonetheless, the EST data generated in this project provide a diverse and rich source for gene discovery in wheat.

Economic substitution for US wheat food use by class*

Wheat for food use is conceptualised as an input into flour production and demand is derived from an industry profit function to quantify price responsiveness and economic substitutability across wheat classes. Price and substitution elasticities are estimated for hard red winter, hard red spring, soft red wheat, soft white winter and durum wheat. In general, hard red winter and spring wheat varieties are much more responsive to their own price than are soft wheat varieties and durum wheat. Substitution elasticities indicate that hard red winter and hard red spring wheat are economic substitutes for milling purposes.

Genetic Relationships among Head Blight Resistant Cultivars of Wheat Assessed on the Basis of Molecular Markers

Wheat head blight (Fusarium graminearum Schwab) can dramatically reduce grain yield and quality. Breeding for resistance is an effective measure of disease control. Wheat (Triticum aestivum L.) cultivars with various levels of Type II resistance have been reported worldwide; however, the genetic relationships among the cultivars with different origins are not well characterized. Sixty-five wheat cultivars from eight countries varying in head blight resistance levels were evaluated for Type II resistance and for genetic diversity on the basis of 322 amplified fragment length polymorphism (AFLP) and 19 simple sequence repeat (SSR) marker alleles. Cluster analysis using AFLP and SSR markers indicated that two Japanese landraces and most of the cultivars that relate to 'Ning 7840' aarry the Ning 7840 marker alleles that are tightly linked to the major quantitative trait locus (QTL) on chromosome 3BS. However, banding patterns of the markers linked to the major QTL in Ning 7840 were different from most of the Chinese landraces and those that originated from countries other than China and Japan. DNA fingerprinting data suggested that Chinese landrace Taiwan Wheat may be the donor of the QTL on chromosome 3BS. Combining the major QTL from Ning 7840 and other sources may facilitate pyramiding of different QTL. Cluster analysis and principal coordinate analysis (PCA) based on AFLPs and SSRs provided the best estimate of genetic relationships among wheat accessions studied. The result indicates that U.S. cultivars are more closely related to cultivars from Europe and Argentina than cultivars from Asia; therefore, integrating head blight resistance QTL from Asian sources into US wheat may increase the genetic diversity in U.S. wheat.

Genetic Relationships among Head Blight Resistant Cultivars of Wheat Assessed on the Basis of Molecular Markers

Wheat head blight (Fusarium graminearum Schwab) can dramatically reduce grain yield and quality. Breeding for resistance is an effective measure of disease control. Wheat (Triticum aestivum L.) cultivars with various levels of Type II resistance have been reported worldwide; however, the genetic relationships among the cultivars with different origins are not well characterized. Sixty-five wheat cultivars from eight countries varying in head blight resistance levels were evaluated for Type II resistance and for genetic diversity on the basis of 322 amplified fragment length polymorphism (AFLP) and 19 simple sequence repeat (SSR) marker alleles. Cluster analysis using AFLP and SSR markers indicated that two Japanese landraces and most of the cultivars that relate to ‘Ning 7840’ carry the Ning 7840 marker alleles that are tightly linked to the major quantitative trait locus (QTL) on chromosome 3BS. However, banding patterns of the markers linked to the major QTL in Ning 7840 were different from most of the Chinese landraces and those that originated from countries other than China and Japan. DNA fingerprinting data suggested that Chinese landrace Taiwan Wheat may be the donor of the QTL on chromosome 3BS. Combining the major QTL from Ning 7840 and other sources may facilitate pyramiding of different QTL. Cluster analysis and principal coordinate analysis (PCA) based on AFLPs and SSRs provided the best estimate of genetic relationships among wheat accessions studied. The result indicates that U.S. cultivars are more closely related to cultivars from Europe and Argentina than cultivars from Asia; therefore, integrating head blight resistance QTL from Asian sources into US wheat may increase the genetic diversity in U.S. wheat.

The effects of the US Plant Variety Protection Act on wheat genetic improvement

In our model of partially appropriable invention, if the US Plant Variety Protection Act (PVPA) of 1970 succeeded in strengthening intellectual property protection for plant breeders, it should have led to increases in investment in varietal R&D, improved varietal quality, and enhanced royalties. These hypotheses are tested using data on US wheat. We find that the PVPA may have stimulated public (but not private-sector) investment in wheat varietal improvement but that the PVPA did not cause any increase in experimental or commercial wheat yields. These findings indicate that the PVPA had little impact on excludability or appropriability in wheat varieties.

Distribution of microsatellite alleles linked to Rht8 dwarfing gene in wheat

A wheat microsatellite locus, Xgwm 261, whose 192-bp allele closelylinked to the dwarfing gene Rht8, on chromosome 2D, was used toscreen 71 wheat cultivars from 13 countries to assess the variation at thislocus. Screening of this wheat collection showed that a 165-bp allele anda 174-bp allele were the most frequent. None of the New Zealand cultivarspossessed a 192-bp allele specific to Rht8, while only one cultivarfrom the US produced this important allele. The frequency of a 192-bpallele among these wheat cultivars was 5.63%. The highest allelefrequency was observed for a 174-bp fragment (52.11%) followed by a165-bp fragment (26.76%). The only durum wheat `Cham 1', did notshow any amplification due to the absence of D genome. Four new novelalleles, 180-bp, 198-bp, 200-bp and 204-bp present in the US and NewZealand wheat cultivars are reported.

Attribution and other problems in assessing the returns to agricultural R&amp;D

AbstractEstimated rates of return to research are distorted by problems of attributing the credit for particular research results, or for particular research‐induced productivity increases, among research expenditures undertaken at different times, in different places, and by different agencies. A comprehensive assessment of the evidence from past economic evaluations of the returns to agricultural R&amp;D indicates that studies generally report high rates of return, with enormous variation among studies, but that much of this evidence has been tainted by inadequate attention to attribution problems. This paper raises these concerns in a general way and illustrates their importance with reference to two particular types of attribution problem. First, we consider the problem of accounting for locational spillovers in attributing varietal‐improvement technology among research performers, using US wheat varieties as an example. Second, we consider the temporal aspects of the attribution problem using the specification of research lags in econometric models to illustrate the problem of attributing aggregate productivity gains to research expenditures made at different times.

Wheat demand in Japanese flour milling industry: a production theory approach

AbstractA production approach based on the translog cost function is used to analyze import demand for wheat differentiated by class and country of origin in the Japanese wheat flour milling industry. Results indicate that US wheat faces strong competition in the Japanese wheat market, but its multiple classes and end‐use characteristics enable the US to preserve the largest market share in Japan.

Comparing the value of Southern Oscillation Index-based climate forecast methods for Canadian and US wheat producers

Southern Oscillation Index (SOI) based forecasting methods are compared to determine which method is more valuable to Canadian and US wheat producers. Using decision theory approach to valuing information, the more commonly used three-phase method of El Niño, La Niña, and other is compared to a five-phase system. Because of differences in growing season and yearly SOI classification schemes, two different three-phase methods are used. The five-phase system is based on the level and rate of change of the SOI over a 2 month period. Phases are consistently negative, consistently positive, rapidly falling, rapidly rising, and near zero. As expected, results vary by the method used. Winter wheat producers in Illinois place no value on either of the SOI-based forecasting systems. Producers at seven of the 13 sites prefer the five-phase method over either of the three-phase method (spring wheat producers in Manitoba, Alberta, North Dakota and South Dakota, along with winter wheat producers in Oklahoma, Texas, and Washington). The value of the five-phase approach is up to 70 times more valuable than the three-phase approach. Producers growing spring wheat in Saskatchewan and Montana, along with winter wheat producers in Ohio and Kansas value the three-phase approach more than the five-phase. In this case, the value of the three-phase system is up to two times more valuable than the five-phase system. Depending on expected price and region, the values of the SOI-based forecasts range from 0 to 22% of the value of perfect forecasts. In both absolute and percentage of perfect forecasts, producers in Oklahoma, Texas, Manitoba, Saskatchewan, and South Dakota value either system more than producers in the remaining regions. Economic value and distributional aspects of the value of climate forecasts have implications for producers, policy makers, and meteorologists. Finally, the results clearly suggest all producers will not prefer one forecast type. Forecasts need to be tailored to specific regions.

No significant difference in antigenicity or tissue transglutaminase substrate specificity of Irish and US wheat gliadins.

The prevalence of clinical celiac disease has been shown to vary both across time and between genetically similar populations. Differences in wheat antigenicity and transglutaminase substrate properties are a possible explanation for these differences. This study assessed the antigenicity and transglutaminase substrate specificities of gliadins from regions of high and low celiac disease prevalence. Gliadin was extracted from three commercial US wheat sources and two Irish sources. SDS-PAGE and western blotting revealed minor, but significant variations in the gliadin extracts. However, ELISA showed no difference in the antigenicity of these gliadins. Transglutaminase pretreatment of gliadin resulted in no significant change in gliadin antigenicity and kinetic studies showed that the Kms of the various gliadins were very similar. Purified IgA and IgG had no effect on transglutaminase activity. In summary, minor variations in wheat gliadins are unlikely to explain the observed differences in disease expression across genetically similar populations.

Wheat demand in Japanese flour milling industry: a production theory approach

A production approach based on the translog cost function is used to analyze import demand for wheat differentiated by class and country of origin in the Japanese wheat flour milling industry. Results indicate that US wheat faces strong competition in the Japanese wheat market, but its multiple classes and end-use characteristics enable the US to preserve the largest market share in Japan.