bluuebunny/crossref_metadata_2025 huggingface dataset:
Herbage Mass, Nutritive Value, and Ergovaline Concentration of Stockpiled Tall Fescue
Authors: Kallenbach R. L. , Bishop‐Hurley G. J. , Massie M. D. , Rottinghaus G. E. , West C. P.
Published: July 2010

Tall fescue (Festuca arundinacea Schreb.) infected with an endophyte that does not produce ergot‐like alkaloids (nontoxic endophyte) has not been evaluated for herbage mass, nutritive value, and ergovaline concentration when stockpiled during winter. Our objective was to quantify these responses for tall fescue infected with a native endophyte (K31 E+), a nontoxic endophyte (HiMag NTE), and with no endophyte (HiMag E−). Responses were measured on a fine, mixed, active, mesic Oxyaquic Fragiudalfs soil monthly from mid‐December through mid‐March in 1999‐2000 (Year 1) and 2000‐2001 (Year 2) in southern Missouri. Herbage mass for K31 E+ averaged 2370 kg ha−1, which was ≈20% greater than HiMag E− or HiMag NTE. Herbage mass did not change from mid‐December through mid‐March for any entry. The nutritive value of all entries was equal on comparable dates with acid detergent fiber (ADF) ranging from 285 to 338 g kg−1 during the winter. Nutritive value was highest in mid‐December of each year and then declined slowly after that. Neither HiMag E− nor HiMag NTE contained ergovaline, but K31 E+ had substantial concentrations of ergovaline in both years. The ergovaline concentration of K31 E+ was 454 μg kg−1 in December of Year 1 and 175 μg kg−1 in December of Year 2, but declined by ≈85% by March each year. The stable herbage mass, slowly declining nutritive value, and absence of ergovaline in HiMag E− and HiMag NTE suggest that livestock producers could eliminate toxicosis problems by stockpiling these forages for winter grazing.
Influence of Cry1Ab Protein and Hybrid Genotype on Fumonisin Contamination and Fusarium Ear Rot of Corn
Authors: Clements M. J. , Campbell K. W. , Maragos C. M. , Pilcher C. , Headrick J. M. , Pataky J. K. , White D. G.
Published: July 2010

Fusarium ear rot of corn (Zea mays L.) is associated with feeding damage from the European corn borer (ECB), Ostrinia nubilalis Hübner, and the corn earworm (CEW), Helicoverpa zea Boddie. Specific transformation events encoding for Cry1Ab protein from Bacillus thuringiensis Berliner (Bt) may reduce Fusarium ear rot and fumonisin concentration in grain by minimizing damage from certain insects. The objective of this study was to determine if effects from Cry1Ab protein in kernels and silks on fumonisin concentration in grain vary depending on the genotype of the hybrid or the predominant insect species. Four Bt corn hybrids and their corresponding nontransgenic, near‐isogenic hybrids were compared for ear rot severity and fumonisin concentration in grain in four environments. Treatments included inoculation with F. verticillioides (Sacc.) Nirenb. (Syn = F. moniliforme J. Sheld.) and F. proliferatum (Matsushima) Nirenb., infestation with ECB larvae, infestation with CEW larvae, and controls. Cry1Ab protein from the Mon810 transformation event was associated with reduced ear rot severity when hybrids were not inoculated with Fusarium spp., regardless of whether hybrids were infested or not infested with insects. Cry1Ab protein was associated with reduced fumonisin concentration in grain when ECB was the predominant insect, but not when CEW was the predominant insect. Cry1Ab protein was not associated with reduced fumonisin concentration in grain for the most resistant hybrid pair in this study. Results suggest that Bt hybrids can reduce fumonisin concentration in grain during seasons when ECB is favored, but not during seasons when CEW is favored. Hybrid genotype was an important factor in reducing fumonisin concentration in grain.
Electrolyte Leakage Assay Capable of Quantifying Freezing Resistance in Rose Clover
Authors: Nunes M. Eugénia S. , Smith G. Ray
Published: July 2010

Rose clover (Trifolium hirtum All.) is a winter annual legume with potential for increased use as a forage crop in Texas, Oklahoma, and the southern U. S. region. However, there is a need for rose clover with improved winter growth, extended seasonal forage production, and improved winter survival to increase the usefulness of this legume as a reseeding forage crop. The objectives of this study were to: (i) develop screening methods to measure freezing resistance; and (ii) discriminate freezing stress resistance differences in selected germplasm, both in controlled and field conditions. An electrolyte leakage (EL) test performed on young leaves (YL) at −14°C temperature for 60 min proved to be the most efficient for detecting both acclimation and cultivar differences in rose clover freezing tolerance. Under the climatic conditions prevalent during the experiment, the rates of acclimation and deacclimation were the same for three cultivars that were tested under controlled conditions and in the field. ‘Overton R18’ exhibited a general trend toward a higher level of freezing tolerance than ‘Kondinin’ or ‘Hykon’, both under controlled conditions and field testing. The experimental lines TX‐B97 and TX‐B29 had the apparent ability to respond rapidly to cold field conditions by reversing the deacclimation process. Other clover entries changed their rate of deacclimation in response to cold temperature but not as rapidly as TX‐B97 and TX‐B29.
Stockpiled Annual Ryegrass for Winter Forage in the Lower Midwestern USA
Authors: Kallenbach R. L. , Bishop‐Hurley G. J. , Massie M. D. , Kerley M. S. , Roberts C. A.
Published: July 2010

Livestock operations, particularly pasture‐based dairies in the lower Midwest, are interested in stockpiling annual ryegrass (Lolium multiflorum Lam.) as a source of high‐quality winter forage. Almost no information exists about stockpiling annual ryegrass in this region. Our objective was to determine the yield and forage quality of stockpiled annual ryegrass compared with cereal rye during winter in the lower Midwest. ‘Barmultra’ and ‘Marshall’ annual ryegrass were evaluated at two locations (Columbia and Mt. Vernon, MO) during the winters of 1998‐1999 (Year 1) and 1999‐2000 (Year 2). ‘Forage Master’ cereal rye (Secale cereale L.) was included as a comparison. Uncut strips (subplots) were harvested monthly from mid‐December through mid‐March each year. Stockpiled annual ryegrass yields ranged from 825 to 2356 kg ha−1, with Marshall yielding more than Barmultra on all but one harvest date during the 2 yr. Forage quality of stockpiled annual ryegrass typically declined from mid‐December through mid‐February, with a larger decline in a normal winter (Year 1) than in a mild winter (Year 2). Although forage quality tended to decline during winter, acid detergent fiber (ADF) never exceeded 252 g kg−1, and neutral detergent fiber (NDF) never exceeded 455 g kg−1 This suggests that stockpiled annual ryegrass could be used in the lower Midwest as a source of high‐quality winter forage for grazing livestock.
RAPD Analysis of 54 North American Flax Cultivars
Authors: Fu Yong‐Bi , Rowland Gordon G. , Duguid Scott D. , Richards Ken W.
Published: July 2010

Broadening the genetic base of linseed flax (Linum usitatissimum L.) cultivars to sustain improvement requires assessment of genetic diversity available in flax germplasm. The objective of this study was to analyze the genetic variation, genetic erosion, and genetic relationship of 54 North American flax cultivars by means of random amplified polymorphic DNA (RAPD) markers. The variations observed at the 84 polymorphic RAPD loci were relatively moderate with respect to primer, polymorphism, and cultivar. The proportions of fixed recessive RAPD loci for all the cultivars ranged from 36.9 to 59.2%, with an average of 45.3%. Genetic erosion in the century‐long breeding programs was not statistically significant as revealed by the proportion of fixed recessive RAPD loci, but the trend appeared to be that 2.5% of variable RAPD loci were fixed over 100 yr. While some variable RAPD loci were fixed over different breeding periods, the genetic relatedness of the cultivars was reduced in the Canadian programs, but not in the U.S. programs. The genetic relationships of the cultivars inferred via RAPD similarity were largely consistent with known, but incomplete, pedigrees. Both Canadian and U.S. cultivars were intermixed in various groups without distinct separation and several genetically distinct cultivars (i.e., NDR 52, Vimy, Rocket, Norland, Dakota, and Marine) were identified.
Quantitative Trait Loci for Partial Resistance to Phytophthora sojae in Soybean
Authors: Burnham K. D. , Dorrance A. E. , VanToai T. T. , St. Martin S. K.
Published: July 2010

Partial resistance to Phytophthora sojae Kauffmann and Gerdemann in soybean [Glycine max (L.) Merr.] is expressed as a reduced level of root rot and is effective against all populations of the pathogen. The objective of this study was to identify simple sequence repeat (SSR) markers associated with putative quantitative trait loci (QTLs) for partial resistance to P. sojae in the soybean ‘Conrad’. Three recombinant inbred soybean populations, Conrad × ‘Sloan’, Conrad × ‘Harosoy’, and Conrad × ‘Williams’, were evaluated for root lesion growth rate in growth chamber experiments following inoculation with P. sojae and with SSR markers to identify putative QTLs. The three populations segregated for root lesion growth rate after root inoculations. Two putative QTLs donated by Conrad were identified in all three populations and were positioned on soybean molecular linkage groups (MLGs) F and D1b+W. The QTL on MLG F explained 32.4, 35.0, and 21.4% of the genotypic variation for Conrad × Sloan, Conrad × Harosoy, and Conrad × Williams populations, respectively. The QTL on MLG D1b+W explained 10.6, 15.9, and 20.7% of the genotypic variation for the same three populations, respectively. The QTL on MLG F appears to be of more value based on the percentage of genotypic variation explained. Because the results indicate that QTLs for partial resistance to P. sojae map to different regions in soybean compared with the known Rps genes poses a challenge to soybean breeders. Marker‐assisted selection may expedite the process of combining both Rps genes with partial resistance into high‐yielding cultivars.
Cytogenetic Analysis of Festuca Species and Amphiploids between Festuca mairei and Lolium perenne
Authors: Cao Mingshu , Bughrara Suleiman S. , Sleper David A.
Published: July 2010

Intergeneric hybridization between Lolium and Festuca has been an interest of forage and turfgrass breeders because most agronomic and economically important traits found in Lolium and Festuca are complementary. However, low fertility of intergeneric hybrids has often been present and difficult to overcome. Synthesis of amphiploids from F1 hybrids was proven to be an effective way in restoring fertility of these intergenic hybrids. Amphiploids were used as bridging germplasm to improve forage quality and persistence in these two genera. In this report, amphiploids (LLM1M1M2M2) between F. mairei St. Yves. (M1M1M2M2, 2n = 4x = 28) and L. perenne L. (LL, 2n = 2x = 14) were produced from the F1 hybrid (F. mairei × L. perenne) through the treatment of colchicine and dimethyl sulfoxide (DMSO). Cytological analyses of pollen mother cells (PMCs) indicated that the amphiploids were unstable in meiosis with chromosome configurations of 9.75 I + 15.32 II + 0.43 III + 0.10 IV at metaphase I (MI). The pollen potassium iodide (KI) stainability of the amphiploids was 21%, while the F1 had only 0.1% pollen stainability. Interspecific hybrids were made through crosses between F. arundinacea Schreb. (6x) and F. mairei (4x). The pentaploid hybrids (PG1M1G2M2) had mean chromosome configurations of 6.47 I + 13.40 II + 0.30 III + 0.19 IV + 0.01 V at MI, indicating a close genomic relationship between F. arundinacea Schreb. (PPG1G1G2G2) and F. mairei (M1M1M2M2). The amphiploids and pentaploid hybrids were proposed to be used for improving drought persistence of tall fescue with incorporation of genes from drought‐tolerant F. mairei
A Low‐Cost, High‐Throughput Polyacrylamide Gel Electrophoresis System for Genotyping with Microsatellite DNA Markers
Authors: Wang D. , Shi J. , Carlson S. R. , Cregan P. B. , Ward R. W. , Diers B. W.
Published: July 2010

Microsatellite DNA markers are widely used in genetic research. Their use, however, can be costly and throughput is sometimes limited. The objective of this paper is to introduce a simple, low‐cost, high‐throughput system that detects amplification products from microsatellite markers by nondenaturing polyacrylamide gel electrophoresis. This system is capable of separating DNA fragments that differ by as little as two base pairs. The electrophoresis unit holds two vertical 100‐sample gels allowing standards and samples from a 96‐well plate to be analyzed on a single gel. DNA samples are stained during electrophoresis by ethidium bromide in the running buffer. In addition, one of the gel plates is UV‐transparent so that gels can be photographed immediately after electrophoresis without disassembling the gel‐plate sandwich. Electrophoresis runs are generally less than two hours. The cost per gel, excluding PCR cost, is currently estimated at about $2.60, or less than $0.03 per data point. This system has been used successfully with soybean [Glycine max (L.) Merr.] and wheat (Triticum aestivum L.) microsatellite markers and could be a valuable tool for researchers employing markers in other species.
Survey of U.S. Land‐Grant Universities for Training of Plant Breeding Students
Authors: Guner Nihat , Wehner Todd C.
Published: July 2010

A survey was conducted to identify land‐grant universities in the USA having plant breeding programs, and to determine the number of domestic and international plant breeding students graduating at the M.S. and Ph.D. levels from those programs in 1995 to 2000. A total of 71 U.S. land‐grant universities were identified. There were 409 (53%) Ph.D. and 361 (47%) M.S. degrees awarded. Of the total, 362 (47%) graduates were domestic and 408 (53%) were international. There was no major change in the total number of plant breeding graduates during the 6‐yr period. The largest numbers of plant breeding students were trained in agronomy (crop science) departments, followed by plant breeding departments or groups, horticulture departments, plant science departments, and combined agronomy–horticulture departments. Universities with an average of seven or more graduates per year were University of Wisconsin‐Madison, North Carolina State University, University of Nebraska‐Lincoln, Cornell University, University of Minnesota‐St. Paul, Iowa State University, and Texas A&M University. The downward trend noted in previous surveys has continued to the point where there are only a few universities with large plant breeding programs remaining in each region of the country. If the USA is going to continue its public effort in plant breeding research and graduate student training, sufficient federal and state funding will have to be provided to support at least the current regional centers.
Comparing Methods for Integrating Exotic Germplasm into European Forage Maize Breeding Programs1
Authors: Šimić Domagoj , Presterl Thomas , Seitz Günter , Geiger Hartwig H.
Published: July 2010

To broaden the genetic base of Central European germplasm of forage maize (Zea mays L.), it is necessary to integrate exotic materials into adapted breeding populations. The aim of the study was to compare several methods of integration by evaluating 18 initial crosses between adapted (recipient) and exotic (donor) elite dent inbred lines with regard to their testcross performance. Specific objectives were (i) to assess the effects of backcrossing the F1 to the recipient and intermating the F2 generation, (ii) to determine the benefit of selection for earliness, and (iii) to examine the influence of the recipient and donor genotype on the integration methods. Three foundation populations were developed from each of the initial crosses: F2, F2–Syn2 (= F2 twice intermated) and BC1 Fifty S1 lines were produced from the 4.4% earliest S0 plants of each foundation population. Bulks of these S1 lines along with the pertinent F1s and recipient parents were testcrossed with an adapted flint line. The testcrosses were evaluated in field trials at three locations in southern Germany in 1994 and 1995. Whole plant quality traits were investigated by near infrared spectroscopy (NIRS). Differences between generation means were significant for all agronomic traits and for starch content and crude protein content. For dry matter yield, the effect of backcrossing varied among the initial crosses, while the influence of intermating was nonsignificant in most instances. Averaged across all generations, initial crosses which had inbred lines B73 or Mo17 as donors were superior to all other crosses for dry matter yield without being later in maturity. For maturity, the effects of backcrossing, intermating, and selection for earliness generally were all germplasm specific. This suggests that the choice of germplasm is more important than the integration method.
Inheritance of Resistance to Fusarium Head Blight in Four Populations of Barley
Authors: Capettini Flavio , Rasmusson Donald C. , Dill‐Macky Ruth , Schiefelbein Edward , Elakkad Amar
Published: July 2010

Fusarium Head Blight (FHB), caused by Fusarium graminearum Schwabe [(teleomorph Giberella Zeae (Schwein.)], has been a major disease problem of barley (Hordeum vulgare L.) in the U.S. Midwest since 1993. It can make a potentially profitable barley crop unusable for malting, and substantially reduce its value as a feed grain. The main cause of economic loss in malting barley is the presence of deoxynivalenol (DON) or vomitoxin, a mycotoxin produced by the fungus. The objective of this research was to investigate the inheritance of resistance to FHB by the estimation of heritability through components of variance in multiple environments. Four populations resulting from crosses between putative resistant and susceptible parents were evaluated in inoculated and mist irrigated nurseries at three locations in Minnesota from 1995 to 1997 and China in 1997. On the basis of multiple environment data, estimates of heritability for FHB ranged from 0.48 to 0.76. Heritability estimates from individual environments for FHB ranged from low to high; these estimates were likely inflated by genotype × environment (G × E) interaction. Resistance levels approximating that of the resistant parent were recovered in most populations and one transgressive resistant line was found in Population 3. Transgressive segregates toward susceptibility were found in Populations 2, 3, and 4 for FHB. The heritability estimates were somewhat encouraging, as they indicated that moderate genetic gain can be expected when selecting for FHB resistance in a breeding program. However, a strong message was conveyed in the variable response of the parents and the ever present G × E interaction that FHB resistance breeding represents an unusually large challenge.
Best Types of Maize Hybrids for the Western High Plains of the USA
Authors: Guillen‐Portal F. R. , Russell W. K. , Baltensperger D. D. , Eskridge K. M. , D'Croz‐Mason N. E. , Nelson L. A.
Published: July 2010

Maize (Zea mays L.) production in the western High Plains of the USA occurs under dryland and irrigated conditions. Thus, an ideal maize hybrid for this region would have stable and high average performance across environments that are highly variable in productivity. Stability of a hybrid in this research was defined as its across‐environmental variance. Nine commercial single‐cross hybrids and 36 related double crosses were evaluated for grain yield in four irrigated and eight dryland environments in Nebraska, Colorado, and Wyoming. Environmental means ranged from 2.10 to 12.01 Mg ha−1 The average superiority of the single crosses over the double crosses in mean grain yield was 11.5%. However, the double crosses were generally more stable than the single crosses. This was true regardless whether stability was measured across all 12 environments or only across the eight dryland environments. The greater stability of the double‐cross hybrids in the dryland environments was the result of fewer extremely low or high yields compared with the single crosses. Hybrids were ranked considering both stability and mean performance with a safety‐first index. Values of this index depended on the value chosen for acceptable minimal yield. Across all 12 environments, a double‐cross hybrid ranked the best when the minimal acceptable yield was <2.68 Mg ha−1, and across the eight dryland environments this happened when the minimal acceptable yield was <1.88 Mg ha−1 Possible use of other types of heterogeneous maize hybrids in the Western High Plains are discussed.
Seed Priming Winter Wheat for Germination, Emergence, and Yield
Authors: Giri Ghana S. , Schillinger William F.
Published: July 2010

Insufficient stand establishment of winter wheat (Triticum aestivum L.) is a major problem in the low‐precipitation (<300 mm annual) dryland summer fallow region of the inland Pacific Northwest, USA. Low seed zone water potential, deep planting depths with 15 cm or more soil covering the seed, and soil crusting caused by rain before seedling emergence frequently impede winter wheat stands. A 2‐yr study involving laboratory, greenhouse, and field components was conducted to determine seed priming effects on winter wheat germination, emergence, and grain yield. Two cultivars were used because of their strong (Edwin) and moderate (Madsen) emergence capabilities. Germination rate was measured in the laboratory by 44 treatment combinations (two cultivars × three priming durations × seven priming media + two checks). Germination rate differed between cultivars as well as by priming duration, priming media, and concentration of priming media. The most promising laboratory treatments were advanced to greenhouse and field experiments where emergence and grain yield (field only) were measured in 10 treatments (two cultivars × four priming media + two checks) from wheat planted deep with 16 cm of soil covering the seed. In the greenhouse, seed primed in potassium chloride (KCl), polyethylene glycol (PEG), and water led to enhanced emergence of Madsen, but not of Edwin, compared with checks. Rate and extent of seedling emergence was greater for Edwin compared with Madsen irrespective of priming media in three of four field plantings at Lind, WA. None of the seed priming media benefited field emergence or subsequent grain yield in either cultivar compared with checks. Overall, results suggest that seed priming has limited practical worth for enhancing emergence and yield of winter wheat planted deep into summer fallow.
AFLP Analyses of Genetic Diversity in Bentgrass
Authors: Vergara G. V. , Bughrara S. S.
Published: July 2010

Bentgrasses (Agrostis spp.) are widely occurring temperate grasses with more than 220 species that represent a vast resource for genetic improvement of turfgrass cultivars. Bentgrasses are normally outcrossing species and exhibit many ploidy levels. Difficulties in morphological characterization, which are largely subjected to environmental influences, have resulted in many synonymous species and uncertainties in phylogenetic relationships. To study the genetic diversity and relationships between bentgrass species, 40 accessions from the USDA's germplasm collection representing 14 species of Agrostis from twenty countries were investigated by fluorescence‐labeled amplified fragment length polymorphism (AFLP) analysis. Four hundred AFLP markers from five chosen primer combinations were used to differentiate between bentgrass accessions of a bulk of 25 genotypes per accession. Genetic similarities between accessions ranged from 0.62 to 0.98 showing no duplication in the collection and a high level of diversity in Agrostis Both principal component analysis and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) dendrogram clearly distinguished seven groups. Genetic relationships between diploids and other polyploids were revealed in the cluster groupings.
Interspecific Hybridization as a Potential Method for Improvement of Agrostis Species
Authors: Belanger F. C. , Plumley K. A. , Day P. R. , Meyer W. A.
Published: July 2010

Some Agrostis spp., such as A. stolonifera L. (creeping bentgrass), A. capillaris L. (colonial bentgrass), and A. canina L. (velvet bentgrass), are commercially important turfgrass species which are used extensively on golf courses. Development of improved cultivars of these species is the focus of many commercial and academic breeding programs. Interspecific hybridization between Agrostis spp. has not yet been utilized in cultivar development. Here we have investigated the frequency of interspecific hybridization between transgenic creeping bentgrass and four related Agrostis spp. using transmission of a herbicide resistance gene as a marker to identify the hybrids. Interspecific hybrids were recovered with all four Agrostis spp. used, although the frequency was lower than the frequency of selfing. The hybrids were found to be fertile. Our results suggest that interspecific hybridization may be a useful approach in future Agrostis breeding, but will benefit from a screening method to distinguish the hybrids from the selfs.
Potential Grain and Forage Production of Early Maturing Pigeonpea in the Southern Great Plains
Authors: Rao S. C. , Phillips W. A. , Mayeux H. S. , Phatak S. C.
Published: July 2010

Forage‐based livestock production is a significant component of the agricultural economy throughout the southern U.S. Great Plains. However, Livestock production in grazing systems is limited by low forage mass and quality from late July to early November. Pigeonpea (Cajanus cajan L. Millsp.) is a warm‐season grain legume that may have potential as a summer forage crop. A 3‐yr (1996–1998) field study was conducted near El Reno, OK, to assess the performance of two early maturing pigeonpea lines, Georgia‐2 and ICPL 85010. The two lines did not differ significantly in forage and grain production and nutritive value. At 96 d after planting (DAP), total aboveground biomass was 5.2 Mg ha−1, N content was 23 g kg−1, and in vitro digestible dry matter (IVDDM) was 580 g kg−1 averaged across years. At final harvest (118 DAP), total dry biomass was 12.6, 6.4, and 9.3 Mg ha−1 in 1996, 1997, and 1998, respectively. Seed yield was 5.4, 1.9, and 1.2 Mg ha−1 in 1996, 1997, and 1998, respectively. Nitrogen concentration and IVDDM at final harvest was 19 and 585 g kg−1 for total plant biomass, 34 and 758 g kg−1 for leaves, 9 and 420 g kg−1 for stems, and 26 and 750 g kg−1 for seed, respectively. Early maturing pigeonpea lines can fill the forage deficit period during late summer and provide protein supplement for livestock.
White Clover Morphology Changes with Stress Treatments
Authors: Seker Hayati , Rowe Dennis E. , Brink Geoffrey E.
Published: July 2010

The plasticity of white clover (Trifolium repens L.) results in changes in plant habit in response to different environmental stresses. The objective of this research was to characterize those morphological changes associated with plasticity in white clover clones derived from ‘Osceola’, ‘Grassland Huia’, and SRVR germplasm. Clones were exposed to treatments in the following two‐way factorial design: no clipping or clipping on 7‐d intervals and barrier to stolon rooting or no barrier. In a three‐season greenhouse test, 90 clones were measured for leaf dry weight (DW), stolon DW, stolon length, root DW, and apex number. Generated parameters were herbage DW (leaf DW + stolon DW), biomass DW (root DW + herbage DW), leaf‐to‐stem ratio (leaf DW ÷ stolon DW), and herbage‐to‐root ratio (herbage DW ÷ root DW). Plant means were significantly reduced for all traits and ratios with repeated clipping. The rooting barrier significantly reduced apex number, root DW, and the leaf‐to‐stem ratio while increasing the stolon DW and the herbage‐to‐root ratio. The interaction of root barrier and repeated clipping was significant for apex number, root DW, and the herbage‐to‐root ratio. Near zero correlations for the same measurements made on the same clone grown with different stress treatments suggest genetic differences in the magnitude of plasticity. Path analysis further described changes in relationships among traits for plants exposed to different stresses. The magnitude of plasticity appeared to be a clone‐specific phenomenon that may frustrate verifying gain with selection for progenies of selections evaluated in different environments.
SEVERITY OF ASCOCHYTA BLIGHT IN RELATION TO LEAF TYPE IN CHICKPEA
Authors: Gan Yantai , Liu Puhai , McDonald Calvin
Published: July 2010

Severity of Ascochyta blight (Ab) [caused by Ascochyta rabiei (Pass.) Labrousse] in chickpea (Cicer arietinum L.) can be reduced by use of cultivars with a desirable plant architecture. Field experiments were conducted in semiarid southwestern Saskatchewan in 2001 and 2002 to determine the relationship between Ab severity and leaf shape in chickpea. Seed was treated with thiabendazole [2‐(thiazol‐4‐yl)benzimidazole], and metalaxyl [N‐(2,6‐dimethylphenyl)‐N‐(methoxyacetyl)‐DL‐alanine methyl ester] to reduce seed‐borne diseases, and plots were sprayed with chlorothalonil (tetrachloroisophthalonitrile) and azoxystrobin [methyl (E)‐2‐{2‐[6‐(2‐cyanophenoxy) pyrimidin‐4‐yloxy]phenyl}‐3‐methoxyacrylate] to minimize leaf diseases. Chickpea with fern leaves were compared with those with unifoliate leaves for their susceptibility to Ab. No diseases were observed during the seedling stage. As the crop approached preflowering, Ab symptoms became evident and the differences in Ab severity became great between fern‐ and unifoliate‐leafed chickpea. Measured at the bloom stage in 2001, Ab severity was 36% for unifoliate‐leafed chickpea and 12% for fern‐leafed chickpea. In the cool, moist year of 2002, the disease was severe with the unifoliate‐leafed chickpea having an Ab severity of 95%, compared with 35% for the fern‐leafed chickpea. The relative rankings of Ab severity between the two leaf types remained the same even when plant population was increased from 21 to 76 plants m−2 Chickpea producers in the semiarid northern Great Plains should select cultivars with a fern leaf shape to reduce the Ascochyta disease pressure and minimize disease damage to the crop.
A Decade of QTL Mapping for Cyst Nematode Resistance in Soybean
Authors: Concibido Vergel C. , Diers Brian W. , Arelli Prakash R.
Published: July 2010

Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe), the most destructive pest of soybean [Glycine max (L.) Merrill], is estimated to be responsible for almost nine million megagrams in annual yield loss worldwide. Host plant resistance is the most cost‐effective and environmentally friendly method of controlling SCN. Resistance is present among soybean plant introductions (PIs) and related wild species, such as Glycine soja Sieb. and Zucc. Molecular marker technology has ushered in a decade devoted to the identification and characterization of quantitative trait loci (QTL) underlying SCN. These genetic mapping efforts uncovered numerous locations of SCN resistance QTL in many PIs. In more than a decade of mapping SCN resistance QTL, there is some consistency in the results. In almost all studies involving various sources of resistance, the QTL conferring the greatest level of resistance mapped to the region containing rhg1 on linkage group (LG) G. In addition, a major resistance QTL was mapped in many sources to the region containing Rhg4 on LG A2. The mapping of QTL to these regions from many sources suggests that these sources may have resistance genes in common, which has caused concern over the possible dependence on a few resistance genes. Recently, two independent research groups reported cloning candidate genes for rhg1 and Rhg4 Despite these advances, there is some degree of trepidation, especially in the public sector, on the use of rhg1 and Rhg4 genetic mapping and cloning information in SCN resistance breeding because of intellectual property issues.
Evaluation of Oat Kernel Size Uniformity
Authors: Doehlert Douglas C. , McMullen Michael S. , Jannink Jean‐Luc , Panigrahi Surangan , Gu Huanzhong , Riveland Neil R.
Published: July 2010

Oat (Avena sativa L.) kernel size uniformity is important to the oat milling industry because oat‐processing mills separate oats according to size to optimize dehulling efficiency. In this study, we compared two different approaches for analyzing oat kernel size uniformity, namely the sequential sieving of oat samples with a gradient of slotted sieve sizes and digital image analysis. Image analysis of size fractions provided evidence that sieving separated oat kernels according to their depth, whereas, digital image analysis measured kernel length and width, and derived a measure of the area of the oat kernel image. Samples identified by sieving with superior uniformity were those with greater proportions of large kernels. Histograms of oat kernel sizes derived from digital image analysis suggested oat kernel sizes were (within a genotype and location) composed of bimodal populations. A new statistical analysis allowed for the derivation of means and variances of each of these subpopulations, the numerical balance between the two subpopulations, and the extent of bimodality. Oat samples with lower levels of bimodality tended to be of higher test weight and groat percentage and thus, of better milling quality. Both methods appear satisfactory for evaluating oat kernel size uniformity, although the sequential sieving method is likely to be more useful to breeding programs because of its relative technical ease and simplicity.
Indehiscence Expression and Capsule Anatomy in Vernola
Authors: Verdolini F. , Anconetani A. , Laureti D. , Pascual‐Villalobos M. J.
Published: July 2010

Euphorbia lagascae Spreng. is a potential new industrial crop because of the synthesis of vernolic acid in about 65% of the total fatty acids in its seed oil. Breeding research in the 1990s gave rise to the indehiscent Vernola cultivar as opposed to a complete dehiscence of the wild types. With the aim to evaluate the environmental influence in the expression of the nonshattering trait, field trials were sown in spring and autumn in Murcia, Spain, and Ancona, Italy, during 2001 and 2002. To further examine the basis of partial indehiscence, a capsule wall histological study was also performed. There was a significant decrease (P < 0.01) from 86.9 to 67.9% in the number of capsules retained per plant in the spring sowing, when mister sprinklers were used to increase relative humidity (RH) during pod formation. Overall, 37.9% indehiscent capsules per plant were retained in the autumn cycle vs. 77.4% in the spring cycle, indicating a strong influence of the growing season, which was associated to a combined effect of higher moisture and lower temperatures during capsule development. Transversal sections of carpel walls from Vernola capsules showed that the physical reason of the partial dehiscence observed in this cultivar is a small portion of the mesocarp remaining near the valve sutures, which makes the fruits susceptible to a slower opening under some environmental conditions.
Biomass and Carbon Partitioning in Switchgrass
Authors: Frank A. B. , Berdahl J. D. , Hanson J. D. , Liebig M. A. , Johnson H. A.
Published: July 2010

Grasslands have an underground biomass component that serves as a carbon (C) storage sink. Switchgrass (Panicum virgatum L.) has potential as a biofuel crop. Our objectives were to determine biomass and C partitioning in aboveground and belowground plant components and changes in soil organic C in switchgrass. Cultivars Sunburst and Dacotah were field grown over 3 yr at Mandan, ND. Aboveground biomass was sampled and separated into leaves, stems, senesced, and litter biomass. Root biomass to 1.1‐m depth and soil organic C to 0.9‐m depth was determined. Soil C loss from respiratory processes was determined by measuring CO2 flux from early May to late October. At seed ripe harvest, stem biomass accounted for 46% of total aboveground biomass, leaves 7%, senesced plant parts 43%, and litter 4%. Excluding crowns, root biomass averaged 27% of the total plant biomass and 84% when crown tissue was included with root biomass. Carbon partitioning among aboveground, crown, and root biomass showed that crown tissue contained approximately 50% of the total biomass C. Regression analysis indicated that soil organic C to 0.9‐m depth increased at the rate of 1.01 kg C m−2 yr−1 Carbon lost through soil respiration processes was equal to 44% of the C content of the total plant biomass. Although an amount equal to nearly half of the C captured in plant biomass during a year is lost through soil respiration, these results suggest that northern Great Plains switchgrass plantings have potential for storing a significant quantity of soil C.
Marker‐Assessed Retention of Wheat Chromatin in Wheat (Triticum aestivum) by Jointed Goatgrass (Aegilops cylindrica) Backcross Derivatives
Authors: Kroiss L. J. , Tempalli P. , Hansen J. L. , Vales M. I. , Riera‐Lizarazu O. , Zemetra R. S. , Mallory‐Smith C. A.
Published: July 2010

With the advent of herbicide‐resistant wheat (Triticum aestivum L.), there is a concern with the potential for gene migration between wheat and jointed goatgrass (Aegilops cylindrica Host.). This is especially true for genes on the D genome, since this genome is shared by wheat and jointed goatgrass. To study the potential for gene migration, BC1 and BC2 plants were produced with jointed goatgrass as the male recurrent parent. To determine if wheat chromatin was retained at expected Mendelian frequencies in these backcrosses, 14 simple sequence repeats (SSR) markers associated with the long and short arms of the D genome chromosomes were used. Chi‐square analysis showed that 12 of the 14 markers fit the expected ratio for retention of wheat alleles in the BC1 generation. In the BC2 generation, 11 of the 14 markers fit the expected frequencies for the retention of wheat alleles. The markers not fitting the expected frequencies in both generations deviated in the direction of more heterozygotes than expected, indicating a higher than expected retention of wheat alleles. Furthermore, recombination between the D genome chromosomes of the two species was observed. On the basis of these results, it appears that it is possible for a gene on the D genome of wheat to move into jointed goatgrass if the BC1 and BC2 generations were produced in the field.
Inheritance of ICA Bunsi‐Derived Resistance to White Mold in a Navy × Pinto Bean Cross
Authors: Miklas Phillip N. , Hauf Darrin C. , Henson Robert A. , Grafton Kenneth F.
Published: July 2010

Pinto beans (Phaseolus vulgaris L.) of cool subtropical and temperate origins are extremely susceptible to white mold disease caused by Sclerotinia sclerotiorum (Lib.) de Bary. Breeding pinto beans with resistance to white mold is difficult because of the paucity of resistant germplasm in a closely related background. White mold resistant ‘ICA Bunsi’, a small white navy bean, is from the same Middle American gene pool, but it is of warm tropical origin and needs to be exploited in pinto bean improvement. Our objectives were to determine inheritance of ICA Bunsi‐derived resistance in a cross with pinto bean, determine association of the resistance with disease avoidance, and identify white mold resistant pinto beans. White mold reactions of 85 F5:8 recombinant inbred lines (RIL) from the cross ‘Aztec’/ND88‐106‐04 were characterized in the field in North Dakota and Washington in 2001 and 2002. Aztec pinto is susceptible to white mold, and ND88‐106‐04 navy bean has partial resistance derived from ICA Bunsi. Disease severity score (1 = no disease to 9 = completely susceptible), yield, and disease avoidance traits were measured. Disease severity for Aztec and ND88‐106‐04 across environments was 6.9 and 2.5, respectively, compared with 4.6 for ICA Bunsi. Reduced lodging and late maturity enhanced disease avoidance. The RILs with stay‐green stem at harvest, similar to ND88‐106‐04, also exhibited less disease. Normal distribution and moderate heritability (Hns = 56 and 36% for WA and ND environments, respectively) for disease score indicated resistance was influenced by environment and likely conditioned by genes with small effects. Nonetheless, white mold resistance was present in a few RILs with high yield potential and pinto seed type.
Nitrogen Rate and Mowing Height Effects on Turf‐Type Buffalograss
Authors: Frank K. W. , Gaussoin R. E. , Riordan T. P. , Shearman R. C. , Fry J. D. , Miltner E. D. , Johnson P. G.
Published: July 2010

Buffalograss [Buchloë dactyloides (Nutt.) Engelm.] is a turfgrass species with reduced irrigation and fertilization requirements, relative to traditional turfgrasses. Interest in reducing the amount of chemicals and water applied to turfgrass has resulted in increased efforts to improve buffalograss as a turfgrass. As interest in using the new turf‐type buffalograss cultivars has increased, the need for nitrogen rate and mowing height recommendations supported by research have become necessary. ‘Cody’, ‘Texoka’, ‘378’, and ‘NE 91‐118’ buffalograss cultivars were planted at sites located in Nebraska, Kansas, and Utah to determine nitrogen rate and mowing height effects on buffalograss quality, color, density, and clipping yield. There were significant cultivar × nitrogen rate interactions at all sites for quality, color, and density. Regardless of cultivar, nitrogen rate × year interactions at all sites revealed that the 98 kg N ha−1 rate sustained quality, color, and density over the 3‐yr evaluation period, while lower nitrogen rates had decreased quality, color, and density. The 195 kg N ha−1 rate improved quality over the 3‐yr period but also had the highest clipping yields. Regardless of the cultivar selected, the data support the general mowing height recommendation for turf‐type buffalograss of 5.0 to 7.5 cm. For golf course fairways maintained at a mowing height of 2.5 cm, the vegetatively established cultivars (NE 91‐118 and 378) are the best choice to achieve high turfgrass quality.
Soybean Allergenicity and Suppression of the Immunodominant Allergen
Authors: Herman Eliot
Published: July 2010

The wide‐spread use of soybean [Glycine max (L.) Merr.] products in processed foods poses a potential threat to soybean‐sensitive, food‐allergic individuals. Clinical symptoms of soybean allergy can be manifested as gastric distress or atopic dermatitis and, while usually not life threatening, suspected cases of anaphylaxis have been reported. In vitro assays of soybean seed proteins with sera collected from soybean‐sensitive individuals have shown that major storage proteins as well as other minor seed proteins account for IgE binding. Gly m Bd 30k, a member of the papain superfamily of cysteine proteases, also referred to as P34, has been identified as a major allergen in soybean seeds. We have used gene silencing to eliminate accumulation of P34/Gly m Bd 30k in transgenic soybean. These transgenic plants, producing P34/Gly m Bd 30k‐null seeds, lacked any obvious developmental or phenotypic differences when compared with control plants. The production of a P34/Gly m Bd 30k‐null line eliminates one of the primary allergens present in soybean seeds.
Fusarium Head Blight Infection following Point Inoculation in the Greenhouse Compared with Movement of Fusarium graminearum in Seed and Floral Components
Authors: Argyris Jason , TeKrony Dennis , Hershman Don , VanSanford David , Hall Marla , Kennedy Brenda , Rucker Marcy , Edge Cheryl
Published: July 2010

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe can cause extensive losses in wheat (Triticum aestivum L.) seed quality and yield. Greenhouse studies were conducted in 2000 and 2001 to investigate the movement of F. graminearum into floral components of the wheat spike following point inoculation (PI) of a middle floret. The visual greenhouse rating of spikelet infection (severity) following PI for all genotypes in the Uniform Northern and Southern FHB Screening Nurseries with various levels of Type II resistance was also related to seed infection by F. graminearum in the same spikes and to field infection of all genotypes in 2001. Greenhouse ratings of FHB spikelet infection were poorly associated with F. graminearum infection in seeds and other floral components from the same spikelets. Pathogen movement was primarily localized around the PI (resistant cultivars) or moved basally from the PI (susceptible cultivars). Greenhouse FHB spikelet infection ranged from 5 (resistant genotypes) to 100% (susceptible genotypes) with a wide but unrelated range in seed infection in the same spikes. Thus, Type II resistance to FHB (measured by spikelet severity) in the greenhouse was not a good indicator of F. graminearum seed infection. Seed infection with F. graminearum exceeded 70% in all genotypes when grown under near epidemic conditions in the field nursery and was poorly related to visual measurements (spikelet severity and scabby seeds) of Type II resistance. It is proposed that a greenhouse rating of those spikes having <30% spikelet FHB infection can be combined with a laboratory evaluation of the same spikes with <30% F. graminearum seed infection to provide a more definitive method of selecting for Type II resistance.
Overseeding Buffalograss Turf with Fine‐Leaved Fescues
Authors: Severmutlu S. , Riordan T. P. , Shearman R. C. , Gaussoin R. E. , Moser L. E.
Published: July 2010

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] use as a turf in the northern USA is limited to a certain extent by its extended winter dormancy. A mixture of buffalograss with cool‐season turfgrasses might extend the turf's green appearance and enhance quality. Research was conducted to determine the effects of overseeding fine‐leaved fescue (Festuca spp.) in buffalograss turf on turfgrass color and quality and the effects of species, seeding rate and date, and core cultivation on fine‐leaved fescue establishment in buffalograss turf. Hard fescue (F. longifolia Thuill.), blue fescue (F. ovina L. var. glauca Lam.), and Chewings fescue (F. rubra L. ssp. commutata Gaud.); seeding rates (10, 20, and 30 g m−2); seeding dates (fall, spring, or split fall–spring); and core cultivation (single or double pass) were evaluated for species composition, turfgrass quality, color, and green cover at the John Seaton Anderson Turfgrass Research Facility located near Mead, NE. Buffalograss turf overseeded with blue fescue in fall had the highest turfgrass quality, color, and green cover ratings. Fall overseeding resulted in the highest shoot density values. Spring overseedings were below acceptable levels. Botanical composition of the mixtures overseeded in fall reached 75 to 80% fescue and 20 to 25% buffalograss after 2 yr. Seeding rate effect was linear with each increment between 10 g m−2 and 30 g m−2 increasing fine‐leaved fescue shoot density, turfgrass quality, color, and green cover. Blue fescue–buffalograss mixtures overseeded in the fall exhibited 80% green cover when buffalograss was dormant. Turfgrass green cover in the mixture was extended by 2 months when compared to buffalograss monostands growing in areas adjacent to the study. The results of this study support the use of fine‐leaved fescue and buffalograss mixtures to extend turfgrass green appearance and enhance quality.