bluuebunny/crossref_metadata_2025 huggingface dataset:
Diversity among Selected Vigna angularis (Azuki) Accessions on the Basis of RAPD and AFLP Markers
Authors: Yee E. , Kidwell K. K. , Sills G. R. , Lumpkin T. A.
Published: July 2010

Genetic diversity within the azuki Vigna angularis (Willd.) Ohwi and Ohashi genepool has not been extensively examined with molecular markers. The objectives of this study were to: (i) use RAPD and AFLP analyses to assess the genetic similarity among selected azuki accessions from distinct production regions in Asia, and( ii) compare the utility of the two DNA marker systems for evaluating similarity. Results also will provide information for parental selection in a breeding program. Fifty‐seven RAPD and 214 AFLP bands were used to assess genetic diversity among 58 azukia acessions. Thirty percent of the RAPD and 18% of the AFLP amplification products were polymorphic among accessions. One AFLP primer pair detected a mean of 11.3 polymorphic bands per reaction versus a mean of 3.2 for each RAPD primer. On the basis of Jaccard's similarity coefficients (JSCs), higher level of molecular genetic variation was detected among accessions evaluated in this study than in other diversity assessments of azuki. Mean JSC based on AFLP data was significantly higher than that obtained from RAPD data (0.71 and 0.52, respectively), and results from phylogenetic analyses varied between DNA marker systems. A substantial difference in the number of polymorphic bands detected through AFLP versus RAPD analysis may have influenced these results since the ability to resolve genetic relationships among genotypes is related to the number of polymorphisms detected. Cluster analysis revealed groupings among accessions; however, no apparent correlations with putative geographic origin were detected. Results of this study suggest that the level of genetic diversity among selected azuki accessions should be sufficient for developing an intraspecific mapping population.
Combining Ability for Rind Puncture Resistance in Maize
Authors: Kang Manjit S. , Din A. Kushairi , Zhang Yudong , Magari Robert
Published: July 2010

Stalk lodging of maize (Zea mays L.) may cause annual yield losses of more than 5%. Stalk strength can be improved by selecting for rind puncture resistance; however, additional information on the genetic nature of rind puncture resistance is needed. A seven‐parent (B73, H111, L266, L329, L605, L668, and L729) diallel was evaluated in 1994 and 1995 with the following objectives: (i) to estimate general (GCA) and specific combining ability (SCA) and reciprocal effects for rind puncture resistance and (ii) to ascertain whether ear‐internode data could be used in lieu of Internode 3 data. General combining ability variance was only significant at the ear internode, whereas SCA variance was not significant at either internode. Reciprocal effects were unimportant at either internode. For the ear internode, progeny performance can be adequately predicted from GCA estimates. Inbred lines L329 and L729 exhibited significant positive GCA effects at the ear internode, whereas B73 and L668 showed significant negative GCA effects at this internode. Inbred lines L329 and L729 could be used for developing hybrids or germplasm with stronger stalks. Year × genotype interactions were detected for both internodes, indicating that genotypes should be evaluated in more than one environment. Ear‐internode data provided experimental precision similar to that for Internode 3, but genetic differences among crosses were detected only in the ear‐internode data. The ear internode provided more convenient and useful information on rind puncture resistance. Rind puncture resistance of the ear internode would be a relatively easy trait to improve by practicing recurrent selection in a population developed from the germplasm evaluated in this study.
Differential Concentration of Ten Minerals among Four Ancestral Alfalfa Germplasms
Authors: Townsend M. S. , Henning J. A. , Smith D. W. , Ray I. M. , Currier C. G.
Published: July 2010

Rapid expansion of dairy herds in the southwestern USA has increased the need for high‐quality alfalfa (Medicago sativa L.) forage in the region. Enhancing mineral balance in alfalfa forage could benefit both plant and animal production. The objective of this study was to survey four ancestral alfalfa germplasms (representing the range in fall dormancy) for variability in shoot mineral concentration and for phenotypic associations among mineral concentrations. African, Chilean, Flemish, and Ladak germplasms, and the check cultivar Moapa 69, were evaluated in a 2‐yr irrigated field study near Las Cruces, NM. Plots consisted of 12.2‐m‐long raised beds spaced 1.2 m apart. Plant spacing within plots was 0.26 m. Ten plants per plot were randomly sampled in the early‐bud stage in 1993 and the late‐bud stage in 1994 and evaluated for P, Ca, S, Mg, K, Na, B, Cu, Fe, and Mn concentration using an inductively‐coupled plasma spectrometer. Years were a significant source of variation for all minerals except Mn, while the population × year interaction was significant for P, Ca, Mg, S, and Mn. The more dormant germplasms, Flemish and Ladak, generally had the highest P and K concentration and the lowest Ca concentration in both years. Flemish germplasm also possessed relatively high concentrations of S, Na, Fe, and Mn. A greater proportion of significant phenotypic correlations between minerals were observed in this study than in previous reports. These results suggest that Flemish‐based parental populations should provide useful genetic materials for enhancing mineral concentration in alfalfa forage.
A Thermosensitivity Index for Lupinus albus L
Authors: Clapham William L. , Willcott Julie B.
Published: July 2010

Phenology and plant architecture of spring lupin Lupinus albus L. vary with early thermal environment, which dramatically affects seed maturation and production. This study was conducted to develop and evaluate an index to quantify the relative differences among a selection of genotypes to “warm” and “cold” temperatures during early development. Seedlings of 27 lupin accessions and cultivars were incubated at 5 and 24°C for 3 wk and then grown to maturity in the greenhouse. The number of mainstem vegetative nodes at maturity were counted and used as the basis for developing an index of thermosensitivity. The simple difference between mainstem vegetative node numbers from seedlings incubated at 24 and 5°C provided a means for quantifying thermosensitivity and identifying thermoneutral genotypes. Significant simple difference values ranged from 4.69 to 20.33 and were not significant for cv ‘start’. An alternative standardized index was developed that allowed for comparisons within genotypes among years.
Thinning Border Rows Differentially Affects Hybrids in Corn Yield Trials
Authors: Esgar R.W. , Bullock D.G.
Published: July 2010

Border rows are used in yield trials to negate the effect of neighboring plots. Border rows are often not thinned to a final stand as are the harvest rows and it is assumed differential density in the border rows has a trivial effect on harvest row yield. In this study, 10 corn (Zea mays L.) hybrids were planted in 1994, 1995, and 1996 at Urbana, IL, in a randomized complete block design with 10 replications. Experimental units were four row plots with the middle two harvest rows thinned to a final stand of 68000 plants/ha while the outer two border rows were either thinned as the harvest rows or not thinned. Seed weight (g/100 seed) was significantly and negatively correlated with plants per row and significantly and positively correlated with grain yield Thinning border rows increased mean grain yield 0.2 Mg/ha and a significant hybrid × treatment interaction was detected. Thinning of border rows decreased the mean square error as much as 26%. Thinning of border rows affected the membership of the highest yielding (elite) group. This is particularly important because it is among this elite group that new hybrids are chosen. We conclude that both border rows and harvest rows should be thinned to a uniform final stand in corn yield trials and failure to do so may result in erroneous conclusions and wrong decisions.
Red Clover Seed Production: V. Root Health and Crop Productivity
Authors: Steiner J.J. , Alderman S.C.
Published: July 2010

Red clover (Trifolium pratense L.) is an important forage legume that is primarily grown for seed in western Oregon, but the effects of root health on red clover seed production systems are not well defined. This study was conducted to determine the effects of root health on red clover seed production. Thirty‐one seed fields were selected in spring 1992 and their cultivar identity, age of stand, and seed certification status (seed source groupings) determined by grower interviews and DNA analyses. Two herbage removal time treatments (early May and late June) were applied and the number of flowers and soil water content measured during the period of flowering and seed production. Root rot [Fusarium solani (Kuhn)] and root borer [Hylastinus obscurus (Marsham)] infestation were measured at early herbage removal time and seed harvest. The percentage of plants infested with root borers was the greatest root health determinate of seed yield, regardless of early or late herbage removal time. Seed yield was also correlated with the regrowth and flower production capacity of plants following herbage removal. For both herbage removal times, regrowth after removal was affected by the plant capacity to deplete soil water. Season‐end root borer infestation and soil water depletion amount were inversely related, indicating root integrity affected water utilization. Second‐year seed crops had greater disease and root borer damage than first‐year crops. Late herbage removal time treatments reduced flower density, seed yield, and season‐end phytomass compared with early removal. Genetic selection for improved root borer resistance may be a useful alternative selection strategy to root rot resistance for increasing red clover seed yields.
Confirmation of QTL Associated with Common Bacterial Blight Resistance in Four Different Genetic Backgrounds in Common Bean
Authors: Jung G. , Skroch P. W. , Nienhuis J. , Coyne D. P. , Arnaud‐Santana E. , Ariyarathne H. M. , Marita J. M.
Published: July 2010

Common bacterial blight (CBB), incited by the bacterial pathogen Xanthomonas campestris pv. phaseoli (Smith) Dye (Xcp) is a major problem in bean (Phaseolus vulgaris L.) producing areas worldwide. Using 128 recombinant inbred (RI) lines derived from the common bean cross BAC 6 × HT 7719, RAPD marker locus‐QTL associations were previously described for resistance to two Xcp strains, EK‐11 and Epif‐IV. The objective of this research was to test these candidate marker locus‐QTL associations in three previously untested genetic populations. In addition, RAPD marker locus‐QTL associations were also investigated for resistance to a third Xcp strain, DR‐7, in the first trifoliolate leaves in the original BAC 6 × HT 7719 population. The three genomic regions most significantly associated with CBB resistance in the original BAC 6 × HT 7719 population were significantly associated with CBB resistance in at least two of the three additional populations. The unmapped marker, BC409.1250, was significantly associated with CBB resistance in all four populations and all three Xcp strains, suggesting that this marker might be tightly linked to genes for CBB resistance. The RAPD marker BC409.1250 was converted into a marker that is a robust and reliable PCR‐based marker. Since similar genomic regions were found for resistance to three different Xcp strains, these QTL may be useful for breeding cultivars with a broad range of resistance.
Genetic Variability as Identified by AP‐PCR and Reaction to Mid‐Stem Infection of Sclerotinia sclerotiorum among Interspecific Sunflower (Helianthus annuus L.) Hybrid Progenies
Authors: Köhler H. , Friedt W.
Published: July 2010

Various diseases limit productivity in the majority of sunflower (Helianthus annuus L.) growing areas. Sunflower cultivars lack acceptable levels of resistance to Sclerotinia sclerotiorum (Lib.) de Bary, which is a major pathogen in sunflower production. Several wild Helianthus species are potential sources of genes for disease resistance and can be used in interspecific crosses to increase the genetic variability of cultivated sunflower. Progenies of interspecific hybrids between cultivated sunflower lines and Helianthus mollis Lam., H. decapetalus L., H. maximiliani Schrader, H. giganteus L., H. tuberosus L., and H. pauciflorus Nutt were tested for their mid‐stem Sclerotinia reaction by an artificial infection method. Compared with the susceptible commercial hybrid check cv. Frankasol, interspecific hybrid progenies were selected that showed reduced Sclerotinia infection. It could be demonstrated by results of AP‐PCR fingerprinting that interspecific hybrids can be a valuable tool for broadening genetic variability in sunflower. In total, 20 AP‐PCR primers were used for the characterization of interspecific hybrid progenies. It was possible to discriminate between the H. annuus parents and their progenies, where an increased genetic variability resulting from the interspecific hybridizations was detectable. Results of an UPGMA cluster analysis showed that interspecific hybrid progenies which originate in the same cross combination share a common cluster. These lines exhibited a large genetic distance from the parental sunflower inbred lines and form their own distinct genetic pool.
Development of Arm Specific RAPD Markers for Rye Chromosome 2R in Wheat
Authors: Brunell Mark S. , Lukaszewski Adam J. , Whitkus Richard
Published: July 2010

Rye (Secale cereale L.) chromosome 2R carries several genes for resistance to biotic and abiotic stresses, which could be used in wheat (Triticum aestivum L.) improvement. To make these genes accessible in breeding, translocations of 2R to wheat chromosome 2B have been generated. To compensate for the lack of clearly identifiable cytological markers on chromosome 2R, random amplified polymorphic DNAs (RAPDs) were employed as markers. Wheat lines homozygous for centric translocations 2RS.2BL and 2BS.2RL were screened with 489 primers, resulting in 65 clear and reproducible RAPD polymorphisms. To assign the polymorphisms to individual arms of chromosomes 2R and 2B, the arms of the translocations were separated by centric misdivision and the resulting progeny with desired chromosome constructs were rescreened. As a result, 17 markers were assigned to chromosome arm 2RS, 15 to 2RL, and the remaining 33 most likely located on 2B. Preliminary mapping studies (not shown here) have indicated that some of these markers are evenly distributed along the chromosome arms. These markers should be useful for the localization of translocation breakpoints in recombinant wheat‐rye chromosomes.
Yield Components of Wheat Grown under High Temperature Stress during Reproductive Growth
Authors: Gibson L. R. , Paulsen G. M.
Published: July 2010

High temperature is a major determinant of wheat (Triticum aestivum L.) development and growth, decreasing yields by 3 to 5% per 1°C increase above 15°C in plants under controlled conditions. Even greater yield differences have been reported between favorable and unfavorable temperature conditions in the field. The objective of this study was to identify the yield components of the hard red winter wheat cultivar Karl 92 that are affected by controlled high temperature during maturation of intact plants under simulated field populations. Plants at a final density of 144 m2 were grown in the greenhouse until anthesis and transferred to growth chambers for temperature treatment. Day/night temperatures of 20/20, 25/20, 30/20, and 35/20°C were imposed from 10 and 15 d after anthesis until ripeness in two experiments, and temperatures of 25/20, 30/20, and 35/20°C were applied from 20 d after anthesis until ripeness in a third experiment. Grain yield was reduced by 78%, kernel number was reduced by 63%, and kernel weight was reduced by 29% at 35/20°C compared with 20/20°C from 10 d after anthesis until ripeness. The yield loss from high temperature applied during this period was much greater than for previous controlled‐environment studies. Kernel numbers in treatments applied during early reproductive growth in our study were as sensitive to high temperature as wheat plants in previous field studies. High temperature applied 15 d after anthesis until ripening reduced grain yield 18%. Since kernel number was set by this time, the loss was exclusively due to decreased kernel weight. High temperature imposed from 20 d after anthesis decreased kernel weight by 18%.
Seed Dormancy and Aging in Atra Paspalum
Authors: Kalmbacher R. S. , West S. H. , Martin F. G.
Published: July 2010

Seed dormancy and aging affect maintenance of germination in storage and ultimately seedling establishment. The effects that year of harvest, heat vs. air drying seed at harvest, storage environment, and aging had on germination of ‘Suerte’ atra paspalum (Paspalum atratum Swallen) were studied. Across 5 yr, average germination of fresh seed at harvest was 0% during 0 to 7 d and 5% during 8 to 14 d of a 28‐d germination period. Total germination depended on year of harvest and ranged from 9 to 46%. Oven drying (40°C for 24 h) at harvest increased germination in 2 of 5 yr. Storing seed for 6 mo in a building with no environmental control (ambient condition) increased germination to 69% (3‐yr average) and shifted most of the germination to the first 7 d, but germination was nil after 1 yr. Germination averaged 55% at 28 d after harvest for seed stored at 3°C and changed little for up to 4 yr. Oven drying seed at harvest delayed the break in dormancy ≈1 mo compared with air drying seed. Chilling air‐dried, ambient stored seed at 3°C for 48 h before testing reduced germination at 84 d after harvest (compared with 28 d and 6 mo). Neither chilling oven‐dried seed nor heat (40°C for 24 h before testing) treatment of oven‐ and air‐dried seed affected germination. Removal of the lemma and palea at harvest resulted in 96% germination compared with 26% for intact seed. Treatment of freshly harvested seed with H2SO4 for 6 min and accelerated aging (48 h at 41°C, 100% relative humidity) increased germination from 29 to 68% and 30 to 48%, respectively. Dormancy in atra paspalum is short‐lived and should be of minor agronomic importance with fall seed harvest and spring sowing. Consideration must be given to seed storage conditions to assure viability beyond 1 yr.
Host Variation in Traits Associated with Crown Nodule Senescence in Soybean
Authors: Espinosa‐Victoria David , Vance Carrol P. , Graham Peter H.
Published: July 2010

Active N2 fixation in soybean [Glycine max (L.) Merr.] in Minnesota is limited by cool early‐season soil temperatures and by postflowering nodule senescence. This study examined variation in onset of nodule senescence among Maturity Group I soybean cultivars and sought traits associated with this variation. Host genotype markedly affected onset of crown nodule senescence. For most cultivars, crown nodule fresh weight and specific nodule activity (SNA) peaked 31 to 38 d after emergence (DAE) and declined rapidly thereafter. In contrast, maximum crown nodule fresh weight in ‘Hardin’ and ‘Hodgson 78’ did not occur until 52 DAE, and SNA was still high 45 to 52 DAE. Two cultivars, Chippewa and Alpha, that exhibited early change in crown nodule mass and SNA, accumulated glyceollin I 10 to 45 DAE at rates significantly greater than for Hardin and Hodgson 78. The four cultivars also differed in phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) gene expression, nodule protease activity, and polyamine accumulation. Morphological changes within the nodule paralleled the biochemical differences, with Chippewa nodules 45 DAE showing more conspicuous deterioration than was evident in Hardin. Because crown‐nodule mass and nitrogenase activity in Hardin and Hodgson 78 declined later than in other Maturity Group I cultivars, with less evidence of host–strain incompatibility, these two lines may have value in breeding programs to extend the period of active nodulation and N2 fixation in soybean.
Effect of Flower Color and Sampling Time on Volatile Emanation in Alfalfa Flowers
Authors: Pecetti Luciano , Tava Aldo
Published: July 2010

Flower volatile compounds of alfalfa (Medicago sativa L.) are involved in attractiveness to pollinating insects, and thus influence seed set. This study investigated differences in volatile emanation in this species by varying flower color of the sampled material or time of flower collection. Chemical determinations were made by gas chromatography and gas chromatography–mass spectrometry analyses. The first investigation examined volatile concentration in clones characterized by seven different color ratings. Significant variation among colors was found with a trend for greater emanation from dark‐ than from light‐colored flowers. This trend could bear an evolutionary significance to compensate for the possibly lower visibility of dark flowers in a stand. The second investigation analyzed volatiles from intact inflorescences and from florets and rachises taken separately. A substantial similarity of volatile amount and composition among the three kinds of samples was observed. The final investigation assessed the volatiles produced at different times of the day in each of the first three flowerings of the growing season, during which alfalfa pollination was expected to take place. Confirming previous evidence, temporal patterns of emanation were observed, with a sharp increase from the flowering in May to those in July and August and a strong time‐of‐day effect during the two summer flowerings (burst of volatiles around midday). The marked seasonal effect appeared somewhat related to temperature increase while the daily variation of emanation in summer paralleled that of solar radiation. There seems to be a coincidence between conditions for maximum volatile emanation and reported optima for insect foraging activity.
Genetic Diversity among Elite Sorghum Inbred Lines Assessed with Simple Sequence Repeats
Authors: Smith J. S. C. , Kresovich S. , Hopkins M. S. , Mitchell S. E. , Dean R. E. , Woodman W. L. , Lee M. , Porter K.
Published: July 2010

DNA markers are being increasingly utilized in cultivar development, quality control of seed production, measurement of genetic diversity for conservation management, varietal identity, and to assist in maintenance of intellectual property protection (IPP). The use of simple sequence repeats (SSRs) for variety profiling can provide high discrimination, with excellent reproducibility at less cost than for restriction fragment length polymorphisms (RFLPs). The objective of this study was to evaluate the potential utility of SSR technology for applications in research, product development, seed production, and genetic resource conservation management for sorghum. Fifty genetically diverse elite sorghum [Sorghum bicolor (L.) Moench] inbreds were used to compare the discrimination abilities of 15 SSR primers with 104 RFLPs and to compare the associations among lines revealed by these molecular data and by pedigrees. RFLP data allowed all lines to be uniquely identified; two lines could not be distinguished by the SSR data. The mean polymorphism information content (PIC) values were 0.62 (RFLPs) and 0.58 (SSRs). Correlations for pairwise molecular profile distances with pedigree distances among the maintainer female (B) lines were 0.52 and 0.53 for RFLP and SSR data, respectively; data for the male parental restorer (R) lines were 0.41 and 0.47. This set of SSRs could be used to help genetic conservation management and to support IPP. Data from additional SSRs that collectively cover more of the genome will be required for applications to assist in breeding.
RFLP Mapping of QTLs Influencing Shoot Regeneration from Mature Seed‐Derived Calli in Rice
Authors: Takeuchi Y. , Abe T. , Sasahara T.
Published: July 2010

This study focused on the mapping of quantitative trait loci (QTLs) related to shoot regeneration from mature seed‐derived calli of rice (Oryza sativa L.) by restriction fragment length polymorphism (RFLP) markers. The F2 population from a cross between ‘Norin 1’ (japonica) and ‘Tadukan’ (indica), which showed lower and higher shoot regeneration rates, respectively, was used for QTL interval mapping. The population was analyzed for 103 RFLP markers distributed over the 12 rice chromosomes. The QTL with the largest effect on shoot regeneration, which accounted for about 19% of the total variation, was mapped on chromosome 2. A minor QTL on chromosome 4 exhibited a smaller effect, accounting for about 3% of the total variation in percentage shoot regeneration. No QTLs were detected on other chromosomes with the RFLP markers that were used in the present experiments. These results indicate that at least one major gene is associated with the percentage shoot regeneration, and agree with previous genetic studies, indicating that one dominant gene is associated with shoot regeneration.
Agronomic and Seed Traits of 1%‐Linolenate Soybean Genotypes
Authors: Ross Andrew J. , Fehr Walter R. , Welke Grace A. , Cianzio Silvia R.
Published: July 2010

An oil from soybean [Glycine max (L.) Merr.] cultivars with <20 g kg−1 linolenate would have a desirable oxidative stability. The objective of our study was to compare the agronomic and seed traits of lines with the genotype fan1(A5)fan1(A5)fan2(A23)fan2(A23)fan3fan3, designated as 1%‐linolenate (<20 g kg −1) lines, and the genotype fan1(A5)fan1(A5)fan2(A23)fan2(A23), designated as 2%‐linolenate lines (>20 g kg−1). Three backcross populations were developed by crossing three high‐yielding, recurrent parents with ≈25 g kg−1 linolenate to a donor line with ≈13 g kg−1 linolenate. For each population, 27 1%‐ and 27 2%‐linolenate BC1F2:4 lines were evaluated at Ames, Grand Junction, and Hubbard, IA during 1998. The mean seed yields of the 1%‐linolenate lines were 47 kg ha−1 lower in Population 1, 65 kg ha−1 lower in Population 2, and 164 kg ha−1 lower in Population 3 than the 2%‐linolenate lines, but the difference was only significant in Population 3. The maximum mean differences between the 1%‐ and 2%‐linolenate lines in any of the populations for the remaining agronomic and seed traits were 1 d for maturity, 0.1 score for lodging, 2 cm for plant height, 4 mg seed−1 for seed weight, 5 g kg−1 each for protein and oil content, 0.6 g kg−1 for palmitate, 2.2 g kg−1 for stearate, 16.4 g kg−1 for oleate, and 6.8 g kg−1 for linoleate. The lack of major differences between the 1%‐ and 2%‐linolenate lines indicated that it should be possible to develop acceptable cultivars with <20 g kg−1 linolenate.
Stigma Receptivity and Seed Set in Protogynous Buffelgrass
Authors: Shafer Gail S. , Burson Byron L. , Hussey Mark A.
Published: July 2010

Buffelgrass, Pennisetum ciliare (L.) Link syn = Cenchrus ciliaris L., is an important warm‐season perennial forage grass that is widely grown throughout the arid tropics. It has perfect florets, and emasculation is thought to be required to produce controlled hybrids. This is a tedious, difficult undertaking because of the small floret size. The flowering behavior of buffelgrass is such that the stigmas are exserted from the floret prior to anthesis, which is referred to here as the protogynous interval. This investigation was conducted to determine the duration of the protogynous interval in 447 buffelgrass accessions and to ascertain stigma receptivity during the protogynous intervals. Protogynous intervals in a field nursery near College Station, TX, for all accessions ranged from 1 to 4 d. Six accessions with protogynous intervals ranging from 1 to 3 d were used to investigate stigma receptivity under both self‐ and cross‐pollinated conditions in a greenhouse. Pollen germination and tube growth were observed with fluorescent microscopy at different time increments following pollination. Across all accessions, pollen germinated within 15 min of contacting the stigma, and pollen tubes grew to the micropyle within 2 to 6 h, depending on the accession and pollen source. Mean seed set ranged from 11 to 76% and from 22 to 80% among accessions following self‐ and cross‐pollination, respectively. This investigation revealed that variation exists for protogynous interval within buffelgrass, and the stigmas are receptive when exserted from the floret and remain receptive throughout duration of the protogynous interval regardless of whether it occurs 3, 2, or 1 d prior to anthesis. These findings demonstrate that protogyny can be used to produced controlled hybrids in sexual buffelgrass without emasculation.
Genetic Mapping of Factors Affecting Quantitative Variation for Flowering in Sunflower
Authors: Leon A. J. , Andrade F. H. , Lee M.
Published: July 2010

The number of days from seedling emergence to flowering (DTF) is a major consideration in sunflower (Helianthus annuus L.) breeding because the maximum yield of the crop can only be achieved if the cultivars are phenologically adapted to the production environment. Identification of genetic factors that affect flowering could create opportunities for improved breeding methods and for more fundamental investigations of this important trait and its interactions with the environment. The objectives of this study were to locate quantitative trait loci (QTL) for DTF in an elite sunflower population evaluated in four environments. Two hundred thirty‐five F2‐generation plants and their F3 progeny of a single‐cross population of two divergent inbred lines were evaluated in four environments (Fargo, ND and Venado Tuerto, Daireaux, and Balcarce in Argentina). Detection of QTL was facilitated with a genetic linkage map of 205 loci defined by restriction fragment length polymorphism (RFLP) and composite interval mapping. Five QTL of five linkage groups accounted for 89% of the genetic variation for DTF. Gene action was additive at four QTL and dominant at the other locus. Three QTL were detected in all environments and generations. The parental effects and the relative magnitudes of the genetic effects of those QTL were consistent across generations and environments.
Copper Reduces Shoot Growth and Root Development of Creeping Bentgrass
Authors: Faust M. B. , Christians N. E.
Published: July 2010

Sand‐based golf course putting greens have been observed to contain elevated Cu concentrations, based on standard soil tests. Little research has been conducted that relates Cu concentration in sand media to turfgrass performance. The objectives of this study were to determine the response of greenhouse‐grown creeping bentgrass (Agrostis palustris Huds. ‘Penncross’) to treatments in rooting media that ranged from 0 to 600 mg Cu kg−1 and to provide an estimate of potentially toxic plant‐available Cu levels by use of the diethylenetriaminepentaacetic acid–triethanolamine (DTPA–TEA) soil test. Calcareous and silica sands were mixed individually with reed sedge peat in a 9:1 (v/v) ratio. Penncross sod plugs were placed on the top of pots containing the premixed sand–peat media and allowed to grow for 12 wk. The silica sand medium pH decreased from 6.8 to 5.4, while the pH of the calcareous medium remained between 7.2 to 7.3 as cupric sulfate (CuSO4 · 5H2O) concentrations increased. The average dry weight of clippings for plants grown in silica sand decreased 16% as Cu treatments increased from 0 to 600 mg kg−1 At 600 mg kg−1 Cu, dry root mass was 56 and 48% lower than the control treatments for plants grown in silica and calcareous sand, respectively. The DTPA–TEA soil test extracted, on average, 19% more Cu from the calcareous sand when compared to the silica sand. However, plant roots contained an average of 34% more Cu when grown in silica sand. These results indicate that the DTPA–TEA soil test was not a good predictor of potentially toxic plant‐available Cu in sand‐based media, and alternative soil test methods should be investigated.
Inheritance of Restriction Amplification Fragment Length Polymorphisms in Perennial Ryegrass
Authors: Sweeney Patricia , Danneberger Karl
Published: July 2010

Restriction amplification fragment length polymorphic (RAFLP) markers show promise as genetic markers in diploid outcrossing turfgrass species such as perennial ryegrass (Lolium perenne L.). The RAFLP markers should combine many advantages of restriction fragment length polymorphisms (RFLP) and random amplified polymorphic DNA (RAPD) markers and should exhibit codominance. After screening 88 primers that produced distinct fragments with five restriction enzymes, 64 restriction loci were identified. Sixteen of these appeared to be polymorphic for the restriction locus and were regarded as potential RAFLP markers. The progeny of crosses of heterozygous perennial ryegrass plants were evaluated to determine whether the proposed RAFLP markers identified in the parental plants segregated according to Mendelian genetics as predicted for codominant markers. Although 16 tentative RAFLP markers were identified, only one segregated as expected for a single locus with two alleles. Our results suggest that useful RAFLP markers will be difficult to find for outcrossing turfgrass species.
Identification of Tropical and Temperate Maize Populations Having Favorable Alleles for Yield and Other Phenotypic Traits
Authors: Kraja Aldi , Dudley John W.
Published: July 2010

If tropical germplasm is to be useful in increasing maize (Zea mays L.) grain yield, populations containing favorable alleles not present in elite hybrids need to be identified. Thus, a major objective of this study was to identify tropical and temperate populations containing favorable alleles useful for improving the Corn Belt hybrid FR1064 × LH185 (a commercial hybrid representative of the typical Stiff‐Stalk × Lancaster heterotic pattern). A group of tropical populations and hybrids from the Germplasm Enhancement of Maize Project (GEM) crossed to either Mo17 or B73 (temperate maize inbreds) was studied. In addition, a group of temperate accessions was evaluated. Grain yield, flowering date, plant height, ear height, and penetrometer reading were evaluated using Dudley's method for identifying populations with favorable alleles. Only three accessions of 41 had positive and significant relative numbers of favorable alleles for yield. For most accessions, unexpectedly, the estimate of l
plμ′ (an estimator of relative number of favorable alleles in the accessions not present in the hybrid to be improved) for yield was negative. Negative l
plμ′ values for yield resulted from low true values of l
plμ′ combined with low frequencies of favorable alleles in the accession for loci having favorable alleles in one inbred and not the other. None of the accessions were identified as having favorable alleles for lowering ear height or increasing stalk penetrometer resistance. These results suggest Dudley's method may not be useful when frequencies of favorable alleles in the populations being evaluated are very low.
Broad‐Sense Heritability and Stability of Internal Heat Necrosis and Specific Gravity in Tetraploid Potatoes
Authors: Henninger M. R. , Sterrett S. B. , Haynes K. G.
Published: July 2010

Internal heat necrosis (IHN), a severe physiological disorder of potato (Solanum tuberosum L.) tubers, is characterized by brown spots or blotches that first appear toward the apical end of the tuber parenchyma but in severe cases may involve most of the parenchyma tissue. The purposes of this study were to determine the amount of genetic variation for and the stability of IHN in tetraploid potato clones, and the relationships among IHN, specific gravity, and tuber size distribution. Nineteen potato clones (four cultivars and 15 breeding selections) were grown in Bridgeton, NJ and Painter, VA from 1991 to 1993 in a randomized complete block with four replications of 20 hills per plot. The crop was harvested 2 to 3 wk later than normal harvest time to provide for maximal exposure to heat stress. All tubers were harvested and graded by size. All tubers >64 mm in diameter were quartered longitudinally and rated by size for IHN Incidence and severity of IHN were recorded. Broad‐sense heritabilities and their 95% confidence intervals were: 0.83 (0.68, 0.93) for incidence of IHN in Size 3 (64–83 mm diameter) tubers; 0.88 (0.71, 0.94) for incidence in Size 4 (>83 mm diameter) tubers; 0.85 (0.72, 0.94) for severity of IHN in Size 3 tubers; 0.90 (0.78, 0.96) for severity of IHN in Size 4 tubers; 0.92 (0.85, 0.97) for specific gravity in Size 3 tubers; 0.77 (0.54, 0.91) for specific gravity in Size 4 tubers; and 0.86 (0.73, 0.94) for total yield. Several of the more IHN‐susceptible clones were unstable for IHN both before and after environmental heterogeneity was removed. The correlation between incidence and severity of IHN was very high. There was no correlation between IHN and total yield or specific gravity. The results of this study indicate that breeding high yielding, high specific gravity cultivars for resistance to IHN should be feasible.
Photoperiod Effects on Seed Quality Traits in Peanut
Authors: Dwivedi S. L. , Nigam S. N. , Rao R. C. Nageswara
Published: July 2010

Peanut (Arachis hypogaea L.) is a rich source of oil, protein, minerals, and vitamins. The chemical and physical seed quality aspects are gaining importance because of increased use of peanut as a food crop; however, little or no investigation has been carried out on the effect of photoperiod on these traits. The objective of this study was to determine the effect of photoperiod on seed quality traits. The experiment was conducted for three seasons in a three replicate split‐plot randomized complete block design with three photoperiods (ND = Normal day, 12 h; SD = Short day, 8 h; LD = Long day, 16 h) as main plots and 10 genotypes as subplots. The SD and LD conditions were created artificially. Pooled analysis of variance, based on a mixed linear model with season (S) as random and photoperiod (Ph) and genotype (G) as fixed effects, indicated significant S and G differences for most of the traits studied. Ph differences were significant only for shelling percentage and palmitic and eicosenoic fatty acids. The interactions S × Ph, S × G, Ph × G, and S × Ph × G were significant for several traits. When SD and LD treatments were compared with ND, shelling percentage increased under SD. Oil content, oleic (O) and linolenic (L) fatty acids, and O/L ratio were not affected due to variation in photoperiod. However, palmitic acid increased and eicosenoic acid decreased under SD. The SD conditions were more interactive with seasons and genotypes for fatty acids. High performing and photoperiod insensitive genotypes were identified for various seed quality traits. These genotypes would be useful in breeding programs aimed at developing high yielding genotypes with improved seed quality for edible purposes.
Hormone‐Containing Products' Impact on Antioxidant Status of Tall Fescue and Creeping Bentgrass Subjected to Drought
Authors: Zhang Xunzhong , Schmidt R. E.
Published: July 2010

This study was conducted to determine whether the plant endogenous antioxidant concentration is responsive to exogenous hormone‐containing products (HCPs) in two turfgrass species subjected to drought. Two‐week‐old seedlings of tall fescue (Festuca arundinacea Schreb.) and creeping bentgrass (Agrostis palustris Huds. A.) were treated with two HCPs, seaweed extract (SWE) at 326 g ha−1 or humic acid (HA, 25% a.i.) at 5 L ha−1, applied alone or in combination and grown under either −0.03 or −0.5 MPa soil moisture for 5 wk. Growth and antioxidant status of leaves were determined subsequently. The HCP treatments significantly improved leaf water status (LWS) and shoot and root growth of the grasses grown under high (−0.03 MPa) and low (−0.5 MPa) soil moisture. α‐Tocopherol concentration increased significantly and ascorbic acid concentration remained unchanged for drought‐stressed compared with nonstressed turfgrass. The HCP treatments significantly increased α‐tocopherol and ascorbic acid concentration of the grasses grown under high and low soil moisture. Positive correlation between antioxidants and shoot or root growth was found in the two grass species. Improvement of growth and LWS of turfgrass treated with HCPs may be related to its high antioxidant concentration.
Simple Sequence Repeat Diversity among Soybean Plant Introductions and Elite Genotypes
Authors: Narvel James M. , Fehr Walter R. , Chu Wen‐Chy , Grant David , Shoemaker Randy C.
Published: July 2010

The use of molecular markers to facilitate the introgression of plant introduction (PI) germplasm into elite soybean [Glycine max (L.) Merr.] cultivars will depend on the amount of polymorphism that exists between elite genotypes and PIs. The objective of this study was to assess the simple sequence repeat (SSR) diversity of 39 elite soybean genotypes (Elites) and 40 PIs that were selected for high yield potential. A total of 397 alleles were detected among the 79 genotypes at 74 SSR marker loci. The number of alleles detected among the PIs was 30% greater than that detected among the Elites. There were 138 alleles specific to the PIs that occurred across 60 SSR loci and 32 alleles specific to the Elites that occurred across 27 SSR loci. Average marker diversity among the PIs was 0.56 and ranged from 0.0 to 0.84. Average marker diversity among the Elites was 0.50 and ranged from 0.0 to 0.79. Genetic similarity estimates based on simple matching coefficients revealed more genetic diversity among the PIs than among the Elites. The greatest genetic diversity was between the PIs and Elites. The ability of SSRs to distinguish among elite soybean genotypes and PIs with agronomic merit may assist with the transfer of favorable alleles from PIs into elite soybean cultivars.
Association of Soybean Seed Traits with Physical Properties of Natto
Authors: Geater Chandler W. , Fehr Walter R. , Wilson Lester A.
Published: July 2010

Breeding of soybean [Glycine max (L.) Merr.] cultivars suitable for natto involves selection for seed traits that influence the quality of the product. The objectives of this study were to evaluate the relationship of 11 seed traits to six natto quality traits and to assess the influence of genotypes and environment on the traits. Sixteen small‐seeded genotypes were grown in replicated tests at three Iowa locations during 2 yr. The natto traits evaluated for each plot were water absorption, water loss, hardness of steamed seeds and natto, and darkness of steamed seeds and natto. Seed traits were total sugar, free sugar, sucrose, raffinose, stachyose, protein, oil, fiber, protein + oil, protein + oil + fiber, and seed size. There were significant differences among genotypes during one or both years for all the traits, except fiber content. Significant differences between years or among locations were observed for all traits, except water loss after steaming and stachyose content. None of the seed traits was significantly correlated with darkness of the steamed seeds or natto. All of the seed traits, except stachyose, oil, and seed size, were significantly correlated with one or more of the other natto quality traits. Protein + oil was significantly correlated with natto quality and other seed traits and can be a useful selection criterion in breeding cultivars for the natto industry.
Blend Response and Stability and Cultivar Blending Ability in Oat
Authors: Helland S. J. , Holland J. B.
Published: July 2010

Genetic diversity in cropping systems can provide buffering against varying environmental conditions. Therefore, cultivar blends may have greater and more stable yields than their pure‐line components. Optimization of cultivar blend development requires knowledge of the relative importance of pure‐line yield potential, blend response, and cultivar interactions to blend yield. Grain yield and volume weight of oat (Avena sativa L.) pure‐line cultivars and cultivar blends were measured in eight Iowa environments in order to compare their productivity and stability and to estimate genetic components of blend yields. In one experiment, five early‐maturing cultivars were grown as pure lines and as all possible two‐ and three‐way cultivar blends. In a second experiment, ten midseason‐maturing cultivars were grown as pure lines and as all possible two‐way blends. Grain yield was 3% greater (P < 0.05) and volume weight was 1% greater (P < 0.05) in blends than in pure lines in the early‐maturity experiment; however, pure line and blends did not differ in the midseason‐maturity experiment. Blends had more stable (P < 0.05) yields than pure lines in the early‐maturity experiment only. Modified diallel analysis was used to partition the variation among two‐way blends into general yielding ability (GYA) and true general competitive ability (TGCA) of each component genotype, and specific competing ability (SCA) interaction between blend components. General yielding ability variation was significant, whereas variation for neither TGCA nor SCA was significant. Oat genotype responses to blending were sufficiently consistent across blending partners that superior blends can be selected based on pure‐line evaluations of early‐maturing cultivars.
Genetic Analysis of Resistance to Soybean mosaic virus in OX670 and Harosoy Soybean
Authors: Gunduz I. , Buss G. R. , Ma G. , Chen P. , Tolin S. A.
Published: July 2010

Soybean mosaic virus (SMV) resistance in the soybean [Glycine max (L.) Merr.] breeding line OX670 previously was postulated to be controlled by a gene derived from the cultivar Raiden and designated as Rsv2 Subsequently, it was shown that Raiden has a single resistance gene at the Rsv1 locus, suggesting that the resistance gene in OX670 was not from Raiden. Most of the remaining ancestry of OX670 is derived from ‘Harosoy’. The objectives of this study were to determine (i) the reaction of Harosoy to SMV‐G1 through G7 strains; (ii) the inheritance of SMV resistance in Harosoy and OX670; and (iii) the allelomorphic relationship of resistance genes in these cultivars with previously described resistance genes. OX670 and Harosoy were crossed with the SMV susceptible cultivar Lee 68 to study the inheritance of resistance. OX670 and Harosoy were also crossed with the resistant lines L78‐379, L88‐8431, PI96983, L29, and V94‐5152 to elucidate the allelomorphic relationships between the genes in OX670, Harosoy, and previously reported genes. Our results indicated that Harosoy, which is resistant to SMV‐G5 through G7 and susceptible to SMV‐G1 through G4, possesses a single partially dominant SMV resistance gene at the Rsv3 locus. Inheritance studies indicated that OX670, which is resistant to SMV‐G1 through G7, possesses two independent dominant genes for SMV resistance. One is allelic to the Rsv1 locus and derived from Raiden, while the other is allelic to the Rsv3 locus and derived from Harosoy. Presence of both Rsv1 and Rsv3 in OX670 confers resistance to SMV‐G1 through G7. Therefore, the previously proposed Rsv2 locus does not appear to exist in OX670 or its ancestors.