bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Drought or Heat Stress Alone and in Combination on Kentucky Bluegrass
Authors: Jiang Yiwei , Huang Bingru
Published: July 2010

Cool‐season turfgrasses are frequently subjected to heat and drought stresses during summer months. This study was conducted to determine physiological responses of Kentucky bluegrass (Poa pratensisL.) to drought and heat alone or together, and the effects of drought preconditioning on plant responses to subsequent heat stress. Kentucky bluegrass (cv. Mystic) was subjected to drought and/or heat stress (35°C/30°C, day/night) in growth chambers for 40 d. Canopy photosynthetic rate (Pn) and leaf photochemical efficiency (Fv/Fm) decreased under drought and heat stress. The decline in Pnwas more severe under heat than under drought stress during the first 12 d of treatment. The reduction in Fv/Fm ratio was more severe under drought stress than under heat stress after 20 d of treatment. The combined heat and drought stresses (H+D) caused more dramatic reductions in Pnand Fv/Fm than either heat or drought alone, starting at 3 and 9 d after treatment, respectively. Drought or heat alone, or H+D, significantly reduced root dry weight. However, reduction was more severe under heat alone than under drought stress, particularly in the top 20 cm of soil. Drought preconditioning enhanced plant tolerance to subsequent heat stress but had no influence on plant tolerance to H+D. Drought‐preconditioned plants maintained higher water status, stomatal conductance, and transpiration rate, and had significantly higher Pnand root dry weight than non‐preconditioned plants during subsequent heat stress. No significant difference in Fv/Fm was observed between drought‐preconditioned and non‐preconditioned plants under either heat alone or H+D. The results indicated that simultaneous drought and heat stresses were more detrimental than either stress alone. Drought preconditioning could improve Kentucky bluegrass tolerance to subsequent heat stress.
Software for Population Genetic Analyses of Molecular Marker Data
Authors: Labate Joanne A.
Published: July 2010

Molecular genetic markers can be used to examine a group of individuals or populations to estimate various diversity measures and genetic distances, infer population structure and clustering patterns, test for Hardy‐Weinberg and multilocus equilibrium, and test polymorphic loci for evidence of selective neutrality. This can be useful to plant breeders, germplasm managers, or others who are interested in population genetic properties of materials that they are working with. Many software programs for molecular population genetics studies have been developed for personal computers. Their easy access, implementation of sophisticated and powerful statistical techniques, and user‐friendliness make them an attractive alternative to performing calculations on spreadsheets or by writing simpler programs for oneself. This review outlines the current major features of six popular programs (TFPGA, Arlequin, GDA, GENEPOP, GeneStrut, and POPGENE), including the types of data they handle, analyses they perform, and where they can be obtained (Table 1). These particular programs were chosen because each can accommodate a variety of molecular marker types and perform many different types of analyses. Although there is much overlap in their functionality, each program has unique features to offer potential users.
Primary Trisomics in Soybean: Origin, Identification, Breeding Behavior, and Use in Linkage Mapping
Authors: Xu S.J. , Singh R.J. , Kollipara K.P. , Hymowitz T.
Published: July 2010

A primary trisomic
is an excellent cytogenetic tool for locating Mendelian genes on a particular chromosome and for associating a conventional genetic linkage group with a specific chromosome. The objectives of this study were to produce and identify 20 primary trisomics
of soybean [Glycine max (L.) Merr.] and use them for associating linkage groups with specific chromosomes. Primary trisomics isolated from the progenies of asynaptic and desynaptic mutants, male sterile lines, neutron‐irradiated plants, and tissue culture‐induced sterile mutants were backcrossed (BC4) with soybean cv. Clark 63. They were identified at pachytene on the basis of the diagnostic landmarks such as association of the extra chromosome with its normal homologues in a trivalent configuration, distribution of euchromatin and heterochromatin, total chromosome length, arm ratios, and by examining chromosome pairing at metaphase I in F1 plants with 2n = 42 chromosomes isolated from crosses among primary trisomics. The F1 plants from similar primary trisomics exclusively showed 21 II and those from dissimilar primary trisomics exhibited microsporocytes with 20 II + 2 I, 1 III + 19 II + 1 I, and 2 III + 18 II configurations. Thus, 20 primary trisomics were tentatively identified and were designated as triplo 1 through triplo 20. Female transmission of the extra chromosome in 20 primary trisomics ranged from 27.3% (triplo 20) to 58.5% (triplo 9). On the basis of the modification ratio (17:1) of a gene located on the extra chromosome in primary trisomic analysis, three marker genes Eul (seed urease), Lx1 (lipoxygenase‐1), and P2 (puberulent) were located on chromosomes 5, 13, and 20, respectively. The ultimate aim of this project is to develop by means of primary trisomics a universal cytogenetic map of soybean by associating existing classical and several molecular maps with the specific chromosomes.
Inbred Line Evaluation and Breeding for Digestibility‐Related Traits in Forage Maize
Authors: Argillier O. , Méchin V. , Barrière Y.
Published: July 2010

Forage maize digestibility is now a major selection criterion in breeding programs, and in hybrid breeding it is useful to select at the inbred level. This study was conducted to evaluate the possibility of doing preliminary selection at the inbred level for digestibility‐related traits in forage maize (Zea mays L.). Maize hybrids from a factorial mating design among nine and six maize inbred lines, and the 15 parental inbred lines per se, were evaluated at silage stage at three locations (France) for 2 yr. Whole plant in vitro digestibility of dry matter and of cell walls, and plant biochemical composition traits were investigated by near infra red reflectance spectroscopy (NIRS). Biomass dry matter content and productivity were also collected. In hybrid trials, general combining ability (GCA) of lines was the most important source of variation in all digestibility traits, compared with specific combining ability (SCA), GCA × environment, and SCA × environment interactions. Some plant biochemical components were associated with the biomass yield, whereas digestibility of cell walls, particularly, was found independent from biomass productivity. The efficiency of predicting the hybrid performance from midparent value, as well as the good relationship between inbred line per se and GCA values, for digestibility‐related traits, and particularly cell wall digestibility, indicated the possibility for maize breeders to improve digestibility of forage maize by selecting inbred lines.
Identification and Mapping of QTLs Conferring Resistance to Ascochyta Blight in Chickpea
Authors: Santra Dipak K. , Tekeoglu Mucella , Ratnaparkhe MiLind , Kaiser Walter J. , Muehlbauer Fred J.
Published: July 2010

Ascochyta blight, caused by Ascochyta rabiei (Pass.) Lab., is a devastating disease of chickpea (Cicer arietinum L.) worldwide. Resistant germplasm has been identified and the genetics of resistance has been the subject of numerous studies. The objectives of the present study were to determine the genetics of resistance to ascochyta blight of chickpea and to map and tag the chromosomal regions involved using molecular markers. We used a set of 142 F5:6 recombinant inbred lines (RILs) obtained from an interspecific cross of C. arietinum (FLIP84‐92C, resistant parent) × C. reticulatum Lad. (PI 599072, susceptible parent). The RILs were scored for disease reactions in the field over 2 yr and were genotyped for polymorphic molecular markers [isozyme, random amplified polymorphic DNA (RAPD), and inter simple sequence repeat (ISSR)] in the laboratory. The disease was scored quantitatively and data were used for QTL analysis. A linkage map was established that comprised nine linkage groups containing 116 markers covering a map distance of 981.6 centimorgans (cM) with an average distance of 8.4 cM between markers. Two quantitative trait loci (QTLs), QTL‐1 and QTL‐2, conferring resistance to ascochyta blight, were identified which accounted for 50.3 and 45.0% of the estimated phenotypic variation in 1997 and 1998, respectively, and were mapped to linkage groups 6 and 1, respectively. Two RAPD markers flanked QTL‐1 and were 10.9 cM apart while one ISSR marker and an isozyme marker flanked QTL‐2 and were 5.9 cM apart. These markers can be used for marker‐assisted selection for ascochyta blight resistance in chickpea breeding programs, and to develop durable resistant cultivars through gene pyramiding.
Semidwarf and Standard‐Height Cowpea Responses to Row Spacing in Different Environments
Authors: Ismail Abdelbagi M. , Hall Anthony E.
Published: July 2010

Yield potential of several grain crops has been increased by breeding semidwarf cultivars with greater harvest index and growing them at high plant densities. We evaluated effects of the semidwarf trait on yield potential of cowpea [Vigna unguiculata(L.) Walp.] in contrasting, but productive, environments. Three semidwarf and three standard‐height cowpea lines with similar indeterminate habits and phenology were evaluated at row spacings of 51, 76, and 102 cm in four field environments where the extent of early vegetative vigor varied. Main stems of semidwarf lines were 33% shorter, and they produced 13% less vegetative shoot biomass than standard lines. Average grain yield of semidwarf lines was 10% greater than that of standard lines and was associated with 11% higher harvest index and 19% greater pod set. Semidwarf lines produced relatively greater yield than standard lines at narrower row spacings (15, 11, and 4% greater than standard lines at 51, 76, and 102 cm row spacing, respectively). Average yield of standard lines did not respond to row spacing. In a stressful soil environment that caused extreme dwarfing of both plant types, there was no difference in grain yield between semidwarf and standard lines. Semidwarf lines produced greater yield than standard lines at narrow row spacing in soil conditions that promoted moderate to vigorous early plant growth due to impaired reproduction of standard, but not semidwarf, lines when competition for light was strong.
Solar Radiation Intercepted during Seed Filling and Oil Production in Two Sunflower Hybrids
Authors: Dosio Guillermo A.A. , Aguirreza´bal Luis A.N. , Andrade Fernando H. , Pereyra Víctor R.
Published: July 2010

The expression of the components of oil yield in sunflower (Helianthus annuusL.) could depend on environmental conditions during the seed filling period. In this work, we investigated the effect of intercepted PAR (photosynthetically active radiation) during seed filling on the weight of individual seeds and oil concentration in two hybrids, one with low and one with high oil concentration potential. Three experiments were carried out in three different years under good water and nutrient conditions. Intercepted PAR was modified by shading or thinning to reduce plant population and by the combination of shading and thinning. The treatment application date corresponded to 46 ± 2°C days (base temperature = 6°C) after R6. Greater intercepted PAR increased weight per seed in both hybrids. Oil concentration was affected in `Dekalb G‐100' (G‐100, high oil concentration and black hull) but remained unaffected in `Northrup King Tordillo' (NKT, low oil concentration and stripped hull) although the thinned treatments intercepted up to 7.5 times the amount of radiation per plant than the shaded ones. About 84 (G‐100) and 80% (NKT) of the variability among treatments and experiments in weight per seed was accounted for by the PAR intercepted during seed filling. The variation in oil concentration in G‐100 was related to intercepted solar radiation (r2= 0.93). Our results suggest that intercepted PAR during seed filling plays a primary role in determining oil production in sunflower, and considering genotypic differences may be important when using relationships between weight per seed or oil concentration and intercepted PAR as modeling tools.
Remobilization of Carbon Reserves Is Improved by Controlled Soil‐Drying during Grain Filling of Wheat
Authors: Yang Jianchang , Zhang Jianhua , Huang Zuliu , Zhu Qingsen , Wang Long
Published: July 2010

Heavy use of N fertilizers delays plant senescence in wheat (Triticum aestivum L.) and results in slow grain filling and a low harvest index. This study investigated whether senescence is enhanced by a controlled soil drying during the late grain‐filling stage and whether such an enhancement can lead to better remobilization of reserved C to the grains. Two wheat cultivars were raised in pots and one was grown in the field. Two levels of nitrogen, either normal (NN) or high (HN) amounts, were applied at heading. Controlled soil drying was imposed 9 d after anthesis until maturity. Leaf water potential and conductance for the soil‐drying treatments were lower during the day but completely recovered by the early morning. Photosynthetic rate and chlorophyll content in the flag leaves declined more quickly in the soil‐drying treatments than in the well‐watered ones, indicating that soil drying enhanced senescence. Nonstructural carbohydrate in the stem and sheath at maturity was greatly reduced, and the partitioning of fixed C from flag leaves into the grains and the final harvest index were significantly increased by soil drying under both nitrogen treatments for the three cultivars. Soil drying shortened the grain‐filling period but grain‐filling rate was substantially increased by all the soil drying treatments except one NN treatment with severe soil drying in the pot experiment. Soil drying actually increased the grain yield at HN in both experiments. We conclude that senescence induced by controlled soil drying during grain filling can promote the remobilization of prestored assimilates to the grains, accelerate grain filling, and improve yield in cases where senescence is unfavorably delayed by heavy use of nitrogen.
Growth and Yield Responses of Winter Wheat to Mixtures of Ozone and Carbon Dioxide
Authors: Heagle A. S. , Miller J. E. , Pursley W. A.
Published: July 2010

Ozone (O3) in the troposphere can cause plant stress, whereas elevated CO2 generally enhances plant growth. Until recently, few studies have considered whether O3 can affect plant response to CO2 or vice versa. We examined these possibilities for soft red winter wheat (Triticum aestivum L.). Plants were grown in 14‐L pots and exposed in open‐top field chambers to all combinations of three CO2 and three O3 treatments. The CO2 treatments were ambient (approximately 380 μL L−1), or ambient with CO2 added for 24 h d−1 to achieve mean concentrations of approximately 540, or 700 μL L−1 The O3 treatments were charcoal‐filtered air (CF), nonfiltered air (NF), or NF with O3 added for 12 h d−1 (NF+). Mean O3 concentrations in the CF, NF, and NF+ treatments were approximately 27, 45, and 90 nL L−1 In the first experiment, eight cultivars with widely different genetic backgrounds were tested. `Coker 9835' was relatively resistant to O3 and `Coker 9904' was relatively sensitive; these cultivars were tested in Exp. 2. Foliar injury caused by O3 was suppressed by elevated CO2 in both experiments. In Exp. 1, plant size and yield increased with CO2 enrichment in the NF and NF+ treatments, but not in the CF treatment. However, the O3 × CO2 interaction was rarely significant. In Exp. 2, growth and yield of C9904 was suppressed more by O3 than was that of C9835. Because of cultivar differences in sensitivity to O3, CO2 enrichment caused greater amelioration of O3 stress and greater enhancement for C9904 than for C9835. Significant cultivar × O3 × CO2 interactions occurred for all growth and yield measures. These results are similar to results with other crops, and further emphasize the need to consider possible interactions between O3 and CO2 when investigating effects of O3 or CO2 on plant systems.
Broadening the Genetic Base of Common Bean Cultivars
Authors: Singh Shree P.
Published: July 2010

Knowledge, access, and use of diversity available in cultivated and wild relatives are essential for broadening the genetic base of cultivars to sustain improvement. My objectives are to review briefly the origin, domestication, and organization of genetic diversity inPhaseolusbeans, highlight production problems and traits deficient in the common bean (P. vulgarisL.) cultivars, cite sources of useful gemplasm, and review progress achieved in broadening the genetic base of cultivars.Phaseolusbeans originated in the Americas. Only five species,P. acutifoliusA. Gray,P. coccineusL.,P. lunatusL.,P. polyanthusGreenman, andP. vulgarisL. were domesticated. The interspecies diversity in relation to common bean is organized in primary, secondary, tertiary, and quaternary gene pools. Intraspecies diversity in common bean is separated into two major gene pools (Andean and Middle American). Cultivars are further divided into races, each with their distinguishing characteristics. Also, cultivars of dry seed and snap bean exist. Abiotic and biotic stresses limit common bean production. The genetic base of cultivars within market classes is narrow and inadequate level of resistance to common bacterial blight [caused byXanthomonas campestrispv.phaseoli(Smith) Dye] and white mold [caused bySclerotinia sclerotiorum(Lib) de Bary] exist in cultivars. High levels of resistance to these and other desirable traits exist in the relatives and gene pools ofP. vulgarisEarly maturity, adaptation to higher latitude, upright plant type, high pod quality and seed yield, and resistance toBean common mosaic virus(a potyvirus) and/or rust [caused byUromyces appendiculatus(Pers.:Pers.) Unger] have been bred into cultivars. However, most of the genetic variability available in the common bean races, gene pools, and wild relatives remains to be utilized. To maximize and sustain bean production, high yielding, high quality cultivars that are less dependent on water, fertilizer, pesticides, and manual labor should be developed. This need warrants sustained, comprehensive, and integrated genetic improvement, in which favorable alleles from cultivated and wild relatives are accumulated in superior cultivars. A three‐tiered breeding approach involving: (i) gene introgression from alien germplasm, (ii) pyramiding favorable alleles from different sources, and (iii) simultaneous improvement of multiple traits for common bean cultivars would be the most appropriate strategies to meet theses needs.
Marker‐Assisted Backcrossing for Simultaneous Introgression of Two Genes
Authors: Frisch Matthias , Melchinger Albrecht E.
Published: July 2010

Marker‐assisted selection is used to accelerate recovery of the recurrent parent genome (RPG) in backcross programs. Our objectives were to compare various selection strategies and breeding plans for the simultaneous introgression of two genes with respect to the RPG recovered and the number of marker data points (MDP) required. Computer simulations were performed with a published genetic map in maize (Zea mays L.) consisting of 80 markers and assuming selection for dominant target genes on the basis of phenotypic evaluation. For unlinked as well as for linked target genes, a shortening of the backcross program from six to three generations resulted from applying marker‐assisted background selection. In breeding programs with three backcross generations, the least MDP were required when (i) applying selection strategies consisting of three or four selection steps on the basis of presence of the target genes and selection indices calculated from the marker genotype, (ii) increasing the population size from early to advanced generations, and (iii) merging the target genes in an early generation. These principles can be used for optimizing the design of marker‐assisted backcross programs for the simultaneous introgression of two genes.
Comparisons of Two‐Row and Six‐Row Barley for Chemical Composition Using Doubled‐Haploid Lines
Authors: Frégeau‐Reid Judith , Choo Thin‐Meiw , Ho Keh‐Ming , Martin Richard A. , Konishi Takeo
Published: July 2010

Comparative studies on chemical composition between two‐row and six‐row barley (Hordeum vulgare L.) and between purple and yellow barley are very limited. Therefore, a study was conducted to compare two‐row and six‐row barley and to compare purple and yellow barley for five chemical traits. In addition, the effects of four other marker loci—srh (short rachilla hair), Raw1 (rough awn), Est1 (esterase 1), and Est5 (esterase 5)—on the five traits were also studied. One hundred ninety doubled‐haploid (DH) lines were derived from a ‘Leger’/‘CI9831’ cross by the bulbosum method. The DH lines and the two parents were evaluated for protein, starch, β‐glucan, neutral‐detergent fiber (NDF), and acid‐detergent fiber (ADF) content at two locations in Eastern Canada in 1993. Results showed that two‐row (vrs1.t) lines contained 14 to 20% more protein, 4% less starch, and 6 to 7% more β‐glucan than six‐row lines; while purple lemma (Pre2) lines contained 2 to 4% less NDF and 0 to 3% less ADF than yellow lemma lines. Differences in grain protein, starch, and β‐glucan content were associated with the Pre2 locus, but they were shown to be caused by linkage between the Pre2 and vrs1 loci. Alleles at the srh, Raw1, Est1, and Est5 loci had very little effect on the five traits. Protein content was not correlated with β‐glucan content for either two‐row or six‐row lines. Protein and β‐glucan content, however, were correlated with NDF and ADF content for the two‐row lines. Additive × additive epistasis was detected for starch and NDF content. The results of this study suggested that selection for high protein or low β‐glucan is possible in two‐row/six‐row crosses.
Attempts to Transfer Russian Wheat Aphid Resistance from a Rye Chromosome in Russian Triticales to Wheat
Authors: Lukaszewski Adam J. , Porter David R. , Baker Cheryl A. , Rybka Krystyna , Lapinski Boguslaw
Published: July 2010

The Russian wheat aphid (Diuraphis noxia Mordvilko) is a serious pest of wheat (Triticum aestivum L.). To extend the range of genetic variation of resistance, attempts were undertaken to transfer near‐immunity to RWA into wheat from two Russian triticales (X. Triticosecale Wittmack) PI 386146 and PI 386156 by irradiation and by induced homologous recombination. The rye genome in the triticale lines was derived from Secale montanum Guss. Tests of resistance in early backcrosses to wheat indicated that the near‐immunity of the triticale lines was controlled by at least two loci, one of which was located on rye chromosome arm 4RLmon Centric wheat‐rye translocation 7DS.4RLmon that appeared to be compensating, was produced. To further reduce the amount of rye chromatin present, its long arm was induced to recombine with wheat chromosomes by the removal of the Ph1 locus. Among 3563 progeny screened, only two wheat‐rye recombinant chromosomes were recovered. Both appeared to be non‐compensating and were involved in multivalents in meiosis. Irradiation of PI 386156 followed by crosses and backcrosses to wheat with several generations of selection for resistance resulted in a wheat line that was found to be a disomic addition of chromosome 4Rmon–centric translocation homozygote of rye chromosome tentatively identified as 5Rmon With only one locus for resistance from the original triticale parents, the addition line of 4Rmon, centric translocation line 7DS.4RLmon and recombinant lines of 4RLmon had only moderate level of resistance to RWA. The study demonstrates that transfers of alien variation into wheat may be severely complicated by unclear genetics of the target traits, low levels of homology, and structural differences between the donor and recipient chromosomes.
Comparing Canola, Field Pea, Dry Bean, and Durum Wheat Crops Grown in Saline Media
Authors: Steppuhn H. , Volkmar K. M. , Miller P. R.
Published: July 2010

Farmers have requested comparative information on the salt tolerance of the field crops they seek to grow as alternatives to wheat. In response, a study was conducted in the Salt Tolerance Testing Laboratory at Swift Current, SK, to compare the productivity of canola (Brassica napus cv. Cyclone), field pea (Pisum sativum cv. green‐seed Radley and cv. yellow‐seed Carneval), and pinto dry bean (Phaseolus vulgaris cv. Othello) crops to that of a durum wheat (Triticum turgidum cv. Kyle) crop grown in saline media. Test solutions were salinized prior to seeding by adding NaCl and CaCl2 (1:1 by mass) to hydroponic nutrients, resulting in three levels of root‐zone salinity: near zero, moderate, and severe [solution electrical conductivities of 1.2 (nutrients only), 11.2, and 24.9 dS m−1, respectively]. Eight response variables evaluated crop performance: time from seeding to initial emergence, emergence rate, final emergence and survival, plant height, aboveground biomass, grain yield, relative grain yield, and grain yield per plant. The durum wheat emerged and survived moderate and severe salinity better than any of the alternative crops. The wheat crop also produced more biomass and grain under moderately saline conditions than produced by the pea and the bean crops, but not the canola. Under severe salinity, neither the field peas nor the dry bean produced any grain, but the wheat and the canola crops managed to yield 0.4 and 20.1% of their respective productivity in nonsaline rooting media. The combined salt tolerance ranking in ascending order for the crop cultivars grown in both saline rooting media was: Othello = Carneval < Radley < Kyle < Cyclone.
Flooding and Temperature Effects on Soybean Germination
Authors: Wuebker Eileen Feilmeier , Mullen Russell E. , Koehler Kenneth
Published: July 2010

During the germination phase of soybean [Glycine max (L.) Merr.] growth, uniform soybean emergence may be reduced when fields are periodically saturated with water from heavy rains and poor drainage. A laboratory study was conducted to determine the effects of timing and duration of flooding, germination temperature, and mechanical damage on the germination of soybean. There were little differences in germination percentage among the flooding duration treatments when flooding began 1 d after the start of imbibition. When seed were flooded 2 or 3 d after the start of imbibition, however, a significant drop in germination percentage occurred in seed flooded for 48 h. Flooding seed 3 d, compared with 1 d, after the start of imbibition was more detrimental, regardless of temperature. Seed injury was observed after only 1 h of flooding. Increasing the duration of flooding from 1 to 48 h at 15°C did not increase injury; however, at 25°C, more seed injury was observed as the duration of flooding increased up to 48 h. Overall, seed were more susceptible to flooding stress at 15°C than at 25°C. These results suggest that soybean seed are susceptible to flooding of 1 to 48 h during the early germination process and the response is influenced by germination stage.
Kentucky Bluegrass Growth Responses to Trinexapac‐Ethyl, Traffic, and Nitrogen
Authors: Ervin E. H. , Koski A. J.
Published: July 2010

Understanding the whole‐plant response of Kentucky bluegrass (Poa pratensis L.) to the plant growth regulator (PGR) trinexapac‐ethyl (TE) [4‐(cyclopropyl‐α‐hydroxy‐methylene)‐3,5‐dioxo‐cyclohexane‐carboxylic acid ethyl ester] while subjected to traffic and variable N rates would facilitate recommendations regarding its safe and effective use. The objectives of this study were (i) to investigate the extent and duration of TE‐induced shoot growth suppression on Kentucky bluegrass and determine any interactive traffic or N effects, and (ii) to investigate if TE‐induced reductions in shoot growth affect tillering, rooting, and quality of Kentucky bluegrass, and determine any interactive traffic or N effects. Trinexapac‐ethyl (0.27 kg ha−1) was applied to main plots three times a year at 6‐wk intervals. Traffic was applied to subplots with a cleated roller. Four increasing rates of a slow‐release N source were applied annually to sub‐subplots. Trinexapac‐ethyl consistently reduced clippings by 1 to 2 wk after treatment (WAT), with maximum suppression occurring at 3 to 4 WAT. Greater suppression occurred for July and August application dates relative to May. Traffic consistently reduced clippings and tiller density. Tiller density was increased by TE in 1996. Higher annual N did not, in general, affect tiller density, root mass, or quality. Repeated TE application did not affect Kentucky bluegrass root mass. Trinexapac‐ethyl did not affect quality, while traffic consistently reduced it. Quality was poorest at the three highest N‐rates under TE and traffic during the last treatment cycle of 1997. These results suggest caution when using TE on highly trafficked Kentucky bluegrass.
Comparing Nitrogen Runoff and Leaching between Newly Established St. Augustinegrass Turf and an Alternative Residential Landscape
Authors: Erickson J. E. , Cisar J. L. , Volin J. C. , Snyder G. H.
Published: July 2010

Turfgrass landscapes have the potential for loss of applied N through both runoff and leaching. Lower maintenance alternative vegetation used in mixed‐species landscapes may reduce N leaching and runoff, which is important for reducing N pollution of surface and ground waters. However, few studies have examined this paradigm. Therefore, we constructed a field‐scale facility to compare fertilizer N runoff and leaching between St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] and a mixed‐species landscape. Four replications of each landscape were randomly assigned to 50‐m2 plots. A medium‐fine sand (75‐cm depth) was used as the root zone mix. A blended granular fertilizer was applied at a rate of 300 and 150 kg N ha−1 yr−1 on the turfgrass and mixed‐species, respectively. Throughout the first year following installation of the landscapes, fertilizer N loss in surface runoff was insignificant. In contrast, N leaching losses were significantly greater on the mixed‐species landscape during three fertilizer cycles, resulting in 48.3 kg N ha−1 compared with 4.1 kg N ha−1 for the St. Augustinegrass annually. The results from the newly established landscapes presented here indicated that St. Augustinegrass was more efficient at using applied N and minimizing N leaching compared with the alternative landscape. Furthermore, the study identified areas of concern with respect to N management practices on alternative landscapes. These results hold implications for future landscape models and management of resources in a residential setting.
Phenotypic Diversity of Modern Chinese and North American Soybean Cultivars
Authors: Cui Zhanglin , Carter Thomas E. , Burton Joseph W. , Wells Randy
Published: July 2010

Chinese and North American (NA) soybean breeding programs have a 70‐yr history of genetic progress in relative isolation from each other. Because both programs rest upon a genetic base that is primarily Chinese in origin, the actual genetic distinctness of Chinese and NA breeding is not clear. The objectives of this study were to (i) develop a phenotypic similarity (PS) index for a large group of Chinese and NA cultivars, on the basis of biochemical, morphological, and agronomic traits, (ii) compare Chinese and NA cultivars for PS through cluster analysis, and (iii) use results to develop guidelines for management of the contrasting Chinese and NA breeding programs as reservoirs of diversity. Chinese (47) and NA (25) cultivars were evaluated for 25 traits in growth chambers. Traits pleiotropic to maturity were avoided. Significant (P < 0.05) differences between Chinese and NA cultivars were noted for leaf and seed traits. Multivariate analysis captured 79% of the total genotypic variation among the 72 cultivars and was used to develop PS estimates. Cluster analysis of PS showed a much greater phenotypic diversity among Chinese than among NA cultivars and a striking distinctness between the two groups. The contrasting nature of Chinese and NA cultivars in this study is theorized to reflect that (i) the NA cultivars may trace to a subset of the Chinese cultivar genetic base, and/or (ii) Chinese and NA cultivars may have diverged phenotypically via breeder selection pressure. Cluster results here, based on PS, agreed roughly with previous cluster analyses, which were derived from pedigree analysis. The physical distinctness of NA and Chinese cultivars shows that introgression of Chinese cultivars into NA breeding should broaden NA germplasm's agronomic, morphological, and biochemical diversity. Introgression may be accomplished most effectively by avoiding matings of Chinese and NA cultivars from the same phenotypic cluster.
Simple partial purification of d‐pinitol from soybean leaves
Authors: Streeter John G.
Published: July 2010

There is growing interest in the use of D‐pinitol (D‐3‐O‐methyl‐chiro‐inositol) as a food supplement because of its reported efficacy in lowering blood glucose levels. Pinitol is a common constituent of legume plants and is a major component of soybean [Glycine max (L.) Merr.] leaves. The objective of the studies was to identify a combination of simple methods that would result in the purification of pinitol from soybean leaves. Ethanolic extracts of soybean leaves following solvent partitioning to remove lipids, passage of the aqueous fraction through ion exchange resins, and treatment of the effluent with activated charcoal yielded a white crystalline product that was 85.5% pinitol by weight. Other components in the product included D‐chiro‐inositol (5.2%), myo‐inositol (3.4%), and ononitol (D‐4‐O‐methyl‐myo‐inositol; 1.9%). Thus, 96% of the crystalline product was cyclitols following the simple purification protocol.
Interrelationships among Seed Quality Attributes in Soybean
Authors: Wilcox James R. , Shibles Richard M.
Published: July 2010

Soybean [Glycine max(L.) Merr.] meal is used primarily as a livestock feed. The high protein concentration and sulfur‐containing amino acids in the meal contribute to its nutritional value. Oligosaccharides, including raffinose and stachyose in the meal, have detrimental effects on the nutritive value of soy meal as a livestock feed. The objective of this research was to determine the interrelationships among seed protein, oil, oligosaccharides, and S in a breeding population that varied widely in seed protein concentration. Forty‐three random breeding lines that varied in seed protein concentration from 413 to 468 g kg−1on a dry seed basis, were grown in replicated tests in three environments. Seed yield, protein, oil, oligosaccharides, and S concentrations were determined for entries in each replication in the three environments. Breeding lines and environments varied significantly for each of the traits measured. Concentrations of carbohydrates were not associated with seed yield. Protein increased at the expense of oil, total carbohydrates, and sucroseSulfur increased with increasing protein, but S/N ratios were constant across protein concentrations. Decreases in carbohydrates with increases in protein would contribute to increased nutritional value of the meal from these breeding lines. The consistent S/N ratio across the range of seed protein concentrations indicates that S‐containing amino acids were not sacrificed with increases in seed protein.
Genetic Markers Associated with Green and Albino Plant Regeneration from Embryogenic Barley Callus
Authors: Bregitzer Phil , Campbell Robert D.
Published: July 2010

Genetic control of plant regeneration from cultured plant tissues has been documented for a number of species. The characterization and manipulation of loci that influence morphogenic responses may be useful for the development of highly regenerable germplasm or for physiological investigations. Quantitative trait loci (QTLs) for morphogenesis from barley cell cultures were identified on the basis of associations of mapped markers with the regeneration responses of 77 doubled haploid (DH) lines derived from the cross Steptoe/Morex. Two models were developed, one describing green plant regeneration, and one describing albino plant regeneration, measured as the numbers of green and albino plants regenerated per gram fresh weight of embryogenic callus. Approximately 62 and 12% of the observed variability for green and albino plant regeneration, respectively, was explained by the models. An independent data set was developed that consisted of the regeneration responses of 25 additional DH lines which were chosen randomly from the same segregating population. The models were tested for their ability to predict the responses of these independent DH lines. This study identified new QTLs for plant regeneration (one for green plants and at least one for albino plants), and confirmed previously reported associations of three QTLs with green plant regeneration.
Identification of QTLs for Resistance to Sclerotinia sclerotiorum in Soybean
Authors: Arahana Venancio S. , Graef George L. , Specht James E. , Steadman James R. , Eskridge Kent M.
Published: July 2010

Sclerotinia stem rot [caused by Sclerotinia sclerotiorum (Lib.) de Bary] is considered the second most important cause of yield loss in soybean [Glycine max (L.) Merr]. Soybean cultivars show variability in susceptibility, but no complete resistance to the disease has been reported and little information on the genetics of resistance is available. The objective of this study was to identify putative quantitative trait loci (QTLs) associated with Sclerotinia stem rot resistance in soybean. Recombinant inbred lines (RILs) from five populations were developed by crossing Williams 82, a susceptible cultivar, with five cultivars exhibiting partial resistance: Corsoy 79, Dassel, DSR173, S19‐90, and Vinton 81. The F2 to F5 generations were advanced by single seed descent. Parental polymorphism was tested with 507 simple sequence repeat (SSR) primers from the integrated linkage map of soybean, and primers were selected for progeny screening in the five populations on the basis of polymorphism and distribution in the genome. Five hundred RILs, consisting of 100 F5:6 lines from each population, were evaluated for resistance to Sclerotinia sclerotiorum isolate 143 by a detached leaf method in the laboratory to measure lesion area on leaves inoculated with mycelium plugs. Single degree‐of‐freedom contrasts in PROC MIXED and interval analysis were used to detect putative QTLs. Twenty‐eight putative QTLs for resistance to Sclerotinia stem rot of soybeans were identified on 15 different linkage groups in five RIL populations by single degree‐of‐freedom contrasts. Alleles involved in reduction of lesion size came from both the resistant and susceptible parents, and transgressive segregates were identified in two populations. The amount of phenotypic variation explained by individual QTLs ranged from 4 to 10%. Seven QTLs on seven different linkage groups were identified in multiple populations with some QTL regions corresponding with mapped resistance genes and resistance gene analogs. The results suggest that several genes control resistance to Sclerotinia stem rot and that markers could facilitate an initial screen of segregating breeding populations.
Prevalence of Puroindoline Grain Hardness Genotypes among Historically Significant North American Spring and Winter Wheats
Authors: Morris Craig F. , Lillemo Morten , Simeone Marco C. , Giroux Michael J. , Babb Sheri L. , Kidwell Kimberlee K.
Published: July 2010

Grain hardness (“hard” or “soft” kernel texture) is the single most important trait in determining the utilization and marketing of wheat (Triticum aestivum L.). Puroindoline a and b proteins represent the molecular basis for this trait. This study surveyed the prevalence of puroindoline hardness mutations (alleles) among North American spring and winter wheat varieties with emphasis on those that are historically important. Each variety was assessed for kernel texture using the Single Kernel Characterization System; Hardness alleles were defined by puroindoline gene sequence and the presence or absence of puroindoline a protein on polyacrylamide gels. A total of 90 spring wheats were examined: nine were soft and possessed wild‐type (“soft”) puroindoline sequences, 10 were mixed hardness, and the remaining 71 were uniformly hard. Of these hard spring wheats, 18 carried the Pina‐D1b hardness allele (null for puroindoline a protein), 47 the Pinb‐D1b allele (Gly‐46–Ser‐46), and four the Pinb‐D1c allele (Leu‐60–Pro‐60). Two hard spring wheats possessed a new allele, designated Pinb‐D1e, which involves a single nucleotide change in Trp‐39 to a “stop” codon. Lastly, among the spring wheats, a new hardness allele was found in the hard component of the variety ‘Utac’ which was mixed. This allele, Pinb‐D1f, also involved a single nucleotide change such that Trp‐44 became a “stop” codon. A total of 62 winter wheat varieties were examined, of which five were soft and three were of mixed hardness. Of interest, the three mixed hardness wheats were ‘Turkey’, ‘Kharkof’, and ‘Weston’. The hard component of each carried the Pinb‐D1b allele. Of the 54 remaining wheats, all of which were hard, all but two carried this same Pinb‐D1b allele. ‘Chiefkan’ winter wheat carried the same Pinb‐D1e allele as ‘Canadian Red’ and ‘Gehun’ spring wheats. ‘Andrews’ hard red winter wheat possessed a new allele, designated Pinb‐D1g, which was a single nucleotide change in Cys‐56 to a “stop” codon. In conclusion, hard grain phenotype results from one of various mutations in either of the puroindoline proteins. To‐date, seven hardness alleles have been discovered and characterized in hexapoid wheat. All but one occur in the puroindoline b gene coding sequence and result from single nucleotide changes. These molecular markers are useful in characterizing lineages and analyzing ancestral relationships.
Milling and Bread Baking Traits Associated with Puroindoline Sequence Type in Hard Red Spring Wheat
Authors: Martin J.M. , Frohberg R.C. , Morris C.F. , Talbert L.E. , Giroux M.J.
Published: July 2010

Recent results have shown that mutations in genes coding for puroindoline a and b (PinA and PinB) are associated with the expression of the hard texture of wheat (Triticum aestivum L.) grain. A majority of hard wheats have a glycine‐to‐serine mutation in puroindoline b (allele PinB‐D1b), or they are devoid of puroindoline a (allele PinA‐D1b). Hard wheats with PinA‐D1b tend to be harder than those with PinB‐D1b Grain hardness is known to affect milling and baking traits. Our objective was to determine the influence of allelic variation in PinA and PinB on milling and bread quality traits in a recombinant inbred population segregating for PinA‐D1b and PinB‐D1b One hundred thirty‐nine recombinant inbred lines from the cross ‘Butte 86’ (PinA‐D1b allele)/ND2603 (PinB‐D1b allele) and parents were grown in a field trial with two replications at two locations. Grain hardness was measured by near‐infrared reflectance (NIR) and the single‐kernel characterization system (SKCS). Grain was milled and baked for each line. Puroindoline allele type was determined for each line. The PinB‐D1b group had significantly softer grain, higher break flour yield, flour yield, milling score, and loaf volume, and lower flour ash and crumb grain score (low score being desirable) than the PinA‐D1b group. Significant genetic variability was detected within allelic classes for all traits. The proportion of variation among entry means attributed to puroindoline classes was 34% for break flour yield, 26% for NIR hardness, and 22% for SKCS harness index. Grain hardness was negatively correlated with break flour yield, flour yield, and mixing score and positively correlated with flour ash. Grain hardness was not correlated with loaf volume or crumb grain score. The PinB‐D1b allele was more desirable for milling and bread baking, although superior milling and bread quality genotypes could be selected within either class.
Combining Ability in Loci for High Oleic and Low Linolenic Acids in Soybean
Authors: Rahman Shaikh M. , Kinoshita Takehito , Anai Toyoaki , Takagi Yutaka
Published: July 2010

Two soybean [Glycine max (L.) Merr.] germplasm lines have been identified for unique fatty acid content. The contents of oleic and linolenic acids in HOLL are controlled by ol and fan loci, respectively, and the very low content of linolenic acid in LOLL is controlled by fan and fanxa loci combined. The fan locus is identical for both HOLL and LOLL. Therefore, if ol and fanxa loci are independent, soybean germplasm could be developed with more unique and useful combinations of these fatty acids. The objectives of this study were to combine the loci of high oleic and low linolenic acids, and determine the effects of altered contents of oleic and linolenic acids on other fatty acids. HOLL was reciprocally crossed to LOLL. The data from F2 seed indicated that the ol locus controlling high oleic acid was independently inherited from the fanxa locus controlling low linolenic acid. Thus, the germplasm (DHL) with the high oleic acid trait from HOLL, and very low linolenic acid trait from LOLL, was easily developed. The increases in oleic acid due to ol was associated completely with changes in linoleic acids, indicating a pleiotropic effect of the ol locus. Decreases in linolenic acid due to fan and fanxa were associated primarily with increases in linoleic acid. The development of DHL with increased contents of oleic acid and decreased contents of polyunsaturated fatty acids could open new markets for soybean oil.
Tifton 85 Bermudagrass—Early History of its Creation, Selection, and Evaluation
Authors: Burton Glenn W.
Published: July 2010

From 1953 to 1983, USDA entomologists and I tried to use 10‐d weight gains of fall armyworms, Spodoptera frugiperda (J.E. Smith), to measure the quality of bermudagrass, Cynodon dactylon (L.) Pers., forage. Tifton 68, Coastal, and Tifton 292 bermudagrasses fed to armyworms enabled them to make 10‐d gains of 147, 50, and 8 mg. In 1984, we space planted 145 Tifton 68 × Tift 292 F1 s in deep sand and in the fall selected 13 of the largest plants showing the least drought injury. Of these, entry 13 (‘Tifton 85’) outyielded other entries in a 3‐yr‐32‐entry small plot test. In duplicate 0.81‐ha pastures, Tifton 85 produced 47% more steer gains than ‘Tifton 78’.
Breeding Potential of Intra‐ and Interheterotic Group Crosses in Maize
Authors: Bernardo Rex
Published: July 2010

New maize (Zea mays L.) inbreds are usually developed within a heterotic group. However, breeders sometimes use commercial hybrids as a nonconventional (i.e., interheterotic group) source of new inbreds. The effects of disrupting heterotic patterns in maize, by selfing from commercial hybrids, are not well understood. My objective was to compare intra‐ and interheterotic group crosses as sources of new inbreds. The inbreds B73 and H93 represented the Iowa Stiff Stalk Synthetic (BSSS) heterotic group, whereas Mo17 and B99 represented the non‐BSSS heterotic group. I estimated testcross means and genetic variances in two intragroup F2 populations: (B73 × H93)F2 testcrossed to Mo17 × B99; and (Mo17 × B99)F2 testcrossed to B73 × H93. Likewise, I estimated testcross means and genetic variances in two intergroup F2 populations: (B73 × Mo17)F2 testcrossed to H93 × B99; and (H93 × B99)F2 testcrossed to B73 × Mo17. Testcrosses of 150 individual plants from each F2 population were evaluated at three Indiana locations in 1999. Testcross means for grain yield were 1.0 Mg ha−1 higher in the intra‐ than in the intergroup F2 populations. Grain moisture and stalk lodging testcross means were lower in the intra‐ than in the intergroup F2 populations. Testcross genetic variances (VTC) for grain yield were similar among the four populations. Favorable epistatic combinations may have been broken up in the (B73 × Mo17)F2 population. The results underscore that the success of developing new inbreds from an intergroup population largely depends on finding a suitable tester for the resulting intergroup inbreds.