bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasirecognition by Prime Graph of the Groups 2D2n(q) Where q < 105
Authors: Moradi Hossein , Darafsheh Mohammad Reza , Iranmanesh Ali
Published: July 2017

Let G be a finite group. The prime graph Γ(G) of G is defined as follows: The set of vertices of Γ(G) is the set of prime divisors of |G| and two distinct vertices p and p' are connected in Γ(G), whenever G has an element of order pp'. A non-abelian simple group P is called recognizable by prime graph if for any finite group G with Γ(G)=Γ(P), G has a composition factor isomorphic to P. In [4] proved finite simple groups 2Dn(q), where n ≠ 4k are quasirecognizable by prime graph. Now in this paper we discuss the quasirecognizability by prime graph of the simple groups 2D2k(q), where k ≥ 9 and q is a prime power less than 105.
Mathematics Support – past, present and, most importantly, future
Authors: Lawson Duncan
Published: July 2017

This article briefly reviews the development of mathematics support in higher education over the last 25 years, highlighting in particular the work of sigma, centre for excellence in university-wide mathematics and statistics support as a Centre for Excellence in Teaching and Learning and subsequently as part of the National HE STEM Programme.  A description of sigma’s current HEFCE-funded programme of activities is included, giving particular attention to the development of the sigma network.  The article closes by focusing on the legacy of sigma’s current work and the future sustainability of the sigma network.
A proactive collaborative workshop approach to supporting student preparation for graduate numerical reasoning tests
Authors: Lingham Eleanor F , Baughan Ann
Published: July 2017

Numerical competency and reasoning skills are of high importance and high concern to graduate recruiters. The use of numerical reasoning tests in graduate recruitment is increasing. Many students are unaware of the prevalence of these tests, and the need for refreshment and practice of numerical skills. We describe a stand-alone workshop that is jointly run by the Maths Learning Centre and the Careers And Employability Service at De Montfort University. This workshop helps students to proactively prepare for these tests by providing test information, preparation tips and signposting to further maths and career support. The workshop’s main feature is a testing activity that is run individually and for small groups. Findings suggest that these workshops have been effective and are popular with students.
Contents Page
Authors: Owen Alun
Published: July 2017

Contents page
Mathematics and Statistics Support Centres: Resources for training postgraduates and others who work in them
Authors: Croft Tony , Grove Michael
Published: July 2017

This article provides a rationale for the focused training of postgraduates (and others) who work inmathematics and statistics support centres. It outlines a format for training that has been found towork well through workshop-style events run at universities around the country over the last fiveyears. Within any form of training there are important topics for discussion and a wealth of resourcesfreely available for those centre managers who wish to develop training for their own tutors. Tutorsare in the front line of tackling the lack of confidence and skill deficits of students who arrive atsupport centres looking for help; tutors who are well-briefed in terms of the challenges they are likelyto face and how they can best respond to students who are finding university mathematics andstatistics particularly difficult will help to ensure that the services offered genuinely contribute toenhancing the student experience. While training for new mathematics support tutors is important,of equal, if not greater importance is identifying tutors with the right skills and abilities to work inmathematics and statistics support. We conclude by considering the recruitment of postgraduatetutors and by undertaking a brief discussion about the value of training to the tutors themselvesincluding contribution to professional recognition that is gaining increased importance. Furthersources of information can be found within Croft and Grove (2011) which forms a training resourcepack, Croft, et al. (2013) and in the resources section of the sigma network website (2016) whichincludes PowerPoint slides and training activities that can be used in, or adapted for, workshops.
Rzadko spotykane znaleziska u pacjenta z urazem wielonarządowym wymagającym pilnej laparotomii. Opis przypadku
Authors: Żyluk Andrzej , Szlosser Zbigniew
Published: July 2017

Urazy wielonarządowe są częste w dobie powszechniej motoryzacji, a obrażenia brzucha występują u ok. 30–40% takich przypadków. Krwawienie do jamy otrzewnowej z pękniętych narządów wewnętrznych: śledziony, wątroby i krezki jelita cienkiego stanowi potencjalne zagrożenie życia i – w większości przypadków – wymaga pilnej interwencji chirurgicznej.W pracy przedstawiono przypadek pacjenta z urazem wielonarządowym, u którego w trakcie laparotomii z powodu krwawienia wewnątrzbrzusznego, poza uszkodzeniami struktur będących źródłem krwawienia (rozerwanie krezki iprzedziurawienie jelita cienkiego), stwierdzono inne, rzadko spotykane patologie – zdrowy uchyłek Meckela i stłuczenie krezeczki wyrostka robaczkowego.Omówiono zasady diagnostyki i leczenia typowych obrażeń w obrębie jamy brzusznej, a także postępowania w przypadku rzadkich i nietypowych patologii stwierdzonych w czasie operacji.
Scaled Experimental and Simulation Study of Segregation in Water-Above-Gas Injection
Authors: Namani Mehran , Souraki Yaser , Kleppe Jon , Høier Lars , Karimaie Hassan
Published: July 2017

The water-above-gas injection has been introduced as a modified injection strategy for simultaneous or alternating water/gas injection to improve the recovery factor. This can be achieved through maximizing the size of the mixed zone and extending the complete-segregation distance. Verifying this approach in the laboratory needs special experimental design in which the effect of capillary force is eliminated or strongly reduced, and viscous and gravity forces are active.

In this study, an experimental setup has been prepared and implemented to verify the advantages of the water-above-gas injection. Key parameters in this experiment have been scaled to reservoir conditions. This was possible through choosing correct porous media and fluid system. The porous media should have high porosity and permeability, and the fluid system should have very low interfacial tension (IFT) between phases. Supplementary experiments have been conducted to prove the reliability of the model before the main experiment.

In addition to the investigation of different injection rates and water/gas injection ratios in this process, the effect of stepwise injection also has been investigated to verify the practical approach, which results in maximized sweep efficiency.

Finally, a simulation study has been conducted, and by comparing its results to experimental results, the applicability of numerical simulation in designing reservoir-scale water-above-gas injection is confirmed.
Effect of Cold Storage on the Germination Success of Four Stonecrop Species
Authors: McDavid Kathryn L. , Sanford David L. , Berghage Robert D.
Published: July 2017

Green roof construction is constrained by cost of labor to install the plant material. Optimizing seed germination and establishment could significantly reduce installation costs but would require specific growing conditions that are difficult to provide during installation. Plants of the stonecrop (Sedum) genus are commonly used for the roof top because they will tolerate the high temperatures. This study compared the germination rates of four stonecrop species {goldmoss sedum (Sedum acre), ‘Oracle’ sedum (Sedum forsterianum), blue spruce sedum (Sedum reflexum), and amur sedum [Sedum selskianum (synonm Phedimus selskianum)]} at two temperatures, 70 and 90 °F, following storage of seed in dry, cool (40 °F) conditions of different durations (54, 98, 157, 197, 255, or 343 days). At 70 °F seed of goldmoss sedum, ‘Oracle’ sedum, and blue spruce sedum produced minimum germination rates of 60% at 21 days in seed stored for 54, 98, 157, 197, 255, or 343 days. Goldmoss sedum, ‘Oracle’ sedum, and blue spruce sedum showed reduced germination in 90 °F, probably due to temperature-induced dormancy. Amur sedum had germination of at least 83% at 21 days in both temperatures tested. As amur sedum germination rates appear to be unaffected in the temperatures tested, it could provide an excellent seed for use on green roofs where ideal temperatures are rarely available.
Frost Protection for Georgia Peach Varieties: Current Practices and Information Needs
Authors: Simnitt Skyler , Borisova Tatiana , Chavez Dario , Olmstead Mercy
Published: July 2017

The study focuses on frost protection for early-season (early-ripening) peach (Prunus persica) varieties, which are an important crop for producers in the southeastern United States. Using in-depth interviews with four major Georgia peach producers, we explore their frost protection management strategies. This information is the first step in developing a comprehensive research agenda to advise cost-effective frost protection methods for peach cultivation. We found that peach producers are concerned about frost impacts on their crops. Although early-season peach varieties are particularly susceptible to frost impacts, producers still dedicate significant acreage to these varieties, aiming to extend the market window, satisfy sales contracts, and meet obligations for hired labor. However, early-season varieties do not result in high profits, so producers prefer to concentrate on frost protection for mid- and late-season varieties. Producers employ a variety of frost protection methods, including passive methods (such as planting sensitive varieties in areas less susceptible to frost and adjusting pruning/thinning schedules) and active methods (such as frost protection irrigation and wind machines). The choice among active frost protection methods is based on factors such as the planning horizon, initial investment needs, frequency of frost events, and the effectiveness of the frost protection method. Problem areas that producers identified included improving the effectiveness of frost protection methods; reducing initial investments required to install frost protection systems; and employing better spatial targeting and configuration of frost protection strategies (to reduce investment costs while maintaining or improving the effectiveness of frost protection). Although the initial investment costs of enhanced protection systems may limit producers from actually adopting such methods, the operating costs of such systems are relatively low and have a limited effect on the decision to employ frost protection during a particular frost event. However, producers use information about critical temperatures for different bud stages, and hence, improving the quality of information regarding frost susceptibility can help producers make better frost protection decisions (and potentially reduce electricity costs and water use for frost protection).
Consumer Perceptions of Aquaponic Systems
Authors: Short Gianna , Yue Chengyan , Anderson Neil , Russell Carol , Phelps Nicholas
Published: July 2017

Aquaponics, an integrated system with both hydroponic plant production and aquaculture fish production, is an expanding alternative agriculture system. Many key questions about the overall feasibility of aquaponic systems remain unanswered. Of particular concern for start-up and established producers alike are consumer perceptions and willingness to pay for aquaponic produce and fish. This study reports results and analysis of a consumer survey about perceptions and preferences for aquaponic-grown products that was conducted in Minnesota during Feb. 2016. Probit and ordered probit models are used to evaluate the probability of different consumer demographic segments having various levels of knowledge and perceptions about aquaponics. About one-third of respondents had previously heard of aquaponics, and upon learning more about the system through the survey, respondents tended to be generally neutral or favorable to aquaponics. Price might be an issue for many consumers, but many tend to believe that aquaponics can impact the environment in a positive way. The results represent a first step toward building knowledge about the potential consumer base for aquaponics, which is a critical piece in the system’s potential overall profitability. It appears that consumer education and marketing will be key for the expansion of the market.
Evaluation of the Sensory, Physicochemical, and Visual Characteristics of a Sweet Cherry Cultivar Treated in a Commercial Orchard with a Cherry Cuticle Supplement when a Rainfall Event Does Not Occur
Authors: Cliff Margaret A. , Stanich Kareen , Toivonen Peter M.A.
Published: July 2017

The splitting of sweet cherry (Prunus avium L.) just before harvest can be a considerable problem in the Okanagan Valley (BC, Canada). In an attempt to minimize economic losses, growers apply a commercial cherry cuticle supplement in anticipation of a rainfall event. However, it is unknown if this product affects flavor, texture (crispness, firmness, and juiciness), or visual characteristics (stem browning, pitting, and pebbling) of sweet cherry. Therefore, this research was undertaken to evaluate the effects of a cherry cuticle supplement on the sensory, physicochemical, and visual characteristics of ‘Skeena’ sweet cherry. Firmness measurements were assessed with a fruit-firmness tester, whereas sensory determinations were assessed at first bite (whole-cherry crispness) and after multiple chews (flesh firmness) by a panel of 14 trained panelists. Fruit treated with the cherry cuticle supplement had lower instrumental firmness compared with the control, which was most pronounced after 28 days, with a reduction of 0.53 N. Treated fruit also had significantly lower sensory firmness and higher juiciness than the control fruit. Fruit treated with the cherry cuticle supplement had reduced water loss, less pitting, and lower stem-pull force, resulting in higher frequency of detachment of the stems. Further research would be necessary to evaluate the effects with other cultivars, and in years with rainfall events, as well as when hydrocooling is used.
Comparative Analysis of Root System Morphology in Tomato Rootstocks
Authors: Suchoff David H. , Gunter Christopher C. , Louws Frank J.
Published: July 2017

At its most basic, grafting is the replacement of one root system with another containing more desirable traits. Grafting of tomato (Solanum lycopersicum) onto disease-resistant rootstocks is an increasingly popular alternative for managing economically damaging soilborne diseases. Although certain rootstocks have demonstrated ancillary benefits in the form of improved tolerance to edaphic abiotic stress, the mechanisms behind the enhanced stress tolerance are not well understood. Specific traits within root system morphology (RSM), in both field crops and vegetables, can improve growth in conditions under abiotic stress. A greenhouse study was conducted to compare the RSM of 17 commercially available tomato rootstocks and one commercial field cultivar (Florida-47). Plants were grown in containers filled with a mixture of clay-based soil conditioner and pool filter sand (2:1 v/v) and harvested at 2, 3, or 4 weeks after emergence. At harvest, roots were cleaned, scanned, and analyzed with an image analysis system. Data collected included total root length (TRL), average root diameter, specific root length (SRL), and relative diameter class. The main effect of cultivar was significant (P ≤ 0.05) for all response variables and the main effect of harvest date was only significant (P ≤ 0.01) for TRL. ‘RST-106’ rootstock had the longest TRL, whereas ‘Beaufort’ had the shortest. ‘BHN-1088’ had the thickest average root diameter, which was 32% thicker than the thinnest, observed in ‘Beaufort’. SRL in ‘Beaufort’ was 60% larger than ‘BHN-1088’. This study demonstrated that gross differences exist in RSM of tomato rootstocks and that, when grown in a solid porous medium, these differences can be determined using an image analysis system.
Evaluation of Flower, Fruit, and Juice Characteristics of a Multinational Collection of Cider Apple Cultivars Grown in the U.S. Pacific Northwest
Authors: Miles Carol A. , King Jacqueline , Alexander Travis Robert , Scheenstra Edward
Published: July 2017

Little information exists on the bloom and fruit characteristics of cider apple (Malus ×domestica) cultivars grown in the United States for the juice and alcoholic beverage markets. In this study, a total of 17 cider apple cultivars, including 4 American, 9 English, and 4 French, plus 1 Danish standard dessert apple cultivar (Red Gravenstein, Worthen strain) commonly used for cider, all grown in northwest Washington, were evaluated from 2000 to 2015 for commercially relevant traits. Trees were rated each year and the cultivars were categorized accordingly by relative bloom time, bloom habit, and productivity. The mean full bloom (FB) date of the 18 apple cultivars evaluated ranged from 25 Apr. to 25 May, with 6 cultivars categorized as early season bloomers, 9 as midseason, and 3 as late season. The mean bloom density (BD) rating (measured on a scale of 1–5) for all cultivars was (mean ± sd) 3.8 ± 0.6 (moderate bloom), with the bloom habit of 1 cultivar categorized as biennial, 11 as consistent, and 6 as strongly consistent. The mean productivity rating (measured on a scale of 1–5) for all cultivars was 2.9 ± 0.6 (light fruiting), with the productivity of 4 cultivars categorized as biennial, 10 as consistent, and 4 as strongly consistent. The mean fruit diameter of the 18 apple cultivars was 2.7 ± 0.4 inches (medium sized), with the fruit size of 2 cultivars categorized as small-fruited, 15 as medium-fruited, and 1 as large-fruited. For the 18 cultivars, the mean tannin and titratable acidity (TA) were 0.20% ± 0.14% and 0.54% ± 0.28%, respectively, and using the English cider apple classification system of juice type, 4 of the cultivars were classified as bittersweet, 1 as bittersharp, 3 as sweet, and 10 as sharp. Three of the cultivars had tannin content lower than what was historically recorded at the Long Ashton Research Station (LARS) in Bristol, England, for those same cultivars. The mean specific gravity (SG) of the 18 cultivars was 1.052 ± 0.007, the average predicted alcohol by volume (ABV) was 6.9% ± 0.9%, and the mean pH was 3.68 ± 0.39. Classification of three cultivars in northwest Washington, based on juice characteristics, differed from their historical classification in England, likely because of differences in climate and management. Only cultivars Golden Russet (sharp), Grimes Golden (sharp), and Yarlington Mill (sweet, but borderline bittersweet) were strongly consistent in productivity, but none produced high levels of tannin, whereas only cultivars Bramtot (bittersweet), Chisel Jersey (bittersweet), and Breakwell Seedling (bittersharp) were consistent in productivity and produced high levels of tannin.
Virginia Nursery and Greenhouse Grower Survey of Best Management Practices
Authors: Mack Rachel , Owen James S. , Niemiera Alex X. , Latimer Joyce
Published: July 2017

A survey, focusing on the use of irrigation and fertilization best management practices (BMPs), was designed and released to Virginia nursery and greenhouse growers. The objectives of the survey were to determine the most widely used BMPs, assess the reasons for their use, and identify barriers to BMP adoption. The survey was distributed in person, via e-mail attachment, or link to 357 Virginia growers in 2016 with 60 respondents. Survey results demonstrate that the most widely used BMPs in Virginia included irrigation scheduling, integrated pest management (IPM) implementation, altering irrigation practices to optimize irrigation efficiency, controlled-release fertilizer (CRF) use, and plant need–based watering. Respondents selected environmental/resource savings as one of the most cited reasons behind BMP use for water, fertilizer, and runoff management. Cost was the most cited barrier to BMP adoption for all BMPs. Fertilizer management BMP implementation was primarily an economic decision. The value of determining the most widely used BMPs and impediments to BMP adoption is that we can 1) communicate this information to growers who currently do not employ BMPs to encourage BMP adoption and 2) subsequently inform the regulatory community of BMP use. Increased BMP use can boost the potential for mitigation of agricultural nutrient and sediment runoff into impaired waterways, including the Chesapeake Bay, and help growers increase efficiency of operation inputs, such as water and fertilizer resources, while potentially saving money.
Duomenų išrinkimo interneto puslapiuose algoritmas, paremtas duomenų tarpusavio panašumu
Authors: Griavev Kiril , Ramanauskaitė Simona
Published: July 2017

Straipsnyje aprašoma ir analizuojama duomenų išrinkimo iš interneto puslapių problema ir egzistuojantys sprendimai. Atsižvelgiant į šiuo metu vyraujančias tendencijas duomenims išrinkti naudoti ne keliu, o duomenimis paremtus algoritmus, pasiūlytas naujas duomenų išrinkimo iš interneto puslapių algoritmas, paremtas kontrolinių duomenų panašumu į interneto puslapyje pateikiamus duomenis ir taip leidžiantis vienu kontroliniu įrašu nustatyti visų duomenų įrašų padėtį puslapyje.Straipsnyje analizuojamas pasiūlyto algoritmo efektyvumas, jį taikant valiutų kursų duomenų stebėjimo atveju, ir įvertintas šio algoritmo sukurto prototipo efektyvumas, lyginant jį su kitais šiuo metu rinkoje siūlomais įrankiais. Šių tyrimų rezultatai parodo, kad siūlomas duomenų išrinkimas, nors ir yra skirtas labiau stebėti nuolat kintančius duomenis bei reikalauja kontrolinių įrašų, vis dėlto pasižymi didesniu efektyvumu nei kiti analogiški produktai.
Netradicinių studentų patirtinio mokymosi teorinės įžvalgos
Authors: Treinienė Daiva
Published: July 2017

Netradiciniais studentais įvardijami asmenys, pasirinkę netradicinį atėjimo į aukštojo mokslo studijas kelią. Esminiai kriterijai, vienijantys šią studentų grupę, yra tai, kad tai yra suaugę ir turintys didelę patirtį studentai. Patirtinis mokymasis straipsnyje apibūdinamas remiantis užsienio autorių teoriniais ir metodologiniais teiginiais. Apibrėžiant patirtinį mokymąsi, išskiriami pagrindiniai kriterijai, atskleidžiantys išsamesnę šio mokymosi metodo sampratą. Straipsnyje aprašomas patirties vaidmuo netradicinių studentų mokymosi procese. Išsamiai pateikiama patirtinio mokymosi koncepcija, patirtinio mokymosi etapai, elementai, ciklai. Straipsnyje keliamas klausimas, kokios teorinės įžvalgos būdingos netradicinių studentų patirtiniam mokymuisi? Tyrimo objektas – netradicinių studentų patirtinis mokymasis. Tyrimo tikslas – atskleisti netradicinių studentų patirtinio mokymosi teorines įžvalgas. Tyrimo metodai: literatūros apžvalga, analizuojant ir išgryninant teorinius patirtinio mokymosi aspektus mokslo šaltiniuose bei pateikiant patirtinio mokymosi teorinių įžvalgų apibendrinimus. Pagrindinės išvados: mokymasis iš patirties suprantamas kaip modelis, metodika ar metodas. Tai mokymasis veikiant, t. y. mokymasis iš patirties arba per patirtį, leidžiantis plėtoti, ugdyti ir perkelti žinias, įgūdžius, gebėjimus, mąstymo būdą iš vieno mokymosi konteksto į kitą. Patirtinis mokymasis suteikia studentams galimybę studijų procese taikyti jau sukauptą patirtį, o realiame gyvenime pritaikyti tai, ką jie sužino studijuodami. Patyrimu grįstoje mokymosi aplinkoje netradiciniai studentai teikia pirmumą aktyvaus mokymosi metodams.
Can Organic Amendments Support Sustainable Vegetable Production?
Authors: de Rosa Daniele , Basso Bruno , Rowlings David W. , Scheer Clemens , Biala Johannes , Grace Peter R.
Published: July 2017

Core Ideas

Accounting for the N release from organic amendments improves N use efficiency and promotes soil C storage in horticultural soils.

Regional N fertilizer recommendations are affected by a high degree of uncertainty.

Crop simulation model can help to develop efficient site‐specific N management.

Application rates of synthetic fertilizer to agricultural fields can be reduced through better understanding of N supplied by organic amendments (OA). Field and simulation experiments were performed to quantify the effect of N released from OA application on crop production and selected soil properties in an intensively managed vegetable crop rotation. The SALUS crop model was used to simulate yield, soil N, and soil organic carbon (SOC) dynamics under different combinations of composted or raw OA and synthetic N fertilizer application rates. SALUS accurately simulated aboveground crop biomass production (r2 = 0.91, RMSE = 1.7 t ha−1) and crop N uptake (r2 = 0.96, RMSE = 15 kg N ha−1) under different N management strategies as well as SOC level (r2 = 0.51, RMSE = 1 t C ha−1) and soil mineral N (r2 = 0.58, RMSE = 56 kg N ha−1). No difference in crop biomass production was found with N fertilizer reductions up to 27% of the conventional N fertilizer rate when combined with OA application. A 12‐yr scenario analysis using SALUS indicated that conventional N fertilizer can be further reduced by up to 50% while sustaining crop biomass production, thereby potentially reducing N losses to the environment. Data gathered from the field study and simulation scenarios highlighted the positive effect of composted OA to maintain soil C levels. This contrasts with average annual SOC losses of 3.7% observed in long‐term simulation scenarios in systems with only N fertilizer or raw OA applications.
Breeding Opportunities for Increasing the Efficiency of Water Use and Crop Yield in Temperate Cereals
Authors: Richards R. A. , Rebetzke G. J. , Condon A. G. , van Herwaarden A. F.
Published: July 2017

Genetic advances in grain yield under rainfed conditions have been achieved by empirical breeding methods. Progress is slowed, however, by large genotype × season and genotype × location interactions arising from unpredictable rainfall, which is a feature of dry environments. A good understanding of factors limiting and/or regulating yield now provides us with an opportunity to identify and then select for physiological and morphological traits that increase the efficiency of water use and yield under rainfed conditions. The incorporation of these traits into breeders' populations should broaden their genetic base. It also may lead to faster selection methods and selection for the traits may result in correlated gains in yield. Here, we undertake a review of factors that limit yield in rainfed environments and discuss genetic opportunities and genetic progress in overcoming them. The examples given are for wheat (Triticum aestivum L.), but the principles apply to all cereal crops grown in dry environments.
Water Relations of Standard Height and Dwarf Sunflower Cultivars
Authors: Angadi S. V. , Entz M. H.
Published: July 2017

Development of early maturing short stature sunflower (Helianthus annuus L.) cultivars followed the success of semi‐dwarf cereals. Although a number of breeding programs have recently released dwarf sunflower cultivars for production in western Canada, the drought adaptability of dwarf cultivars has not been studied. Therefore, field studies were conducted under rainfed conditions at two Manitoba locations during 1994 and 1995 to compare seasonal water relations of ‘Sunwheat‐103’ (SW‐103), a dwarf hybrid, and ‘AC‐Aurora’ (Aurora), a dwarf open pollinated cultivar, with ‘IS‐6111’, a standard height hybrid. The dwarf hybrid, SW‐103, experienced less stress (up to 0.44 MPa higher leaf water potential) than the standard height hybrid, IS‐6111. Genotypic variation for osmotic adjustment was observed in both 1994 and 1995. SW‐103 and Aurora respectively had up to 0.42 and 0.39 MPa lower osmotic potential at full turgor compared with IS‐6111. Aurora displayed greater osmotic adjustment per unit decrease in leaf water potential than other cultivars. All cultivars maintained positive pressure potential during the study and whenever significant differences in pressure potential were observed, SW‐103 usually had higher pressure potential than other cultivars. IS‐6111 maintained higher photosynthetic rate and stomatal conductance than the dwarf cultivars. These results suggest that under conditions of adequate water supply, the tall hybrid had the highest productivity despite experiencing the lowest leaf water potential and osmotic adjustment. The drought tolerance advantages of shorter statured cultivars identified here may be more important to productivity maintenance under limited soil water conditions.
Use of Spectral Radiance to Estimate In‐Season Biomass and Grain Yield in Nitrogen‐ and Water‐Stressed Corn
Authors: Osborne S. L. , Schepers J. S. , Francis D. D. , Schlemmer M. R.
Published: July 2017

Current technologies for measuring plant water status are limited, while recently remote sensing techniques for estimating N status have increased with limited research on the interaction between the two stresses. Because plant water status methods are time‐consuming and require numerous observations to characterize a field, managers could benefit from remote sensing techniques to assist in irrigation and N management decisions. A 2‐yr experiment was initiated to determine specific wavelengths and/or combinations of wavelengths indicative of water stress and N deficiencies, and to evaluate these wavelengths for estimating in‐season biomass and corn (Zea mays L.) grain yield. The experiment was a split‐plot design with three replications. The treatment structure had five N rates (0, 45, 90, 134, and 269 kg N ha−1) and three water treatments [dryland, 0.5 evapotranspiration (ET), and full ET]. Canopy spectral radiance measurements (350–2500 nm) were taken at various growth stages (V6–V7, V13–V16, and V14–R1). Specific wavelengths for estimating crop biomass, N concentration, grain yield, and chlorophyll meter readings changed with growth stage and sampling date. Changes in total N and biomass in the presence of a water stress were estimated using near‐infrared (NIR) reflectance and the water absorption bands. Reflectance in the green and NIR regions were used to estimate total N and biomass without water stress. Reflectance at 510, 705, and 1135 nm were found for estimating chlorophyll meter readings regardless of year or sampling date.
Radiation Use Efficiency and Biomass Production in Soybean at Different Plant Population Densities
Authors: Purcell Larry C. , Ball Rosalind A. , Reaper J. D. , Vories Earl D.
Published: July 2017

As population density (POP) increases in a soybean [Glycine max (L.) Merr.] crop, maximum light interception (LI) occurs earlier in the season. Earlier canopy closure would be expected to increase the cumulative radiation intercepted. We hypothesized that if radiation use efficiency (RUE) was constant across a range of population densities in a nonstressful environment, then increasing POP would increase biomass at the end of the season. To test this hypothesis, we evaluated the response of total biomass produced during the season to cumulative intercepted photosynthetically active radiation (PAR) in field experiments at Fayetteville, AR, with soybean cultivars selected from Maturity Groups (MGs) 00 to IV. Additionally, from field experiments at Keiser, AR, with MG IV soybean cultivars, we assessed the response of RUE to POP. At both locations with MG IV cultivars, a late sowing date shortened the life cycle of the crop by 13 to 25 d compared with an early sowing date, resulting in less PAR accumulated. Similarly, early maturing cultivars had less time for PAR and biomass accumulation relative to later maturing cultivars. At Keiser, in three of the four environments, RUE decreased linearly by 26 to 30% as the POP increased from 7 to 135 plants m−2 Final biomass at the end of the season, as a function of PAR accumulated from emergence to the full‐seed‐size stage of development, responded linearly to intercepted PAR up to ≈400 MJ m−2 Above 400 MJ m−2, the response was curvilinear with little increases in biomass >700 MJ m−2 Our data clearly indicate that RUE decreased as POP increased and that maximum biomass production in these environments was not limited by intercepted PAR.
Cupule Removal and Caryopsis Scarification Improves Germination of Eastern Gamagrass Seed
Authors: Tian X. , Knapp A. D. , Moore K. J. , Brummer E. C. , Bailey T. B.
Published: July 2017

Eastern gamagrass (Tripsacum dactyloides L.) is a warm‐season, perennial grass with high palatability and productivity. However, poor stand establishment, often due to seed dormancy, limits its widespread use. Seed dormancy is often caused by structures surrounding the embryo, the physiological state of the embryo itself, or a combination of these factors. The eastern gamagrass dispersal unit is a floret within a thick, hard cupule. The objective of this study was to evaluate effects of cupule (including lemma and palea) removal and caryopsis scarification on germination of eastern gamagrass by means of different commercial seed lots produced in different locations and years. Germination tests were conducted at 20/30°C alternating temperature with light during 30°C for 8 h daily. Germination counts were made every 7 d. After 28 d, the germination of decupulated caryopses from different seed lots germinated from 16 to 49% across seed lots, compared with 5 to 18% germination for caryopses with cupule intact. Scarifying the pericarp over the embryo, however, resulted in germination of all dormant seeds. We conclude that while the cupule (including the lemma and palea) contributes to the dormancy of eastern gamagrass, the pericarp and/or testa are the main factors restricting germination of this species. In addition, caryopsis scarification increased the germination rate and the germination test could be shortened to 21 or even 14 d depending on the seed lot.
Protein Alterations in Tall Fescue in Response to Drought Stress and Abscisic Acid
Authors: Jiang Yiwei , Huang Bingru
Published: July 2017

Drought stress may alter protein synthesis in turfgrasses. The objectives of this study were to investigate physiological changes associated with the synthesis of dehydrin and a cytosolic‐heat shock protein (HSC 70) in response to drought stress in two tall fescue (Festuca arundinacea L.) cultivars, ‘Southeast’ and ‘Rebel Jr.’. The effects of abscisic acid (ABA) application on the drought tolerance of the cultivars also were evaluated. The cultivars were subjected to three treatments in growth chambers: well‐watered control, drought stress, and drought stress following ABA treatment. Turf quality and leaf relative water content (RWC) decreased and electrolyte leakage (EL) increased during drought stress for both cultivars. The ABA‐treated plants maintained higher turf quality and RWC, and lower EL than untreated plants under drought stress conditions. Levels of 20‐ and 29‐kDa polypeptides increased during drought stress, and a 35‐kDa polypeptide was noted in both cultivars only when subjected to drought stress either with or without ABA treatment. Immunoblot analysis indicated that dehydrin‐like polypeptides of about 23‐60 kDa were induced by progressive water deficit in both cultivars. The 53 kDa dehydrin polypeptide was present in Southeast with or without ABA treatment at 10 d of drought stress, whereas the 40 kDa dehydrin polypeptide accumulated in Rebel Jr. in both treatment. The 23‐ and 27‐kDa dehydrin polypeptides were present at 10 d in drought‐stressed and ABA‐treated plants in both cultivars, but were more pronounced in the drought‐stressed plants without ABA. A cytosolic‐heat shock protein (HSC 70) was detected in plants in all treatments including well‐watered plants of both cultivars, but its levels were higher in drought‐stressed and ABA‐treated plants. No single dehydrin polypeptide was induced by ABA treatment under drought stress, however, the promotive effects of ABA on the reduced drought stress paralleled the delayed induction of protein synthesis in tall fescue.
Seedling Development and Field Performance of Prairiegrass, Grazing Bromegrass, and Orchardgrass
Authors: Sanderson Matt A. , Skinner R. H. , Elwinger Gerald F.
Published: July 2017

Seedling establishment is a critical phase in pasture management. Knowledge of the seedling development of new forages is necessary to develop management practices and recommend species mixtures for pasture seedings. We compared seedling growth and development of prairiegrass (Bromus willdenowii Kunth = B catharticus Vahl), grazing bromegrass (B stamineus Desv.), and orchardgrass (Dactylis glomerata L.) in controlled environment and field studies. Seedlings were sampled weekly for 7 wk in the growth chamber and greenhouse beginning 8 to 10 d after planting (DAP). The number and mass of leaves and roots were recorded. In the field, leaf development was measured during spring and fall of 1997, and leaf and root development were measured during spring and fall of 1999. Forage dry matter (DM) yield was measured in clipped field plots during 1998 to 2000. Grazing bromegrass had more leaves, about twice the number of tillers per seedling, and a greater seedling mass than other grasses. Grazing bromegrass also had 50 to 100% more tillers m−2 than other grasses in clipped field plots. The larger seedling size and greater tiller density, however, did not translate into greater yield in clipped plots. Grazing bromegrass yielded 10 to 15% less than orchardgrass or prairiegrass. Because of their large seedlings and rapid development, prairiegrass and grazing bromegrass probably should be used at a lower seeding rate or perhaps not used in seed mixtures with small‐seeded grasses. Seedlings of these grasses should be fully established by 40 to 50 DAP under favorable moisture and temperatures in the spring and late summer.
Rate of Leaf Appearance in Crimson Clover
Authors: Butler Twain J. , Evers Gerald W. , Hussey Mark A. , Ringer Larry J.
Published: July 2017

Understanding factors that affect growth and development of crimson clover (Trifolium incarnatum L.) are important for the development of management practices to optimize forage utilization. In a 3‐yr field experiment at College Station, TX, we evaluated the effects of planting date on rate of leaf appearance of an intermediate‐ and late‐maturing crimson clover. We wanted to determine if growing degree days (GDD) or a photothermal index (PTI) could be used to predict growth. Leaf appearance rates (LAR) did not differ between ‘Tibbee’ and ‘Columbus’ crimson clover. Leaf appearance rate was primarily controlled by temperature or GDD, which accounted for 90 to 99% of the variability within each planting date. Photoperiod did not consistently influence the rate of leaf appearance under normal daylengths of 10 h 12 min to 14 h 6 min used in this study. Predictions of LAR were not improved when photoperiod was combined with temperature in a photothermal index than with predictions that used GDD alone. Leaf appearance rate of crimson clover was generally higher when planted in October, November, and December and lower when planted in September, February, and March.
Flowering in Crimson Clover as Affected by Planting Date
Authors: Butler Twain J. , Evers Gerald W. , Hussey Mark A. , Ringer Larry J.
Published: July 2017

Understanding factors that affect flowering of crimson clover (Trifolium incarnatum L.) could improve management decisions to optimize utilization by improving season of use. The experiment was a split‐plot randomized complete block design with three replications at College Station, TX, in the 1997‐1998 and 1999‐2000 growing seasons, and Overton, TX, in the 1998‐1999 growing season. Main plot treatments of two crimson clover cultivars and subplot treatments of six planting dates (PDs) were used to evaluate the effect of date to reach 50% budding and 50% flowering based on day of year (DOY), days after planting (DAP), photothermal index (PTI), and growing degree days (GDD) under field conditions. Correlations with 50% bud and 50% flower were almost identical. ‘Columbus’ planted in the autumn flowered an average of 49 d later than ‘Tibbee’. Date to reach 50% flowering was best correlated with DOY (r = 0.93 and 0.97) and DAP (r = 0.92 and 0.98) for Columbus and Tibbee. Date to reach flowering was not as highly correlated with PTI (r = 0.66 and 0.82) or GDD (r = 0.71 and 0.85) for Columbus and Tibbee, thus temperature could not be used to predict flowering. Planting after 21 December delayed flowering in Tibbee 2 to 9 wks, whereas, Columbus planted after 21 December did not flower. It is important to plant early in the growing season or to use later‐maturing cultivars to maximize the length of the growing season and possible total production in grazed environments.
Effective Population Size during Grass Germplasm Seed Regeneration
Authors: Johnson R. C. , Bradley V. L. , Evans M. A.
Published: July 2017

Effective population size (N
e) is the key parameter for predicting genetic drift associated with germplasm regeneration. A major factor reducing N
e below the census population size (N
c) is variation in seed production among plants in a given population. The objectives of this study were to estimate N
e/N
c associated with variation in seed production in three model wind pollinated, perennial grass species [Lolium perenne L., Festuca pratensis Huds., and Pseudoroegneria spicata (Pursh) Á. Löve] and to recommend cost effective sampling methodology to maximize N
e/N
c during seed regeneration. Three accessions of each species were grown at two field locations and variation in seed number among plants and mean seed production per plant used to estimate N
e/N
c Mean seeds per whole plant, standard deviations, and N
e/N
c differed among species, and accessions within species (P < 0.05). For whole plant samples, average N
e/N
c for each species differed with values of 0.42, 0.51, and 0.63 for L. perenne, F. pratensis, and P. spicata, respectively. However, average N
e/N
c based on two inflorescences per plant was 0.69, 0.88, and 0.86 for L. perenne, F. pratensis, and P. spicata, respectively, which was higher than that of whole plant samples. This higher N
e/N
c resulted from the elimination of the variation in inflorescence number per plant, a major source of variation in seed number among plants. The results showed the high potential for genetic drift in small regeneration populations. Increased plant populations and harvesting a constant number of inflorescences per plant are recommended as cost‐effective methods to minimize genetic drift during regeneration of outcrossing grass germplasm.
Comparative Assessment of Variation among Sorghum Germplasm Accessions Using Seed Morphology and RAPD Measurements
Authors: Dahlberg J. A. , Zhang X. , Hart G. E. , Mullet J. E.
Published: July 2017

The sorghum germplasm collection currently contains over 42 000 accessions, a number that is too large to manage efficiently. The specific objective of this research was to compare clusters developed from agronomic descriptors with phylogenetic groupings based on random amplified polymorphic DNA (RAPD) fingerprinting of selected sorghum [Sorghum bicolor (L.) Moench] races. Our intent was to identify one approach using agronomic descriptors that would most closely approximate the groupings produced by RAPD markers. Ninety‐four accessions of sorghum were grouped into four of the five major races. Differences among accessions determined by various clustering procedures based on agronomic characteristics were compared with clusters developed by means of RAPD markers. Each race varied in the degree of similarity between the four clustering approaches taken and the information provided by RAPD fingerprinting. Test 2, standardization of data by Z‐scores and cluster analysis using the complete set of data, provided the highest similarity score for the race bicolor, while Test 3, standardization of data by Z‐scores and cluster analysis based on a reduced set of variables selected from principle component analysis, provided the highest similarity scores for the races guinea. Test 1, random selection, was highest for the races caudatum and durra. When averaged over all the races, Test 2 provided the highest similarity score. The results of this study indicate that no one approach to develop clusters by means of agronomic descriptors closely approximate the groupings produced by RAPD markers. These results underscore the need for further research in the evaluation of techniques used to develop core collections and their validity.
Inheritance and Interaction of Low Palmitic and Low Linolenic Soybean
Authors: Primomo Valerio S. , Falk Duane E. , Ablett Gary R. , Tanner Jack W. , Rajcan Istvan
Published: July 2017

Decreasing the palmitic and linolenic acid content of soybean [Glycine max (L.) Merrill] oil would help improve its nutritional quality and oxidative stability. The altered fatty acid profile in soybean germplasm lines with decreased levels of palmitic and linolenic acid have been developed at the University of Guelph, Canada, by combining different mutant alleles through hybridization. The objectives of this study were to determine the inheritance and interaction of palmitic and linolenic acid levels in RG3 and RG1, and the effects of these altered fatty acid levels on other fatty acids. RG3 and RG1 (low palmitic ≈45 g kg−1 and linolenic ≈40 g kg−1) were crossed reciprocally to several soybean lines with altered or normal fatty acid profiles. Analysis of the reciprocal F2 generations indicated no maternal or cytoplasmic effects for palmitic or linolenic acid content. Chi‐square analyses of the F2 generation demonstrated that RG3 and RG1 contained two alleles, fap1 and fapx, that controlled palmitic acid content. In addition, RG1 had a third allele, fan, which reduced its linolenic acid content. Calculation of gene substitution values indicated additive gene action at the fap1 and fan loci, whereas the fapx locus involved partial dominance. Correlation coefficients indicated no association between palmitic and linolenic acid. Decreases in palmitic and linolenic acid content were associated primarily with increases in linoleic acid content. Since fap1, fapx, and fan were inherited independently of each other and appeared to behave in an additive manner, RG3 and RG1 can be used in breeding programs as additional valuable sources of germplasm with altered fatty acid profiles.
Genotype × Environment Interactions, Stability, and Agronomic Performance of Soybean with Altered Fatty Acid Profiles
Authors: Primomo Valerio S. , Falk Duane E. , Ablett Gary R. , Tanner Jack W. , Rajcan Istvan
Published: July 2017

There has been a major effort to produce soybean [Glycine max (L.) Merr.] lines with modified fatty acid profiles in order to improve quality and develop new uses for soybean oil. Utilization of the lines depends on their agronomic traits and stability of the fatty acid profiles in diverse environments. The objectives of this study were to (i) evaluate the influence of years and locations on the fatty acid composition of soybean genotypes with unique fatty acid profiles, (ii) determine which fatty acids and fatty acid profiles are the most stable, and (iii) evaluate agronomic and seed quality traits of mutant soybean lines. Genotypes were evaluated over three years (1996, 1997, and 1998) at four locations in Southern Ontario, Canada. Year effects had the largest impact on all fatty acid levels. Location effects were significant only for oleic and linolenic acids. Genotype × year interaction effect was significant for all fatty acids whereas genotype × location and genotype × year × location interaction effects were significant only for oleic, linoleic, and linolenic acids. Mutants with reduced or elevated palmitic, elevated oleic, or reduced linolenic acid concentrations exhibited average or higher stability than lines with normal levels of these fatty acids. Therefore, these lines may be suitable for growing in a wide range of environments. Maturity, plant height, lodging, seed size, and seed quality were significantly different between mutants and cultivars. Seed yield was significantly reduced in mutants compared to cultivars.