bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling new particle formation events in the South African savannah
Authors: Gierens Rosa T. , Laakso Lauri , Mogensen Ditte , Vakkari Ville , Beukes Johan P. , Van Zyl Pieter G. , Hakola Hannele , Guenther Alex , Pienaar Jacobus J. , Boy Michael
Published: May 2014

Africa is one of the less studied continents with respect to atmospheric aerosols. Savannahs are complex dynamic systems sensitive to climate and land-use changes, but the interaction of these systems with the atmosphere is not well understood. Atmospheric particles, called aerosols, affect the climate on regional and global scales, and are an important factor in air quality. In this study, measurements from a relatively clean savannah environment in South Africa were used to model new particle formation and growth. There already are some combined long-term measurements of trace gas concentrations together with aerosol and meteorological variables available, but to our knowledge this is the first detailed simulation that includes all the main processes relevant to particle formation. The results show that both of the particle formation mechanisms investigated overestimated the dependency of the formation rates on sulphuric acid. From the two particle formation mechanisms tested in this work, the approach that included low volatile organic compounds to the particle formation process was more accurate in describing the nucleation events than the approach that did not. To obtain a reliable estimate of aerosol concentration in simulations for larger scales, nucleation mechanisms would need to include organic compounds, at least in southern Africa. This work is the first step in developing a more comprehensive new particle formation model applicable to the unique environment in southern Africa. Such a model will assist in better understanding and predicting new particle formation – knowledge which could ultimately be used to mitigate impacts of climate change and air quality.
Review of carbon dioxide capture and storage with relevance to the South African power sector
Authors: Osman Khalid , Coquelet Christophe , Ramjugernath Deresh
Published: May 2014

Carbon dioxide (CO2) emissions and their association with climate change are currently a major discussion point in government and amongst the public at large in South Africa, especially because of the country’s heavy reliance on fossil fuels for electricity production. Here we review the current situation regarding CO2 emissions in the South African power generation sector, and potential process engineering solutions to reduce these emissions. Estimates of CO2 emissions are presented, with the main sources of emissions identified and benchmarked to other countries. A promising mid-term solution for mitigation of high CO2 emissions, known as CO2 capture and storage, is reviewed. The various aspects of CO2 capture and storage technology and techniques for CO2 capture from pulverised coal power plants are discussed; these techniques include processes such as gas absorption, hydrate formation, cryogenic separation, membrane usage, sorbent usage, enzyme-based systems and metal organic frameworks. The latest power plant designs which optimise CO2 capture are also discussed and include integrated gasification combined cycle, oxy-fuel combustion, integrated gasification steam cycle and chemical looping combustion. Each CO2 capture technique and plant modification is presented in terms of the conceptual idea, the advantages and disadvantages, and the extent of development and applicability in a South African context. Lastly, CO2 transportation, storage, and potential uses are also presented. The main conclusions of this review are that gas absorption using solvents is currently most applicable for CO2 capture and that enhanced coal bed methane recovery could provide the best disposal route for CO2 emissions mitigation in South Africa.
Climate and the mfecane (with erratum)
Authors: Garstang Michael , Coleman Anthony D. , Therrell Matthew
Published: May 2014

The mfecane is thought to be a massive upheaval and devastation of Nguni tribal chiefdoms in the second decade of the 19th century in what is now KwaZulu-Natal and the Eastern Cape of South Africa. Other historians have challenged this extreme interpretation suggesting that the use of the term mfecane be discontinued. We show that pervasive cycles of drought and cold periods in southern Africa are significantly amplified and extended by volcanic eruptions and that, in particular, the eruption of Tambora in 1815 triggered a prolonged and extreme climatic event which bears all of the characteristics ascribed to the mfecane. These findings are supported by a coupled ocean–atmosphere numerical model and by tree-ring rainfall and sea surface temperature analyses, suggesting that the term mfecane is an appropriate description of a singular climatic event.

Erratum
Current Status of Gene Expression Profiling to Assist Decision Making in Stage II Colon Cancer
Authors: Chee Cheng E. , Meropol Neal J.
Published: May 2014

The decision regarding adjuvant therapy for patients with stage II colon cancer remains a challenge. In contrast to stage III colon cancer, for which compelling clinical data support the use of adjuvant chemotherapy, the clinical benefit of systemic therapy in unselected patients with stage II disease is modest at best. Risk stratification based on clinicopathologic features and DNA mismatch repair status is commonly used in adjuvant therapy decisions, but these factors do not have a desired level of precision in identifying patients at high risk. Recently, gene expression platforms have been developed to further define risk and to assist in therapeutic decision making for patients with stage II disease. This review describes those platforms that are furthest along in clinical development, in an effort to place their potential clinical application in context.
Assessing durability of superhydrophobic surfaces
Authors: Malavasi Ileana , Bernagozzi Ilaria , Antonini Carlo , Marengo Marco
Published: May 2014

Superhydrophobic surfaces (SHS) show remarkable water repellency properties, and their use may have a tremendous impact for a plethora of applications, where liquid water accumulation needs to be controlled or minimised. However, the durability of SHS in operational conditions is a severe issue that currently represents a bottleneck for the technology transfer from laboratory to industrial applications. In the present work, we try to fill in the gap caused by the absence of a standard for evaluation for SHS durability, by developing a protocol for testing surface durability. The proposed protocol includes nine tests as follows: water immersion, acidic environment, alkaline environment, ionic solution, mechanical erosion, ultraviolet exposure, resistance to heating, alcohol immersion and hydrocarbon immersion. The protocol can serve to give an indication of surface robustness in a variety of potentially harmful environments, by providing a global figure of merit and ranking for different SHS and thereby allowing for identifying those surfaces fulfilling requirements for a specific application. To illustrate the protocol, we tested a SHS developed in-house by grafting of lauric acid molecules on an aluminum substrate. This article contains supporting information that is available online.
High‐arctic plants like it hot: a long‐term investigation of between‐year variability in plant biomass
Authors: van der Wal René , Stien Audun
Published: May 2014

The Arctic is viewed as most sensitive to climate warming and subject to a general greening. Yet, summer weather conditions, which differ greatly among years, are believed to have little direct effect on arctic plant productivity. The dominant view is that between‐year variation in aboveground plant biomass is small and poorly related to weather conditions in the same year in the Arctic. Here, we test this view based on a 12‐year investigation of peak plant biomass among habitats, plant functional types, and species in high‐arctic Svalbard.

Our study revealed twofold variation (range 23–46 g/m2) in plant biomass between years, this being strongly related to summer temperature (r = 0.92). Importantly, we found strong plant biomass–summer temperature relationships across habitats, plant functional types, and species, and little evidence for a lagged effect of previous year's biomass. Responses were of similar orders of magnitude, indicating that summer weather conditions were the key driver of plant productivity at all three levels of investigation.

We propose three key factors behind such tight relationships between summer temperature and plant biomass in the same year. First, our methodological approach, a combination of nondestructive shoot density estimates in small, permanent plots and destructive shoot mass estimates outside these plots, allowed us to overcome the otherwise overwhelming small‐scale spatial heterogeneity in aboveground plant biomass typical for high‐arctic tundra vegetation. Second, the high‐latitude location (78° N) makes the vegetation most susceptible to temperature differences due to their influence on process rates. Third, Svalbard's oceanic nature dictates prevalent cloud cover, making summer temperature a good proxy for light availability and thus an index of photosynthetic activity required for plants to produce biomass.

The present study challenges the prevailing notion that relationships between summer weather and vascular plant performance in the Arctic are weak and highly variable among plant species. This has important implications for our understanding of how and at which temporal scales future climate change will shape arctic plant productivity and, in turn, the dynamics of other ecosystem components in the low‐productivity, bottom‐up regulated ecosystems of the High Arctic.
Diverse Responses of Winter Wheat Yield and Water Use to Climate Change and Variability on the Semiarid Loess Plateau in China
Authors: He Liang , Cleverly James , Chen Chao , Yang Xiaoya , Li Jun , Liu Wenzhao , Yu Qiang
Published: May 2014

Crop production and water use in rainfed cropland are vulnerable to climate change. This study was to quantify diverse responses of winter wheat (Triticum aestivum L.) yield and water use to climate change on the Loess Plateau (LP) under different combinations of climatic variables. The crop model APSIM was validated against field experimental data and applied to calculate yield and water use at 18 sites on the LP during 1961 to 2010. The coefficient of variation of yield ranged from 12 to 66%, in which the vulnerability of yield increased from the southeast (12%) to the northwest (66%). This change was attributed to the gradual increase in precipitation variation from the southeast to the northwest. An obvious warming trend during 1961 to 2010 resulted in a significant decrease in the growth duration by 1 to 5 d decade−1. The yield at 12 sites was significantly reduced by 120 to 720 kg ha−1 decade−1. Evapotranspiration was significantly decreased by 1 to 26 mm decade−1; however, water use efficiency at most sites showed no significant trend. Eighteen sites were classified into three climatic zones by cluster analysis: high temperature–high precipitation–low radiation (HHL), medium temperature–medium precipitation–medium radiation (MMM), and low temperature–low precipitation–high radiation (LLH). The trend of decreasing yield was smallest in the HHL cluster because of a minimal reduction in precipitation, while decreasing trends in yield and evapotranspiration were larger in the LLH and MMM because of larger reductions in precipitation. The results imply that among strategies such as breeding for long duration or drought tolerance, modification of the planting date will be necessary to avoid high temperatures associated with climate change.
Management of Furrow Irrigation and Nitrogen Application on Summer Maize
Authors: Han Kun , Yang Yang , Zhou Chunju , Shangguan Yuxian , Zhang Liang , Li Na , Wang Linquan
Published: May 2014

The efficient use of water and N represents a primary concern to agricultural production in Northwest China. The objective of this study was to assess the impacts of irrigation and fertilization on water and N use, soil volatilized NH3, soil NO3 leaching, and NO3 transfer in soil profiles. A 2‐yr field experiment was conducted to assess the separation of N fertilizer and water with alternating furrow irrigation (SNWAFI) and conventional irrigation and fertilization (CIF) in a maize (Zea mays L.) production system. The yields with SNWAFI were 10 to 16% greater than with CIF. Compared with CIF, SNWAFI increased water use efficiencies (WUEs) by 13 to 33%, agronomic efficiency of fertilizer N by 36 to 56%, and NO3−–N in the upper soil layers (0–60 cm) by 30 to 60%. However, SNWAFI reduced NO3−–N in the deeper soil layers (60–200 cm) by 8 to 44% compared with CIF. The use of SNWAFI also decreased soil NH3 emission with the combination with lower irrigation (40 mm) and N rate (100 kg N ha−1), which indicated that SNWAFI emitted less soil NH3 than CIF. Therefore, compared with CIF, SNWAFI increased maize yield WUE and N use efficiency, reduced N leaching, and curtailed soil NH3 loss with appropriate irrigation and N rates. The use of SNWAFI, leading to better spatial management of irrigation water and N application, can provide both agronomic and environmental benefits.
Windblown Dust Potential from Oilseed Cropping Systems in the Pacific Northwest United States
Authors: Sharratt Brenton , Schillinger William F.
Published: May 2014

The volatility of petroleum reserves and prices coupled with concerns about greenhouse gas emissions and climate change has created worldwide interest in renewable fuels. Little is known, however, about the impact on natural resources of growing oilseed crops for biofuel. This study examined the impact of growing oilseed crops in winter wheat (Triticum aestivum L.) rotations on wind erosion and emissions of particles ≤10 μm in aerodynamic diameter (PM10) in eastern Washington, where atmospheric PM10 is an acute environmental concern. Wind erosion and PM10 emissions were measured immediately after sowing winter wheat in a winter wheat–summer fallow (WW‐SF) rotation, a winter wheat–camelina [Camelina sativa (L.) Crantz]–summer fallow (WW‐C‐SF) rotation, and a winter wheat–safflower (Carthamus tinctorius L.)–summer fallow (WW‐S‐SF) rotation. Best management practices were implemented during the 13‐mo fallow phase of the rotation, which included undercutting and fertilizing the soil in spring and rodweeding during summer to control weeds. A wind tunnel was used to assess horizontal sediment and PM10 flux after sowing wheat because this is the time when the soil is most susceptible to wind erosion. Horizontal sediment and PM10 flux were as much as 250% higher after sowing winter wheat in the WW‐C‐SF and WW‐S‐SF rotations than the WW‐SF rotation. Vertical PM10 flux was higher in the WW‐C‐SF and WW‐S‐SF rotations, in part due to the aerodynamically smoother surface of these rotations compared with the WW‐SF rotation. Farmers must be especially judicious in protecting the soil from wind erosion during the fallow phase of the WW‐C‐SF and WW‐S‐SF rotations.
Selecting Cover Crop Mulches for Organic Rotational No‐Till Systems in Manitoba, Canada
Authors: Halde Caroline , Gulden Robert H. , Entz Martin H.
Published: May 2014

In western Canada, limited research has been conducted on reduced‐tillage grain production systems managed organically. The objective was to select cover crop mulches for an organic rotational no‐till system in Manitoba. A 2‐yr field study (2010–2011, and repeated 2011–2012) was conducted in Carman, MB, Canada. In the cover crop year, 10 different combinations of cover crop species were seeded in the spring, in pure stand or in mixtures, and rolled using a roller‐crimper in mid‐summer, at the flowering stage. These rolled mulches were then left on the soil surface over the fall and winter. The following spring, spring wheat (Triticum aestivum L.) was seeded directly into these mulches (no‐till). Mulches with hairy vetch (Vicia villosa Roth) showed the most promising results. Cover crop treatments with vetch had the highest mulch biomass in September of the cover crop year (9.1–10.7 Mg ha−1), and in the following spring (6.0–7.6 Mg ha−1) and provided the best weed control. In late fall of the cover crop year, N content of mulches with vetch reached high levels (308 kg N ha−1 on average), and high amounts of N (93–164 kg N ha−1) were released from these mulches over winter. Organic spring wheat no‐till planted into mulches with vetch produced yields comparable to regional conventional average yields. Mulches with vetch used in an organic rotational no‐till system reduced the need for tillage for a period of 1.5 to 2 yr without affecting yields of organic spring wheat.
Analysis and Interpretation of Interactions in Agricultural Research
Authors: Vargas Mateo , Glaz Barry , Alvarado Gregorio , Pietragalla Julian , Morgounov Alexey , Zelenskiy Yuriy , Crossa Jose
Published: May 2014

When reporting on well‐conducted research, a characteristic of a complete and proper manuscript is one that includes analyses and interpretations of all interactions. Our purpose is to show how to analyze and interpret interactions in agronomy and breeding research by means of three data sets comprising random and fixed effects. Experiment 1 tested wheat (Triticum aestivumL.) at two N and four P fertilizer rates in two soil types. For this data set, we used a fixed‐effect linear model with the highest order (three‐way) interaction considered first and then worked down through the lower order interactions and main effects to illustrate the importance of interactions in data analysis. Experiment 2 evaluated maize (Zea maysL.) hybrids under four rates of N for 3 yr. For this data set, we used a linear mixed model and partitioned the four N rates into orthogonal polynomials. Experiment 3 evaluated genotypes in six environments where the objective was to show how to study genotype × environment interactions. Researchers must analyze all interactions, determine if they are due to changes in rank (crossover) or only to changes in scale, and then judge whether reporting on significant main effects or interactions would best explain the biological responses in their experiments. In an experiment with more than one factor, complete and correct analysis of interactions is essential for reporting and interpreting the research properly.
Analysis of Combined Experiments Revisited
Authors: Moore Kenneth J. , Dixon Philip M.
Published: May 2014

Agronomic experiments are often replicated over time and space to evaluate how treatments perform across a range of environments. The analysis of experiments conducted for more than one growing season (years) and/or places (locations) is commonly referred to as analysis of combined experiments. Common analyses of these studies treat some effects as fixed, treat others as random, and usually include interactions between fixed and random effects, which we call mixed interactions. Recommendations for how to treat mixed interactions has changed. In the traditional practice, the effects of interactions between fixed and random effects were assumed to sum to zero within each level of a fixed factor. Contemporary practice considers these effects to be mutually independent. This latter assumption is used to construct F tests by many of the statistical analysis programs that are widely used to analyze data from agronomic experiments but is inconsistent with that used in many previously published studies. The assumptions made about mixed interactions in the analysis of variance can result in very different interpretations and can potentially lead to different conclusions. We address the discrepancy between the analyses that were formerly recommended and those that are currently implemented by popular software programs and provide recommendations for analyzing data from combined experiments.
Fall Dormancy and Harvest Stage Impact on Alfalfa Persistence in a Subtropical Climate
Authors: Rimi Filippo , Macolino Stefano , Leinauer Bernd , Lauriault Leonard M. , Ziliotto Umberto
Published: May 2014

Persistence of alfalfa (Medicago sativa L.) is a critical component of productivity and can be influenced by genetics and management; however the responses of fall dormancy (FD) level to harvest regimes are unclear. This study was conducted to investigate the effect of three FD categories and two phenologically based harvest regimes on stand persistence and characteristics of taproot and crown in a humid subtropical climate. Cultivars with FD ratings of 7.5 (less non‐dormant), 8.5 (non‐dormant), and 10.5 (very non‐dormant) were seeded in April 2005 at the experimental farm of Padova University in Legnaro, northeastern Italy. Plots were harvested at early bud or early flower for 3 yr and plant samples were collected in November 2005, April 2006, November 2006, April 2007, and November 2007. On each sampling date, stand density, mass of taproot (to a 15‐cm depth) and crown, water soluble carbohydrate (WSC) concentration of taproots and crowns, and taproot diameter at 3‐, 5‐, and 15‐cm depth were measured. Changing the cutting stage from early flower to early bud reduced the average stand density from 242 to 218 plants m−2, irrespective of FD category and date. In November, plants harvested at early bud had smaller taproots and crowns compared to those harvested at early flower but generally had higher concentrations of WSC. The implications of FD category appeared secondary in comparison to harvest regime to maintain alfalfa persistence in an environment characterized by temperate winters.
Optimizing Irrigation and Plant Density for Improved Cotton Yield and Fiber Quality
Authors: Feng Lu , Mathis Garrett , Ritchie Glen , Han Yinchun , Li Yabing , Wang Guoping , Zhi Xiaoyu , Bednarz Craig W.
Published: May 2014

An important limitation to cotton (Gossypium hirsutum L.) production in the Texas High Plains is water shortage. A 2‐yr study was conducted at two locations in Lubbock, TX, in 2007 and 2008 to determine the optimal irrigation and plant density for cotton production in the Texas High Plains based on yield and fiber quality. A field experiment was conducted by using a split plot design, with irrigation (0, 2.54 and 5.08 mm d−1) as the main plot, and plant density (75,300; 150,600; and 226,000 plants ha−1) as the subplot. Two central rows of each plot were machine harvested to determine lint yield. Fiber quality was tested by both High Volume Instrument (HVI) and Advanced Fiber Information Systems (AFIS). The results showed environmental conditions heavily impact lint yield and fiber quality. Irrigation played a significant role in yield and fiber quality. Under appropriate weather conditions at Quaker 2008, 5.08 mm d−1 irrigation rate increased seed cotton yield by 36.4 and 214.3%, compared with 2.54 and 0 mm d−1, respectively. Irrigation of 5.08 mm d−1 increased fiber length by number, uniformity, and short fiber content. The fineness and maturity ratio and subsequently micronaire decreased. Plant density seemed to play a smaller role in determining yield and fiber quality. Based on profitability, higher yield did not necessarily translate to higher net returns. We concluded that weather pattern and irrigation heavily impact yield and fiber quality in the Texas High Plains.
Quantifying Temperature Effects on Cotton Reproductive Efficiency and Fiber Quality
Authors: Lokhande Suresh , Reddy K. Raja
Published: May 2014

Quantitative functional relationships between temperature and fiber quality are needed to improve predictive capability of cotton (Gossypium hirsutum L.) models. An experiment was conducted by varying day/night temperatures, 22/14, 26/18, 30/22, and 34/26°C, imposed at flowering. Upland cotton cultivar, TM‐1, was seeded in the soil bins using fine sand as the rooting medium and allowed to grow under optimum water and nutrients. Flowers and bolls were tagged daily to estimate the boll maturation period. Plant height and node numbers were recorded from emergence to 21 d after treatment. Stem, leaf, boll dry weights, and boll numbers were recorded at maturity. Measured fiber quality parameters were regressed against temperature to develop mathematical functions for modeling. The optimum temperature for biomass was between 18.1 and 21.5°C and biomass declined by 10% at 25.5°C and 19% at 29.5°C. More bolls were produced at 25.5°C, but declined sharply at 29.5°C. Reproductive potential, boll mass per unit total weight, peaked at 25.5°C and was lower by 21% at 18.1°C and 53% at 29.5°C. Fiber micronaire and uniformity increased with temperature up to 26°C and declined at higher temperature, while fiber strength increased linearly with temperature. Fiber length increased linearly from 18 to 22°C, and declined at higher temperatures. Fiber micronaire was more responsive to changes in temperature followed by strength, length, and uniformity. The functional relationships between temperature and fiber properties will be useful to optimize management decisions such as planting dates and to develop fiber submodel under optimal water and nutrient conditions.
High‐Yield Maize Production in Relation to Potassium Uptake Requirements in China
Authors: Wu Liangquan , Cui Zhenling , Chen Xinping , Zhao Rongfang , Si Dongxia , Sun Yixiang , Yue Shanchao
Published: May 2014

Understanding maize (Zea mays L.) grain yield in relation to K uptake requirements is essential for devising optimized K fertilizer management practices and agricultural policies to increase grain yield for food security. A database comprising 953 measurements was created using 56 on‐farm and research station experiments during 2000 to 2012 in the North China Plain (NCP) to determine K uptake requirements and patterns of K accumulation pre‐ and post‐silking with different yield levels. The K requirement Mg−1 grain yield (Kreq.) in the K = Opt. treatment was 15.0 kg, which was lower than 20.0 kg in the K > Opt. treatment. In the Optimal K treatment, average Kreq. values were 15.0, 14.8, 14.8, and 15.7 kg for grain yields ranging from <8.0, 8 to 10, 10 to 12, and >12.0 Mg ha−1, respectively. The relative consistency of Kreq. values with increasing grain yield was mainly attributed to an offset in the increase in stover K (from 14.0 to 18.1 g kg−1), an increase in harvest index (HI) from 0.49 to 0.54, and the stability of grain K concentrations (about 3.2 g kg−1). Higher percentages for K accumulation at the post‐silking stage were observed with >12 Mg ha−1 (24%) and 10 to 12 Mg ha−1 (22%) compared to <10 Mg ha−1 (9%). In conclusion, maintaining adequate K supply and post‐silking K accumulation is essential for achieving high‐yield maize production.
Organic Cropping System Effects on Fiber Quality of Three Cotton Cultivars in Greece
Authors: Patsiali Sotiria , Papastylianou Panayiota , Travlos Ilias S. , Bilalis Dimitrios J.
Published: May 2014

Markets for organically produced high quality cotton (Gossypium hirsutumL.) are projected to increase. Field experiments were conducted to compare the effects of two cropping systems on seed and lint yield and fiber quality of three cotton cultivars. The experiments, conducted during 2008, 2009, and 2010, were laid out in a split plot design with four replicates, two main plots (organic and conventional system) and three subplots (cotton cultivars: Athena, Alexander, and Fandom). The organic system resulted to a seed cotton yield at greater or same levels than the conventional system. Micronaire values and maturity for all the cultivars at 2009 and 2010 were satisfactory, while fiber length did not differ between cropping systems, except in 2009. Elongation of the fiber differed among cropping systems only in 2010 and Fandom had the highest rate of fiber elongation. For the organic and conventional systems, fiber strength reached values of 34.47 and 32.5 g tex−1, respectively. Short fiber index declined throughout the 3‐yr period in the organic system. This study confirmed that organic cultivation does not negatively affect lint yield or fiber quality, while in the same time it also produced high seed yield. Findings suggest that despite the significant role of genotype, the interactions of year with cultivar and cropping system have a decisive impact on fiber quality.
Trinexapac‐Ethyl and Burning Effects on Seed Yield Components in Strong Creeping Red Fescue
Authors: Zapiola Maria L. , Chastain Thomas G. , Garbacik Carol J. , Young William C.
Published: May 2014

Open‐field burning has been used to remove post‐harvest residue for high seed yield and quality in strong creeping red fescue (CRF) (Festuca rubra L. subsp. rubra) but concern over air pollution and safety issues has resulted in legislatively mandated reductions of this practice in Oregon. The effects of spring and fall applications of the plant growth regulator trinexapac‐ethyl (TE), and burning (burn) and mechanical removal (flail) of post‐harvest residue on seed yield components, were evaluated in strong CRF over a 4‐yr period. Response to treatments was different among years but burn was critical for maintaining high potential seed yields as the stand aged. Burn increased panicles m−2 and spikelets panicle−1 by up to 120 and 22%, respectively, over flail, and in turn, resulted in higher seed yields. Spring TE applications increased florets spikelet−1 by up to 14% in Years 1, 3, and 4. Fertile tiller height and lodging were reduced by spring‐applied TE. The combination of burn and spring TE produced highest seed yields in Years 3 and 4 as a result of increased seed number m−2 and seed weight. Fall TE did not affect seed yield components or yield and therefore, is not an effective management tool in strong CRF seed production.
Environmental Impact of Water Use in Agriculture
Authors: Hatfield Jerry L.
Published: May 2014

Agriculture is an important component of the hydrologic cycle and the use of water in agricultural production is necessary to feed the world's population and provide ecosystem services. As the population increases there is more concern about the potential role of agriculture on environmental quality and the role water management has on environmental quality. Water use by agricultural systems through evapotranspiration effects both the plant and the surrounding microclimate and the modification of the microclimate is a major environmental impact from agricultural water use. Sources of water for agriculture are from direct use of precipitation and indirect through irrigation from either surface or groundwater resources. Irrigation has an effect on the hydrologic cycle and alters groundwater recharge and the development of the infrastructure to support irrigation disrupts the landscape with effects extending beyond agriculture into wildlife habitat and wetlands. The environmental impacts of water use in agriculture range from onsite effects within the field to the offsite impacts from surface runoff and chemical transport. Our challenge is to understand that agriculture is part of the hydrologic cycle and develop methods which can reduce the environmental impact.
Seedbed Preparation Techniques and Weed Control Strategies for Strip‐Planting Rhizoma Peanut into Warm‐Season Grass Pastures
Authors: Castillo Miguel , Sollenberger Lynn , Blount Ann , Ferrell Jason , Na Chae‐In , Williams Mary , Mackowiak Cheryl
Published: May 2014

Planting rhizoma peanut (Arachis glabrata Benth.; RP) in strips into bahiagrass (Paspalum notatum Flüggé) pastures can reduce establishment cost relative to conventional techniques, but research is needed to determine the best seedbed preparation methods. The objectives were to quantify the effects of four seedbed preparation techniques: glyphosate + tillage, tillage only, glyphosate + no‐till, and sod removal; and four postemergence weed control strategies: control (no herbicides, no mowing), mowing (every 28 d to 10‐cm stubble height), imazapic (0.29 L ha–1), and imazapic + 2,4‐D amine (0.29 and 0.58 L ha–1, respectively). Sprout emergence ranged from 90 to 119 m2 in treatments where tillage occurred compared with 54 to 58 m–2 in no‐till and sod removal. Nevertheless, by season end RP canopy cover and frequency of occurrence favored no‐till (21% cover and 70% frequency) compared with the other treatments (≤14% cover and 53% frequency). Weed control strategy after planting had a greater effect on establishment success than seedbed preparation. By season end, RP cover and frequency were greater for imazapic (25 and 64%, respectively) and imazapic + 2,4‐D (23 and 64%, respectively) than for the control (10 and 42%, respectively) and mowing treatments (7 and 36%, respectively). Glyphosate followed by no‐till planting and postemergence use of imazapic with or without 2,4‐D is a viable option for reduced‐cost establishment of RP in strips into bahiagrass pastures.
Glyphosate Effects on Yield, Nitrogen Fixation, and Seed Quality in Glyphosate‐Resistant Soybean
Authors: Bärwald Bohm Giani Mariza , Rombaldi Cesar Valmor , Genovese Maria Inés , Castilhos Danilo , Rodrigues Alves Bruno José , Rumjanek Norma Gouvêa
Published: May 2014

Genetically‐modified soybean [Glycine max (L.) Merr.] resistant to glyphosate (N‐phosphono‐methyl‐glycine) herbicide (GR) has turned out to be one of the most highly‐used products of plant engineering. The impacts of the soybean, genetically transformed for glyphosate resistance, on the environment under Brazilian soil and climatic conditions are still unknown. For this purpose, two soybean genotypes, one genetically modified (GR BRS 244 RR) and a conventional isogenic genotype were grown under different weed‐control methods: hand weeding and glyphosate or imazethapyr herbicide application. The study was performed in Rio Grande do Sul State with evaluations of soil microbial biomass and respiration, biological nitrogen fixation, isoflavone content in seed and glyphosate, and aminomethylphosphonic acid (AMPA) residues in seeds and soil. The use of GR did not affect soil microbial population, biological nitrogen fixation, or plant yield or isoflavone contents in seed. However, even though we used the recommended application doses, the glyphosate residues in the seeds were above levels permitted by Brazilian law. Also, AMPA residues were detected in the soil and the seeds.
Ground‐Based Digital Imaging as a Tool to Assess Soybean Growth and Yield
Authors: Hoyos‐Villegas V. , Houx J.H. , Singh S.K. , Fritschi F.B.
Published: May 2014

Leaf and canopy characteristics influence light interception and photosynthesis, which ultimately contribute to total biomass production and crop yield. Inexpensive hand‐held digital cameras may provide an alternative to time‐consuming destructive sampling methods used to assess these traits. The objective of this study was to test the use of common digital cameras as a potential phenotyping tool to predict yield and other crop traits in two soybean (Glycine max L. Merr.) cultivars subjected to differences in soil moisture availability. Weekly digital images were acquired from each plot and used to estimate canopy cover, total aboveground biomass, leaf biomass, photosynthesis, and grain yield. The method proved effective in identifying the dynamics of canopy cover and changes in biomass and grain yield as influenced by soil water availability. Further, it was possible to differentiate between cultivars and accurately determine the timing of maximum crop biomass and canopy cover. The image analysis also indicated the onset of leaf senescence which led to a decrease in total biomass around 90 to 105 d after planting. Principal components analysis showed that canopy coverage extracted from images collected spanning a period from beginning pod to seed filling was positively correlated with grain yield. Models developed using multiple regression analysis exhibited strong relationships between the ground cover data obtained using image analysis and grain yield (R2 = 0.74), crop growth rate (R2 = 0.69), and photosynthesis (R2 = 0.80). Based on these results, digital imaging has potential as a tool to rapidly assess soybean canopy development and estimate biomass accumulation and grain yield.
Molecular Markers Linked to Important Genes in Hard Winter Wheat
Authors: Liu Shuyu , Rudd Jackie C. , Bai Guihua , Haley Scott D. , Ibrahim Amir M.H. , Xue Qingwu , Hays Dirk B. , Graybosch Robert A. , Devkota Ravindra N. , St. Amand Paul
Published: May 2014

Biotic stresses including diseases (leaf, stem and stripe rusts), arthropods (greenbug [GB], Hessian fly [Hf], Russian wheat aphid [RWA], and wheat curl mite [WCM]) and their transmitted viral diseases significantly affect grain yield and end‐use quality of hard winter wheat (Triticum aestivum L.) in the U.S. Great Plains. Many genes or quantitative trait loci (QTL) have been identified for seedling or adult‐plant resistance to these stresses. Molecular markers for these genes or QTL have been identified using mapping or cloning. This study summarizes the markers associated with various effective genes, including genes or QTL conferring resistances to arthropods, such as GB (7), RWA (4), Hf (9), and WCM (4) and diseases including leaf, stem and stripe rusts (26) and Wheat streak mosaic virus (WSMV; 2); genes or QTL for end‐use quality traits such as high (3) and low (13) molecular weight glutenin subunits, gliadin (3), polyphenol oxidase (2), granule‐bound starch synthase (3), puroindoline (2), and preharvesting sprouting (1); genes on wheat–rye (Secale cereale L.) chromosomal translocations of 1AL.1RS and 1BL.1RS; and genes controlling plant height (12), photoperiod sensitivity (1), and vernalization (2). A subset of the markers was validated using a set of diverse wheat lines developed by breeding programs in the Great Plains. These analyses showed that most markers are diagnostic in only limited genetic backgrounds. However, some markers developed from the gene sequences or alien fragments are highly diagnostic across various backgrounds, such as those markers linked to Rht‐B1, Rht‐D1, Ppd‐D1, Glu‐D1, Glu‐A1, and 1AL.1RS. Knowledge of both genotype and phenotype of advanced breeding lines could help breeders to select the optimal parents to integrate various genes into new cultivars and increase the efficiency of wheat breeding.
Optimizing Laccase Application on Creeping Bentgrass (Agrostis stolonifera L.) to Facilitate Biodethatching
Authors: Sidhu Sudeep S. , Huang Qingguo , Carrow Robert N. , Raymer Paul L.
Published: May 2014

Organic matter buildup in the form of thatch or mat layers leads to several problems in turfgrass management systems. In a previous greenhouse study, laccase enzyme solution reduced the rate of accumulation of organic matter when applied at an activity level of 2.0 units cm−2 every 2 wk for 9 mo on ‘Crenshaw’ creeping bentgrass (Agrostis stolonifera L.). A 2‐yr field experiment was conducted on creeping bentgrass to optimize the laccase activity level, frequency of application, and to determine potential interactions with core aeration and topdressing cultural practices. Laccase enzyme at five activity levels, 0, 0.5, 1.0, 2.0, and 4.0 units cm−2, was applied every 2 wk. The frequency of laccase application was tested using a laccase activity level of 2.0 units cm−2 applied at frequencies of 2, 4, 8, or 12 wk. The common cultural management practices of core aeration and sand topdressing were compared with and without laccase enzyme at an activity level of 2.0 units cm−2 applied once a month. Results indicated that laccase treatments were effective in reducing thatch layer thickness (TLT) at rates as low as 0.5 units cm−2 applied every 2 wk and as infrequent as once a month when applied at a rate of 2.0 units cm−2. Laccase application at 2.0 units cm−2 once in 4 wk was just as effective at reducing TLT as was core aeration and sand topdressing twice per year. Even greater reductions in TLT were observed when laccase was applied in combination with core aeration and sand topdressing.
Evaluation of Three Breeding Cycles for Seedling Weight of Switchgrass, Big Bluestem, and Indiangrass
Authors: Sebolai Boingotlo , Vogel Kenneth P.
Published: May 2014

A modified form of restricted, recurrent phenotypic selection was used to select for seedling shoot weight in switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and indiangrass [Sorghastrum nutans (L.) Nash] populations for three generations. Seedlings were grown in micropots in trays in a greenhouse and were individually clipped and weighed 4 wk after emergence. The seedlings were allowed to regrow, and the heaviest seedlings were transplanted to field nurseries for polycrossing to produce Syn 1 seed. Three breeding cycles were conducted for each grass. After the third breeding cycle, Syn 2 generation seed was produced for each cycle, including cycle 0 for 2 yr, and was used in subsequent greenhouse and field evaluations to determine if the breeding procedure improved seedling vigor as measured by seedling shoot weight. In two greenhouse evaluation trials, the increase in seedling weight per cycle was 7.8, 5.6, and 10.2% for big bluestem, switchgrass, and indiangrass, respectively. In two field trials, seedling weight also increased with successive cycles of selection except for indiangrass in one trial. Establishment success as measured by stand counts did not differ among the cycles of selection for the three grasses in the field trials. Based on these results and the results of subsequent breeding and field evaluation work on seedling tiller number, it is apparent that seedling traits of these grasses can be modified by breeding. To improve establishment of these grasses, research on developing agronomic seed production practices that result in improved seed quality would also be beneficial.
CO2 Enrichment at Night Affects the Growth and Yield of Common Beans
Authors: Bunce James A.
Published: May 2014

Many experiments to determine the crop yield increase expected with rising atmospheric carbon dioxide concentration added carbon dioxide only during the daytime, without tests of whether elevation of carbon dioxide at night affected plant growth. In this experiment, two cultivars of common bean (Phaseolus vulgaris L.) were grown in the field for 4 yr in open‐top chambers in which CO2 was added during the day or the night, both day and night, or not at all. CO2 was added to increase the concentration by 180 μmol mol−1 above that of the ambient outside air, which averaged 392 μmol mol−1 during the daytime and 503 μmol mol−1 at night. In the two cultivars, the average increase in seed yield above the ambient CO2 treatment was 42% with daytime CO2 enrichment and 77% with continuous enrichment. In both cultivars, continuous CO2 enrichment increased the area of individual leaflets by about 40% compared with daytime enrichment. Leaflet size was the same with daytime CO2 enrichment and with no enrichment. In one of the cultivars, nighttime CO2 elevation alone increased leaflet size and seed yield. The results indicated that CO2 enrichment at night had important consequences for the growth and yield of these bean cultivars, and that daytime‐only CO2 enrichment greatly underestimated the yield increase likely to occur with rising atmospheric CO2 concentrations.
Combined Orthodontic-surgical Treatment for Skeletal Class III Malocclusion with Multiple Impacted Permanent and Supernumerary Teeth: Case Report
Authors: Xue Dai Juan and Feng
Published: May 2014

In this report we describe a combined orthodontic and surgical treatment for a 14-year-old boy with severe skeletal class III deformity and dental problem. His upper posterior primary teeth in the left side were over-retained and 6 maxillary teeth (bilateral central incisors and canines, left first and second premolars) were impacted, together with 5 supernumerary teeth in both arches. The treatment protocol involved extraction of all the supernumerary and deciduous teeth, surgical exposure and orthodontic traction of the impacted teeth, a bimaxillary orthognathic approach including Lefort I osteotomy. Bilateral sagittal split ramus osteotomy (BSSRO) and genioplasty was performed to correct skeletal problem. After treatment, all of the impacted teeth were brought to proper alignment in the maxillary arch. A satisfied profile and good posterior occlusion was achieved. Treatment mechanics and consideration during different stages are discussed.
A Brief Historical Perspective on Dental Implants, Their Surface Coatings and Treatments
Authors: Abraham Celeste M
Published: May 2014

This review highlights a brief, chronological sequence of the history of dental implants. This historical perspective begins with ancient civilizations and spotlights predominant dentists and their contributions to implant development through time. The physical, chemical and biologic properties of various dental implant surfaces and coatings are discussed, and specific surface treatments include an overview of machined implants, etched implants, and sand-blasted implants. Dental implant coatings such as hydroxyapatite, fluoride, and statin usage are further reviewed.
Mechanisms of Guided Bone Regeneration: A Review
Authors: Liu Jie , Kerns David G
Published: May 2014

Post-extraction crestal bone resorption is common and unavoidable which can lead to significant ridge dimensional changes. To regenerate enough bone for successful implant placement, Guided Bone Regeneration (GBR) is often required. GBR is a surgical procedure that uses barrier membranes with or without particulate bone grafts or/and bone substitutes. There are two approaches of GBR in implant therapy: GBR at implant placement (simultaneous approach) and GBR before implant placement to increase the alveolar ridge or improve ridge morphology (staged approach). Angiogenesis and ample blood supply play a critical role in promoting bone regeneration.
Bilateral Congenital Adrenal Agenesis: A Rare Disease Entity and Not a Result of Poor Autopsy Technique
Authors: D'Arcy Colleen , Pertile Mark , Goodwin Tess , Bittinger Sophie
Published: May 2014

Congenital adrenal agenesis is an extremely rare condition wherein the adrenal glands fail to develop. The absence of adrenal tissue results in the complete absence of hormones produced in the adrenal cortex (cortisol, aldosterone) and medulla (catecholamines), and is not compatible with postnatal life without artificial hormone replacement therapy. To date, 9 cases of adrenal agenesis have been reported, many of which are associated with additional congenital anomalies. Most cases were not detected on antenatal imaging and were detected incidentally at postmortem examination. We present a case of adrenal agenesis, detected incidentally at postmortem examination after termination of pregnancy for suspected fetal hydrops, and review the heterogeneous phenotype of this condition with associated abnormalities and molecular genetics. This case reinforces the role of the perinatal autopsy to investigate cause of perinatal mortality, allowing correlation of pathology with antenatal imaging findings and clinical details.