Genetic and physiological characterization of seed dormancy regulation in common waterhemp [Amaranthus tuberculatus (Moq) Sauer]

Common waterhemp [Amaranthus tuberculatus (Moq.) Sauer.] is an annual plant native to the Midwest United States and is considered a troublesome weed species. The economic importance of common waterhemp is attributable to rapid population increases, the appearance of herbicide resistant biotypes, and the emergence phenology during the cropping season. Because seed dormancy levels can determine seedling emergence patterns, and the requirements necessary to remove common waterhemp seed dormancy and enhance germination are not well understood, we characterized the genetic and physiological regulation of common waterhemp seed dormancy and how seed dormancy is regulated by environmental signals such as moisture and temperature. The results indicated that seed dormancy levels in common waterhemp are highly influenced by temperature. Interactions between daily average temperatures and seed moisture reduce seed dormancy, and temperature fluctuation alleviates dormancy and triggers germination. The heritability of seed dormancy in common waterhemp is high. The heritability of genes involved in environmental signal sensing and seed dormancy regulation is more difficult to determine, but the existence and importance of these genes in seed dormancy was confirmed. In addition, the existence of intra-specific seed dormancy variation in common waterhemp was demonstrated. The evidence suggests that selection for complex seed dormancy regulatory mechanisms in common waterhemp is possible and might be one of the reasons why this weed has successfully thrived in the Midwest Region

Environmental control of seed dormancy, germination and seedling emergence of three weed species

Seed germination is a critical event in the success of any weed species. However, germination of weed seeds is conditioned by the presence of dormancy. Dormancy is controlled by genes as influenced by seed developmental processes and by environmental factors. We studied how chilling (12 weeks at 4 C and wet conditions), temperature, temperature fluctuation, and light quality affect the seed dormancy of common waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer. synonymous A. rudis J.D. Sauer), giant foxtail (Setaria faberi Herrm.) and velvetleaf (Abutilon theophrasti Medicus). Also we studied how temperature requirements for seed germination can be used for analyzing seedling emergence in artificial and natural seed banks. Chilling did not affect the dormancy level of giant foxtail or velvetleaf seeds. However, common waterhemp seeds reduced dormancy level after chilling and were more responsive to temperature fluctuation and light exposure. Only common waterhemp germination was promoted by exposure to red light (660nm). There was a positive relationship between the amplitude of temperature fluctuation and common waterhemp and giant foxtail germination. Common waterhemp seeds also increased germination rate with increasing amplitude of temperature fluctuation. Temperature requirements for germination cannot alone be used to describe weed emergence in the field. Artificial seed banks showed different emergence patterns of the weed species studied compared to the natural seed banks. The large differences between seed banks were due to soil physical characteristics and seed dormancy level

Coordination chemistry of amide-functionalised tetraazamacrocycles: structural, relaxometric and cytotoxicity studies

Three different tetraazamacrocyclic ligands containing four amide substituents that feature groups (namely allyl, styryl and propargyl groups) suitable for polymerisation have been synthesised. Gadolinium(III) complexes of these three ligands have been prepared as potential monomers for the synthesis of polymeric MRI contrast agents. To assess the potential of these monomers as MRI contrast agents, their relaxation enhancement properties and cytotoxicity have been determined. A europium(III) complex of one of these ligands (with propargyl substituents) is also presented together with its PARACEST properties. In addition, to gain further insight into the coordination chemistry of the tetra-propargyl substituted ligand, the corresponding zinc(II) and cadmium(II) complexes have been prepared. The X-ray crystal structures of the tetra-propargyl ligand and its corresponding gadolinium(III), zinc(II) and cadmium(II) complexes are also presented

Simulation models on the ecology and management of arableweeds: Structure, quantitative insights, and applications

In weed science and management, models are important and can be used to better understand what has occurred in management scenarios, to predict what will happen and to evaluate the outcomes of control methods. To-date, perspectives on and the understanding of weed models have been disjointed, especially in terms of how they have been applied to advance weed science and management. This paper presents a general overview of the nature and application of a full range of simulation models on the ecology, biology, and management of arable weeds, and how they have been used to provide insights and directions for decision making when long-term weed population trajectories are impractical to be determined using field experimentation. While research on weed biology and ecology has gained momentum over the past four decades, especially for species with high risk for herbicide resistance evolution, knowledge gaps still exist for several life cycle parameters for many agriculturally important weed species. More research efforts should be invested in filling these knowledge gaps, which will lead to better models and ultimately better inform weed management decision making.Fil: Bagavathiannan, Muthukumar V.. Texas A&M University; Estados UnidosFil: Beckie, Hugh J.. University of Western Australia; AustraliaFil: Chantre Balacca, Guillermo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: González Andujar, José L.. Consejo Superior de Investigaciones Científicas; EspañaFil: Leon, Ramon G.. North Carolina State University; Estados UnidosFil: Neve, Paul. Agriculture & Horticulture Development Board; Reino UnidoFil: Poggio, Santiago Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Schutte, Brian J.. New Mexico State University.; Estados UnidosFil: Somerville, Gayle J.. Sustainable Agriculture Sciences; Reino UnidoFil: Werle, Rodrigo. University of Wisconsin; Estados UnidosFil: Acker, Rene Van. University of Guelph; Canad

An Environmental Watch System for the Andean Countries: El Observatorio Andino

An experimental Environmental Watch System, the so-called Observatorio Andino (OA), has been implemented in Venezuela, Colombia, Ecuador, Peru, Bolivia, and Chile over the past 2 yr. The OA is a collaborative and regional network that aims to monitor several environmental variables and develop accurate forecasts based on different scientific tools. Its overall goal is to improve risk assessments, set up early warning systems, support decision-making processes, and provide easily and intuitively understandable spatial maps to end users. The initiative works under the scientific and logistic coordination of the Centro de Modelado Científico (CMC) at Zulia University, Venezuela, and the Centro Internacional para la Investigación del Fenómeno “El Niño” (CIIFEN), and it is operated at a local level by the national weather services (NWSs) of the above-mentioned six Andean nations. The OA provides several freely available model outputs, including meteorological and hydrological forecasts, droughts, fire and flood indices, ecosystems dynamics, climate and health applications, and 5-day high-resolution oceanographic predictions for the eastern Pacific. This article briefly describes the current products, methodologies, and dynamical and statistical modeling outputs provided by the OA. Also, a discussion on how these sets of tools have been put together as a coordinated scientific watch and forecast system for each country and for the entire region is presented. Our experiences over the past 2 yr suggest that this initiative would significantly improve the current decision-making processes in Andean countries

Short-term surgical complications after radical hysterectomy - a nationwide cohort study

Introduction: Centralization has, among other aspects, been argued to have an impact on quality of care in terms of surgical morbidity. Next, monitoring quality of care is essential in identifying areas of improvement. This nationwide cohort study was conducted to determine the rate of short-term surgical complications and to evaluate its possible predictors in women with early-stage cervical cancer. Material and methods: Women diagnosed with early-stage cervical cancer, 2009 FIGO stages IB1 and IIA1, between 2015 and 2017 who underwent radical hysterectomy with pelvic lymphadenectomy in 1 of the 9 specialized medical centers in the Netherlands, were identified from the Netherlands Cancer Registry. Women were excluded if primary treatment consisted of hysterectomy without parametrial dissection or radical trachelectomy. Women in whom radical hysterectomy was aborted during the procedure, were also excluded. Occurrence of intraoperative and postoperative complications and type of complications, developing within 30 days after surgery, were prospectively registered. Multivariable logistic regression analysis was used to identify predictors of surgical complications. Results: A total of 472 women were selected, of whom 166 (35%) developed surgical complications within 30 days after radical hysterectomy. The most frequent complications were urinary retention with catheterization in 73 women (15%) and excessive perioperative blood loss >1000 mL in 50 women (11%). Open surgery (odds ratio [OR] 3.42; 95% CI 1.73-6.76), chronic pulmonary disease (OR 3.14; 95% CI 1.45-6.79), vascular disease (OR 1.90; 95% CI 1.07-3.38), and medical center (OR 2.83; 95% CI 1.18-6.77) emerged as independent predictors of the occurrence of complications. Body mass index (OR 0.94; 95% CI 0.89-1.00) was found as a negative predictor of urinary retention. Open surgery (OR 36.65; 95% CI 7.10-189.12) and body mass index (OR 1.15; 95% CI 1.08-1.22) were found to be independent predictors of excessive perioperative blood loss. Conclusions: Short-term surgical complications developed in 35% of the women after radical hysterectomy for early-stage cervical cancer in the Netherlands, a nation with centralized surgical care. Comorbidities predict surgical complications, and open surgery is associated with excessive perioperative blood loss

Managing Wicked Herbicide-Resistance: Lessons from the Field

Herbicide resistance is ‘wicked’ in nature; therefore, results of the many educational efforts to encourage diversification of weed control practices in the United States have been mixed. It is clear that we do not sufficiently understand the totality of the grassroots obstacles, concerns, challenges, and specific solutions needed for varied crop production systems. Weed management issues and solutions vary with such variables as management styles, regions, cropping systems, and available or affordable technologies. Therefore, to help the weed science community better understand the needs and ideas of those directly dealing with herbicide resistance, seven half-day regional listening sessions were held across the United States between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide resistance management. The major goals of the sessions were to gain an understanding of stakeholders and their goals and concerns related to herbicide resistance management, to become familiar with regional differences, and to identify decision maker needs to address herbicide resistance. The messages shared by listening-session participants could be summarized by six themes: we need new herbicides; there is no need for more regulation; there is a need for more education, especially for others who were not present; diversity is hard; the agricultural economy makes it difficult to make changes; and we are aware of herbicide resistance but are managing it. The authors concluded that more work is needed to bring a community-wide, interdisciplinary approach to understanding the complexity of managing weeds within the context of the whole farm operation and for communicating the need to address herbicide resistance

Managing Wicked Herbicide-Resistance: Lessons from the Field

Herbicide resistance is ‘wicked’ in nature; therefore, results of the many educational efforts to encourage diversification of weed control practices in the United States have been mixed. It is clear that we do not sufficiently understand the totality of the grassroots obstacles, concerns, challenges, and specific solutions needed for varied crop production systems. Weed management issues and solutions vary with such variables as management styles, regions, cropping systems, and available or affordable technologies. Therefore, to help the weed science community better understand the needs and ideas of those directly dealing with herbicide resistance, seven half-day regional listening sessions were held across the United States between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide resistance management. The major goals of the sessions were to gain an understanding of stakeholders and their goals and concerns related to herbicide resistance management, to become familiar with regional differences, and to identify decision maker needs to address herbicide resistance. The messages shared by listening-session participants could be summarized by six themes: we need new herbicides; there is no need for more regulation; there is a need for more education, especially for others who were not present; diversity is hard; the agricultural economy makes it difficult to make changes; and we are aware of herbicide resistance but are managing it. The authors concluded that more work is needed to bring a community-wide, interdisciplinary approach to understanding the complexity of managing weeds within the context of the whole farm operation and for communicating the need to address herbicide resistance

Managing Herbicide Resistance: Listening to the Perspectives of Practitioners. Procedures for Conducting Listening Sessions and an Evaluation of the Process

Seven half-day regional listening sessions were held between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide-resistance management. The objective of the listening sessions was to connect with stakeholders and hear their challenges and recommendations for addressing herbicide resistance. The coordinating team hired Strategic Conservation Solutions, LLC, to facilitate all the sessions. They and the coordinating team used in-person meetings, teleconferences, and email to communicate and coordinate the activities leading up to each regional listening session. The agenda was the same across all sessions and included small-group discussions followed by reporting to the full group for discussion. The planning process was the same across all the sessions, although the selection of venue, time of day, and stakeholder participants differed to accommodate the differences among regions. The listening-session format required a great deal of work and flexibility on the part of the coordinating team and regional coordinators. Overall, the participant evaluations from the sessions were positive, with participants expressing appreciation that they were asked for their thoughts on the subject of herbicide resistance. This paper details the methods and processes used to conduct these regional listening sessions and provides an assessment of the strengths and limitations of those processes

Oncologic outcomes of screen-detected and non-screen-detected T1 colorectal cancers

Background:The incidence of T1 colorectal cancer (CRC) has increased with the implementation of CRC screening programs. It is unknown whether the outcomes and risk models for T1 CRC based on non-screen-detected patients can be extrapolated to screen-detected T1 CRC. This study aimed to compare the stage distribution and oncologic outcomes of T1 CRC patients within and outside the screening program. Methods: Data from T1 CRC patients diagnosed between 2014 and 2017 were collected from 12 hospitals in the Netherlands. The presence of lymph node metastasis (LNM) at diagnosis was compared between screen-detected and non-screen-detected patients using multivariable logistic regression. Cox proportional hazard regression was used to analyze differences in the time to recurrence (TTR), metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival. Additionally, the performance of conventional risk factors for LNM was evaluated across the groups. Results: 1803 patients were included (1114 [62%] screendetected), with median follow-up of 51 months (interquartile range 30). The proportion of LNM did not significantly differ between screen- and non-screen-detected patients (12.6% vs. 8.9%; odds ratio 1.41; 95%CI 0.89-2.23); a prediction model for LNM performed equally in both groups. The 3- and 5-year TTR, MFS, and CSS were similar for patients within and outside the screening program. However, overall survival was significantly longer in screen-detected T1 CRC patients (adjusted hazard ratio 0.51; 95%CI 0.38- 0.68). Conclusions: Screen-detected and non-screen-detected T1 CRCs have similar stage distributions and oncologic outcomes and can therefore be treated equally. However, screen-detected T1 CRC patients exhibit a lower rate of non-CRC-related mortality, resulting in longer overall survival.</p