Optimising cutting method and timing for the control of Abutilon theophrasti seed production     

Farnaz Kordbacheh  Charles L. Mohler  Alan G. Taylor  Anna S. Westbrook  Hamid Rahimian-Mashhadi  Hassan M. Alizadeh  Antonio DiTommaso 《Weed Research》2023,63(1):34-44

Abutilon theophrasti (velvetleaf) is a widespread and problematic annual weed. Greenhouse and field experiments were conducted to investigate the effects of different cutting methods on the viability of A. theophrasti seeds. Three cutting methods were assessed: (1) Entire plant cut and dried (EPD)—plants were cut at soil level and dried with capsules attached on the greenhouse bench or soil surface for 4 weeks; (2) capsules detached and dried (CD)—capsules were removed from plants and dried for 4 weeks; and (3) capsules detached and tested while fresh (CF)—a control treatment. Before drying, the developmental stage (stage one, dark green; stage two, light green; stage three, yellowish-green; or stage four, black with the slightly open capsule) and age (days after flowering, DAF) of each capsule was recorded. Seed viability was measured immediately in the CF treatment and after the 4-week drying period in the EPD and CD treatments. No seeds in the EPD and CD treatments were viable when harvested at the first developmental stage (1–8 DAF) in either experiment, but 100% of seeds in the CF treatment in the field were viable when harvested at 8 DAF. In both greenhouse and field experiments, seeds attained full viability at earlier harvest ages in CF than in EPD or CD treatments, suggesting that seeds might become viable relatively early in development but lose viability if allowed to dry. These findings could be applied to optimise late-season mechanical control of A. theophrasti.  相似文献   

Welfare and environmental benefits of integrating commercially viable free-range broiler chickens into newly planted woodland: A UK case study     

Tracey Jones  Ruth Feber  Gabriel Hemery  Paul Cook  Katy James  Curt Lamberth  Marian Dawkins 《Agricultural Systems》2007

The commercial, welfare and environmental impacts of rearing small colonies of free-range chickens in newly planted woodland at two sites in the UK, during the first 2 years of the enterprise, were investigated. Newly planted rather than established trees were used so that commercially viable species could be planted in a way that would suit the management of the chicken enterprise, and small colonies were used so that farmers wishing to diversify could buy into the system progressively. It was anticipated that marketing a high specification product would provide an immediate income, whilst waiting for the future investment in trees to grow.  相似文献   

A tool for community-based assessment of the implications of development on water security in hillside watersheds   总被引：1，自引：0，他引：1  

J. C. Luijten  E. B. Knapp  J. W. Jones 《Agricultural Systems》2001,70(2-3):603-622

Development and population growth in Latin American countries with steep slope farming are likely to further increase pressures on water and land resources. A methodology was developed for assessing water availability and use under different development pathways at a watershed scale to determine whether water security is a potential problem, and if so, under what conditions it is likely to occur. This methodology makes use of a GIS-based spatial water budget model for simulating stream water availability, water use and stream flow control on a daily basis at a watershed scale. Here, we analysed water availability under three plausible development scenarios for the 3246 ha Cabuyal River watershed in southwest Colombia in the year 2025: Corporate Farming (CF), Ecological Watershed (EW), and Business as Usual (BU). Simulated average river flows at the watershed outlet were, respectively, 874, 796 and 925 l s⁻¹ for the CF, EW and BU scenarios. The contribution of base flow to river flow (base flow index) was on average, 80.8, 85.6 and 77.9%, respectively, for the three scenarios. The watershed had the potential to meet the anticipated increase in water use under each explorative scenario. However, dams were necessary to store irrigation water in the CF scenario, otherwise over 60% of the available water would have been used during the dry season. Such a high figure raises concerns about effects on aquatic and riparian ecology, concentrations of potential contaminants, water reserves for especially low rainfall years, and the watershed resilience to meet temporarily higher water needs during the day. Analyses indicated that current water-use conflicts in the watershed can be resolved if irrigation water supply is separated from drinking water supply. This study helped reduce some of the complexity associated with the interdependencies between land and water resources, the impact of using them, and spatial linkages within the watershed. Results of this study can be used for teaching local stakeholders about basic landscape responses and helping multi-institutional alliances to become proactive and to guide development to the benefit of local communities.  相似文献   

Opportunities for chiral agrochemicals     

Alan Williams 《Pest management science》1996,46(1):3-9

Chiral compounds account for 25% of all agrochemical compounds used commercially and for 26% of the total value of the world agrochemical market. However, those sold in single isomer form contribute only 7% to the market value despite many potential advantages in terms of regulatory, intellectual property and marketing benefits. Limited access to chiral raw materials and economic synthesis routes are key reasons why single isomers are less common than they might be. The development of more chiral routes will encourage the development of single isomer compounds to capitalise on their advantages.  相似文献   

Origin of resistance to pyrethroids in the redlegged earth mite (Halotydeus destructor) in Australia: repeated local evolution and migration     

Qiong Yang  Paul A Umina  Gordana Ra&#x;i&#x;  Nicholas Bell  Jichao Fang  Alan Lord  Ary A Hoffmann 《Pest management science》2020,76(2):509-519

  相似文献   

Projecting the suitability of global and local habitats for myrtle rust (Austropuccinia psidii) using model consensus     

H. A. Narouei-Khandan  S. P. Worner  S. L. H. Viljanen  A. H. C. van Bruggen  E. E. Jones 《Plant pathology》2020,69(1):17-27

Myrtle rust (caused by Austropuccinia psidii) affects more than 500 known host species in the Myrtaceae family. Three different modelling approaches (CLIMEX, MaxEnt and Multi-Model Framework) were used to project the habitat suitability for myrtle rust at both global and local scales. Current data on the global occurrence of myrtle rust were collected from online literature and expert solicitation. Long-term averages of climate data (1960–1990) were sourced from WorldClim and CliMond websites. Recent reports of myrtle rust in New Zealand were used for validation of model outputs but not in model training and testing. The model outputs were combined into a consensus model to identify localities projected to be suitable for myrtle rust according to two or three models (hotspots). In addition to the locations where the pathogen is currently present, all models successfully projected independent occurrence data in New Zealand suitable for establishment of the pathogen. Climate suitability for the pathogen was primarily related to temperature followed by rainfall in MaxEnt and the CLIMEX model. The results confirmed the optimum temperature range of this pathogen in the literature (15–25 °C). Additional analysis of the precipitation variables indicated that excessive rain (more than 2000 mm in warmest quarter of the year) combined with high temperatures (>30 °C) constrain pathogen establishment. The results of the current study can be useful for countries such as New Zealand, China, South Africa and Singapore where the pathogen has not fully spread or established.  相似文献   

Hybridisation in kiwi (Apteryx; Apterygidae) requires taxonomic revision for the Great Spotted Kiwi     

Lara D.Shepherd  Alan J.D.Tennyson  Hugh A.Robertson  Rogan M.Colbourne  Kristina M.Ramstad 《中国鸟类》2021,(2):195-207

Background: Kiwi (Apteryx spp.) are flightless ratites from New Zealand whose numbers and distributions have declined following human arrival. Some of the kiwi ...  相似文献   

INTEGRATED CROP-LIVESTOCK SYSTEMS: LESSONS FROM NEW YORK,BRITISH COLUMBIA,AND THE SOUTH-EASTERN UNITED STATES     

Alan FRANZLUEBBERS  Derek HUNT  Gary TELFORD  Shabtai BITTMAN  Quirine KETTERINGS 《农业科学与工程前沿(英文版)》2021,8(1):81-96

• Livestock production in North America has moved to fewer farms with greater inventories • Land application of livestock manures is a preferred nutrient recycling strategy • Confined animal feeding operations have challenges to utilize livestock manure sustainably • Integration of livestock and cropping systems is possible on a farm or among farms • Nutrient balance is needed for environmental sustainability Livestock production in the United States (US) and Canada is diverse, but shows a common trend in most livestock sectors toward fewer farms producing the majority of animal products despite a large number of farms still small in production scale. The migration to larger and more concentrated animal feeding operations in beef finishing and poultry, swine, and dairy production allows processors to streamline supplies to meet market demand for abundant, low-cost livestock products, whether that be for packaged meat, dairy products, or eggs. With concentration of livestock operations comes the challenge of managing manures. When sufficient land is available and nutrients are needed, livestock manure is an excellent nutrient source and land application is the preferred method of recycling this resource. However, when livestock production is constrained in a geographical area and animal densities are high, manure may become an environmental liability with potentially greater risk for runoff and leaching of nutrients, emission of odors, ammonia, and greenhouse gases, and release to the environment of pathogens and chemicals of emerging concern. Addressing these challenges now and into the future requires learning from mistakes and adopting successful approaches. We describe different levels of integration between livestock and crop producers in New York, British Columbia, and the south-eastern US as learning opportunities to improve economic and environmental sustainability. Examples show that effective solutions should recognize (1) manure has value and is not just a cost, (2) farmers, farm advisors, extension educators, nutrient management planners, crop advisors, nutritionists, state agency personnel, regulators, and university researchers need to be active participants in development of solutions, and (3) change to a sustainable future requires a combination of government regulation and outcome-based incentives.  相似文献   

Using knowledge of behaviour and optic physiology to improve fish passage through culverts     

Matthew Jon Jones  Robin Hale 《Fish and Fisheries》2020,21(3):557-569

Culverts reduce connectivity for aquatic animals by being both a hydraulic and physical barrier. However, altered light intensity may also be a behavioural barrier to fish movement, especially for diurnal species that have adapted to moving when it is light. We propose that knowledge of optical physiology and fish behaviour, two important mechanisms underpinning movement, can inform efforts to improve fish movement through culverts. We firstly review the sensory systems of fish with reference to visual sense and explore how this affects fish movement. We then highlight theoretical knowledge that can help us understand fish behaviour and the potential mismatch between the conditions under which fish have evolved and altered conditions within culverts. We describe potential knowledge gaps and directions for future research to improve our understanding of how culverts may affect fish movement. Finally, we explore the potential costs and ecological benefits of different mitigation options to identify those with the most promise for managing the light environment in culverts to facilitate movement. For researchers and managers exploring this subject, we suggest an approach that: (a) identifies light requirements for movement by different species, (b) tests movement under different light conditions and (c) considers an integrative assessment method for testing fish behaviour around culverts. Understanding how optical physiology, fish behaviour and culvert design influence fish movement can improve connectivity for a range of species.  相似文献   

Thirty years of change and the future of Alaskan fisheries: Shifts in fishing participation and diversification in response to environmental,regulatory and economic pressures     

Anne H. Beaudreau  Eric J. Ward  Richard E. Brenner  Andrew O. Shelton  Jordan T. Watson  Jennifer C. Womack  Sean C. Anderson  Alan C. Haynie  Kristin N. Marshall  Benjamin C. Williams 《Fish and Fisheries》2019,20(4):601-619

Heterogeneity in human responses and decision‐making can contribute to the resilience of social–ecological systems in the face of environmental, political and economic pressures. In fishery systems worldwide, the ability of harvesters to maintain a diverse portfolio of fishing strategies is important for building adaptive capacity. We used a case‐study approach to examine the complexity of factors that inhibit or promote diversification in fisheries of Alaska, one of the major fishing regions of the world. Through a combination of harvest records and literature review, we explored shifts in participation and portfolio diversity in Alaskan fisheries over three decades. The four case‐studies examined the responses of fishers, fleets and communities to multiple, intersecting pressures, including biological declines, market and price dynamics, fishery privatization and the 1989 Exxon Valdez oil spill. These cases illustrate how stressors acting at multiple scales can encourage or constrain opportunities for diversification, and that these opportunities may be spread inequitably across participants. Overall, we found evidence for reduced participation and increasing specialization in Alaskan commercial fisheries. While numerous factors explain these trends, policies like individual quota systems and the increasing cost of entry into fisheries are forcing consolidation at local to regional scales. A portfolio approach to managing fisheries that reduces barriers to diversification and includes broad representation of resource users and communities in management may help to maintain opportunity and choice for fishers.  相似文献