An axenic plant culture system for optimal growth in long-term studies

The symbiotic co-evolution of plants and microbes leads to difficulties in understanding which of the two components is responsible for a given environmental response. Plant-microbe studies greatly benefit from the ability to grow plants in axenic (sterile) culture. Several studies have used axenic plant culture systems, but experimental procedures are often poorly documented, the plant growth environment is not optimal, and axenic conditions are not rigorously verified. We developed a unique axenic system using inert components that promotes plant health and can be kept sterile for at least 70 d. Crested wheatgrass (Agropyron cristatum cv. CDII) plants were grown in sand within flow-through glass columns that were positively pressured with filtered air. Plant health was optimized by regulating temperature, light level, CO2 concentration, humidity, and nutrients. The design incorporates several novel aspects, such as pretreatment of the sand with Fe, graduated sand layers to optimize the air-water balance of the root zone, and modification of a laminar flow hood to serve as a plant growth chamber. Adaptations of several sterile techniques were necessary for maintenance of axenic conditions. Axenic conditions were verified by plating and staining leachates as well as a rhizoplane stain. This system was designed to study nutrient and water stress effects on root exudates, but is useful for assessing a broad range of plant-microbe-environment interactions. Based on total organic C analysis, 74% of exudates was recovered in the leachate, 6% was recovered in the bulk sand, and 17% was recovered in the rhizosphere sand. Carbon in the leachate after 70 d reached 255 microg d(-1). Fumaric, malic, malonic, oxalic, and succinic acids were measured as components of the root exudates.     

Weed manipulation for insect pest management in corn

Populations of insect pests and associated predaceous arthropods were sampled by direct observation and other relative methods in simple and diversified corn habitats at two sites in north Florida during 1978 and 1979. Through various cultural manipulations, characteristic weed communities were established selectively in alternate rows within corn plots.Fall armyworm (Spodoptera frugiperda J. E. Smith) incidence was consistently higher in the weed-free habitats than in the corn habitats containing natural weed complexes or selected weed associations. Corn earworm (Heliothis zea Boddie) damage was similar in all weed-free and weedy treatments, suggesting that this insect is not affected greatly by weed diversity. Only the diversification of corn with a strip of soybean significantly reduced corn earworm damage.In one site, distance between plots was reduced. Because predators moved freely between habitats, it was difficult to identify between-treatment differences in the composition of predator communities. In the other site, increased distances between plots minimized such migrations, resulting in greater population densities and diversity of common foliage insect predators in the weed-manipulated corn systems than in the weed-free plots. Trophic relationships in the weedy habitats were more complex than food webs in monocultures.Predator diversity (measured as mean number of species per area) and predator density was higher in com plots surrounded by mature, complex vegetation than at those surrounded by annual crops. This suggests that diverse adjacent areas to crops provide refuge for predators, thus acting as colonization sources.     

Reactivity of the plant growth regulator paclobutrazol (cultar) with two tropical soils of the northeast semiarid region of Brazil

The reactivity of paclobutrazol (PBZ, a plant growth retardant) with a Yellow Ultisol and a Vertisol from the semiarid northeast region of Brazil was evaluated through batch sorption experiments and modeling. Although not instantaneous, the sorption kinetic of PBZ (pure and formulated) was fast (a few hours) in both soils. The sorption kinetics were well described by a second-order (dS(t)/dt=k(2)(S(e2)-S(t))(2)) but not by a first-order model. The sorption isotherms were found to be linear and the calculated K(D) values were 8.8 +/- 0.11 and 7.4 +/- 0.2 L kg(-1) for pure PBZ in the Ultisol and the Vertisol, respectively. The corresponding K(OC) values were 1275 +/- 34 (logK(OC) = 3.11) and 1156 +/- 49 (logK(OC) = 3.06) L kg(-1), respectively. Considering the very different texture of the two soils and the similar K(OC) values determined, these results showed that in both soils, the sorption of PBZ is dominantly controlled by organic matter, although some interactions of PBZ with iron oxides (goethite) were observed in the Ultisol. Based on these sorption parameters a low leachability potential of PBZ in soils is anticipated, as they correspond to a groundwater ubiquity score (GUS) ranging from 2.0 to 2.7, i.e., moderately to not mobile, in contradiction with the actual groundwater situation in Brazil. This work stresses the need to evaluate and predict the risk associated with aquifer contamination by this widely used plant growth regulator.     

Regulating insect resistance management: the case of non-Bt corn refuges in the US

In this paper, we analyze the insect resistance management (IRM) plan put in place by the US Environmental Protection Agency (EPA) to delay the evolution of resistance to Bt corn in natural populations of the European corn borer, Ostrinia nubilalis Hübner. This IRM plan is the most impressive mandatory IRM system ever developed. It forms a coherent whole and includes mandatory refuges, actions to increase growers' compliance and a program for monitoring the evolution of resistance. However, our analysis suggests that two components of this IRM plan are not entirely satisfactory: growers' compliance and monitoring of the evolution of resistance. Moreover, the implementation of these two components of IRM has been required of the registrants, whose incentives for IRM are probably lower than the social optimum. Our analysis suggests that alternatives to the IRM plan currently in place could improve these two components.     

Economic growth,national income and the blocked choices for the environment

Summary This paper explains why the identification of the increase of national income (or GNP) with economic growth, increase in welfare and economic success is theoretically wrong. This incorrect use of terms strengthens the one-sided orientation of economic policy on the growth of production, often at the expense of the environment. Two examples are given of how this course of affairs is blocking the social choices regarding a fundamental solution of the environmental problem. An overview is given of the possibilities of correcting the Gross National Product (GNP) figures for environmental losses. None of these are perfect, since shadow prices for environmental functions directly comparable with the market prices of goods produced can be construed only in exceptional cases. The conclusion is that the only way to arrive at national income figures corrected for environmental losses is to supplement the corrections for expenditures on preventive, restoratory and compensatory measures (defensive expenditures) with the estimated expenditures on measures required to meet physical standards, based on health and a sustainable economic development.Dr Roefie Hueting is Head of the Department of Environment Statistics at the Netherlands Central Bureau of Statistics and a Visiting Fellow at the International Institute for Environment and Society (IIUG). He is a previous contributor toThe Environmentalist (1985, pp.253–262). Dr Christian Leipert is a staff member at IIUG.     

关于改进“绿色化税制”测量方法的探讨

“绿色化税制”通常使用两项指标来进行测量：环境相关税收入占GDP的百分比和环境相关税收入占国家税收总收入的百分比。但是,这两个指标也存在着一个很大的缺点：当污染税增加时,税收收入也增加。因此,本文通过探讨测量绿色税制的指标,建立一个简单的分析框架,通过有效性、数据的可用性、全时段的比较、国际相似性、易聚合性、免税和减税、有限的复杂性七个指标来进行评价。最后,基于四种类型的指标的优缺点来做总结,对绿色税制的优化给出建议。     

A project-based system for including farmers in the EU ETS

Farmers in the EU do not trade greenhouse gases under the Kyoto agreement. This is an empirical puzzle because agriculture is a significant contributor of greenhouse gases (GHG) in the EU and may harvest private net gains from trade. Furthermore, the US has strongly advocated land-use practices as 'the missing link' in past climate negotiations. We argue that farmers have relatively low marginal reduction costs and that consequences in terms of the effect on permit price and technology are overall positive in the EU Emission Trading System (ETS). Thus, we propose a project-based system for including the farming practices in the EU ETS that reduces the uncertainty from measuring emission reduction in this sector. The system encourages GHG reduction either by introducing a new and less polluting practice or by reducing the polluting activity. When doing so, farmers will receive GHG permits corresponding to the amount of reduction which can be stored for later use or sold in the EU ETS.     

Towards a new planning system for the 1990s and beyond

The paper outlines the emerging effects of the Information Technological revolution and examines the likely consequences for planning in Britain. A number of possible scenarios are described as a basis for thinking about the design of a new planning system for the future.     

Sustainable growth: Compatibility between a plausible growth criterion and the initial state

There is a large body of research devoted to understanding sustainable growth in resource-based economies. Some of this research cannot be applied to real economies directly because the initial states of real economies do not match the initial states assumed in the models. Using a model of theDasgupta–Heal–Solow–Stiglitz variety the paper shows that inconsistency between assumed and actual initial states can lead to a less desirable, in particular, a Pareto inferior path of consumption per capita. The paper also presents a methodology for constructing transition paths from an imperfect initial state to an initial state compatible with the standard steady state consumption path.     

A spatial-temporal system for dynamic cadastral management

A practical spatio-temporal database (STDB) technique for dynamic urban land management is presented. One of the STDB models, the expanded model of Base State with Amendments (BSA), is selected as the basis for developing the dynamic cadastral management technique. Two approaches, the Section Fast Indexing (SFI) and the Storage Factors of Variable Granularity (SFVG), are used to improve the efficiency of the BSA model. Both spatial graphic data and attribute data, through a succinct engine, are stored in standard relational database management systems (RDBMS) for the actual implementation of the BSA model. The spatio-temporal database is divided into three interdependent sub-databases: present DB, history DB and the procedures-tracing DB. The efficiency of database operation is improved by the database connection in the bottom layer of the Microsoft SQL Server. The spatio-temporal system can be provided at a low-cost while satisfying the basic needs of urban land management in China. The approaches presented in this paper may also be of significance to countries where land patterns change frequently or to agencies where financial resources are limited.     

The need for growth promoting compounds in poultry meat production

Modern strains of broiler chicken are capable of achieving a 2.4 kg liveweight at 42d of age. This extremely fast growth is accomplished in part by balanced diets containing pharmaceutical growth promoting compounds. Over the last few years, a number of ethical questions have arisen regarding the use of such compounds. Such fast growth rate is accompanied by reduced bird welfare related to morbidity and mortality of a proportion of the birds. In two trials we have shown that acceptable growth rate can be achieved in diets without these compounds, and that economics of production are not adversely affected. It is concluded that future management programs for broiler chickens should consider a tempering of growth rate and that this could lead to improved bird well-being.     

Allowing for sustainable growth under drastic immigration stress in Israel

Between 1990 and 1992 Israel's population grew by almost 10%, as a result of a sudden immigration influx. A national plan was prepared to accommodate this population growth in a sustainable manner. This paper reviews how the national plan set to accommodate such population growth without imposing undue environmental hardships on either current or future generations. Using a comprehensive environmental guidelines map and adjunct measures, the plan was able to point a way by which the population increase could be accommodated without damaging sensitive natural resources, increasing pollution to unacceptable levels or aggravating population exposure to hazards or nuisances. This plan thus provides a real‐world illustration of how, with adequate institutional structure, organization, scientific base and political resolve, a large population increase can be accommodated in a manner that does not preclude sustainability notions, even in a highly vulnerable environment.     

An intelligent disaster decision support system for increasing the sustainability of transport networks

The increase in extreme weather events arising from climate change is posing serious threats to the sustainability of transport systems, creating the need for improved tools for decision support for more effectively managing natural disasters. There are numerous transport‐related decisions that are required during the response, recovery and preparedness stages of the disaster management cycle. This paper describes the development and application of the Intelligent Disaster Decision Support System (IDDSS), which provides a platform for integrating a vast range of road network, traffic, geographic, economic and meteorological data, as well as dynamic disaster and transport models. Initial applications to the response and planning for floods and fires are presented to illustrate some of its capabilities. The IDDSS can be used to improve disaster management, which in turn will increase the sustainability of transport networks.     

企业环境责任评价体系及成果应用分析

随着环境保护部近年来众多环保举措的提出,企业的环境责任研究引起了学者和相关政府机构的重视。企业环境责任评价有利于提高企业环保意识和规范企业的环境行为,但目前仍缺乏相关机构对企业环境责任评价体系的独立研究和实践。本文通过对国内外企业环境责任的研究现状进行分析,引入了企业环境责任评价的必要性;在相关概念界定的基础上构建了企业环境责任评价指标体系,最后对评价成果的应用进行了探讨和研究。     

Nutrient requirements for the growth of waterleaf (Talinum triangulare) in Uyo metropolis, Nigeria

The all-season vegetable known as waterleaf (Talinum triangulare) is extensively grown in Nigeria's metropolistan market gardens. This paper examines the soil compositions of some of the cultivation areas for this crop to determine the impacts of its very intensive repetitive cultivation. In general, the regular application of organic manures and mineral fertilizers has maintained the fertility status of the market garden soils. Multiple regression analysis indicated that base saturation, available phosphorus and organic matter were the most significant determinants to variations in crop production.     

对应RoHS指令的体制提案

本文提出了对应RoHS的体制提案,供参考.