Nitrogen is the most limiting element for crop production. Traditionally, expensive commercial fertilizers are used to correct soil nitrogen deficiencies. Indeed, 50% of the increase in rice yields after World War II can be attributed to increased fertilizer nitrogen use. Although an increased rate of fertilizer nitrogen application has been advocated to meet the growing demand for food, it is unrealistic to advise the farmers to apply fertilizers they could hardly afford, and whose prices are likely to escalate in the years ahead. In addition, when they are not applied judiciously there are problems of environmental pollution as plants are capable of taking up only a relatively small portion of the applied nitrogen, a substantial amount being lost through various chemical and biological processes. The exploitation of cheaper alternatives or supplements to fertilizers have therefore gained much interest in recent years. Our increased interest in biological nitrogen fixation as a supplement or alternative to nitrogen fertilizers led to the convening of a consultants' meeting on The Role of Isotopes in Studies on Nitrogen Fixation and Nitrogen Cycling by Blue-Green Algae and the Azolla-Anabaena azollae Association', in Vienna from 11--15 October 1982. The consultants' group recommended that the Joint FAI/IAEA Division of Nuclear Techniques in Food and Agriculture embark on a coordinated research programme in this field and that initial emphasis should be placed on Azolla-Anabaena symbiosis. As a result, such a programme was initiated in 1984, which was concluded in 1989. The results and conclusions reported here are those that were generated during the five years of its operation.

Transport properties of plant cuticles are important for different ?elds of modern plant sciences. Ecologists and physiologists are interested in water losses to the environment via the cuticle. Penetration of plant protecting agents and nutrients into leaves and fruits is relevant for research in agriculture and plant protection. Ecotoxicologists need to know the amounts of environmental xenobiotics which accumulate in leaves and other primary plant organs from the environment. For all of these studies suitable methods should be used, and a sound theoretical basis helps to formulate testable hypotheses and to interpret experimental data. Unnecessary experiments and experiments which yield ambiguous results can be avoided. In this monograph, we have analysed on a molecular basis the movement of molecules across plant cuticles. Based on current knowledge of chemistry and str- ture of cuticles, we have characterised the aqueous and lipophilic pathways, the nature and mechanisms of mass transport and the factors controlling the rate of movement. We have focused on structure-property relationships for penetrant tra- port, which can explain why water and solute permeabilities of cuticles differ widely among plant species. Based on this knowledge, mechanisms of adaptation to en- ronmental factors can be better understood, and rates of cuticular penetration can be optimised by plant physiologists and pesticide chemists.

Principles of Soil and Plant Water Relations, Third Edition describes the fundamental principles of soil and water relationships in relation to water storage in soil and water uptake by plants. The book explains why it is important to know about soil-plant-water relations, with subsequent chapters providing the definition of all physical units and the SI system and dealing with the structure of water and its special properties. Final sections explain the structure of plants and the mechanisms behind their interrelationships, especially the mechanism of water uptake and water flow within plants and how to assess parameters. All chapters begin with a brief paragraph about why the topic is important and include all formulas necessary to calculate respective parameters. This third edition includes a new chapter on water relations of plants and soils in space as well as textbook problems and answers.

A Honeybee Heart Has Five Openings begins as Helen Jukes is entering her thirties and struggling to settle into her new job and home. Then friends gift her a colony of honeybees-a gift that, according to folklore, brings good luck-and Jukes embarks on the rewarding, perilous journey of becoming a beekeeper. Jukes writes about what it means to "keep" wild creatures and to live alongside beings whose laws of life are so different from our own. She delves into the history of beekeeping, exploring the ancient-and sometimes disturbing-relationship between keeper and bee, human and wild thing. And as her colony grows, the very act of beekeeping seems to open new perspectives, making her world come alive again. A beautifully wrought meditation on uncertainty and hope, feelings of restlessness and home, and how we might better know ourselves, A Honeybee Heart Has Five Openings shows us how to be alert to these small creatures flitting among us that are yet so vital a force for the continuation of life.

The First Asia --- Pacific Conference on Agricultural Biotechnology was held in Beijing, China on 20-24, August, 1992. Over half the population in the world is in the Asian and Pacific Region. With an increasing population and decreasing farming lands, it is important to develop agricultural biotechnology for improvement of the productivity, profitability and stability of the farming system. The Conference's main objectives were to bring together scientists working in different fields of agricultural biotechnology to stimulate discussion on this important process and to have an appraisal of the most recent studies concerning genetic manipulation of plants, plant cell and tissue culture, plant gene regulation, plant-microbe interaction, animal biotechnology etc. The Conference was attended by 391 scientists from different countries and regions. This volume presents the contributions of the lectures and a selected number of posters, which are an up-to-date account of the state of knowledge on agricultural biotechnology. The book provides a valuable reference source not only for specialists in agricultural biotechnology, but also for researchers working on related aspects of agronomy, biochemistry, genetics, molecular biology, microbiology and animal sciences. It is with great pleasure to acknowledge the contributions of the authors in assuring the prompt publication of this volume. We would also extend our sincere thank to Kluwer Academic Publishers for the publication of these proceedings.

Consumers have always been concerned about the quality, and particularly the safety, of the foods they eat. In recent years this concern has taken on additional prominence. Consumer focus on food safety has been sharpened by reports about new risks, such as that posed by "mad cow" disease, and about more familiar sources of risk, such as food borne pathogens, pesticides, and hormones. At the same time, some consumers are in creasingly interested in knowing more about how their food is produced and in selecting products based on production practices. Some of the questions consumers are asking in clude whether food is produced with the use of modern biotechnology, whether it is or ganically produced, how animals are treated in meat and egg production systems, and whether food is produced using traditional methods. Recent trends also show increased consumer demand for a variety of food products that are fresh, tasty, and available on a year-round basis. This has fostered increased global trade in food. For example, consumers in temperate climates such as North America are able to buy raspberries throughout the year, and Europeans can enjoy South American coffee. Trade in processed food products is actually increasing more rapidly than trade in agricultural commodities, further addressing the demand for variety among consumers."

Agricultural markets have entered a long-term process of liberalization, with the aim of reducing imposed market imperfections such as monopolistic public trade, entry barriers and subsidies. The experience of more than a decade of agriculture liberalization offers a good opportunity to review and analyze the outcome of this process and to draw lessons for the future. The central topic in Agricultural Markets Beyond Liberalization is the relationship between market structure and how markets perform in a dynamic context during a liberalization process. The topic is studied from both a micro and macro viewpoint and refers to different types of agricultural markets. This volume brings together the dynamics of agricultural markets in several parts of the world, with a special focus on transition economics and Africa. The different studies cover geographical areas as wide as a district as well as a group of countries, and institutions from individual contracts to multi-national organizations. The analysis of liberalization under different circumstances, and the different methods of analysis used by the authors provide a valuable foundation for the assessment of liberalization.

In the first section dedicated to theoretical thoughts on comparative agriculture, Hubert Cochet introduces the notion of "agricultural development", the very subject of comparative agriculture, with a restored endogenous dimension. He then describes how this approach was slowly consolidated, around the concept of agrarian system in particular. The comparison of agricultural transformations in time and space highlights the importance of the comparatist approach to production processes, their trajectories and differentiation on a worldwide scale. The second section which focuses on the methods and expertise of comparative agriculture, tackles the issues of landscape analysis, field surveys and the historical approach underlying comparative agriculture. It sums up the economic tools mobilised as well as the evaluation perspectives opened up by comparative agriculture.

As the world's population continues to expand, maintaining and indeed increasing agricultural productivity is more important than ever, though it is also more difficult than ever in the face of changing weather patterns that in some cases are leading to aridity and desertification. The absence of scientific soil inventories, especially in arid areas, leads to mistaken decisions about soil use that, in the end, reduce a region's capacity to feed its population, or to guarantee a clean water supply. Greater efficiency in soil use is possible when these resources are properly classified using international standards. Focusing on arid regions, this volume details soil classification from many countries. It is only once this information is properly assimilated by policymakers it becomes a foundation for informed decisions in land use planning for rational and sustainable uses.

The Symposium on high salinity tolerant plants, held at the University of Al Ain in December 1990, dealt primarily with plants tolerating salinity levels exceeding that of ocean water and which at the same time are promising for utilization in agriculture or forestry. These plants could be very useful for a country like the UAE where fresh water resources are very scarce and the groundwater available at some places is already very salty. More than 60 million woody trees/shrubs have been planted so far and more are planned for the inland plains underlain with brackish groundwater. These species were no solution for the widely barren shoreline of the UAE. Here mangrove species were of potential use, and one species, Avicennia Marina, occurs widely and has been successfully planted for about a decade. Converting the tree plantations into economically useful cropping systems is still a problem requiring much research and development. The book deals in several sections with conventional irrigation systems using marginal water. The species used in these systems are mostly hybrids of conventional crops. The irrigation systems, however, have similar problems as may be expected for irrigation with seawater. Papers show the participants' experiments in this area. The volume serves as a link between scientists working for the improvement of classical irrigation systems and those interested in the application of a new dimension of salinity levels for irrigation water.

Post-agricultural studies have been central to the development of both the science of plant ecology and ecology in general. The study of old field succession in particular allows us to observe the development of the structure and function of communities, as well as understand the roles of history and initial conditions in that process. Understanding old field succession can help the public address important scientific and social issues, such as deforestation and forest regeneration, forest restoration, sustainability of agriculture, maintenance of biodiversity, and impacts of global climate change on forest dynamics. Post-Agricultural Succession in the Neotropics focuses on published scientific work and its implications for wise management of old field ecosystems in the neotropics, where conversion of land to cropping systems is the most common kind of disturbance and many landscapes are defined by areas recovering from agriculture. Written for researchers, professionals, and students of ecology, the book provides a background in old field ecosystems and proposes restoration strategies and a trajectory for future research. methodologies and management strategies proposed.

Concern about the environmental impacts of transgenic crops is one of the major reasons for the EU 's quasi-moratorium on GMOs. This book shows that the economic implications of these concerns are far-reaching and complex, ranging from the farm to research and technology development to consumer reactions, and that they influence government response, international trade and public and private incentives for R & D.

Earthworms, which belong to the order Oligochaeta, comprise roughly 3,000 species grouped into five families. Earthworms have been called 'ecosystem engineers'; much like human engineers, they change the structure of their environments. Earthworms are very versatile and are found in nearly all terrestrial ecosystems. They play an important role in forest and agricultural ecosystems. This Soil Biology volume describes the various facets of earthworms, such as their role in soil improvement, soil structure, and the biocontrol of soil-borne plant fungal diseases. Reviews discuss earthworms' innate immune system, molecular markers to address various issues of earthworm ecology, earthworm population dynamics, and the influences of organic farming systems and tillage. Further topics include the characteristics of vermicompost, relationships between soil earthworms and enzymes, the role of spermathecae, copulatory behavior, and adjustment of the donated sperm volume.

Plant biotechnology offers important opportunities for agriculture, horticulture, and the pharmaceutical and food industry by generating transgenic varieties with altered properties. This is likely to change farming practice and reduce the potential negative impact of plant production on the environment. This volume shows the worldwide advances and potential benefits of plant genetic engineering focusing on the third millennium.
The authors discuss the production of transgenic plants resistant to biotic and abiotic stress, the improvement of plant qualities, the use of transgenic plants as bioreactors, and the use of plant genomics for genetic improvement and gene cloning. Unique to this book is the integrative point of view taken between plant genetic engineering and socioeconomic and environmental issues. Considerations of regulatory processes to release genetically modified plants, as well as the public acceptance of the transgenic plants are also discussed.
This book will be welcomed by biotechnologists, researchers and students alike working in the biological sciences. It should also prove useful to everyone dedicated to the study of the socioeconomic and environmental impact of the new technologies, while providing recent scientific information on the progress and perspectives of the production of genetically modified plants.

The work is dedicated to Professor Marc van Montagu.