Pork continues to occupy an important position as a food source in affluent societies as well as in developing countries with slower economic growth. The growth of the world swine population continues at a faster rate than that of the human population, a reflection of the sustained demand for pork in all parts of the world. The technical basis for commercial production of swine was presented in our two earlier textbooks-Swine Production in Temperate and Tropical Environ ments, by Pond and Maner, 1974, and Swine Production and Nutrition, by Pond and Maner, 1984. In view of rapidly advancing technology and an appreciation for the systems approach in industry and agriculture, this third book has been restructured to provide the student and practitioner with an integrated concept of pork production. We have attempted to blend the fundamental principles from genetics, physiology, nutrition, and biotechnology into the modern concepts of systems analysis and simulation modeling. The objective is to create a teaching approach which empha sizes the integrated synthesis of biological with physical and environmental sci ences and economics. This approach is expected to provide an overall pork pro duction systems view that individual producers can adapt to their specific resources, needs, and goals. Our new co-author, Dr. Dewey Harris, has used his expertise and perspective on interacting systems to change the complexion of the book to fulfill this objective. In addition, Dr."

William C. Taylor Department of Genetics University of California Berkeley, California 94720 It is evident by now that there is a great deal of interest in exploiting the new technologies to genetically engineer new forms of plants. A purpose of this meeting is to assess the possibilities. The papers that follow are concerned with the analysis of single genes or small gene families. We will read about genes found within the nucleus, plastids, and bacteria which are responsible for agri culturally important traits. Given that these genes can be isolated by recombinant DNA techniques, there are two possible strategies for plant engineering. One involves isolating a gene from a cultivated plant, changing it in a specific way and then inserting it back into the same plant where it produces an altered gene product. An example might be changing the amino acid composition of a seed pro tein so as to make the seed a more efficient food source. A second strategy is to isolate a gene from one species and transfer it to another species where it produces a desirable feature. An example might be the transfer of a gene which encodes a more efficient pho tosynthetic enzyme from a wild relative into a cultivated species. There are three technical hurdles which must be overcome for either strategy to work. The gene of interest must be physically isolated.

It is appropriate at this time to reflect on two decades of research in biological control of weeds with fungal plant pathogens. Some remarkable events have occurred in the last 20 years that represent a flurry of activity far beyond what could reasonably have been predicted. In 1969 a special topics review article by C. L. Wilson was published in Annual Reviews of Phytopathology that examined the literature and the potential for biological control of weeds with plant pathogens. In that same year, experiments were conducted in Arkansas that determined whether a fungal plant pathogen could reduce the infestation of a single weed species in rice fields. In Florida a project was under way to determine the potential use of a soil-borne plant pathogen as a means for controlling a single weed species in citrus groves. Work in Australia was published that described experiments that sought to determine whether a pathogen could safely and deliberately be imported and released into a country to control a weed of agricultural importance. All three projects were successful in the sense that Puccinia chondrillina was released into Australia to control rush skeleton weed and was released later into the United States as well, and that Colletotrichum gloeosporioides f.sp. aeschynomene and Phytophthora palmivora were later both marketed for the specific purpose of controlling specific weed species.

This volume is the last contribution of a series of With the present book, a further gap concern studies concerned with the plant material of one ing leaf morphology and leaf venation, as well and the same area of Venezuelan Guiana. The as some structural peculiarities of physiological importance, is closed so that an exhaustive survey studies originated through a collaboration with the forest engineer Dr. B. Rollet, the FAO expert in of bark and leaf morphology and anatomy as well forest inventory who collected the material of tree as of fruit and seed structure of the plants of a barks, leaves, fruits and seeds in Venezuelan certain well-known area is herewith given. Not Guiana around the "Rio Grande," "EI Paraiso," only were hundreds of species studied, but and "EI Dorado" camps. In the first place, tree structural characteristics were related to "forest barks of about 280 species of dicotyledons stratification," i. e. to the different micro climatic belonging to 48 families were studied (family by conditions in the forest, as the height of the trees family) by Roth in separate publications which and shrubs studied was known. It is of common mainly appeared in Acta Botanica Venezuelica knowledge that in the lower forest layers, light is a and in Acta Biol6gica Venezuelica (see the bibli limiting factor, while humidity is sufficiently avail ography in Roth 1981)."

This book provides a comprehensive, global synthesis of current knowledge on the potential and challenges associated with the multiple roles, use, management and marketing of non-timber forest products (NTFPs). There has been considerable research and policy effort surrounding NTFPs over the last two and half decades. The book explores the evolution of sentiments regarding the potential of NTFPs in promoting options for sustainable multi-purpose forest management, income generation and poverty alleviation. Based on a critical analysis of the debates and discourses it employs a systematic approach to present a balanced and realistic perspective on the benefits and challenges associated with NTFP use and management within local livelihoods and landscapes, supported with case examples from both the southern and northern hemispheres. This book covers the social, economic and ecological dimensions of NTFPs and closes with an examination of future prospects and research directions.

Thrips (fhysanoptera) are very small insects, widespread throughout the world with a preponderance of tropical species, many temperate ones, and even a few living in arctic regions. Of the approximately 5,000 species so far identified, only a few hundred are crop pests, causing serious damage or transmitting diseases to growing crops and harvestable produce in most countries. Their fringed wings confer a natural ability to disperse widely, blown by the wind. Their minute size and cryptic behavior make them difficult to detect either in the field or in fresh vegetation transported during international trade of vegetables, fruit and ornamental flowers. Many species have now spread from their original natural habitats and hosts to favorable new environments where they often reproduce rapidly to develop intense damaging infestations that are costly to control. Over the past decade there have been several spectacular examples of this. The western flower thrips has expanded its range from the North American continent to Europe, Australia and South Africa. Thrips palmi has spread from its presumed origin, the island of Sumatra, to the coast of Florida, and threatens to extend its distribution throughout North and South America. Pear thrips, a known orchard pest of Europe and the western United States and Canada has recently become a major defoliator of hardwood trees in Vermont and the neighboring states. Local outbreaks of other species are also becoming problems in field and glasshouse crops as the effectiveness of insecticides against them decline.

The XXX Congress of the International Union of Physiological Sciences took place in Vancouver, Canada, in July 1986; and this Volume contains a selection of the Review Lectures which formed part of the Congress programme. They cover most of the areas of contemporary physiology and were presented by distinguished scientists from many parts of the world. An innovation at this Congress was the inclusion in the programme of a number of lectures devoted to historical subjects. These lectures attracted large audiences at the meetings, and three of them also appear in this book. Finally, the Plenary Lectures which formed part of the opening and closing ceremonies and which deal with some aspects of Canadian physiological history, find a place here as well. The Editors are grateful to all of the authors who provided the manuscripts which go to make up this book, and to John Donald for his invaluable assistance in the preparation of the final text; as well of course to all of the contributors whose participation made the Congress the success which it was. It is hoped that this Volume will provide a useful memento of the event.

Temperate forests cover large areas of Europe and perform a number of important functions such as the regulation of energy and matter, production of wood and other resources, and conservation of biodiversity and habitats; they also have special signi?cance in social and cultural contexts. Initiated in 1960s, the ?rst International Biological Program (IBP) focused on ''the biological basis of productivity and human welfare. '' As the German contribution to the IBP, ecosystem research has been carried out since 1966 in the Solling area (Ellenberg H., Ecological Studies 2, 1971), an upland region in Northwest Germany. This study provided clear evidence that the stability of forest ecosystems was threatened by the high inputs of at- spheric pollutants. This promoted many interdisciplinary research programs which were coordinated by Prof. Dr. Bernhard Ulrich and the Forest Ecosystems Research Center of the University of Go]ttingen. This involved, in addition to the Solling site, the establishment of two other sites for long-term monitoring of ecosystem pro- ] cesses. The two contrasting sites were established in 1980 at Gottinger Wald on base-rich calcareous soil and in 1989 at Zierenberg on volcanic soil. These projects were funded initially by the Federal Ministry of Research and Technology (BMBF) as interdisciplinary projects under the titles: ''Conditions of Stability of Forest Ecosystems'' (1989-1993), and ''Dynamics of Forest Ecos- tems'' (1993-1998). The primary goal of these studies was to quantify the ecolo- cal condition of forests in a changing environment and element ?uxes."

The oil crisis during the 1970s turned interest towards the utilization of renewable resources and towards lignocellulosics in particular. The 1970s were also the cradle period of biotechnology, and the years when biotechnical utilization of lignocellulosic waste from agriculture and forestry gained priori ty. This was a logical conclusion since one of nature's most important biologi cal reactions is the conversion of wood and other lignocellulosic materials to carbon dioxide, water and humic substances. However, while biotechnology in other areas like medicine and pharmacology concerned production of expen sive products on a small scale, biotechnical utilization and conversion of ligno cellulosics meant production of inexpensive products on a large scale. Biotechnical utilization of lignocellulosic materials is therefore a very difficult task, and the commercial utilization of this technology has not progressed as rapidly as one would have desired. One reason for this was the lack of basic knowledge of enzyme mechanisms involved in the degradation and conversion of wood, other lignocellulosics and their individual components. There are also risks associated with initiating a technical development before a stable platform of knowledge is available. Several of the projects started with en thusiasm have therefore suffered some loss of interest. Also contributing to this failing interest is the fact that the oil crisis at the time was not a real one. At present, nobody predicts a rapid exhaustion of the oil resources and fuel production from lignocellulosics is no longer a high priority."

As forests decline in temperate and tropical climates, highly-developed countries and those striving for greater economic and social benefits are beginning to utilize marginal forests of high-latitude and mountainous regions for resources to satisfy human needs. The benefits of marginal forests range from purely aesthetic to providing resources for producing many goods and services demanded by a growing world population. Increased demands for forest resources and amenities and recent warming of high latitude climates have generated interest in reforestation and afforestation of marginal habitats in cold regions. Afforestation of treeless landscapes improves the environment for human habitation and provides for land use and economic prosperity. Trees are frequently planted in cold climates to rehabilitate denuded sites, for the amenity of homes and villages, and for wind shelter, recreation, agroforestry, and industrial uses. In addition, forests in cold climates reduce the albedo of the earth's surface in winter, and in summer they are small but significant long-lived sinks for atmospheric carbon dioxide. Finally, growth and reproductive success of forests at their geographic limits are sensitive indices of climatic change. As efforts to adapt forests to cold climates increase, however, new afforestation problems arise and old ones intensify. Austral, northern, and altitudinal tree limits are determined by many different factors. Current hypotheses for high-latitude tree limits are based on low growing-season temperatures that inhibit plant development and reproduction.

Air pollutants provide environmental conditions that drastically differ in many respects from those to which forest trees are naturally adapted. Leading experts in the field here consider these questions of immediate relevance arising from the changing environment: (1) Do air pollutants introduce effects of selection that differ from those known for populations that are not subject to such stress conditions? (2) If air pollutants introduce quantitatively or even qualitatively novel selective effects, which consequences might arise from the adaptation of forest tree populations to the present conditions as well as for the preservation of adaptability to future conditions? In addition to these questions, concepts for preservation of genetic resources are discussed.

Interdependence between species is a law of nature. The degree of this interdependence is vividly evident in the plant-microbial world. Indeed, there is no axenic plant in nature and one finds various forms of interac tions between these two kingdoms ranging from completely innocuous to obligate parasitic. Most of these interactions are poorly understood at the molecular and physiological levels. Only those few cases for which a molecular picture is emerging are discussed in this volume. With the advent of recombinant DNA technology and the realization that some of these interactions are very beneficial to the host plant, a spate of activity to understand and manipulate these processes is occurring. Microbes interact with plants for nutrition. In spite of the large number of plant-microbe interactions, those microbes that cause harm to the plants (i. e., cause disease) are very few. It is thus obvious that plants have evolved various defense mechanisms to deal with the microbial world. The mecha nisms for protection are highly diverse and poorly understood. Some pathogens have developed very sophisticated mechanisms to parasitize plants, an excellent example for this being crown gall caused by a soil bac terium, Agrobacterium tumefaciens. A remarkable ingenuity is exhibited by this bacterium to manipulate its host to provide nitrogenous compounds which only this bacterium can catabolize. This is carried out by a direct gene transfer mechanism from bacteria to plants."

This book is the first comprehensive description of development of the Acipenserid fish published in the English language. It con tains the results of more than 40 years of studies by the authors and their colleagues. My own life in science has been intimately related both with the authors and the fish, which are the subject of this book. Therefore, it gives me a great pleasure to present to the English reader an expanded version of the book. Those interested in the history of biology must be well aware of the fact that genetics in the USSR was practically demolished by Lysenko at the session of the Lenin All-Union Academy of Agricultural Sciences in 1948. However, it is much less well known that other fundamental branches of biology were also persecuted at that time, experimental embryology (developmental mechanics) among them. As a result, many embryologists, in cluding the authors of this book, were forced to turn to more ap plied problems, this being the only way to continue research. They had to abandon amphibians and concentrate their efforts on sturgeon."

Rice is the most important cereal crop which feeds more than half the population of the world. It is being grown in more than 144. 641 million ha with a production of over 468. 275 million tons (in 1988). Rice is attacked by a large number of pests and diseases which cause an enormous loss in its yield. Therefore, the major objectives in rice breeding are the development of disease resistance, tolerance to insects, adverse soil water, and drought; and improvement of quality including increased protein content. Tremendous efforts being made at the International Rice Research Institute have resulted in the release of improved varieties. It is estimated that the world's annual rice production must increase from 460 million tons (in 1987) to 560 million tons by the year 2000, and to 760 million tons by 2020 (a 65% increase) in order to keep up with the population growth (IRRI Rice Facts 1988). To achieve this gigantic goal, new strategies have to be evolved. Since the success of any crop improvement program de pends on the extent of genetic variability in the base population, new techniques need to be developed not only to generate the much needed variability but also for its conservation. In this regard the progress made in the biotechnology of rice during the last 5 years has amply demonstrated the immense value of innovative approaches for further improvement of this crop.

Charles E. Hess Department of Environmental Horticulture University of California Davis, CA 95616 Research in the biology of adventitious root formation has a special place in science. It provides an excellent forum in which to pursue fundamental research on the regulation of plant growth and development. At the same time the results of the research have been quickly applied by commercial plant propagators, agronomists, foresters and horticulturists (see the chapter by Kovar and Kuchenbuch, by Ritchie, and by Davies and coworkers in this volume). In an era when there is great interest in speeding technology transfer, the experiences gained in research in adventitious root formation may provide useful examples for other areas of science. Interaction between the fundamental and the applied have been and continue to be facilitated by the establishment, in 1951, of the Plant Propagators' Society, which has evolved into the International Plant Propagators' Society, with active programs in six regions around the world. It is a unique organization which brings together researchers in universities, botanical gardens and arboreta, and commercial plant propagators. In this synergistic environment new knowledge is rapidly transferred and new ideas for fundamental research evolve from the presentations and discussions by experienced plant propagators. In the past 50 years, based on research related to the biology of adventitious root formation, advances in plant propagation have been made on two major fronts.

Somatic hybrids through the fusion of plant protoplasts have widened the genetic variability of cultivated plants. As "Somatic Hybridization in Crop Improvement I," published in 1994, this volume describes how this discipline can contribute to the improvement of crops. It comprises 24 chapters dealing with interspecific and intergeneric somatic hybridization and cybridization. It is divided into four sections:
I. Cereals: Barley, rice, and wheat.
II. Vegetables and Fruits: "Arabidopsis," "Asparagus," "Brassica," chicory, "Citrus," "Cucumis," "Diospyros," "Ipomoea," and various Solanaceous species, e.g., tomato, potato, and eggplant.
III. Medicinal and Aromatic Plants: "Atropa," "Dianthus," "Nicotiana," and "Senecio."
IV. Legumes/Pasture Crops: Alfalfa.
This book is tailored to the needs of advanced students, teachers and researchers in the fields of plant breeding, genetic engineering, and plant tissue culture.

The aim of this Handbook is to cover all fields that are necessary for the management of tropical forest resources. It provides proven and/or promis ing concepts, methods and available comparative data. The exten sive references cited are a valuable source for further in-depth research on specific subjects. The handbook is addressed to forestry professionals, natural re source managers and all those interested in the understanding and hand ling of day-to-day problems of tropical forest resources. It is an attempt to present, in a concentrated form, the vast ex perience gathered in tropical forestry. The available knowledge although far from complete, does not permit us to stand idly by when confronted with the dwindling tropical forests. Excuses not to tackle this problem are not acceptable. The experience of the last decades gives us sufficient background to apply techniques and concepts successfully, to encom pass the complexity of the human and the natural tropical environment. The authors responsible for the respective sections have been recom mended by institutions or individuals specialized in the subject. Our thanks go to aH those unnamed individuals whose dedication and responsible work made this handbook a reality. Our gratitude also to all the colleagues who supported the handbook in its early stages by their firm commitment."

Major and exciting changes have taken place recently in various aspects of bio technology and its applications to forestry. Even more exciting is the prospect of major innovations that the entire field of biotechnology holds for plant growth in general. The importance of these developments for the forestry sector is considerable, particu larly since forestry science has not received the kinds of technical and R&D inputs that, say, agriculture has received in the past few decades. Y ct the problems of defor estation as well as stagnation in yields and productivity of existing forests throughout the world are becoming increasingly apparent, with consequences and ecological ef fects that cause growing worldwide concern. Policies for application of existing knowl edge in biotechnology to the field of forestry and priorities for future research and development are, therefore, of considerable value, because it is only through the adop tion of the right priorities and enlightened policies that scientific developments will move along the right direction, leading to improvements in forestry practices through out the world. It was against this backdrop that the Tata Energy Research Institute (TERI) or ganised a major international workshop on the "Applications of Biotechnology in For estry and Horticulture" at New Delhi in January 1988. The present volume covers the proceedings of this international workshop."

Agricultural, natural resource, and environmental problems are becom ing increasingly interdependent. For example, soil erosion is largely determined by agricultural land use. Both water use and water con tamination depend on land use and technology choice in agriculture. In many areas, the fertilizers and pesticides used in agriculture are ma jor pollutants of ground and surface water, having adverse effects on drinking water and fisheries. Agricultural pollutants such as pesticides also produce adverse health effects for agricultural workers and the consuming public. On the other hand, the availability of water resources and the value of competing land uses influence agricultural production. Additionally, regional air quality problems may affect crops and global environmental trends may have long-term implica tions for farming. Agriculture, natural resources and environmental quality are all heavily regulated in the U. S., but they are done so by a vast array of competing or unrelated agencies within the U. S. Departments of Agriculture, Interior, and Commerce, the Environmental Protection Agency; and numerous state agencies. Considering the large number of bureaucratically remote public agencies involved and the pervasive in terdependencies between agriculture, natural resources and the environ ment, policies develop which are at best uncoordinated and at worst conflicting and counterproductive. These policies have become sources of controversy as different interest groups struggle to affect their im plementation, as different agencies have fought for administrative con trol and as legislative bodies have attempted to enact piecemeal changes."

Genetic engineering through DNA recombinants and the in vitro manipulation of isolated protoplasts has recently attracted much atten- tion in agricultural biotechnology, and has greatly advanced during the last 5 years. In an earlier book, Plant Protoplasts and Genetic Engineer- ing I, methods for the isolation, fusion and culture of protoplasts were reviewed and the regeneration of complete plants from isolated pro- toplasts of rice, potato, soybean, linseed, cabbage, chicory, lettuce, but- terbur, orchids, citrus and some other tree species, and interspecific and intergeneric somatic hybrids in Lycopersicon, Petunia, Nicotiana, Solanum, Glycine, Citrus, Brassica, Medicago and Trifolium spp. were discussed. The present volume, Plant Protoplasts and Genetic Engineering II, deals with some of the newer techniques such as microinjections, elec- trofusion, flow cytometry, uptake and integration of DNA, nuclei, iso- lated chromosomes by plant protoplasts and the subsequent regeneration of transgenic plants. The literature on the DNA recombinants and genetic transformation, both Agrobacterium-mediated and direct gene transfer in agricultural crops and trees, such as poplars, is reviewed, and the uses of cytoplasts and miniprotoplasts in genetic manipulation are highlighted.

The aim of this book is to provide an accessible overview for advanced students, resource professionals such as land managers, and policy makers to acquaint themselves with the established science, management practices and policies that facilitate sequestration and allow for the storage of carbon in forests. The book has value to the reader to better understand: a) carbon science and management of forests and wood products; b) the underlying social mechanisms of deforestation; and c) the policy options in order to formulate a cohesive strategy for implementing forest carbon projects and ultimately reducing emissions from forest land use.

Provided here are both underlying theory and recent results concerning the propagation and use of clones in research and in production forestry. State-of-the-art science and case histories treating production, testing, multiplication and deployment of clones are presented. Agroforestry, urban forestry and christmas-tree farming are covered, along with more traditional multiple-use forestry and high-intensity forestry for biomass, wood and fiber production. Clonal forestry is contrasted to the more recent developments of "family forestry," and the classical tree-improvement approach relying on seed-orchards. The history of clonal forestry is covered with reviews of several centuries experience with Sugi in Japan and poplars in Europe. The impacts and use of clones in the contexts of genetic conservation and biodiversity are discussed, as are the laws and regulations affecting clonal production and deployment.

Wild taxa are invaluable sources of resistance to diseases, insects/ pests, nematodes, temperature extremes, salinity and alkalinity stresses, and also of nutritional quality; adaptation; genetic diversity and new species. Utilization of wild relatives of a crop depends largely upon its crossability relations with cultivated varieties. Sev eral wild species are not crossable with the commercial cultivars due to various isolation barriers. Furthermore, in a few cases, hybridiza tion is possible only in one direction and reciprocal crosses are not successful, thus depriving the utilization of desired cytoplasm of many species. However, techniques have been developed to over come many barriers and hybrid plants are produced. New crop species have been developed by overcoming the F 1 sterility and producing amphidiploids and such crops are commercially being grown in the field. The segregation pattern ofF 1 hybrids produced by distant hybridization in segregating generations are different from the intervarietal hybrids. In former cases, generally, unidirectional segregation takes place in early generations and accordingly, selec tion procedures are adopted. In most of the cases, backcross or modified backcross methods have been followed to utilize wild species, and thus numerous types of resistance and other economical attributes have been transferred in the recurrent parents. Protoplast fusion has been amply demonstrated in a number of cases where sexual hybridization was not possible and, as a result, hybrids have been produced."

T. C. Hutchinson The NATO Advanced Research Workshop detailed in this volume was held in Toronto, Canada, in 1985. The purpose of the Workshop was to provide a "state of the art" report on our knowledge of the sensitivities and responses of forests, wetlands and crops to airborne pollutants. Approximately 40 scientific experts from nine countries participated. Most participants were actively involved in research concerning the effects of air pollutants on natural or agro-ecosystems. These pollutants included acidic deposition, heavy metal particulates, sulphur dioxide, ozone, nitrogen oxides, acid fogs and mixtures of these. Also invited were experts on various types of ecosystem stresses, physiologi cal mechanisms pertinent to acid deposition, and other areas that were felt by the director to be of direct relevance, including: effects of ethylene on vegetation, the physiology of drought in trees, the nature and role of plant cuticles as barriers to acid rain penetration, the use of dendrochronological techniques in reconstructing the time of onset and the subsequent progression of growth declines, the ability of soils to naturally generate acidity, the role of Sphagnum moss in natural peat land acidity, the use of lichens as indicators of changing air quality, and the magnitude of natural emissions of reduced sulphur gases from tropical rainforests and temperate deciduous forests. The Workshop included a series of invited presentations and subsequent group discussions. These presentations were designed to allow syntheses of our present knowledge as well as detailed questioning and discussion."