As the world population increases, there is increasing competition for waterquantity as well as quality. Provided here is an up-to-date perspective on Available Water Resources (Part I), Water Conservation and Technology inAgricultural Systems (Part II), Problem Water Uses and Treatment (Part III), and Management and Policy Evaluation (Part IV). The book is an invaluable source of information for water resource planners, managers and policy makers, researchers and students, and irrigationists.

The series "Chemistry of Plant Protection" continues the handbook "Chemie der Pflanzenschutz- und Schadlingsbekampfungsmittel", edited by R. Wegler. This volume covers contributions in the fields of pyrethroid residues and immunoassays.

Modem Methods of Plant Analysis When the handbook Modern Methods of Plant Analysis was first introduced in 1954 the considerations were: 1. the dependence of scientific progress in biology on the improvement of existing and the introduction of new methods; 2. the difficulty in finding many new analytical methods in specialized journals which are normally not accessible to experimental plant biologists; 3. the fact that in the methods sections of papers the description of methods is frequently so compact, or even sometimes so incomplete that it is difficult to reproduce experiments. These considerations still stand today. The series was highly successful, seven volumes appearing between 1956 and 1964. Since there is still today a demand for the old series, the publisher has decided to resume pUblication of Modern Methods of Plant Analysis. It is hoped that the New Series will be just as acceptable to those working in plant sciences and related fields as the early volumes undoubtedly were. It is difficult to single out the major reasons for success of any publication, but we believe that the methods published in the first series were up-to-date at the time and presented in a way that made description, as applied to plant material, complete in itself with little need to consult other publications. Contributing autllors have attempted to follow these guidelines in this New Series of volumes.

When trying to solicit authors for this book it became apparent that the causal factors for heterosis at the physiological and biochemical level are today almost as obscure as they were 30 years ago. Though biometrical-genetical analyses point to dispersion of complementary genes - not overdominance - as the major cause of the phenomenon, plant breeders' experience still suggests a cautious, pragmatic approach to the dominance-overdominance controversy in breeding hybrid cultivars. Thus we are faced with a striking discordance between our limited comprehension of the causal factors and mechanism of heter osis on the one hand, and the extensive agricultural practice of utiliza tion of hybrid vigor on the other. Such utilization is the result of the economic value of hybrid combinations displaying superior yields and qualities as well as stability of performance, of benefits derived in breeding programs, and of the enhanced varietal protection of proprietary rights. No comprehensive and critical analysis of the phenomenon of heterosis in economic plants has been published for the last three decades since the now classical book Heterosis, edited by J . W. Gowen (Iowa State College Press, Ames, Iowa, 1952). The present book attempts to fill the gap and to assess the status of our present knowl edge of the concept, the basis, the extent, and the application of heterosis in economic plants."

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.

With one new volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of botany. The present volume includes reviews on structural botany, plant physiology, genetics, taxonomy, and geobotany.

Cotton is a multipurpose crop and produces lint, the most important source of fiber used in the textile industry, oil, seed meal, and hulls.
Twenty-three chapters on various aspects of in vitro manipulation and other biotechnological approaches to the improvement of cotton are arranged in six sections. Special emphasis is placed on interspecific hybridization, somaclonal variation, transgenic cotton resistant to insects and herbicides, and re-engineering of fiber.
This book is of special interest to advanced students, teachers, and research workers in the field of cotton breeding, genetics, tissue culture, molecular biology, and plant biotechnology in general.

The understanding of pollutant transformations, sorption and transport in soils and uptake by plants is the key to controlling contaminant movement towards groundwater and accumulation in food-chains. Some of these major processes were discussed in the first International Workshop on Pollutants in Porous Media, con vened in Israel in 1983 (pollutants in Porous Media, Eds. Yaron, Dagan and Goldshmid, Springer-Verlag, 1984). Since that meeting, research on contaminant impact on the environment expanded considerably. New mechanisms explaining inorganic pollutant par titioning between solid and solution phases in soils were proposed and tested; specific elements and specific reactions were investigat ed, and more case studies to evaluate management practice effects on drinking water quality and accumulation of contaminants in crops were carried out. The recognition that the new knowledge needs to be discussed and evaluated, and the scientific and engineering communities be updated, led the IUPAC (Interna tional Union of Pure and Applied Chemistry) and IAHS (Interna tional Association of Hydrological Sciences) Water Quality Com missions to organize a second International Workshop on pollu tant behaviour in the vadose zone, hosted by the Institute of Soils and Water of the Agricultural Research Organization, Israel. In this workshop, taking place in June 1987, attention was focused on chemical, physico-chemical and microbial-mediated reactions of different contaminants in the vadose zone. This book contains selected works presented in the 1987 workshop by invited special ists from various disciplines and countries."

With one new volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of botany.
The present volume includes reviews on structural botany, plant taxonomy, physiology, genetics and geobotany.

In November 1988 the "'Third Oberursel Symposium" devoted to the problems of input of pollutions into forest-ecosystems and their effects on plants or soil convened. After several years of intensive research on the effects of pollutions on forest ecosystems it is obvious that not a single specific pollutant can be made responsible but a mixture of several components act together or interact with each other. The contributions of the workshop _ reflect to a large extend the results of research projects which were started at the beginning of the eighties. They review our improved knowledge on the patterns of concentration, of the mechanism of wet and dry deposition and fog interception, modelling studies and the effect of the processes on plant receptors and surfaces. Since the 1985 symposium the pathways of pollutants leading to biological damage have been examined and are more clearly recognised. The book reflects the common interest and the continuous effort of scientists from many different disciplines to better understand the physical and chemical processes which finally lead to the observed damage of forest-trees. Comparing the conclusions of the contributions of this book _ with the results of the first Oberursel symposium in 1981, our knowledge on the relevance of the different mechanisms leading to forest-decay has been considerably improved. The book indicates also in which directions future work should be concentrated. Again, I have to thank the authors for their cooperation by submitting their recent research-results."

Advances in Soil Science is a review series relevant to all areas of soil science. These reviews, intended primarily for scientists, teachers, and students of soil science, also provide technical background information for many additional workers and groups interested in our natural resources and man's influence on them. This is the eighth volume in the series with an international list of contributors from the United States, India, Canada and New Zealand. It contains four review chapters on the following subjects: factors affecting aluminum transformations in soil; soil productivity in dryland regions of developing countries; changes in soil structure under different cropping systems; properties and management of the depleted soils of India. These contributions present valuable information on a diversity of topics and serve as an excellent source of references.

In 1977, the Volkswagen Foundation sponsored the first of a series of International Symposia on Fire Ecology at Freiburg University, Federal Republic of Germany. The scope of the congresses was to create a platform for researchers at a time when the science of fire ecology was not yet recognized and established outside of North America and Australia. Whereas comprehensive information on the fire ecology of the northern boreal, the temperate, and the mediter ranean biotas is meanwhile available, it was recognized that conside rable gaps in information exist on the role of fire in tropical und sub tropical ecosystems. Thus it seemed timely to meet the growing scientific interest and public demand for reliable and updated infor mation and to synthesize the available knowledge of tropical fire ecology and the impact of tropical biomass burning on global eco system processes. The Third Symposium on Fire Ecology, again sponsored by the Volkswagen Foundation and held at Freiburg University in May 1989, was convened to prepare this first pantropical and multidisci plinary monograph on fire ecology . The book, in which 46 scientists cooperated, analyzes those fire-related ecosystem processes which have not yet been described in a synoptic way. Following the editor's concept, duplication at previous efforts in describing tropical vegeta tion patterns and dynamics was avoided. Extensive bibliographical sources are given in the reference lists of the chapters."

Deals with biotechnological approaches incorporated into po- tato improvement progammes. These methods have far-reaching implications for the synthesis of improved, disease- resist- ant and nutritious cultivars of potato.

Recently, the pharmaceutical industry has shown considerable interest in the en masse micropropagation of elite plants, and the large-scale produc- tion of secondary metabolites in plant cell cultures through the use of bioreactors. This is now being realized by the selection of high-yielding somac1ones or through the production of hairy roots by transformation with Agrobacterium rhizogenes. These new developments need to be high-lighted and brought to the attention of workers dealing with medicinal, aromatic, and other plants of industrial importance. A series of books on the biotech- nology of medicinal and aromatic plants is therefore being compiled to provide a survey of the literature focusing on recent information and the state of the art. This book, Medicinal and Aromatic Plants IV, like the previous three volumes (Medicinal and Aromatic Plants I, II, and III, published in 1988, 1989, and 1991, respectively) is unique in its approach. It comprises 28 chapters dealing with the distribution, economic importance, conventional propagation, review of tissue culture studies, and the in vitro production of important medicinal and pharmaceutical compounds in various species of Ammi, Bergenia, Canavalia, Capsicum, Cassia, Cephaelis, Cornus, Cucurbita, Elettaria, Eupatorium, Genipa, Gentiana, Gypsophila, Hygrophila, Leon- topodium, Nerium, Picrasma, Polygonum, Ptelea, Rheum, Scopolia, Silene, Solanum, Strophanthus, Tagetes, Thymus, and Uncaria. This book is tailored to the needs of advanced students, teachers, and research workers in the fields of plant biotechnology and chemical engineer- ing, pharmacy, botany, and phytochemistry.

An increase in the demand for wood results in improved recovery and less residual biomass in the forests. Paradoxically, interest in forest residue as a renewable source of raw material seems to be in a reverse ratio to its availability in a certain area. Finland and Sweden are probably more dependent on forestry and forest in dustries than any other developed countries in the world. A sufficiency of raw ma terial for integrated forest industries is vital for the national economy of both countries, and a great deal of attention is being paid to the long-term potential of unutilized biomass left behind in logging operations. Furthermore, since these countries possess no reserves of fossil fuels, and since their per-capita consump tion of primary energy is exceptionally high, they also consider unmerchantable forest biomass a realistic source of indigenous energy. A joint Nordic research project on harvesting and utilization of logging residue was carried out in 1969-1976 under the auspices of the Nordic Research Council on Forest Operations. This fruitful cooperation soon gave rise to related national projects in Sweden, Finland, Norway, and Denmark, stimulating further research and producing practical applications. Concurrently, particularly after the worldwide energy crisis in 1973, research on all aspects of utilization of forest bio mass mushroomed in the United States, Canada, and the Soviet Union. An ex plosive increase occurred in both the number and diversity of biomass studies.

Forest decline became a matter of public and scientific concern in France in 1983 when conifers in the Vosges mountains were found to exhibit unusual crown deterioration. An impassioned controversy on a supposedly large scale forest health problem was then in full swing in Central Europe. A co-ordinated research programme entitled DEFORPA ("Deperissement des For ts et Pollution AtmospMrique") was launched in 1984. This programme ran from 1984 to 1991 and a number of projects are still in progress. The Programme was sponsored by three French ministries (Enviroument, Agriculture and Forestry, Research and Technologyl), several state agencies, various regional authorities and the Commission of the European Communities (DO xn and DG VI). Initially, emphasis was solely laid on the understanding of forest decline in the mountainous areas - because damage was most obvious there - in relation to natural and man-made factors. Air pollution was given high but not overwhelming priority. Thus, the DEFORPA Programme was not in its essence a nation-wide assessment of air pollution effects, unlike a number of national acidification research programmes in Europe and North America. During. the programme, however, the areas of concern expanded. In particular, research into water acidification in the Vosges mountains was developed in parallel with the DEFORPA Programme, and possible eutrophication of the ground flora in northeastern France became the subject of new research.

Isolated protoplasts are a unique tool for genetic manipulation of plants. Since the discovery of a method for the enzymatic isolation of pro-. toplasts by Professor E. C. Cocking in 1960, tremendous progress has been made in this very fascinating area of research. I have witnessed the struggle in the 1960's and early 1970's, when obtaining a clean prepara tion of protoplasts was considered an achievement. I also shared the pioneering excitement and enthusiasm in this field during the 2nd Inter national Congress of Plant Tissue Culture held at Strasbourg in 1970, where Dr. I. Thkebe of Japan presented his work on the induction of division in tobacco protoplasts. This was followed by my participation in three international conferences devoted to plant protoplasts held in 1972 in Salamanca (Spain) and Versailles (France), and then in 1975 in Nottingham (England). The enthusiasm shown by plant scientists at these meetings was ample proof of the bright future of protoplast technology, and it became evident that protoplasts would playa major role in plant biotechnology, especially in genetic engineering. Since then we have never looked back, and now the methods for isolation, fusion, and culture, as well as regeneration of somatic hybrids, have become routine laboratory procedures for most plant species. Currently the focus is on cereal and tree protoplasts. In order to bring about any genetic manipulation through fusion, in corporation of DNA, and transformation, the regeneration of the entire plant through manipulation of protoplasts is a prerequisite."

The rapid increase in environmental measurements during the past few decades is associated with (1) increasing awareness of the complex relations linking biological responses to atmospheric variables, (2) development of improved data acquisition and handling equipment, (3) the application of modeling to environmental problems, and (4) the implementation of large, cooperative studies of international scope. The consequences of man's possible alteration of the environment have increased our interest in the complex nature of biological responses to meteorological variables. This has generated activity in both measurements and in the application of modeling techniques. The virtual explosion of modeling activity is also associated with the development oflarge computers. The testing of these models has demonstrated the need for more, different, and better environmental data. In addition, technological developments, such as integrated circuits, have reduced the cost, power consumption, and complexity of data acquisition systems, thus promoting more environmental measurements. The emergence of scientific cooperation on a global scale has increased measurement activities markedly. The International Geophysical Year (1958) has been followed by the International Hydrologic Decade, the Inter national Biological Program, the Global Atmospheric Research Program, and a host of environmental studies of a regional nature that have all emphasized field data collection."

Latest techniques for the analysis of plant cell or tissue structure and the registration of physiological pathways are topics of this volume. The subjects include: - Laser Doppler Vibrometer Measurements of Leaves; - Laster Physical Methods. Laser Microprobe Mass Spectrometry; - Triplet States in Photosynthesis: Linear Dichroic Optical Difference Spectra via Magnetic Resonance; - Fast Atom Bombardment Mass Spectrometry; -Microdissection and Biochemical Analysis of Plant Tissues; - Photoacoustic Spectroscopy - Photoacoustic and Photothermal Effects; - Membrane Operational Impedance of Spectra of Plant Cell.

In order to provide meaningful information for evaluating environmental consequences of alternative control strategies of air pollutant emissions, scientists have recently initiated numerous studies aiming at collecting and making use of regional data. New kinds of mathematical models have been developed that no longer are calibrated just for individual stands or catchments but can be applied on a large regional scale. Such regional models and data were reviewed at a meeting" Models to describe the geographic extent and time evolution of acidification and air pollution damage", organized by the Finnjsh Research Project on Acidification (HAPRO), and held in Aulanko, Hiimeenlinna, Finland, July 5-8, 1988. This volume is based on the outcome of that meeting. The chapters of the volume are written by leading scientists in the field. The main objective of this volume is to discuss the potential of regional models to analyze the geographic extent of acidification as well as the environmental damage and the time evolution of:the responses of the environment. First, in Part I of the volume, sensitivity distributions of ecosystems, forest soils and surface waters are described. The focus of interest is therefore extended from the most sensitive ecosystems to sensitive and moderately sensitive parts of the environment. When formulating national and interna tional targets, it is of crucial importance to know the whole distribution of critical loads within the area, and not only the level the most sensitive ecosystem can tolerate.

In a very real sense, much of North American physiological plant ecol ogy began in the Basin and Range and has been researched there over the last four decades. However, we believe that this book may be the first attempt to bring together the full range of contemporary research into the fascinating plant biology of the Basin and Range Province. We have invited contributions from researchers presently working in and around the Province and asked them to review the major vegetation zones and distinctive environmental issues from a predominantly plant ecophysiological perspective. As researchers interested in plant physi ological and ecological processes, and in atmospheric processes affect ing vegetation, we have tended to emphasize the atmosphere, plant, soil continuum in structuring this book. After an introduction to the geography of the region, we deal with atmospheric processes and climates of the Great Basin, follow with chapters on the different vegetational zones, treated from ecophysiological perspectives, and then place emphasis on plant-soil relations. We have not treated plant animal interactions in the detail that the impacts of man and his domesticated animals on the desert ecosystem deserve. However we have included a review of a very promising technique (analysis of stable isotopes at natural abundance) for integration of these processes. We close with a compelling statement of the case for the Great Basin as a laboratory for climatic change research, prepared by a multidisciplinary team from the Desert Research Institute.

The 50th volume of Progress in Botany appears in new guise. In cooperation with Springer-Verlag we have changed from the less attractive typewriter composition to the direct reproduction of a manuscript which was writ ten by means of a text editing system and produced by a laser printer. We, the editors, should like to take the appearance of Volume 50 as the occasion for a few short remarks. Our younger readers are perhaps not aware that our Book Series was founded in 1931 by Fritz von Wettstein, based on the following thoughts and considerations, aptly formulated by him in the Preface to the first volume. "One of the greatest dangers threatening progress in the science of botany is the absolutely unbelievable growth in volume of the literature. The quality of journals, books and individual works that are daily sent to us makes it impossible for anyone person to maintain a general view of the progress made in botany in all the specialized fields, let alone to find time for results from associated su bjects. For varying reasons, every botanist must find this state of matters insupportable. Let us endeavor, in the general interest, to retain a wide background of knowledge, and not become limited specialists. The vitally necessary connections between the specialized fields can only flourish, or even exist, if the general view of botany as a whole can be maintained."