This proceedings is based on a joint meeting of the two IUFRO (International Union of Forestry Research Organizations) Working Parties, Somatic Cell Genetics (S2.04-07) and Molecular Genetics (S2.04-06) held in Gent, Belgium, 26-30 September, 1995. Although a joint meeting of the two Working Parties had been discussed in the past, this was the first such meeting that became a successful reality. In fact this meeting provided an excellent forum for discussions and interactions in forest bioteclUlology that encouraged the participants to vote for a next joint meeting. In the past decade rapid progress has been made in the somatic cell genetics and molecular genetics of forest trees. In order to cover recent developments in the broad area of biotechnology, the scientific program of the meeting was divided into several sessions. These included somatic embryogenesis, regeneration, transformation, gene expression, molecular markers, genome mapping, and biotic and abiotic stresses. The regeneration of plants, produced by organogenesis or somatic embryogenesis, is necessary not only for mass cloning of forest trees, but also for its application in genetic transformation and molecular biology. Although micropropagation has been achieved from juvenile tissues in a number of forest tree species, in vitro regeneration from mature trees remains a challenging problem in most hardwoods and conifers. The mechanisms involved in the transition from juvenile to mature phase in woody plants are poorly understood. This transition can now be investigated at the molecular level.

r-------------{ Environment (Disease) Fig. 1. A schematic presentation of the interplay between the external environment, pathogen and animal, which influences resistance to infectious disease. Disturbance in equilibrium results in infection and disease skin and the mucous membranes of the respiratory tract. These tissues are in contact with the environment, and direct injury to them facilitate entry of pathogenic microorganisms through these important natural barriers. Sunburn and frostbite are examples of such adverse effects. Climatic factors such as heat and cold may also act as physiological stress factors which affect the specific and non-specific responses of the body to infection. 1.1.2 Pathogen Survival Climatic factors may affect dispersal, spread and survival of pathogenic micro organisms in the environment. This is also true for arthropod vectors such as mosquitos and ticks (Smith 1970; Ferguson and Branagan 1972). The density of the animal population is an important factor determining the concentration of patho gens in the environment. Population density can be influenced by weather condi tions, as animals respond to heat and cold by typical changes in behaviour. For example, in cold weather they tend to huddle together. This behaviour results in increased population density, which in turn involves an increased risk of the spread of airborne infections."

The rapidly growing human population has increased the dependence on fossil fuel-based agrochemicals, such as fertilizers and pesticides, to produce the required agricultural and forestry products. This has exerted great pressure on non-renewable fossil fuel resources, which cannot last indefinitely. Not only do agrochemicals pollute the environment, but pests also become resistant to pesticides. Thus, present agricultural practices exploit natural resources, and damage fauna and flora and agroecosystems. One safe alternative to overcome these problems is the use of allelopathy to sustain development in agriculture and forestry and maintain a clean environment for future generations. This book is the Proceedings of the III International Congress on Allelopathy in Ecological Agriculture and Forestry, held on August 18-21, 1998, at the University of Agricultural Sciences, Dharwad, Karnataka, India, and provides an updated status of current allelopathy research in various leading countries, with the overall aim of developing new technologies for ecological agriculture and forestry in the 21st century. To date, no book on ecological agriculture has discussed these aspects, hence it is the first time that such information is available. The chapter contributors are leading specialists in their fields, and all chapters have been peer-reviewed by international referees. This book will be indispensable for agricultural scientists (agronomists, entomologists, nematologists, plant pathologists, horticulturists, plant breeders, agroforesters, foresters, soil scientists), bioscientists (biochemists, organic chemists, plant ecologists, microbiologists and limnologists), environmentalists, graduate students and farmers, as well as for organizations engaged in sustainable agriculture and organic agriculture.

The anther tapetum, present in all land plants, is a highly specialized, transient tissue surrounding the (micro-)spores and/or pollen grains during their development. Any tapetum malfunction causes male sterility. The exact knowledge of tapetum form and function therefore is indispensable not only for basic research, but also and especially in plant breeding and plant genetics. In fourteen contributions by reknown experts, a comprehensive account of the various characters and functions of the tapetum is provided, covering the areas of cytology, cytophysiology, biochemistry, tapetum development and function.

Fantasies and dreams have their rightful place in science, and sometimes they turn into reality. Regeneration of hybrid plants through protoplast fusion is one such dream come true. In the early 1970s I shared the pioneering excitement in the field of protoplast technology at the Second International Congress of Plant Tissue Culture held in Strasbourg, France. Subsequently, I participated in three international conferences devoted to plant protoplasts, in Salamanca, Spain (1972), Versailles, France (1972), and Nottingham, England (1975). At Versailles Dr. P.S. Carlson presented his work on the successful regeneration of somatic hybrids between Nicotiana glauca and Nicotiana langsdorfii. The enthusi- asm shown by the participants was sufficient indication of the bright future of somatic hybridization. On my return from Versailles, I gathered my thoughts and prepared a concept paper on Potentials of Protoplast Culture Work in Agriculture which was published in Euphytica (Bajaj 1974). The studies on protoplast fusion and somatic hybridization then gained momentum and active work started in many laboratories. Very significant work was done by Melchers et al. (1978) who obtained a somatic hybrid between potato and tomato, calling it "Pomato".

Second in the series, High-Tech and Micropropagation, this work covers the micropropagation of trees and fruit-bearing plants, such as poplar, birches, larch, American sweetgum, black locust, "Sorbus," sandalwood, "Quercus," cedar, Persian walnut, date palm, cocoa, "Citrus," olive, apple, pear, peach, plum, cherry, papaya, pineapple, kiwi, Japanese persimmon, grapevine, strawberry, and raspberry. The importance and distribution of conventional propagation and in vitro studies on individual species are discussed. In particular detail, the transfer of in vitro plants to the greenhouse or the field, and the prospects of commercial exploitation are examined. The book will be of use to advanced students, research workers and teachers in horticulture, forestry and plant biotechnology in general, and also to individuals interested in industrial micropropagation.

Global attention in scientific, industrial, and governmental communities to traces of toxic chemicals in foodstuffs and in both abiotic and biotic environ ments has justified the present triumvirate of specialized publications in this field: comprehensive reviews, rapidly published progress reports, and archival documentations. These three publications are integrated and scheduled to pro vide in international communication the coherency essential for nonduplicative and current progress in a field as dynamic and complex as environmental con tamination and toxicology. Until now there has been no journal or other publica tion series reserved exclusively for the diversified literature on "toxic" chemicals in our foods, our feeds, our geographical surroundings, our domestic animals, our wildlife, and ourselves. Around the world immense efforts and many talents have been mobilized to technical and other evaluations of natures, locales, magnitudes, fates, and toxicology of the persisting residues of these chemicals loosed upon the world. Among the sequelae of this broad new emphasis has been an inescapable need for an articulated set of authoritative publications where one could expect to find the latest important world literature produced by this emerging area of science together with documentation of pertinent ancil lary legislation."

No matter what forests are used for, forest managers have to deal with interactions between individual trees and between trees and other forest organisms. To understand these interactions, long-term monitoring of spontaneous forest development is necessary. A complete monitoring system has been developed including a computer package for analysis of long-term observation of forest dynamics. The system's name, "SILVI-STAR," is an acronym of SILVIgenesis and Single-tree Three-dimensional Architecture. A method of nested plot data collection on forest architecture and plant species composition has been developed out for monitoring purposes.

"Azospirillum" is a plant growth promoting rhizobacterium used for inoculation of cereal and forage crops. The book covers its physiology, ecology, biochemistry, and molecular biology. The most advanced molecular techniques to understand the regulatory mechanisms of nitrogen fixation and ammonia assimilation, as well as the basis of phytohormone production, are included. In particular, the identification of novel types of promoters, specific regulatory circuits, and new regulatory proteins is described. New insights in the plant growth promoting role of the bacteria through the analysis of their interactions with the plant are presented. Also discussed are field applications, allowing the evaluation of the physiological and agronomic involvement of "Azospirillum" inoculations.

Ecologists are increasingly being drawn into the task of addressing problems of environmental degradation. They are expected to find solutions that will lead to sustainable resource use throughout the world. In doing so, the robustness of the science becomes increasingly important, and the problem of extrapolating the results of research conducted within what is usually a relatively limited geographical scope is increasingly highlighted. One approach to developing a globally robust ecology involves more or less formal intercontinental comparative studies, usually focused on the question of ecological convergence. These studies are directed at testing the prediction that similar physical and other environmental factors in different parts of the world, through their selective influences, will give rise to ecosystems which share com mon structural and functional features. Should this be true, the predictive power of ecology developed within such a framework should be sufficient to solve similar problems elsewhere in such biomes. There is a long history of such an approach in mediterranean type ecosystems, documented in a series of volumes and their accompanying scientific papers beginning with that of Di Castri and Mooney (1973).

This volume has been produced for the XI 11th EUCARPIA Congress. EUCARPIA (the European Association for Plant breeding) currently has 1.200 members, including scientists and staff of both publ ic and private organizations. Its aim is to promote scientific and technical research and cooperation In the field of plant breeding, and thereby to contribute to the development of agriculture. Every three years, EUCARPIA organizes a scientific congress. In 1992, the Xilith EUCARPIA Congress will be held In ANGERS (Fran- ce) and the theme Is "Reproductive biology and plant breeding". Reproduction of plant material Is central to selection. The geneti- cist, the plant breeder and the seed grower all use sexual and ve- getative reproduction during the various stages of plant breeding and creation of variety. The possibility of unlimited interspecific reproduction, the use of gametogenesis dysfunction, the creation of auto and allogamy, and the cloning of the best genotypes are the challenges before the plant breeder. To understand how the reproductive system conditions the genetic structure of a population, and to Investigate the relation- ships between the reproductive mode and the organization of varia- bility Is a central key to genetic progress. The articles presented In this book review the current state of knowledge of reproductive biology, and Its impact on variety crea- tion.

Root disease epidemics, because much of the activity takes place in soil and out of sight, pose special challenges to growers who seek to manage them and to scientists who study them. All relevant topics of root disease epidemics and their management are presented: The critical aspects of specific disease components including inoculum, host roots, mycorrhiza and the soil environment are explored. Challenges of disease assessment and the temporal and spatial aspects of epidemic development are considered, and approaches to root disease management including host resistance, chemical, biological and cultural management are discussed in detail. The book fulfills the needs of researchers, teachers, and practitioners of plant pathology.

Most books on epidemiology have treated the subject from a statistical, mathematical or computer applicational point of view. However, experiments must be performed first to provide the data for models which in turn can then be proven by further experimentation. This mutual interplay of theory and empirics gives epidemiology its scientific thrust and charm. This book provides a choice of methods for varying applications and objectives, covering all important aspects for the designing of experiments. Furthermore, the reader is supplied with solutions to his experimental problems and many "tricks of the trade." The newcomer to the field will also profit by this methodology guide.

Tropical climates, which occur between 23 Degrees30'N and S latitude (Jacob 1988), encompass a wide variety of plant communities (Hartshorn 1983, 1988), many of which are diverse in their woody floras. Within this geographic region, temperature and the amount and seasonality of rainfall define habitat types (UNESCO 1978). The F AO has estimated that there 1 are about 19 million km of potentially forested area in the global tropics, of which 58% were estimated to still be in closed forest in the mid-1970s (Sommers 1976; UNESCO 1978). Of this potentially forested region, 42% is categorized as dry forest lifezone, 33% is tropical moist forest, and 25% is wet or rain forest (Lugo 1988). The species diversity of these tropical habitats is very high. Raven (1976, in Mooney 1988) estimated that 65% of the 250,000 or more plant species of the earth are found in tropical regions. Of this floristic assemblage, a large fraction are woody species. In the well-collected tropical moist forest of Barro Colorado Island, Panama, 39. 7% (481 of 1212 species) of the native phanerogams are woody, arborescent species (Croat 1978). Another 21. 9% are woody vines and lianas. Southeast Asian Dipterocarp forests may contain 120-200 species of trees per hectare (Whitmore 1984), and recent surveys in upper Amazonia re corded from 89 to 283 woody species ~ 10 cm dbh per hectare (Gentry 1988). Tropical communities thus represent a global woody flora of significant scope.

This volume presents a body of research conducted over more than thirty years, including an intensive interdisciplinary five-year study begun in 1991. Chapters include studies of the relationships of biogeography and climate to the region's air pollution, the chemical and physiological mechanisms of ozone injury, as well as the impacts of nitrogen-containing pollutants and natural stresses on polluted forests.

The Dictionary contains the names of nearly 2500 plant species, in some cases including subspecies and varieties. Tropical crops from all parts of the world receive the same attention as those from the temperate zone. Common names are given not only in English, French, German, Portuguese and Spanish but also in many other languages, where such names are used in the technical literature. Agronomic plants' comprise not only the agricultural and horticultural crops but also pasture plants, green manure, soil covers, trees used in agroforestry, and major weeds. Also included are plants which are presently being discussed as new crops, with considerable economic value. The Dictionary will meet the needs not only of scientists in agriculture, botany and geography but also those of agricultural extensionists, merchants in agricultural products and professional translators.

Based on papers presented at the International Symposium on Sexual Reproduction in Higher Plants, this volume covers the topics: micro- and macrosporogenesis, the activation and recognition of mature pollen, pollen germination and tube emission in vivo and in vitro, pollen and pollen tube cytoskeleton, stigma and style morphology, pollen/stigma interactions, incompatibility mechanisms and gene expression. The reinvestigation of classical topics using modern methods such as immunofluorescence, micromanipulation, freeze-substitution, electron microscopy, etc., is the common basis of all results presented. Especially applied aspects of sexual reproduction important e.g. for crop improvement, are discussed in detail.

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."

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.

Starting with the description of meteorological variables in forest canopies and its parameter variations, a numerical three-dimentional model is developed. Its applicability is demonstrated, first, by wind sheltering effects of hedges and, second, by the effects of deforestation on local climate in complex terrain. Scientists in ecology, agricultural botany and meteorology, but also urban and regional lanners will profit from this study finding the most effective solution for their specific problems.

A year has passed since Eshel Bresler, my good friend and colleague, and a member of the editorial board of the Advanced Series in Agricultural Sciences, died suddenly while on a visit to the Chinese Academy of Sciences in Beijing. We had worked together for almost 30 years at the Institute of Soils and Water, ARO, The Volcani Center at Bet Dagan. At the very beginning of our scientific careers we cooperated directly and as a result one of our first publications was coauthored (Soil Sci. 101:205-209, 1966). Thereafter, our specific research interests diver sified, but we continued to work together, with similar approaches to research, and to strive towards the development of Israel soil science and its integration into general worldwide scientific progress. I don't need to emphasize Eshel's contribution to the understan ding of the processes governing water flow and solute transport pro cesses in soils and unsaturated zones. The contributions to this Volume by such a body of outstanding scientists shows the apprecia tion of the international scientific community to his research achievements."

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."

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."