This comprehensive review presents all modern methods for plant root research, both in the field and in the laboratory. It covers the effects of environmental interactions with root growth and function, and focuses in particular on the assessment of root distribution and dynamics. The processing of root observations, analysis and modelling of root growth and architecture, root-image analysis, computer-assisted tomography and magnetic resonance imaging, are described and discussed. Furthermore, a survey of the application of isotope techniques in root physiology is given.

Current phase-out schedules of the production and emission of CFC's indicate that chlorine loading in the stratosphere is not yet at its maximum. The recovery of stratospheric ozone is estimated to take time and ele vated levels of UV-B radiation are expected to occur throughout most of the next century. Despite numerous physiological studies of UV-B effects on plants, often grown in climate chambers, knowledge of UV-B effects on organisms and processes in natural aquatic or terrestrial ecosystems is poor. Currently it appears that UV-B radiation is not just an environmental stress' factor to plants. In various ways, which are incompletely understood, UV-B affects a wide range of physiological and ecological processes. Remarkably, recent field studies indicate that enhanced UV-B does not markedly affect photosynthesis, growth and primary production, but rather interferes with plant morphogenesis and plant and ecosystem functions relating to the secondary metabolism. This special issue and book UV-B and Biosphere is an attempt to cover this range and to report the progress made in the research of ecological effects of enhanced solar UV-B radiation. The papers in this book formed the basis of an international workshop entitled' UV-B and Biosphere', December 15-18, 1995, in Wageningen, The Netherlands. A first reaction of Hans de Boois on the number of papers and sessions scheduled from Friday to Sunday morning was: far too many."

During the 4th ESA-Congress, held in the Netherlands, 7-11 July 1996, a new perspective for agronomy emerged. Various contributions demonstrate the need for a new role of agronomy and its tools. In recent decades, agriculture has evolved from an activity with mainly productivity aims, into an issue conciliating environmental, agricultural, and economic and social objectives. Placing agriculture in such a broadened perspective requires a different agronomy, with new tools and approaches at a range of aggregration levels. It calls for detailed knowledge concerning the functioning, productivity and ecological relationships of agricultural plants and crops. In addition, it calls for a constant update and synthesis of existing and newly generated knowledge, the design of new ideotypes and genotypes, new production technologies, cropping systems, farming systems and agro-ecological land use systems.

This proceedings book presents a set of case studies illustrating the various agronomic tools that can be used for specific agronomic questions. The case studies are grouped in sections illustrating relevant subquestions in developing an agriculture with broadened objectives. The book starts with an introductory paper on the role of agronomy in research and education in Europe. The second section deals with agricultural land use, food security and environment. This is followed by a set of papers describing experimental research and modeling approaches used to design new ideotypes of crops, including physiological properties in relation to growth factors such as radiation, CO2, temperature and water.

Sustained soil fertility directly links to nutrient cycling and soil organic matter. A selected set of papers addresses the improvements in resource use efficiency and as such their contribution towards economic, environmental and agricultural objectives. The final section addresses the design of integrated and ecological arable farming systems. It highlights the role of prototyping interaction with leading-edge farmers, as promising tools to design, implement and test new farming systems.

It is hoped that the activities of the European Society for Agronomy and the "Proceedings" of its 4th Congress will stimulate to serve the new perspectives of agronomy, i.e. to adopt ecological principles, to optimally manage the use of resources and to meet social and economic objectives.

Current phase-out schedules of the production and emission of CFC's indicate that chlorine loading in the stratosphere is not yet at its maximum. The recovery of stratospheric ozone is estimated to take time and ele vated levels of UV-B radiation are expected to occur throughout most of the next century. Despite numerous physiological studies of UV-B effects on plants, often grown in climate chambers, knowledge of UV-B effects on organisms and processes in natural aquatic or terrestrial ecosystems is poor. Currently it appears that UV-B radiation is not just an environmental stress' factor to plants. In various ways, which are incompletely understood, UV-B affects a wide range of physiological and ecological processes. Remarkably, recent field studies indicate that enhanced UV-B does not markedly affect photosynthesis, growth and primary production, but rather interferes with plant morphogenesis and plant and ecosystem functions relating to the secondary metabolism. This special issue and book UV-B and Biosphere is an attempt to cover this range and to report the progress made in the research of ecological effects of enhanced solar UV-B radiation. The papers in this book formed the basis of an international workshop entitled' UV-B and Biosphere' , December 15-18, 1995, in Wageningen, The Netherlands. A first reaction of Hans de Boois on the number of papers and sessions scheduled from Friday to Sunday morning was: far too many.