Bøger i Developments in Plant and Soil Sciences serien

In the 100 years since the legume-Rhizobium symbiotic nitrogen fixation interaction was first described, interest in this field has grown rapidly. The types of studies have been cyclical in nature, involving a cross-section of disciplines. The availability of cheap nitrogenous fertilizers caused much of the biological nitrogen fixation research to become more theoretical in the developed world. The high cost of energy, coupled with environmental concerns and the interest in sustainable agriculture, has stimulated research in symbiotic nitrogen fixation. The development of modern genetic techniques has resulted in interdisciplinary research on plant-microbe interactions controlling nitrogen fixation. This has resulted in a better understanding of environmental factors influencing the nodulation process, chemical signalling between the symbiotic partners and the nature of the specificity between host plant and microsymbiotant. This volume summarizes the diverse research efforts in biological nitrogen fixation by presenting a collection of papers in the areas of physiology and metabolism, taxonomy and evolution, genetics and ecology.

Iron is a major constituent of the earth crust. However, under alkaline conditions commonly found in arid and semi-arid environments iron becomes unavailable to plants. When plants are affected by a shortage of iron their leaves become yellow (chlorotic), and both plant growth and crop yield are reduced. The roots of plants affected by iron deficiency may develop a series of responses directed to improve iron uptake, such as increased proton excretion and iron reduction capabilities or excretion of iron chela tors called siderophores. Iron deficiency affects major crops worldwide, including some of major economic importance such as fruit trees and others. Correction of iron deficiency is usually implemented through costly application of synthetic chelates. Since these correction methods are very expensive, the competitivity of farmers is often reduced and iron deficiency may become a limiting factor for the maintenance, introduction or expansion of some crops. In spite of the many years devoted to the study of iron deficiency, the knowledge of iron deficiency in soils and plants is still fragmentary in many aspects. We have only incomplete information on the processes at the molecular level that make some plant species and cultivars unable to take and utilize iron from the soil, whereas other plants grow satisfactorily under the same conditions.

Plant Nutrition - From Genetic Engineering to Field Practice, the 12th International Colloquium on Plant Nutrition, is the latest in a series which began in 1954. Early meetings were mainly concerned with the practical problems of soil fertility, with soil assessment, fertilizer requirements and methods of analysis. As the colloquia have progressed, the emphasis has slowly changed. The practical problems are still important, but there is increasing emphasis on plant physiology, plant biochemistry, membrane biochemistry, and even on the chemistry of genes which control the proteins which transfer nutrient ions to the inside of cells. The meetings therefore provide a valuable opportunity for each half of the science of plant nutrition to interact with, and learn from the other half. This volume begins with five papers which review current knowledge in important fields: the rhizosphere, molecular biology, electron microscopy, location and function of elements in vivo, and modelling nutrient responses in the field. These themes are continued in groups of shorter papers which follow. In addition, there are sections on nutrient dynamics and partitioning, diagnostic techniques, plant survival strategies, mycorrhizas, and on nutrients such as P, N, S, K, Ca, Mg, and micronutrients. A large section is devoted specifically to boron - reflecting the considerable current interest in this element. In total there are 177 refereed papers providing both a broad overview and a detailed picture of the latest developments in pure and applied plant nutrition.

The International Society of Root Research sponsored the Symposium "e;Root Demographics and Their Efficiencies in Sustainable Agriculture, GrassLands and Forest Ecosystems,"e; July 14-18, 1996, at the Madren Conference Center, Clemson University, Clemson, South Carolina, USA. The conference was a continuation of a series of international symposiums on root research held every three to four years. Symposiums have also been held twice in Vienna, Austria, and once in Uppsala, Sweden, and Almaty, Kazahkstan prior to the meeting at Clemson University. The sponsoring society has made a particular effort in these symposia to include root scientists from the former Soviet Union because of the importance of exchanging information on a worldwide basis. This symposium continued and promoted that effort by providing travel grants to several scientists from that region; however, funds for that purpose were limited. Therefore, in compiling these proceedings, a number of papers from scientists from the former Soviet Union and former Warsaw Pack countries have been included even though the scientists were not actually present for the SymPOSIum.

This book provides a comprehensive and interactive view of recent advances in the cytology, anatomy, and physiology of roots as presented at the 5th International Symposium on Structure and Function of Roots, held on 31 August-4 September, 1998, in Stara Lesna, Slovakia. This edition differs from previous ones by including some aspects of functional genetics and plant morphogenesis. The book is intended to serve both students and researchers as a valuable source of updated information, ideas, and concepts dealing with the most fundamental questions of development and function of plant roots.

In 1971, the late Dr. J. Kolek of the Institute of Botany, Bratislava, organized the first International Symposium devoted exclusively to plant roots. At that time, perhaps only a few of the participants, gathered together in Tatranska Lomnica, sensed that a new era of root meetings was beginning. Nevertheless, it is now clear that Dr. Kolek's action, undertaken with his characteristic enormous enthusiasm, was rather pioneering, for it started a series a similar meetings. Moreover, what was rather exceptional at the time was the fact that the meeting was devoted to the functioning of just a single organ, the root. One possible reason for the unexpected success of the original, perhaps naive, idea of a Root Symposium might lie with the fact that plant roots have always been extremely popular as experimental material for cytologists, biochemists and physiologists whishing to probe processes as diverse as cell division and solute transport. Of course, the connection of roots with the rest of the plant is not forgotten either. This wide variety of disciplines is now coupled with the development of increasingly sophisticated experimental techniques to study some of these old problems. These factors undoubtedly contribute to the necessity of continuing the tradition of the root symposia. The common theme of root function gives, in addition, a certain unity to all these diverse activities.