This volume looks at the impact that different cropping systems and tillage have on soil’s biologically active substances. It considers how phytotoxins accumulate and can inhibit the development of cultivated plants. Coverage explores the continuous cropping of rye, crop rotation, no tillage, and conventional tillage. It offers a comprehensive, comparative approach to allelopathic plant-soil interactions. The authors focus on free and bounded biologically active substances such as amino acids, auxins, humic and fulvic acids, transient radicals, and enzymes in light sand soils fertilized with different mineral and organic fertilizers. The chapters address fundamental questions relevant to the environmental challenges we face today and will deal with in the future. The results involve asking basic questions motivated by soil's chemical and biochemical processes. The answers will lead to the improvement of the quality of soil’s organic matter, which, in turn, can lead to increased crop yields. Readers will come to understand the relationship between ecological processes and environmental change on individual levels of biocomplexity as well as on systems in their entirety. The title is ideal for students and teachers for laboratory practical classes. Soil scientists, biochemists, chemists, plant ecophysiologists, “Natural Products” organic chemists, and other environmental scientists and specialists will also find it useful.

This is the second of the set of three volumes in the Encyclopedia of Plant Physiology, New Series, that will cover the area of the hormonal regulation of plant growth and development. The overall plan for the set assumes that this area of plant physiology is sufficiently mature for a review of current knowl edge to be organized in terms of unifying principles and processes. Reviews in the past have generally treated each class of hormone individually, but this set of volumes is subdivided according to the properties common to all classes. Such an organization permits the examination of the hypothesis that differing classes of hormones, acting according to common principles, are determinants of processes and phases in plant development. Also in keeping with this theme, a plant hormone is defined as a compound with the properties held in common by the native members of the recognized classes of hormone. Current knowledge of the hormonal regulation of plant development is grouped so that the three volumes consider advancing levels of organizational complexity, viz: molecular and subcellular; cells, tissues, organs, and the plant as an organized whole; and the plant in relation to its environment.