The 12th International Conference on Plant Growth Substances was held from 26th to 31st August 1985 in Heidelberg, F. R. G. , under the auspices of the IPGSA (International Plant Growth Sub stances Association) and the University of Heidelberg in its 599th year. As many as 750 participants from 40 countries all over the world attended the conference, including guests and staff members of the local organizers. Fine days provided an excellent background for a fruitful and pleasant meeting and all the activities accompanying the scientific programme. During the conference all current aspects concerning growth substances were treated. Altogether the par ticipants presented 207 oral reports organized in four parallel sessions and about 300 posters, for which 2 hours' poster sessions were reserved each day. The conference gained in perspective from the arrangement of five workshops in which special aspects and the most recent results could be presented by specialists in the particular fields. The topics of the workshop were: actual methods of hormone detection (orga nizer H. Kende), auxin transport (organizer R. Hertel), growth sub stances and tumour formation (organizer J. Schroder), evolution of the hormone system (organizer W. Jacobs) and problems of ap plication (organizer J. Jung). The abstracts of all presentations were collected in a Book of Abstracts available during the conference, giving a rough surveY of the whole field of plant growth substances in its present state.

Inhalt
Plant Cell Responses and the Role of Growth Substances.- I. Methods.- The Use of Immunological Techniques in Plant Hormone Analysis.- Immunoassays for the Quantitation of Plant Growth Regulators Using Monoclonal Antibodies.- Immunoassays for Plant Growth Regulators A Help or a Hindrance?.- Validation of Immunoassays.- Immunoaffinity Columns for the Isolation and Analysis of Plant Hormones.- II. Hormones: Synthesis, Metabolism and Biochemistry.- Dwarf Mutants in Maize The Gibberellin Biosynthetic Pathway and its Molecular Future.- Gibberellins: Structure-Activity Relationships and the Design of Molecular Probes.- Gibberellin Biosynthesis from Gibberellin A12-Aldehyde.- Biosynthetic and Metabolic Aspects of Auxins.- Cytokinin Biosynthesis and Metabolism.- The Nomenclature of Abscisic Acid and its Metabolites.- Metabolism of Abscisic Acid.- The Shapes of Abscisic Acid and the Active Site.- Enzymes of Ethylene Biosynthesis.- Chemistry, Physiology and Agricultural Application of Brassinolide and Related Steroids.- Plant Growth Substances of Plant and Microbial Origin.- III. Hormones: Mechanism.- Plant Growth Substances and the Ionic Permeability of Membranes.- Ca2+: Calmodulin Phytohormone-Linked Plant Senescence Control.- Phytohormones and Gene Expression.- Enzymes of Auxin and Cytokinin Biosynthesis Encoded in Ti Plasmids.- Cytokinin Biosynthetic Genes and Enzymes from Agrobacterium tumefaciens and other Plant-Associated Procaryotes.- The Evolution of Polar Transport Models, and some Possibilities for the Regulation of Auxin Carriers.- Roles of Transport and Binding in the Specific ?pH-Dependent Accumulation of Auxin by Zucchini Membrane Vesicles.- Active Auxin Uptake by Specific Plasma Membrane Carriers.- Two Comments on Auxin Transport: TheUptake/Efflux-Mechanism and the Problem of Adaptation.- Further Characterization of the Presumptive Auxin Transport Carrier Using Monoclonal Antibodies.- The Requirement for Calcium and Boron in Auxin Transport.- Cellular Patterns Determined by Polar Transport.- Auxin Transport and Shoot Tropisms: The Need for Precise Models.- Auxin and Root Gravitropism: The State of Our Knowledge.- IV. Hormones: Effects.- Are Angiosperm Hormones Present in, and Used as Hormones by, Algae?.- Hormonal Coordination of the Processes Leading to Cell Fusion in Algae: A Glycoprotein Hormone from Red Algae.- On the Hormonal System of Mosses.- Phytohormones and Filicinae: Chemical Signals Triggering Morphogenesis in Schizaeaceae.- The Control of Plant Cell Elongation by Auxin and Gibberellin.- Mechanism of Growth Induction by Ester Compounds. Studies with Segments and Protoplasts of Oat Coleoptiles.- The Control of Flower Initiation and Development.- Hormonal Regulation of Plant Flowering.- Phytohormones in Seed and Fruit Development.- A Revision of the Hormone Balance Theory of Seed Dormancy: Studies on Gibberellin and/or Abscisic Acid-Deficient Mutants of Arabidopsis thaliana.- Cytokinin Control of Monocarpic Senescence in Soybean.- Epigenetic and Genetic Factors Regulating the Cytokinin Requirement of Cultured Cells.- Apical Dominance and Correlations by Hormones.- Hormonal Control of Assimilate Movement and Compartmentation.- V. Hormones: Applications.- Aims and Possibilities of Applied Plant Bioregulation.- Growth Regulation of Arable Crops.- Ethylene as an Indicator and Regulator in the Development of Field Crops.- Effects of Endogenous and Exogenous Plant Growth Substances on Development and Yield of Soybeans.- Natural and Synthetic Plant Growth Substances in Fruit Growing.- Recent Advances in the Use of Growth Substances in Ornamental Horticulture.- Interrelations of Plant Growth Substances, Mineral Nutrition and Crop Yield.- Examples of the Use of Natural and Synthetic Plant Growth Substances in Cereal Breeding.