All measurements of intact leaf 02 sensitivity can be explained by the oxygenation model for glycolate formation and glycolate metabolism by established pathways. Predicting the rate of oxygenation from the underlying biochemistry is more reliable than calculating the rate of oxygenation from intact leaf gas exchange measurements. REFERENCES 1. Badger MR, TD Sharkey, S von Caemmerer: The relationship between steady-state gas exchange of bean leaves and the levels of carbon reduction cycle intermediates. Planta 160:305-313, 1984. 2. Bowes, G, WL Ogren, RH Hageman: Phosphoglycolate production catalyzed by ribulose diphosphate carboxylase. Biochem. Biophys. Res. Commun. 45:716-722, 1971. 3. Farquhar GD, S von Caemmerer, JA Berry: A biochemical model of photosynthetic C02 assimilation in leaves of C3 species. Planta 149: 78-90, 1980. 4. Farquhar GD, S von Caemmerer: Modelling of photosynthetic response to environmental conditions. In OL Lange, PS Nobel, CB Osmond, H Ziegler, eds, Encycl. of Plant Physiol., New Series, Springer Verlag, Heidelberg 12b: 549-587, 1982. 5. Jordan DB, WL Ogren: The C02/02 specificity of ribulose 1- bisphosphate carboxylase/oxygenase. Dependence on ribulose bisphosphate concentration, pH and temperature. Planta 161: 308-313, 1984. 6. Ku SB, GE Edwards: Oxygen inhibition of photosynthesis. I. Temperature dependence and relation to 02/C02 solubility ratio. Plant Physiol 59: 986-990, 1977. 7. Laing WA, WL Ogren, RL Hageman: Regulation of soybean net photosynthetic C02 fixation by the interaction of C02' 02 and ribulose l,5-diphosphate carboxylase. Plant Physiol 54: 678-685, 1974."

With the demonstration of the "triple response" in plants by Neljubow at the turn of the century, ethylene has been identified as a substance specifically affecting plant growth. Yet it took a few more decades to show that ethylene is a naturally occurring product of plants having all the characteristics of a phytohormone. Ever since much effort has been devoted to a wide variety of physiological and biochemical problems relevant to ethylene. A first meeting was organized in Israel in 1984 to bring together many people active in this rapidly expanding field of experimental research. It is the aim of the present symposium to provide once more a forum at which researchers might expose and comment progress in their work over the last few years. Speakers were invi ted and their contri buti ons ordered ina number of sessions, each of which was centered on a particular topiC. Much of the benefit came from ensuing discussion sessions which were conducted with much competence and expertise by Anderson, Ben-Arie, Goren, Morgan and Osborne. All of these colleagues are recognized leaders in ethylene research today and the organizers owe a very special gratitude to them for their substantial contribution to the programme. It is well to remember the friendly atmosphere, so essential to the success of the whole meeting and so much enjoyed by every partiCipant. Prompt publi ca tion of the papers was made possi ble by the camera-ready procedure offered by the publisher.

This book contains the proceedings of a symposium, held in the Limburgs Universitair Centrum, Diepenbeek, Belgium, from July 23 to 29, 1978.1t can be considered as a continuation of the publication 'Environmental and Biological Control of Photosynthesis' (Dr. W. Junk b.v. Publishers, The Hague, 1975). In the last meeting, however, emphasis was much more on the biological control of photosynthesis. The sequence of the different topic sessions and papers on the symposium programme is maintained in the publication; the editors are aware of the fact that different contributions might figure equally well in more than one session. A limited number of speakers was invited; time for discussion therefore could generously be provided to the audience. We thank all the participants for their active contribution to the success of this conception of organizing a meeting. The quality of a discussion session also depends on the performance of the discussion leader; thanks are due to Drs. G. Bernier, J.J. Landsberg, C.J. Pearson, R. Sachs, I.A. Tamas and K.J. Treharne who took the chair with scientific authority and enthusiasm. In order to keep in memory the flavor of this aspect of the meeting, an account of the discussion on one particular topic, the relationship between photosynthesis and flowering, was made by Dr. R. Sachs (reporter) and Dr. G. Bernier (discussion leader) and is published here after the reports on this topic.

All measurements of intact leaf 02 sensitivity can be explained by the oxygenation model for glycolate formation and glycolate metabolism by established pathways. Predicting the rate of oxygenation from the underlying biochemistry is more reliable than calculating the rate of oxygenation from intact leaf gas exchange measurements. REFERENCES 1. Badger MR, TD Sharkey, S von Caemmerer: The relationship between steady-state gas exchange of bean leaves and the levels of carbon reduction cycle intermediates. Planta 160:305-313, 1984. 2. Bowes, G, WL Ogren, RH Hageman: Phosphoglycolate production catalyzed by ribulose diphosphate carboxylase. Biochem. Biophys. Res. Commun. 45:716-722, 1971. 3. Farquhar GD, S von Caemmerer, JA Berry: A biochemical model of photosynthetic C02 assimilation in leaves of C3 species. Planta 149: 78-90, 1980. 4. Farquhar GD, S von Caemmerer: Modelling of photosynthetic response to environmental conditions. In OL Lange, PS Nobel, CB Osmond, H Ziegler, eds, Encycl. of Plant Physiol., New Series, Springer Verlag, Heidelberg 12b: 549-587, 1982. 5. Jordan DB, WL Ogren: The C02/02 specificity of ribulose 1- bisphosphate carboxylase/oxygenase. Dependence on ribulose bisphosphate concentration, pH and temperature. Planta 161: 308-313, 1984. 6. Ku SB, GE Edwards: Oxygen inhibition of photosynthesis. I. Temperature dependence and relation to 02/C02 solubility ratio. Plant Physiol 59: 986-990, 1977. 7. Laing WA, WL Ogren, RL Hageman: Regulation of soybean net photosynthetic C02 fixation by the interaction of C02' 02 and ribulose l,5-diphosphate carboxylase. Plant Physiol 54: 678-685, 1974."

With the demonstration of the "triple response" in plants by Neljubow at the turn of the century, ethylene has been identified as a substance specifically affecting plant growth. Yet it took a few more decades to show that ethylene is a naturally occurring product of plants having all the characteristics of a phytohormone. Ever since much effort has been devoted to a wide variety of physiological and biochemical problems relevant to ethylene. A first meeting was organized in Israel in 1984 to bring together many people active in this rapidly expanding field of experimental research. It is the aim of the present symposium to provide once more a forum at which researchers might expose and comment progress in their work over the last few years. Speakers were invi ted and their contri buti ons ordered ina number of sessions, each of which was centered on a particular topiC. Much of the benefit came from ensuing discussion sessions which were conducted with much competence and expertise by Anderson, Ben-Arie, Goren, Morgan and Osborne. All of these colleagues are recognized leaders in ethylene research today and the organizers owe a very special gratitude to them for their substantial contribution to the programme. It is well to remember the friendly atmosphere, so essential to the success of the whole meeting and so much enjoyed by every partiCipant. Prompt publi ca tion of the papers was made possi ble by the camera-ready procedure offered by the publisher.