PREFACE

All over the world, cultural possibilities were broadened by research into growth and development of the chrysanthemum. In the course of time the culture was settled and not much further research seemed necessary.

However, since the symposium in 1981, in Versailles, France, some factors drastically have changed with respect to the culture of this flower crop. Due to the strongly increased prices of energy proper heating has become a problem especially in mid-winter culture.

Investments in energy saving measures, such as thermal screens and air-tight greenhouses, require adapted climate control procedures and additional understanding of the plant-climate interaction.

Also, new varieties, especially bred for mid-winter cultivation are being developed.

No wonder that research has been intensified with respect to climate conditions such as optimising day and night temperature regimes and daylength control, specifically with respect to developmental phases of the crop.

Concerning these topics, papers were presented during the morning and the evening sessions of the workshop on Greenhouse Chrysanthemum.

Several afternoon visits were organized to plant breeding companies, to commercial chrysanthemum growers and to the Westland flower auction. The lectures were of very good quality. Enough time was reserved for discussion, which was used intensively and with good attendance of all participants, so that at the end of the workshop all had a good knowledge of the problems and possible solutions of chrysanthemum propagation and research in the home countries of the various participants.

We cordially thank the financial sponsors and the I.S.H.S. for the fine and informative days.

We hope that with this issue of Acta Horticulturae every reader, interested in the research work on chrysanthemum, is offered useful further information.

G. Heij