INTRODUCTION

Therefore, we want firstly to concentrate on an important tool of growth analysis - on growth chambers, secondly in all the problems of transferring experimental results from the growth chambers to the conditions found in the field, a complex of questions that so far have hardly been approached, but whose answers, however, may be of decisive importance for future experimental work in plant physiology and plant cultivation. We shall be further occupied with the effects of single and several growth factors on root - and air environments and in conclusion turn to an especially modern but also difficult problem - the possibilities of a synthesis of the actions of single processes into growth models.

I want to thank all the gentlemen, who have undertaken to give us a survey of this group of themes in their introductory lectures. My thanks is also extended to the Chairmen and all, who contribute to the symposium through their papers.


OPENING ADDRESS

A. Lecrenier

In my quality of Chairman of the Commission of Protected Cultivation I have the honour and the pleasure to introduce this Symposium sponsored by the International Society for Horticultural Science.

The term "Protected Cultivation" is rather new. Although the culture of some plants has been done under protection since some centuries we can see here in Hannover Herrenhausen splendid orangeries dating back 300 years - the evolution of the glasshouses has been slow, not only regarding the structures, but also concerning covering material. It is only at the beginning of this century that we assist to a quick evolution of the design of glasshouses used for special cultures. Remember here the "warenhuizen" of our dutch friends with remarkable improvements during the 20th century. Essentially used for the production of vegetables, these "warenhuizen" have been submitted to basic modifications which have led these structures to be true factories, able to produce tremendous crops. Since a long time, researches on both technical and economical sides have conducted to a progressive amelioration of the techniques of culture. However, it is only through the adaptation of controls, mainly electronic, that the study of basic problems of protected cultures has been possible with great precision. These controls have permitted to appreciate not only the needs of plants in varied conditions as soil, water, light, temperature, air, etc, but they have established the relations which exist between these different elements in determined conditions for determined plants. The result has been to define the ideal conditions of culture. These efforts must be pursued in numerous directions. We are delighted that under the active direction of our collegues of Hannover, an initiative has been taken to assemble specialists of basic problems of protected vegetable cultivation. With regard to growth chambers, control of plant growth and development by root environment or by climatic growth factors, interest for these problems is important and is able to lead to an increase of the productivity of the protected cultures and by this way to an amelioration of life conditions of population. It's a social point of view which, in the actual stage of evolution of peoples, cannot be neglected.

The programme of the Symposium has been drawn carefully by the organizers; it is divided in five parts, each of which presided over by a well - known name in the speciality. We are quite sure that the discussions that will be held after the reports will be most profitable. Some very interesting aspects of the general theme "Basic problems of protected vegetable cultivation" will be treated in the five sections considering mainly the growth chambers and the control of plant growth.

As you can judge by yourselves, this symposium is the first of the kind, for one has seldom dealt with so new problems linked up with the latest progress of Science and Technique before such an important assembly.

As far as we are concerned, we are sure to be greatly interested in the various lectures, and, while refreshing our memories in some field we shall learn about new techniques that already now are quite certain to meet success in the future.

After this intensive work, you will certainly appreciate a visit to the Institutes of the Faculty of Horticulture and Agriculture of Hannover, where the work that has kept our attention has been performed.

Also you will agree that we must congratulate all the organizers and thank them deeply for the arrangement of this symposium.

Zum Herrn Professor Krug geht em ersten unsere Dankbarkeit. Er hatte die Güte geahbt, nicht nur den Teilnehmern des Symposions in den Raümen seiner lehrstelle zu begegnen, sondern auch den Vorsitz anzunehmen und zur Verfügung der I.S.H.S. seine Dienstelle zu stellen. Möge er hier die Bezeugung unserer aufrichtigen Dankbarkeit finden und seinen Stab, insbesondere Herrn Wilhelm, unsren verbindlichsten Dank zukommen lassen.

I like to underline the active collaboration which has been established between the organizers of this Symposium and the Chairman of the Section Vegetables of the I.S.H.S., Prof. Fritz, and also the Commission for Protected Cultivation.

Our sincere thanks are presented to the speakers, who have kindly accepted to give a lecture over their work. In this manner, we shall have the benefit of their valuable experience.

Some words to the participants' You are, Gentlemen, the condition of the success of this Symposium. Your presence must be active, that's to say you must take an intensive part in the discussions which shall be open at the end of the sessions. That will be the mark of a complete success of this organization. Thank you in advance for your cooperation.