DEVELOPMENTS IN THE CONTROL OF THE GLASSHOUSE CLIMATE
The achievement of complete growth control with planned production is still most hampered by inadequate knowledge of the requirements of crops.
These plant requirements are extremely complicated because various physiological processes, such as growth and flowering must be controlled at the same time. This makes very difficult the formulation of the climatic conditions necessary for a desired growth response. In addition we are concerned with the interaction between the crop and the climate inside the house and outside.
What in fact happens is that a list of requirements is drawn up step by step from various data obtained from horticultural, physiological and climatological research. These specified conditions are established and tested in practice; the experience gained then leads to a better formulation of the required conditions.
This is a laborious method; consequently, more efficient methods are tried, such as the use of mathematical models, multi-factorial experiments and simultaneous measurements of the climatic conditions and plant activity. In addition it remains necessary to evaluate the findings in practice. At this stage, modern control systems are indispensable in creating the climatic regimes to be investigated, which still must be considered as prototypes. The effect of differential ventilation and the consequent specification of the equipment, for example, could only be studied when automated ventilation systems became available.
This resulted in a considerable improvement in the original equipment. The control systems produced in the last year make possible the further investigation of the desired glasshouse climate and its regulation. The supposition that first horticulturists should formulate the required climatic conditions is misleading. The technicians should be drawn into the research at an earlier stage.