So much knowledge has been acquired about glasshouse production that we feel it is worth proposing two new avenues to specialist research workers.
Firstly, standardization of covering material for plant-growing structures.
This suggestion seems to be of undoubted interest as current economic circumstances impose on research workers a development which they tend to avoid or at least delay, be it only unconsciously.
Secondly, studies on greenhouse covering materials with special properties ensuring that the greenhouse acts both as a heat trap and as a light trap and prevents its escape.
The second avenue to which we are trying to lead greenhouse research is more specialized and may appear difficult.
With our account of the work we have done in this field and the main results already obtained, we shall try to show that this avenue is promising and of undoubted future.
"Protected plant-growing" cannot be satisfied with half measures particularly when highest yields are required from crops grown during the periods of most adverse climatic conditions.
The search for greenhouse covering material cannot be passive, limited to determining the value of a few materials offered by producers and selected among materials destined for another use.
This search must be active, and go so far as to demand industry to make glass or plastic products of properties specially designed for horticulture.