PREVAILING CO₂ CONCENTRATIONS IN GLASSHOUSES

On days with spring lightintensities, CO₂ concentrations in glasshouses with a full-grown crop drops considerably below the ambient concentration of 340 ppm.

In order to know which CO₂ concentrations are prevailing under Dutch circumstances in the course of a year a recording of the CO₂ concentrations was performed.

On twenty-four holdings with a variety of types of glasshouses and crops the CO₂ concentration, the opening of the ventilators and the position of the CO₂ valve were recorded continuously during a period of eigtheen months.

For five crops a sample out of this registration, over the three weeks in March, is given.
Further, the situation during the five spring months in a crop of aubergine was worked out and presented.

Finally, the data of a whole year regarding a house with both a sweet pepper crop and with yearround chrysanthemums are presented with respect to the amount of CO₂ deficient hours.

In summer, during many hours there is a shortage of CO₂ in the glasshouses.
From winter till midsummer the number of hours with reduced CO₂ concentrations increases from 0 till 11 hours per day.

Over the whole season it is seen from the registration on a sweet pepper holding, that from the ca. 4500 dayhours, at least during 1500 hours CO₂ concentrations were below 340 ppm.
For yearround chrysanthemum about 10 % deficient hours are registered.

Symposium on CO2 Enrichment

G. Heij, P.J.A.L. de Lint

https://doi.org/10.17660/ActaHortic.1984.162.8