EFFECTS OF GREENHOUSE TYPE AND RESTRICTED VENTILATION ON INTERNAL CLIMATE, LETTUCE YIELD AND BOTRYTIS CONTROL

Protected horticulture in the "Entre Douro e Minho" region is based on the utilisation of metallic structures covered by polyethylene films without heating, the climatic control being achieved through ventilation management.
In these greenhouses, one usually finds poor environmental control, which limits the productivity of the crop and the frequent appearance of infections due to fungi, in particular Botrytis cinerea (grey mould), which is responsible for considerable economic damage.

We compared the climate between two different kinds of greenhouse which are the most common in this region (a semi-cylindrical tunnel and a bitunnel greenhouse with lateral upright walls), both with the same areas for ventilation during this first year.

The equipment used to measure the climate was placed on meteorological stations one in each greenhouse and another outside.
Each station had equipment to measure the following parameters: air temperature at different levels, soil temperature, relative humidity, photosynthetic active radiation (PAR); wind velocity was also measured outside the greenhouses.
The development of the lettuce crop was evaluated according to its productivity and the incidence of B. cinerea.

The results obtained show significant differences between the yield of the different greenhouse structures and the different cultivars.
The cv.
Omega is more sensible to attacks by Botrytis. With relation to the air temperature, relative humidity and PAR radiation, important differences were not found between the two greenhouses.

International Symposium Greenhouse Management for Better Yield & Quality in Mild Winter Climates

M.J. Abreu, V.C. Ferreira, A. Sottomayor, A.C. Vargues, J.F. Meneses

Greenhouses, ventilation, lettuce, grey mould (Botrytis cinerea), environment

https://doi.org/10.17660/ActaHortic.1999.491.18