|Riassunto in Inglese:|
A study on four double-span greenhouses differing on roof vents and type of ventilation (natural or forced), in the presence of a Lisianthus soilless cultivation, was carried out in order to evaluate the effect of roof opening and ventilation systems on internal climate and crop behaviour. A nine-months trial was conducted in a NW Sicily coastal area, in shelters with metal structure and polyethylene cover, with different roof vent typology and differing for presence, number and location of air mixers and fans. Data on internal climate were collected by a system of thermic and hygrometric sensors connected to a data logger and analysed with a specific software. Roof opening and ventilation system influenced greenhouse microclimate: during summer, maximum air temperatures and vapour pressure deficit as well lowest air relative humidity were measured in the shelter equipped with chimney top vents only (G1); lowest thermal values were recorded in the structure with gull-wing opening vents and two head-fans (G4). Roof vent and ventilation typology significantly affected Lisianthus yield: the highest amount of cut flower stems was produced in G4 greenhouse; lowest productive performances were achieved in G1.