RADIOMETRIC PROPERTIES AND FIELD PERFORMANCES OF DIFFERENT GREENHOUSE PLASTIC COVERINGS

In this paper different field and laboratory trials are compared in order to analyze the radiometric properties of different plastic films and their effect on the performances of the greenhouse system. Several trials have been carried out in different locations in Sicily, Italy. Climatic parameters were monitored inside and outside the greenhouses covered by different plastic films: EVA, PE, ETFE, photo-selective red coloured and UV-absorbing films. Laboratory measurements of perpendicular spectral transmissivity of these films were performed in the wavelength of the solar emission from 200 nm to 2500 nm and in the long-wave range from 2500 nm to 25000 nm. Poor results were obtained with the photo-selective film as it was not able to contain maximum air temperature as an ordinary PE cover does. The better spectroradiometric characteristics of the ETFE covering film compared to those of an EVA film allowed to achieve higher air temperature and soil temperature, improving the efficacy of a solarization trial. The UV-absorbing film assured a very low level of Bemisia tabaci infestation guaranteeing thermal conditions inside the greenhouse very similar to the ones obtained in the greenhouse covered by the EVA film.