J.J. Magán, J.C. López, R. Granados, J. Pérez-Parra, T. Soriano, M. Romero-Gámez, N. Castilla
Increasing global radiation transmission in Mediterranean greenhouses, especially during the low radiation season, has been reported to be one of the most effective methods to raise the yields and quality of the produce. The east-west orientation improves radiation transmission in the low radiation season, as compared with the north-south orientation, but generates radiation transmission differences between the different zones of the greenhouse. A study on the transmission and spatial uniformity of solar radiation of two east-west oriented greenhouses was conducted in Almeria (Spain). The greenhouses, each with a floor area of 960 m2 (40×24 m) and a similar volume, were a Venlo type glasshouse, covered with conventional 4 mm glass, and a gothic arch-roofed plastic multispan, covered with 0.2 mm thick plastic film. The radiation transmission data, quantified using linear solarimeters along the transverse section of the spans at the eaves level, show transmission differences across the span section in both greenhouses, during the winter and spring seasons. Global radiation differences between greenhouses were very small, with slightly higher radiation in the glasshouse during the first part of the winter, which reversed later, though the differences continued to be very small. The total and marketable yields of a cucumber crop were higher in the plastic multispan than in the glasshouse; these differences were attributed to the quality of global radiation. The diffusive properties of the plastic cover contributed to a higher content of diffuse radiation in the plastic greenhouse compared with the glasshouse.
Magán, J.J., López, J.C., Granados, R., Pérez-Parra, J., Soriano, T., Romero-Gámez, M. and Castilla, N. (2011). GLOBAL RADIATION DIFFERENCES UNDER A GLASSHOUSE AND A PLASTIC GREENHOUSE IN ALMERIA (SPAIN): PRELIMINARY REPORT. Acta Hortic. 907, 125-130
DOI: 10.17660/ActaHortic.2011.907.15
diffuse radiation, direct radiation, light transmission, radiation uniformity

Acta Horticulturae