Effect of Glasshouse Maintenance on the Quality of Irradiance Spectrum under Mediterranean Climates

Abstract

Glasshouses in Mediterranean areas are mainly used for experimental or nursery purposes and the production of high value ornamental species. In addition, glasshouses may be covered by dust and other particles in these areas as rainfalls are relatively scarce. Consequently, the quality of photosynthetically active radiation (PAR) may be affected. In the present experiment we evaluated the effect of dirt on the PAR spectrum in glasshouses in Valencia (Spain), compared to glasshouses submitted to suitable maintenance and washing. Photosynthetic Photon Flux Density (PPFD) measurements were done in March 2017 at 13h, and visible, UV-C and near infrared regions were recorded with a portable spectrometer. PPFD maximum values differed depending on the spectral region and glass conditions, with higher values corresponding to the visible region. Thus, clean glass showed values of 609, 588 and 423 μmol/m2s for PPFDR, PPFDG and PPFDB, respectively and 436 and 34 μmol/m2s for PPFDIR and PPFDUV. In comparison to clean glass, dirty glass decreased PPFD in all regions, particularly UV and blue region.

Keywords

• Venlo glasshouse, dust, photosynthetic photon flux density