Effect of shading on photosynthesis in greenhouse hydroponic cucumber crops

Abstract

In this work an attempt was made to investigate the effect of shading on the photosynthesis rate of cucumber cultivation in a greenhouse. To this end, autumnal hydroponic cultivation of cucumbers was installed in three same arched greenhouses with lateral ventilation openings at the University of Thessaly experimental farm in Volos, Greece. One greenhouse had no other air conditioning system than the natural ventilation openings. The other two greenhouses in addition to the natural ventilation system were equipped with an external shading net mounted on the roof as follows: One with a 30% shading intensity (SI) and the other with a 40% SI. For two months a series of photosynthesis intensity measurements were performed on leaves of randomly selected plants per greenhouse under natural illumination and using artificial illumination conditions of 1000 μmol m-2 s-1 with the LCpro+ instrument. Statistical processing of the results showed that shading reduced the photosynthesis of the cucumber leaf almost linearly. Thus, it seems that shade plants do not acclimatize to shade conditions and respond directly to lighting conditions which practically enhance the usefulness of periodic shading as a tool for improving the microclimate in greenhouses. © 2021 International Society for Horticultural Science. All rights reserved.