Effect of screenhouse cover optical properties on sweet pepper fruit quality

The effects of cover optical properties and screenhouse radiative environment on sweet pepper fruit quality and productivity were investigated in a Mediterranean climate (Eastern Greece) under two covering materials (i) a pearl insect-proof screen (IP-78) and (ii) a white insect proof screen (IP-59) with values of the transmittance to solar radiation measured in the field of 78 and 59%, respectively. Sweet pepper plants (Capsicum annuum) were grown under open field (control) and under the above mentioned screens and the microclimate parameters along with fruit production and quality characteristic were measured during a spring-autumn crop circle. The screenhouse microclimate parameters were similar to those measured outside but the radiative environment was significantly different between the three cases. Concerning the fruit quality characteristics, compared to open field, fruits under screens had lower fruit lightness and titratable acidity, higher chroma, fruit weight and volume, and total soluble solids. The effects of screens were most pronounced on early-season-harvested fruits. Significant interactions were obtained between shading and harvest date. The results indicate that compared to open field, screens were able to maintain pepper fruit quality throughout the harvesting period, especially on early-season, where open field climate conditions (solar radiation and fruit temperature levels) induced severe crop stress conditions.