Yield and quality of greenhouse organic pepper as affected by shading net in Mediterranean area

In the Mediterranean area the light intensity during the spring-summer season exceeds the optimal requirement of pepper plants, thus impairing production and quality of fruits. Research was carried out in Fisciano district (Salerno, southern Italy) on bell pepper organically grown in greenhouse with the purpose to assess the effect of shading net on yield and fruit quality. Two black shading nets (25 or 35% light reduction) placed on a polytunnel covered with a long life PE film, and a control (unshaded polytunnel) were compared. A randomized complete block design with three replicates was used and the experimental unit covered a 32.0 m2 (8.0×4.0 m) surface area, with plants spaced 1.0×0.4 m (2.5 plants m-2). The crops grown under 35% shaded polytunnel gave the highest yield, as a consequence of the highest number of fruits plant-1 whose mean weight was not affected by shading. Dry residue, soluble solids and sugars, as well as the concentration of cations (Ca, Mg, K) and anions (nitrates, phosphates, sulphates, chlorides) of the fruits grown under the unshaded polytunnel were highest. Proteins, carotenoids, ascorbic acid and α-tocopherol were best favored by the 35% shaded polytunnel. The shading net represents a beneficial tool to best fit the light and temperature conditions in greenhouse to pepper plant requirement, thus enhancing fruit yield and antioxidant content.