Effects of polyethylene films with different UV-A transmittance on quality parameters and physiology of greenhouse-grown tomato

In this study, the effects of three different polyethylene (PE) greenhouse covering materials (CMs) with varying thicknesses and ultraviolet-A (UV-A) transmittance on greenhouse microclimate, plant growth, yield, fruit quality, and chlorophyll fluorescence parameters (Chl FPs) in tomatoes were investigated. The CMs used in the study were 180 μm thick ultraviolet (UV) + ethylene vinyl acetate (EVA) + long-wave infrared (IR) + light diffuser (LD) + antifog (AF) added PE (CM1), 160 μm thick PLUS UV + EVA + IR + LD + AF added PE (CM2), and 200 μm thick UV + EVA + IR + LD added PE (CM3). As Chl FPs, relative variable Chl fluorescence at 2 ms (Vj), relative variable Chl fluorescence at 30 ms (Vi), and estimated maximum quantum efficiency of photosystem II photochemistry (Fv/ Fm) were taken into account. In addition, leaf temperatures were obtained by thermal images during the growing season. The thickness and IR efficiency rate of the CMs have significant effects on the average and minimum inside temperature values, and thus on related parameters in tomato, including plant height, yield, fruit juice pH, total soluble solids, fruit flesh firmness, fruit skin color, and leaf temperature. Plant development periods, rather than CM characteristics, affect Fv/Fm and Vj values. CM1 provided a significant yield increase in tomato cultivation under greenhouse conditions.