Technical properties of new agrotextile fabrics improving vineyard microclimate, table grape yield and quality

Light, temperature and humidity are major environmental factors to control in order to achieve high table grape yield and quality, especially in vineyards with overhead canopies protected by plastic covers. The overall covering effect is often not-well understood: it is related to final air/soil microclimate that, in turn, depends mainly on technical properties of cover materials. Two new agrotextile plastic fabrics were tested to evaluate their effects on vineyard microclimate and grape yield/quality. Two plots were covered with two types of transparent sheets apt to advance berry ripening: a new PE fabric (Coverlys®, E), and a PE based reference commercial film (R). Moreover, a new white reflective woven groundcover (Lumilys®, G) was laid out on some inter-rows of each plot (E+G, R+G). Air/soil microenvironment, vine phenology, shoot growth and berry ripening were monitored. Optical properties of E and R were analysed. The E cover showed a higher IRlong retention, UV transmittance, and light diffusivity; R showed a higher transmittance to PAR and IRshort. Air temperature and humidity, vine growth and phenology were similar for both plots, indicating a compensatory balance among the radiometric properties that influence thermal regime. The groundcover, compared to bare soil, intensified PAR reflection, lowered soil temperature, improved soil humidity. In the first year, Coverlys® enhanced berry weight (+10%) and, slightly, the theoretical yield, possibly due to more diffuse light that, being better distributed into the canopy, improve light photosynthetic efficiency. In the second year, Lumilys® increased bunch weight and productivity by 18%, thanks to a greater large berry percentage likely related to the improved soil humidity and light environment. Coverlys® plus Lumilys® intensified skin colour and phenol contents, that are known to increase with high PAR and UV irradiance.