Alterações micrometeorológicas em vinhedos pelo uso de coberturas de plástico

Abstract

The objective of this work was to evaluate the effects of plastic covering on the microclimate of vineyards (Vitis vinifera L., cultivar Moscato Giallo), in Serra Gaúcha region in Rio Grande do Sul State, Brazil. The experiment was performed in Flores da Cunha, RS, during the 2005/2006 growing season. It comprised uncovered and covered rows of vines, using a 160 ?m thick plastic film. Photossinthetically active radiation (PAR), air temperature and humidity, and wind velocity were monitored: over the plastic covering; between the film and the canopy; over the uncovered canopy; and close to grapes of both treatments. Reference evapotranspiration was estimated for both treatments. From the incoming PAR, 67.5% reached the covered canopy, 16% reached the covered grapes, and 36% reached the uncovered grapes. The plastic covering increased by 3.4°C the maximum air temperatures close to plants. Diurnal air relative humidity was reduced, while water vapor pressure and vapor pressure deficit were increased because of the plastic covering, which also reduced in 88% the wind velocity in comparison to open air. The reference evapotranspiration on the covered canopy was 35% lower than in open air. Although increasing diurnal air temperatures, the plastic covering may reduce the evaporative demand on vineyards, by reducing the incoming solar radiation and the wind velocity.