At the grapevine growing region of Jundiaí (State of São Paulo - Brazil) the trellis system with single unilateral cordon and vertical upward branches is the most used by the growers. Nowadays it is been gradually replaced by the Y shaped trellis system. Still, some producers have been using plastic overhead cover for protection of the grape clusters. The different trellis systems cause modifications in the microclimate of the vineyard, so measurements of daily values of solar radiation, relative humidity, maximum and minimum air temperatures were taken in the external environment and at cluster height in 'Niagara Rosada' vineyards conducted in vertical with upward branches trellis system under open sky conditions and Y shaped trellis system, with and without plastic overhead cover, during the winter and the summer crops. During the summer growing season the differences in daily values of solar radiation, maximum air temperature and relative humidity obtained at cluster height and at external conditions were higher when compared to the winter crop for the different trellising systems evaluated. The vines in the vertical trellis system showed lower values of solar radiation and relative humidity at cluster height when compared to the Y shaped system. The values of maximum and minimum temperatures were similar in the vertical trellis and Y shaped system, during the winter and the summer crop. The plastic overhead cover on the Y shaped trellis did not influence the values of relative humidity and minimum temperature, however, resulted higher values of maximum air temperature.
table grape; solar radiation; temperature; relative humidity; plastic overhead cover; trellis system
