The use of plastic covering on vineyards has increased in Southern Brazil, allowing mitigating climate limitations. This study aimed to quantify micrometeorological alterations caused by plastic covering over grapevines 'Niagara Rosada', and the effects on plant growth and grapes production in organic cultivation. A field experiment was conducted in Bento Gonçalves, state of Rio Grande do Sul (Brazil), in a vineyard conducted in pergola system, under two conditions: in open sky and covered with a transparent plastic film (160µm) in discontinuous arcs. The photosynthetically active radiation (PAR) and air temperature were monitored in both environments. The crop phenology, leaf area index (LAI), the weight, diameter, sugar concentration and acidity of grapes, the incidence of fungal diseases, and yield were determined. The plastic covering reduced the incoming PAR in about 34% and increased the maximum air temperature (+3.1 ºC). It accelerated the plant phenology until ripening, but delayed the leaf senescence. LAI and leaf area duration have also increased, while fungal diseases did not occur on covered plants. Grape yields were 12.3 and 27.1 t ha-1 for the uncovered and covered vineyards, respectively. Therefore, the plastic covering may be an important alternative for producing table grapes in organic systems, in Southern Brazil.
Vitis labrusca; phenology; plasticulture
