Data from field experiments conducted in table grape vineyards variety of Festival in Petrolina-PE in the period from September 19 to October 12, 2010 were used to evaluate the influence of plastic cover on microclimate conditions of vineyards in São Francisco River Valley region. Three treatments were studied: canopies without plastic cover (WC); with plastic cover positioned at 50 cm (PC50), and at 100 cm (PC100) above canopy. The results indicate that the plastic cover prevented the passage of about 40% of the global and net radiation, retained the relative humidity inside the canopy, generated an increase of air temperature and marked reduction in wind speed over the canopy of treatment PC50. However, treatment PC100 had a higher incidence of short wavelength and net radiation under canopy (on the berries) than WC and PC50 treatments, resulting in more favorable weather conditions, providing about 40% greater productivity in this treatment. Therefore, the vineyard with plastic cover placed at 100 cm above canopy represents a more suitable alternative to the climatic conditions of the region of the São Francisco River Valley.

Abstract Data from field experiments conducted in vineyards table grape variety of Festival in Petrolina-PE, from October/2009 to November/2010, were used to evaluate the influence of the plastic cover on productivity and economic profitability of the viticulture in the São Francisco River Valley. Three treatments were studied: uncovered canopy (UC), plastic cover placed at 50 cm above the canopy (PC50), and a plastic cover placed at 100 cm above the canopy (PC100). The results indicated that the increased supply of radiative fluxes at the height of the berries in the treatment PC100 contributed to higher productivity, while treatment PC50 had the lowest offer of irradiative fluxes at the height of berries and much lower productivity. The yield obtained in the treatment PC100 exceeded 11 t ha-1 and 12.3 t ha-1 to those of treatments at UC and PC50, respectively. Treatment PC100 also had the lowest amounts of defects of berries, which contributed to higher total revenue. By contrast, treatment PC50 had markedly lower productivity, which represented considerable economic losses.

Revista Brasileira de Geografia Física 01 (2011) R E S U M OO presente trabalho teve como objetivo avaliar a influência da cobertura plástica sobre a temperatura do ar em parreirais no Vale do Submédio São Francisco. A pesquisa foi conduzida em parreirais produtivos de uva de mesa variedade Festival em Petrolina, PE (09º 06' 14'' S; 40º 29' 52" W; altitude 360 m), no período de 17/09/2010 a 10/10/2010, durante a fase de maturação e colheita da uva. Foram empregados três tratamentos, cada um representado por 12 m de fileira, descritos a seguir: tratamento 1 -sem cobertura plástica (SCob); tratamento 2 -com cobertura plástica posicionada a 50 cm acima do dossel (CP50); e tratamento 3 -com cobertura plástica posicionada a 100 cm acima do dossel (CP100). Medidas de temperatura do ar e velocidade do vento foram efetuadas a 20 cm acima e abaixo do dossel, esta última na altura média dos cachos. Os resultados mostraram que o tratamento CP50 proporcionou aquecimento acentuado na camada do ar sobre o dossel do parreiral com a temperatura máxima atingindo 45,4 °C, valor 10,1 °C maior do que a temperatura máxima no tratamento SCob e 7,3 °C maior do que a temperatura máxima no tratamento CP100. Isso evidenciou que a altura da cobertura plástica sobre o dossel do parreiral influencia no seu microclima e deve ser levada em consideração quando do planejamento de sua utilização.Palavras-chave: Uva de mesa, Cultivo Protegido, Aquecimento, Parreiral. Influence of the Plastic Cover on the Vineyard Temperature in the Submédium São Francisco Valley A B S T R A C TThis study evaluated the influence of the plastic cover on the air temperature in vineyards in the region of the São Francisco Valley. The study was conducted in vineyards of table grape variety Festival in Petrolina, PE, Brazil (09º 06 '14" S; 4 ° 29' 52" W; elevation 360 m) in the period from Sep./17/2010 to Oct./10/2010. The following treatments were evaluated, each represented by 12 m of row: treatment 1 -no plastic cover (SCob); treatment 2 -plastic cover 50 cm above the canopy (CP50); and treatment 3 -plastic cover 100 cm above the canopy (CP100). Measurements of air temperature and wind speed were made at 20 cm above and below the canopy around the location of grapes bunches. The results showed that the plastic at the height of 50 cm provided a dramatic warming in the layer of air above the vineyard canopy with the maximum temperature reaching 45.4 °C which represents a value 10.1 °C greater than the maximum temperature without the canopy cover and 7.3 °C higher than the maximum temperature of the canopy of 100 cm. This evidence showed the influence of de height of the plastic cover on the canopy of the vineyard microclimate and it has to be considerade when planning their use.