Effect of polyethylene soil coverage, in the maturation of Vitis vinifera grape in the variety Tannat

Abstract

The effect of soil cover with polyethylene on the physiological and grape quality parameters was evaluated during three seasons in a commercial vineyard in southern Uruguay. The experimental setup consisted of two plots of 20 plants each of the Tannat variety grafted on 3309. When 50% of veraison was reached, one of the plots was covered with polyethylene until harvest. The polyethylene used was white on both sides, 220 microns thick and with ultraviolet protection. The same polyethylene was used during the three seasons. The modification of the microclimate (soil temperature, canopy, relative humidity and luminosity) and its influence on the synthesis of primary metabolism (acidity and sugars) and secondary (anthocyanins) in our growing conditions were evaluated. Soil temperature increased under polyethylene on average almost 1.5 ° C and relative humidity decreased. Moreover, the photosynthetically active radiation reflected by the cover was significantly higher than in bare soil conditions at the bunchs level. Berry components such as weight, sugar content and extractable and total anthocyanins for the three-year trial were significantly higher under polyethylene. The results show that the white polyethylene placed in the maturation period enables the modification of the microclimate at the bunch level and of the plant in general, which allows a higher level of photosynthesis and metabolic activity that results in an increase of quality parameters.