Impact of microclimate on berry quality parameters of white Riesling (Vitis vinifera L.)

Knowledge has been accumulated on the impact of microclimate, in particular berry temperature and irradiation, for a wide range of red varieties. However, little research has been dedicated on the effects of the same factors on the quality of white grape varieties.

In this study we present results of the effects of microclimate on the composition of white Riesling (Vitis vinifera L.) under different row orientations. The microclimatic parameters monitored in this study were canopy humidity and temperature, berry surface temperature using infrared thermography, ambient humidity, temperature, wind speed and irradiation parameters. Bunches of different exposure within the canopy of three different row orientations (North to South; East to West; South-West to North-East) were monitored. In addition to the natural environment, some bunches were sheltered in boxes to exclude any impact of light. Further, a defoliation treatment was established to provide maximum light interception.

Results of the study showed that bunches under higher radiation interception, had a faster malic acid degradation and berries were accumulating more flavonols, while the differences in sugar accumulation seemed to depend on leaf peak temperatures rather than on the exposure of the berries.