Impact of light exposure on fruit composition of white 'Riesling' grape berries (Vitis vinifera L.)

Authors

  • M. Friedel Department of General and Organic Viticulture, Hochschule Geisenheim University, Geisenheim, Germany
  • M. Stoll Department of General and Organic Viticulture, Hochschule Geisenheim University, Geisenheim, Germany
  • C. D. Patz Department of Wine Chemistry and Beverage Technology, Hochschule Geisenheim University, Geisenheim, Germany
  • F. Will Department of Wine Chemistry and Beverage Technology, Hochschule Geisenheim University, Geisenheim, Germany
  • H. Dietrich Department of Wine Chemistry and Beverage Technology, Hochschule Geisenheim University, Geisenheim, Germany

DOI:

https://doi.org/10.5073/vitis.2015.54.107-116

Keywords:

berry composition, leaf removal, light exposure, phenolics

Abstract

Microclimate and irradiation have long been known to influence winegrape (Vitis vinifera) quality. However, microclimate influence on white grape quality has remained understudied, as most research efforts have focused on red varieties and their anthocyanin content. In this study, we investigated microclimatic effects on the phenolic and amino acid composition of white 'Riesling' grapes using bunch shading and leaf removal to manipulate grape microclimate. Both treatments were applied directly after fruit set (modified E‑L 27; (Coombe 1995)) as well as at the onset of veraison (E-L 34), and compared to a non-manipulated control. The concentration of malic acid, amino acids and total nitrogen were decreased by illumination during the berry growth, while content and concentration of phenolics were significantly increased by illumination. Strong negative correlations were observed between accumulation of amino acids and flavonols. Although accumulation of flavonols occurred throughout berry development, the most important phase of accumulation was post-veraison.



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Published

2015-10-09

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