Effects of the Annual Nitrogen Fertilization Rate on Vine Performance and Grape Quality for Winemaking: Insights from a Meta-Analysis

Figure 6

Density surfaces of the scatter plots in Figure 5 for the trial-normalized grape quality traits against the annual nitrogen rate. (a) Total soluble solids. (b) Titratable acidity. (c) Hydrogen ion activity. (d) Malic acid concentration. (e) Tartaric acid concentration. (f) Anthocyanin concentration. (g) Total polyphenol index. (h) Yeast assimilable nitrogen.

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