# Influence of Region on Sensory and Chemical Profiles of Pennsylvania Gruner Veltliner Wines
## 3 Results and Discussion
### Relating Wine Data with Weather Conditions  
To gain insight on what may be driving regional differences in Gruner V. wines, weather data were added to the PCA as supplementary variables (Figure 4). In Year 1 (Figure 4A,C), 58.2% of variance was explained in the first two dimensions. In the samples plot, NW wines grouped in the second quadrant of the plot. SE2 and SE3, the samples from different vineyard plots of the same site, grouped in quadrant 3, as did the wine from the NC region. The remaining four samples were positively loaded on PC1, with NE1 and SE5 positively loaded on PC2 and SE3 and SE4 negatively loaded on PC2. When examining weather parameters along with the wine data, some positive and negative associations can be observed (Figure 4C). In Year 1, both total and veraison to harvest GDD (GDD_T and GDD_V) were positively associated with green apple and thiol flavors, octanoic acid, and \(a^{\star}\), while negatively associated with yellow color, VA, and phenylethyl alcohol. In Year 2 (Figure 4B,D), 55.4% of the variance was captured in the first two dimensions. NW1 and NW3 were the only wines negatively loaded on PC1. NW1 was positively loaded on PC2 while NW3 was negatively loaded on PC2, along with NW2, SE2, and NC1. SE1 and SE3 were positively loaded on both dimensions. Contrary to Year 1, cumulative rainfall (Rainfall_T) and GDD for the whole growing season (GDD_T) and during fruit ripening (veraison to harvest; GDD_V) had varying associations with chemical data. Veraison to harvest GDD was positively associated with the volatile compounds phenylethyl alcohol and methionol, while negatively associated with various aromatic esters. Total GDD of the whole growing season was positively associated with 1-hexanol, isobutanol, and 3-hexen-1-ol, while it was negatively associated with malate and a number of esters, including isopentyl hexanoate, ethyl decanoate, and ethyl hexanoate. Rainfall from veraison to harvest (Rainfall_V) was positively associated with yellow color and phenylethyll 2-methylpropanoate. Total growing season rainfall was positively associated with various acetate and ethyl esters, while GDD_V was negatively associated with these compounds, as seen in their opposing locations on the plot (Figure 4D). Regional trends were apparent and consistent from year to year when examining sensory data alone, but when combined with chemical and weather data, regional trends are not as well captured. In Year 1, both Rainfall_V and GDD_V were positively correlated to each other and appear to be independent from the total values of the respective parameter; however, in Year 2, GDD_V was negatively correlated with GDD_T, and the same correlation was seen for rainfall values. These trends were not surprising as there was not equal distribution of precipitation throughout the growing season among the  
Figure 4: Principal component analysis (PCA) results for wine samples (**A**,**B**) and sensory and chemical variables (**C**,**D**) for Year 1 (**A**,**C**) and Year 2 (**B**,**D**) results. Rainfall and GDD data shown in blue were superimposed as supplementary variables onto the PCA and quantified in two ways: veraison to harvest (_V) and total (_T) values. See Tables S6 and S8 for variable loadings. regions (Table S1). For example, in Year 1, NW sites on average received 33% of total precipitation between veraison and harvest, while NE and SE sites received only 18% of total precipitation during this period. In Year 2, a similar pattern was observed, with approximately 26% of total precipitation being received from veraison to harvest at NW sites, while sites in the SE region received, on average, 8% of precipitation during this period. Distribution of GDD was more consistent across regions. In Year 1, 26-38% of total GDD was accumulated during the ripening period in all regions, while in Year 2, 24-31% of total GDD was accumulated during this period in all regions.