## 2 Materials and Methods
### Sample Preparation for Anthocyanin Analysis  
Three independent biological replications were collected twice in an approximately weekly interval at mid-harvest at each location per cultivar (Figure 1 and Table 1). Thus, the samples (500 g) consisted mainly of secondary and tertiary fruits, being fully ripe and undamaged. Each biological replicate of freshly harvested strawberries was promptly prepared for analytical purposes by first cutting the calyx and then slicing the fruits into 2-4 pieces. Slices were frozen in a liquid nitrogen bath for at least 10 s. For anthocyanin analysis, the frozen slices were ground either in a lab mill (e.g., Retsch GM 200) or crushed under liquid nitrogen with a precooled mortar and pistil to a fine powder. The frozen powders were filled into 50 mL plastic tubes with screw caps, and stored at \(-20^{\circ}\) C. Anthocyanin analysis was carried out at Geisenheim. Suitable shipping conditions were chosen to prevent thawing of the samples during transportation until solvent extraction. The frozen  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **NIBIO** & **INHORT** & **HGU** & **Sant’Orsola** & **INVENIO** \\  & **Norway** & **Poland** & **Germany** & **Italy** & **France** \\ \hline Latitude & 60\({}^{\circ}\)40\({}^{\prime}\) N & 51\({}^{\circ}\)95\({}^{\prime}\) N & 49\({}^{\circ}\)59\({}^{\prime}\) N & 46\({}^{\circ}\)4\({}^{\prime}\) N & 44\({}^{\circ}\)85\({}^{\prime}\) N \\ Altitude (m a.s.l.) & 262 & 252 & 95 & 925 & 145 \\ Yearly mean temperature (\({}^{\circ}\)C) (\({}^{\text{a}}\)) & 5.0 & 7.9 & 9.9 & 11.3 & 12.9 \\ \hline Soil type & Loam &
\begin{tabular}{c} Pseudopodsol \\ with light clay \\ \end{tabular} & Sandy loam & Soilless culture & Soilless culture \\ pH of the soil/substrate & 5.7–6.2 & 6.5–7.0 & 6.5–7.0 & 5.5–6.0 & 6.1 \\ Cultivation type & open field & open field & open field & tunnel & tunnel \\ \hline Yearly mean temperature & 2017 & 2018 & 2017 & 2018 & 2017 & 2018 & 2017 & 2018 \\ (\({}^{\circ}\)C) (\({}^{\text{a}}\)) & 5.0 & 5.7 & 9.1 & 9.8 & 11.3 & 12.4 & 15.6 & 15.1 & 13.2 & 13.8 \\ Start of flowering (\({}^{\text{b}}\)) & 06.06. & 21.05. & 16.05 & 30.04. & 04.04. & 04.04. & 11.04. & 04.04. & 07.04. \\ Start of harvest (\({}^{\text{b}}\)) & 07.07. & 17.06. & 13.06. & 22.05. & 29.05. & 14.05. & 19.05. & 17.05. & 09.05. & 09.05. \\ End of harvest (\({}^{\text{c}}\)) & 16.08. & 21.07. & 07.07. & 19.06. & 16.06. & 18.06. & 12.06. & 13.06. & 22.06. & 22.06. \\ Day length at start of & 18.40 & 19.09 & 16:43 & 16:04 & 15:56 & 15:20 & 14:30 & 14:30 & 14:36 & 14:36 \\ harvest (h) & \\ \hline \hline \end{tabular}  
* For the period 1981–2010. (\({}^{\text{b}}\)) Earliest cultivar. (\({}^{\text{c}}\)) Latest cultivar. (\({}^{\text{d}}\)) Warm temperature in March enhanced start of flowering followed by extremely cold temperature delaying fruit development.  
\end{table}
Table 1: Geographical location, soil and climatic conditions, cultivation type and harvest season for the five experimental locations in Europe.  
powders (5.0 g) were weighed into a 50 mL plastic tube and extracted twice in an ultrasonic bath (30 min, 120 W, Bandelin Sonorex RK 106, VWR, Darmstadt, Germany) and intermediate centrifugation (4500 upm 15 min, Hettich Rotanta 460, Tuttlingen, Germany) with a total of 2 \(\times\) 10 mL acidified methanol/water/formic acid (80/20/1 \(v\)/\(v\)/\(v\)). Sonication and centrifugation were performed under cool conditions. After final centrifugation, the pooled supernatants were made up to 25 mL in a volumetric flask; aliquots were 0.45 um filtered prior to HPLC analysis.