## 3 Results and Discussion
### Impact of Temperature and Global Radiation on Cultivar-Specific Anthocyanin Profiles
Numerous studies evaluated the effect of temperature on the anthocyanin content of strawberry. In general, the content of total anthocyanin was enhanced with increasing temperature when plants were grown under controlled conditions [9; 19; 20]). However, the major anthocyanin pel-3-glc was less affected than the minor abundant pel-3-mal-glc [19]. Moreover, increased night temperature induced higher anthocyanin levels [9]. A contrasting result was obtained in a study with Japanese cultivars where high growing temperature (30/15 \({}^{\circ}\)C day/night) decreased the anthocyanin content compared to the control (20/15 \({}^{\circ}\)C), due to differently expressed genes involved in the anthocyanin synthesis [37]. There are only few studies evaluating latitudinal or altitudinal effects on the anthocyanin content of strawberry. In general, although pre-harvest weather conditions modified the data, fruits grown at higher latitudes had less anthocyanins than the southern ones [13; 22; 38]. In addition, quantitative changes in the anthocyanin profiles were found [20], giving northern fruits a higher percentage of minor anthocyanins like cya-3-glc and cya-3-mal-glc. These latitudinal depending results confirm our findings. In a study comparing different altitudes (differences \(\sim\)600 m) with increased temperature but lower radiation in the period 10 days before harvest at the higher altitude, no influence on total anthocyanin and pel-3-glc were found, but cultivar specifically increased levels of cya-3-gluc and minor pel-derivates [31]. In contrast, [PERSON] et al. [39] found a decrease of total anthocyanin, mainly pel-3-glc and an unnamed pel-derivate, with increasing altitude (\(\sim\)600 m) in fruits of 'Elsanta'. Furthermore, in a recent study, temperature, UV radiation and sunshine duration were found to affect bioactive compounds of strawberry stronger than locations differing nearly by 800 m altitude. However, anthocyanin was the compound class that showed significant differences between locations in one cultivar only [32]. In this experiment, 'Florence' and 'Frida' showed a high adaptation to their breeding place, and in case of 'Candonga', to the tunnel cultivation technique used during selection. High adaption ability is well known for wild species. For example, wild populations of different _Vaccinium_ species, grown from South to North Scandinavia, showed significant variations in the anthocyanin profile and total anthocyanin content giving northern populations a higher anthocyanin content in their berries [40; 41; 42]. It was explained by the long photoperiod at northern sites and its intense radiation of UV, visible and far-red wavelength [42], but also by its lower mean temperature or by the interaction of both. The adaption was under strong genetic control and remained when cloned plants of the Nordic populations were grown in South Scandinavia [42]. Figure 5: Coefficient of determinations (R\({}^{2}\)) between cya-3-glc, pel-3-glc, pel-3-rut, cya-3-mal-glc, ple-3-mal-glc and total anthocyanin (shown top to bottom) and the environmental factors’ mean temperature (T\({}_{\text{mean}}\)), maximum temperature (T\({}_{\text{max}}\)), minimum temperature (T\({}_{\text{min}}\)) and global radiation accumulated for 3, 5, 10 and 15 days (3d, 5d, 10d and 15d) before sampling of the berries to be analyzed for each cultivar ‘Candonga’ (Can), ‘Clery’ (Cle), ‘Florence’ (Flo), ‘Frida’ (Fri), ‘Gariguette’ (Gar) and ‘Sonata’ (Son), shown left to right. Cultivars with no data (blank) indicate the observed correlation between different anthocyanin components, and mean, maximum, minimum temperatures and global radiation were statistically insignificant. The pigmentation of strawberry occurs relatively rapid at the end of the fruit development. Metabolomic studies indicate the first appearance of anthocyanins with rapidly increasing amounts until ripeness around 5-10 days after the fruit's white stage [38; 43; 44; 45].