# Grapevine Phenology in Four Portuguese Wine Regions: Modeling and Predictions
## 3 Results  
### Characterization of the Phenological Stages  
The average values observed for the three main phenological stages (budburst, flowering, and veraison) for each variety and wine region from 1990 to 2018 are represented in Figure 2. In the analysis of the average values of the different phenological stages, the grapevine varieties were split into early, intermediate, and late, which correspond to Quartile 1 (\(\leq\) 25%), Quartile 2 + Quartile 3 (between 25% and 75%), and Quartile 4 (\(\geq\) 75%), respectively. It should be highlighted that this classification depends on the phenological stage, that is, the same variety can be keyed to different classes. Concerning budburst, the Lisboa wine region reveals 16 early varieties, ranging from cv. _Moscatel Galego_ (DOY: 68), the earliest, to cv. _Encruzado_ (DOY: 77). Between Q2 and Q3, 24 intermediate varieties are included in the three regions (Lisboa, Douro and Vinhos Verdes). In this case, the earliest varieties to complete this stage are cv. _Aragonez_/Douro and _Touriga Nacional_/Douro (DOY: 78), but some varieties need nine days more to achieve budburst, such as cv. _Trajadura_/Lisboa and cv. _Azal Branco_/Vinhos Verdes (DOY: 87). Regarding the late varieties (Q4), they vary from cv. _Vinhao_/Lisboa (DOY: 88) to cv. _Baga_/Dao (DOY: 100), thus showing a 12 day lag. For flowering, they bear the accumulated effect of the budburst date, being cv. _Touriga Nacional_/Douro the earliest (DOY: 136). Furthermore, 27 intermediate red and white varieties are found in the different wine regions, with cv. _Riesling_/Lisboa (DOY: 143) reaching flowering six days earlier than cv. _Arinto_/Lisboa (DOY: 149). Among the late grape varieties, the earliest is cv. _Bical_/Dao (DOY: 150), whereas cv. _Vinhao_/Vinhos Verdes (DOY: 155) is five days delayed. For veraison, there are 14 early grapevine varieties among the three regions (Lisboa, Dao and Douro), of which the earliest is cv. _Touriga Franca_/Douro (DOY: 201), whereas cv. _Tinta Franca_/Lisboa (DOY: 215) needs 14 more days to fulfill veraison. For the 24 intermediate varieties, cv. _[PERSON]_/Lisboa completes the stage in DOY 216, while cv. _Trajadura_/Lisboa needs eight more days on average. Regarding the late varieties, there is a greater precocity of cv. _Encruzado_/Lisboa (DOY: 225), the last variety to complete the stage being cv. _Azal Branco_/Lisboa (DOY: 232). For the budburst-flowering phenophase, cv. _Touriga Nacional_/Dao shows the shortest length (50 days), while cv. _Azal Branco_/Lisboa (71 days) reveals the longest length. For the flowering-veraison phenophase, cv. _[PERSON]_/Douro (58 days) depicts the shortest period, whereas cv. _Avesso_/Lisboa (91 days) shows the longest duration. As for some major grapevine varieties growing in Portugal, there are data available in more than one wine region, and comparisons can still be made between regions based on the average phenological dates (Figure 2). For cv. _Touriga Nacional_, a widely known Portuguese variety with data available in three wine regions (Douro, Dao, and Lisboa) and for the three selected phenological stages, some regional differences can be found (Figure 2). This variety fulfills budburst, on average, in DOY 78 in both the Douro and the Lisboa wine regions, whereas it needs 21 more days in the Dao region (DOY: 99). Conversely, this variety presents a shorter budburst-flowering phenophase length in the Dao region (50 days), requiring eight more days in the Douro and 15 days in the Lisboa wine region. The flowering-veraison phenophase is also shorter in Dao (69 days), being one day longer in the Douro and more than that in Lisboa (78 days). Hence, the veraison occurs, on average, in DOY 206 (Douro), 218 (Dao), and 221 (Lisboa). Concerning cv. _Touriga Franca_, phenological data are available in two wine regions (Douro and Lisboa).