# Grapevine Phenology in Four Portuguese Wine Regions: Modeling and Predictions
## 3 Results
### Characterization of the Phenological Stages
According to the mean observed values, there are also slight differences between regions  
Figure 2: Average day of the year (DOY) observed for each variety, phenological stage (budburst, flowering, and veraison, cf. legend) and wine region: Vinhos Verdes (1), Dão (2), Douro (3), and Lisboa (4). The average values are ranked according to the veraison date. The values outlined in the bars correspond to the mean duration of each phenophase (1 January–budburst; budburst–flowering; flowering–veraison). (Figure 2). For budburst, it completes this stage in DOY 76 in Lisboa, while it needs four more days in the Douro region. The budburst-flowering phenophase length is shorter in the Douro (57 days), while it requires nine more days in the Lisboa wine region. For the flowering-veraison phenophase, the difference is of only one day between the Douro and the Lisboa regions (64 and 65 days, respectively). As such, veraison is observed, on average, in DOY 201 in Douro and in DOY 207 in Lisboa, respectively. Cv. _Touriga Franca_ is an earlier variety when compared to cv. _Touriga Nacional_ in the same regions. With respect to cv. _Baga_ and for the two regions (Dao and Lisboa) with data available, it achieves, on average, budburst first in the Lisboa wine region (DOY 84) and much later in Dao (DOY 100) (Figure 2). On the contrary, the budburst-flowering phenophase duration is 11 days shorter in the Dao region than in the Lisboa wine region. For the flowering-veraison phenophase, there is a difference of 13 days between Dao and Lisboa wine regions (59 and 72 days, respectively). Therefore, the average veraison dates are in DOY 210 in the Dao wine region and DOY 218 in the Lisboa wine region. Cv. _Baga_ is also an earlier variety when compared to cv. _Touriga Nacional_ in the same regions. For cv. _Alfrocheiro_, there are also some noteworthy differences between the Lisboa and the Dao wine regions (Figure 2). It accomplishes budburst in DOY 75 in Lisboa and takes 18 days more in the Dao region (DOY 93). The budburst-flowering phenophase length is 14 days shorter in Dao than in Lisboa (55 and 69 days, respectively). The flowering-veraison phenophase length is accomplished in 64 days in Dao and 71 days in Lisboa. Thus, the veraison timings are as follows: DOY 212 in Dao and DOY 215 in Lisboa, being a slightly earlier variety when compared with cv. _Touriga Nacional_. Finally, regarding cv. _Alvarinho_ with data for the Vinhos Verdes and the Lisboa wine regions (Figure 2), it completes budburst in DOY 79 in Lisboa and takes three days more in Vinhos Verdes (DOY 82). There is a difference of only two days in the budburst-flowering phenophase duration between Vinhos Verdes and Lisboa (64 and 66 days, respectively). The flowering-veraison phenophase length is fulfilled in 71 days in Vinhos Verdes and 78 days in Lisboa. As such, veraison occurs, on average, in DOY 217 in Vinhos Verdes and DOY 223 in the Lisboa wine region. It is thereby the later variety of the previous five. Overall, these temporal lags in the phenological timings of the same variety grown in different wine regions can be largely attributed to their different climatic conditions. In fact, the existence of more continental climates (cooler winters and warmer summers) in the Douro or the Dao wine regions than in the Vinhos Verdes or the Lisboa wine regions, which have more maritime climates, explains the delay of budburst and the generally shorter budburst-flowering and flowering-veraison phenophase lengths in the former. Soils, rootstocks, cultural practices, and clonal diversity may also play an important role in these phenological heterogeneities among regions, though these assessments would require a substantially larger dataset of field measurements and experimental vineyards, which is out of the scope of the present study.