SUMMARYPhenological models are considered key tools for the short-term planning of viticultural activities and long-term impact assessment of climate change. In the present study, statistical phenological models were developed for budburst (BUD), flowering (FLO) and veraison (VER) of 16 grapevine varieties (autochthonous and international) from the Portuguese wine-making regions of Douro, Lisbon and Vinhos Verdes. For model calibration, monthly averages of daily minimum (Tmin), maximum (Tmax) and mean (Tmean) temperatures were selected as potential regressors by a stepwise methodology. Significant predictors included Tmin in January–February–March for BUD, Tmax in March–April for FLO, and Tmin, Tmax and Tmean in March–July for VER. Developed models showed a high degree of accuracy after validation, representing 0·71 of total variance for BUD, 0·83 for FLO and 0·78 for VER. Model errors were in most cases < 5 days, outperforming classic growing degree-day models, including models based on optimized temperature thresholds for each variety. Applied to the future scenarios RCP4·5/8·5, projections indicate earlier phenophase onset and shorter interphases for all varieties. These changes may bring significant challenges to the Portuguese wine-making sector, highlighting the need for suitable adaptation/mitigation strategies, to ensure its future sustainability.

<p style="text-align: justify;"><strong>Aim</strong>: To investigate the characteristics, relationships and trends in the phenology of four winegrape varieties and associated temperature relationships in the Lisbon wine region (LWR), between 1990 and 2011.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Budburst, flowering and véraison dates of red (Castelão and Aragonez, syn. Tempranillo) and white (Chasselas and Fernão Pires) varieties were taken from an experimental vineyard in the LWR. Harvest dates were determined based on a similar maturity level for all varieties. From these data, varietal characteristics, temporal trends as well as relationships between phenology and temperature were assessed through stepwise multivariate linear regressions. Flowering was the most sensitive to temperature in the preceding months (March-April). Differences/similarities between the phenological timing of the different varieties are presented. With few exceptions, no trends were found in phenophases over the 1990-2011 period, whereas several significant negative slopes were displayed for phenological intervals, suggesting a role for accumulated thermal effects in phenological timing. Strong correlations were observed between phenophases, especially between flowering and véraison.</p><p style="text-align: justify;"><strong>Conclusion</strong>: The study highlights the key role played by temperature on phenology, particularly during springtime. Furthermore, an increase in temperature during that period will cause an advance in the timing of the following phenological events. Given the significant trends found, phenological shifts may occur in the long term, emphasizing the need to assess varietal characteristics and responses to regional climate.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: The present work is the first attempt to systematically examine temporal trends in phenology and corresponding relationships with temperature in a Portuguese viticultural area, providing valuable information on the development and suitability of grapevine varieties, which determine viticultural practices and winegrower’s income.</p>

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The SIMDualKc model was used to simulate crop water requirements for a super high density olive orchard in the region of Alentejo, Portugal. This model uses the dual crop coefficient approach to estimate and partitioning the actual crop evapotranspiration (ETc act) and therefore to perform the soil water balance. The model was calibrated with 2011 tree transpiration using trunk sap flow measurements and was validated using similar data from 2012 and tested with 2013 data. Low root mean square errors (RMSE < 0.53 mm·d−1) and acceptable modelling efficiency indicators (EF > 0.25) were obtained. Further validation was performed comparing modelled ETc act with eddy covariance measurements. These indicators support the appropriateness of using SIMDualKc to guide irrigation management. The basal crop coefficient (Kcb) curves obtained with SIMDualKc for those 3 years were compared with the Kcb values computed with the Allen and Pereira approach (A&P approach) where Kcb is estimated from the fraction of ground cover and plant height considering an adjustment factor for crop stomatal control (Fr). Fr values were obtained through a trial and error procedure through comparing the Kcb estimated with this approach and with SIMDualKc. The Kcb curves obtained by both methods resulted highly correlated, which indicates that the A&P approach may be used in the irrigation management practice to estimate crop water requirements. Results of performing the soil water balance with SIMDualKc have shown that soil evaporation is a large fraction of ETc act, varying between 41% and 45% for the 3 years under study. Irrigation, applied with a drip system, represented 39 to 56% of ETc act, which shows the great importance of irrigation to achieve the water requirements of super intensive olive orchards. Nevertheless, the analysis has shown that the irrigation management adopted at the orchard produces a water deficit larger than desirable, with a ratio of ETc act to non-stressed crop evapotranspiration (ETc) varying from 70% to 94% during the mid-season, when that ratio for a eustress irrigation management could be around 90%.