Projected warming and drying trends over the Mediterranean region represent a substantial threat for wheat production. The present study assesses winter wheat yield response to potential climate change and estimates the quantitative effectiveness of using early flowering cultivars and early sowing dates as adaptation options for the major wheat production region of Portugal. A crop model (STICS) is used for this purpose, which is calibrated for yield simulations before projecting future yields. Climate projections over 2021-2050 and 2051-2080 under two emission scenarios (RCP4.5 and RCP8.5) are retrieved from bias-adjusted datasets, generated by a ten-member climate model ensemble. Projected intensification of water deficits and more frequent hightemperature events during late spring (April-June), coinciding with the sensitive grain filling stage, primarily result in continuous mean yield losses (relative to 1981-2010) by − 14% (both scenarios) during 2021-2050 and by − 17% (RCP4.5) or − 27% (RCP8.5) during 2051-2080, also accompanied by increased yield variabilities. Of evaluated adaptation options at various levels, using earlier flowering cultivars reveals higher yield gains (26-38%) than that of early sowings (6-10%), which are able to reverse the yield reductions. The adopted early flowering cultivars successfully advance the anthesis onset and grain filling period, which reduces or avoids the risks of exposure to enhanced drought and heat stresses in late spring. In contrast, winter warming during early sowing window could affect vernalization fulfillment by slowing effective chilling accumulation, thus increasing the pre-anthesis growth length with limited effects on advancing reproductive stage. Crop yield projections and explored adaptation options are essential

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Wheat yield potentials under rainfed Mediterranean conditions have been long limited by late-in-season occurrence of enhanced water deficits and high temperatures, coinciding with sensitive reproductive stages.Present study aims to quantify and separate the impacts of two main abiotic stresses (drought & heat) on potentially attainable wheat yields, in a typical Mediterranean environment of southern Portugal (Alentejo) over 1986-2015. We also evaluate how possible adaptation options could mitigate potential yield losses (reduce the gap between actual and potential yield). Previously calibrated STICS soil-crop model is used for these purposes, which has been satisfactorily evaluated herein for yield simulations using additional field data before running at regional level. By coupling with high-resolution gridded soil and climate datasets, STICS simulations reliably reproduce the inter-annual variability of 30-year regional yield statistics, together with reasonable estimations of experimental potential yields. Therefore, the model is useful to explore the source of yield gap in the region. The quantified impacts, though with some uncertainties, identify the prolonged terminal drought stress as the major cause of yield gap, causing 40-70% mean potential yield losses. In contrast, a short-duration of crop heat stress (≥38℃) during late grainfilling phase only results in small-to-moderate reductions (up to 20%). Supplemental Irrigation (SI) during reproductive stages provides good adaptive gains to recover potential yield losses by 15-30%, while the proposed early-flowering cultivar is more useful in escaping the terminal heat stress (5-15% adaptive gains) than avoiding prolonged drought stress. In addition, advancing sowing date generally favours wheat production with a robust spatial-temporal pattern. Therefore, combined options based on application of SI, using balanced early-flowering cultivar and early sowing date, may contribute to considerably reduce local yield gap, where current yields can account for 60% of potential yields (26-32% without adaptation).Regional impact assessment and adaptation modelling studies are essential to support agricultural policy development under climate change and variability. The recommended combined adaptation may also represent a promising adaptation strategy for rainfed wheat cropping system in other regions with similar Mediterranean conditions. However, the existing spatial-temporal variability of adaptation response highlights the need to address adaptation strategies at a more detailed local scale with better flexible design.

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Little field research has documented the water use of peppermint (Mentha piperita L.), an important irrigated crop of the Pacific Northwest grown for oil and tea leaves. Our objective was to determine a peppermint yield—water use function and to develop a crop coefficient (Kc) to relate crop evapotranspiration (ET) to potential ET. Trials were conducted from 1992 to 1994 at Madras, OR on a Madras loam mesic Aridic Argixeroll (fine‐loamy, mixed, mesic Xerollic Duriargid). A line‐source sprinkler irrigation system was used to impose five irrigation treatments ranging from 30 to 120% of the ET required for maximum yield. Evapotranspiration was measured by monitoring the water balance components of irrigation, precipitation, drainage, and soil water storage. Peppermint yield was sensitive to irrigation, with both deficit and excess irrigation lowering oil yields compared with the optimum treatment, which was 324, 388, 364, and 487 mm season‐1 for the four trials. Peppermint ET‐yield functions exhibited a greater transpiration component (89%) than other crops due to its thick canopy that reduces soil evaporation. The highest yielding irrigation treatment kept the soil water pressure between −18 and −50 kPa in the top 0.3 m. The Kc followed the general three‐lines model with an initial value of 0.3 that increased to 0.85 at mid‐season and declined to 0.5 at harvest. Thermal units were used to normalize the inflection points for the Kc curve for 2 yr of the trial (1993 and 1994). Late winter tillage in 1992 delayed peppermint growth and shifted the Kc curve.

Climate change projections for Portugal showed warming and drying trends, representing a substantial threat for the sustainability of forage production in perennial grassland. The objective of the present study was to assess climate change impacts on seasonal dry matter yield (DMY) in three locations (North-west-, Central-inner and South-Portugal) with different climatic conditions, for two grassland production systems deviating in growing season length, either early cuts in spring (ES) or late cuts in summer (LS). Impacts were estimated using the STICS (Simulateur mulTIdisciplinaire pour les Cultures Standard) crop model, by comparing a historical baseline period (1985–2006) with simulated projections over future periods (2021–2080). For this purpose, the STICS crop model was driven by high-resolution climate data from a coupled Global Climate Model/Regional Climate Model chain. As a result, we obtained that, during the baseline period, DMY of LS was consistently much higher than that of ES in all three locations. For LS, significant reductions in mean DMY were forecasted during 2061–2080, ranging from mild (–13%) in the north to severe (–31%) in the south of Portugal. In contrast, seasonal DMY was largely maintained for ES among sites until 2080, benefiting from low water deficits, the expected atmospheric CO2 rise and the forecasted temperature increase during cool season. Thus, the yield gap was projected to gradually decrease between the two regimes, in which mean DMY for ES was foreseen to exceed that of LS over 2061–2080 in the southern site. Moreover, ES was projected to have very low exposure to extreme heat and severe water stresses. Conversely, LS, subjected to high summer water deficit and irrigation needs, was projected to experience increased summertime water stress (9–11%) and drastically increased heat stress (33–57%) in 2061–2080, with more pronounced heat stress occurring in the south. Frequency of occurrence of extreme heat stress was projected to gradually increase in summer over successive study periods, with a concomitant increased intensity of DMY response to inter-annual variability of heat stress during 2061–2080. Heat stress tended to be more important than water stress under the prescribed irrigation strategy for LS, potentially being the main limiting factor for summertime DMY production under climate change scenario.

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Viticulture is exposed and vulnerable to extreme weather and climate change. In Europe, owing to the high socio-economic value of the winemaking sector, the development of adaptation strategies to mitigate climate change impacts will be of foremost relevance for its future sustainability and competitiveness. Some guidelines on feasible short-term adaptation strategies are provided here (Figure 1), collected by the Clim4Vitis action (https://clim4vitis.eu/). Long-term adapation startegies are described in an accompanying technical review.