## 3 Results and Discussion
### Impact of Drought on Cereal Yields  
Analyzing the Pearson correlation between the cereal yield (SYRS) and the SPEI derived from the CHIRPS gridded data aggregated at the provincial scale across different timescales (1, 3, 6, and 12 months) for the agricultural years ranging from 2003 to 2018 provides insights into the relationship between the drought conditions and cereal production (Figures 7 and S4). We tested all the correlations for statistical significance at the 5% level (\(p\)-value \(<\) 0.05). The results show that all the moderate-to-high correlations (\(r\)\(>\) 0.5) are statistically significant, indicating a reliable relationship between the SPEI-based CHIRPS estimates and the SYRS. We marked these significant correlations with (*) in the graphs for clarity. In contrast, the weaker correlations were not statistically significant, suggesting that their relationship with the SYRS may not be reliable (Figures 7 and S4). Several provinces, including Safi (\(r\) = 0.80 for SPEI-6 in April and \(r\) = 0.79 for SPEI-12 in June), Rehamna (\(r\) = 0.69 for SPEI-6 in April and \(r\) = 0.68 for SPEI-12 in June), Marrakech (\(r\) = 0.69 for SPEI-6 in April and \(r\) = 0.63 for SPEI-12 in June), and Essaouira (\(r\) = 0.55 for SPEI-6 in April and \(r\) = 0.64 for SPEI-12 in June), show the highest statistically significant correlations with SPEI-12 in June and SPEI-6 in April, indicating the strong influence of precipitation over 12 months in June and 6 months in April on cereal yields. El Kelaa des Sraghna and Al Haouz also display this trend (\(r\) = 0.58 for SPEI-12 in June and \(r\) = 0.65 for SPEI-6 in April). In contrast, Chichaoua shows its highest correlations with shorter-term indices, such as SPEI-3 in January (\(r\) = 0.64) and SPEI-1 in December (\(r\) = 0.63), highlighting the importance of winter precipitation. Youssoufia, however, displays weaker and statistically non-significant correlations, possibly due to data quality issues, such as inaccuracies in the data collection process or errors in the data from this province (Figures 7 and S4). Figure 6: Temporal variations in SYRS for each province in MS region (2003–2018). The most influential precipitation patterns on cereal yields are the 6-month cumulative rainfall to April (SPEI-6_Apr) and the 12-month cumulative rainfall to June (SPEI-12_Jun). Short-term 1-month and medium-term 3-month precipitation have comparatively smaller impacts, highlighting the crucial role of yearly cumulative and late-season precipitation in determining cereal yields. Ensuring sufficient soil moisture levels before higher temperatures and increased crop water demand in April is essential for optimal crop growth. Numerous recent studies, including those conducted by the authors of [6; 25; 33; 72], have demonstrated the significant impact of meteorological drought on the yields of essential cereal crops, notably durum wheat, common wheat, and barley. Climate change, characterized by decreasing precipitation, increasing temperatures, and higher evapotranspiration, has intensified droughts and other extreme weather phenomena [3; 33; 73]. Droughts affect cereals completely by inducing water stress that impairs germination, root development, and nutrient absorption, thereby reducing the yield potential [74; 75; 76]. The high temperatures associated with droughts exacerbate these negative effects by inhibiting photosynthesis and accelerating cereal maturation. Drought-induced premature flowering and early senescence shorten the growing cycle, reducing biomass and grain yields [76; 77]. However, it is essential to note that the impacts of droughts vary across regions, depending on factors such as climatic conditions, soil characteristics, cereal varieties, agricultural practices, access to resources, and socio-economic factors [78; 79]. This vulnerability of cereals to droughts underscores the importance of understanding and managing the impacts of droughts to ensure food security.