Climatic Structure Analysis of Olive Growing in Extremadura, South-West Spain

This study analysed the climatic characteristics of olive growing in Extremadura, a region in western Spain with some of the largest areas and production in Europe. A daily database was created from 47 weather stations located throughout Extremadura during the olive growing season from 1990-2021. To characterise and determine the olive growing climatology in Extremadura, the climatic variables and ten bioclimatic-physiological indices that provide information on the be-haviour of the olive tree have been calculated. The correlation between the fourteen variables used was carried out, a reduction was made and the number of minimum factors was determined using principal component analysis (PCA) and, in order to obtain homogeneous groups, cluster analysis was carried out. The result of index reduction revealed that annual rainfall (Rr), annual water re-quirement (AWR), mean annual temperature (Tavg), degree days above 14.4 °C accumulated in the olive growing period (GDD14.4) and the number of days with optimal temperatures for carbohy-drate synthesis in leaves (NDCHS) were sufficient to characterise the agricultural regions of Ex-tremadura, explaining between them 97.24% of the observed variability. The results indicate the presence of two principal components, one pertaining to thermal-physiological factors (PC1) and the other to hydric variables (PC2). Three homogeneous groups were determined by cluster analysis, one of which had cooler thermal conditions and no water requirements. The study found that an increase in the olive growing season or a shortening of the dormant period could result in a higher water input during the growing season and a lack of accumulation of chilling hours during the dormant period, causing crop maintenance problems in warmer locations. Climate change is expected to have significant impacts on this crop where climatic conditions are already very hot and dry. In the future, it is possible that the current olive growing areas in Extremadura will move to other areas where the temperature is cooler.