Climate and Region-Specific CO2 Effects on Wheat Phenology in Greece and Cyprus: A Satellite-Based Assessment

Accurate assessment of crop phenology under changing climate conditions is essential for agricultural planning and food security, particularly in regions where wheat production is sensitive to temperature and water availability. This study examines the long-term phenological responses of wheat across six sites in Greece and five in Cyprus over a 24-year period (2001–2024), using MODIS-derived NDVI time series to extract start of season (SOS), end of season (EOS) and length of season (LOS). SOS advanced consistently in both countries, while EOS was delayed in Greece but advanced in Cyprus. As a result, LOS increased across Greek sites but showed mixed responses in Cyprus, with no significant average change. Spatial differences were associated with latitude, with higher-latitude Greek sites exhibiting later SOS and EOS, whereas temporal trends were linked to climatic variability. Linear mixed-model analyses identified temperature as the dominant climatic driver of SOS and EOS in both regions, with precipitation exerting additional, but region-specific influences. A key finding is that atmospheric CO2 emerged as an additional statistical predictor of EOS in Greece, where it was associated with later EOS, offsetting the climate-driven advance in the model, and was marginally associated with LOS extension. In contrast, no CO2 association was detected for Cyprus, possibly reflecting more constrained environmental conditions. These findings highlight the importance of integrating geographic, climatic and atmospheric variables to capture crop-specific responses and support region-specific adaptation strategies in Mediterranean agroecosystems vulnerable to climate change.