Temperature-dependent variations in saffron (Crocus sativus L.) quality: A GIS-based suitability analysis of apocarotenoid concentrations

Abstract

The quality of saffron (Crocus sativus L.) stigma is determined through its apocarotenoid content, especially crocin, picrocrocin, and safranal (C-P-S), which affect its dye, flavour and fragrance, respectively. This study provides a GIS-based technique to assess land suitability for saffron cultivation, emphasizing the crucial role of summer temperature in optimizing C-P-S concentrations. Data were collected from 23 saffron fields, where C-P-S content was quantified using High-Performance Liquid Chromatography (HPLC). Long-term temperature data were extracted from TerraClimate database using Google Earth Engine and analyzed in a GIS environment to identify optimal summer temperature ranges. Optimal temperature ranges were established based on conditions observed in the best-performing fields, with deviations classified as suboptimal. These temperature thresholds were used to define climatic and quality zones, resulting in the identification of 34 climatic zones and 71 stigma quality zones across the studied provinces. Results indicate that only 5 % of the total arable land falls within the highest-quality zone, with the most suitable regions located in Razavi Khorasan Province. A strong negative correlation was observed between increasing summer temperatures and declining crocin and picrocrocin levels, demonstrating a temperature-sensitive response. These findings provide a perspective for agricultural decision-makers and support the development of climate-adaptive strategies for saffron cultivation.