Evaluating quantitative and qualitative variations in saffron across different regions, focusing on physiological, biochemical, and stigma-related traits, is vital for identifying the optimal cultivation areas. This work aimed to investigate the quantitative, qualitative, and biochemical characteristics of saffron grown at five research locations across Iran (Torogh Rood: RL-1, Natanz: RL-2, Kashan: RL-3, Qaenat: RL-4, and Badrood: RL-5) over two growing seasons. The results revealed that RL-2 and RL-4 significantly outperformed the yield and quality of other regions. Maximum flower count and dried stigma yields were recorded in RL-4, with 79.32 and 99.76 flowers/m² and 0.934 and 1.179 g/m² in the first and second years, respectively. Furthermore, RL-4 exhibited the highest concentrations of safranal (18.0 and 16.8 ), picrocrocin (110.9 and 133.2 ), and crocin (264.0 and 306.5 ) during the first and second years, respectively. Significant variations were observed across the regions in chlorophyll pigments, proline levels, total phenolic content, and antioxidant enzyme activity. A positive and significant relationship between yield, quality, and secondary metabolite content. Conversely, an important negative correlation was observed between the output and antioxidant enzyme activity levels. Higher levels of clay, silt, iron, and magnesium had a positive influence on the yield, quality, and secondary metabolite content. In contrast, elevated temperatures, sand content, and zinc levels were associated with decreased yield and quality. This study identifies RL-2 and RL-4 as optimal cultivation regions for saffron, attributed to their enhanced yield, superior quality, and elevated concentrations of key bioactive compounds, including safranal, picrocrocin, and crocin. |