Modeling Free Proline Accumulation in Four Mediterranean Geophytes: A Comparative Analysis of Pancratium maritimum, Sternbergia lutea, Iris germanica, and Cyclamen graecum

Free proline accumulation is an important physiological trait frequently associated with plant responses to changing environmental conditions. This study investigated seasonal patterns of free proline concentration in the underground organs of four Mediterranean geophytes—Pancratium maritimum, Sternbergia lutea, Iris germanica, and Cyclamen graecum—under natural environmental conditions. Monthly temperature and precipitation data were incorporated to examine the influence of environmental factors on proline dynamics. The results revealed clear species-specific and seasonal variation in proline accumulation. Sternbergia lutea exhibited the highest proline concentrations and the greatest seasonal variability, whereas Iris germanica maintained comparatively low and stable levels. To evaluate descriptive performance, both a linear seasonal regression model and a Random Forest regression model were applied. The linear model showed moderate predictive performance (R2 = 0.488), slightly outperforming the Random Forest model (R2 = 0.350). Overall, the findings demonstrate clear species-specific differences in seasonal proline accumulation that are consistent with differing physiological responses among the studied geophytes. The pronounced interspecific differences observed in this study suggest that proline accumulation is a species-specific physiological trait rather than a universal response among Mediterranean geophytes. The integration of physiological measurements with statistical and machine learning approaches provides an exploratory framework for examining seasonal variation in proline accumulation and evaluating statistical approaches for describing species-specific patterns.