Stomatal traits in pecan [Carya illinoinensis (Wangenh.) K. Koch]: varietal differences and seasonal adaptations under mediterranean conditions

In recent years, interest in non-traditional fruit species has grown, particularly as a strategy to diversify agricultural production in areas increasingly affected by extreme climatic conditions. In this context, pecan [Carya illinoinensis (Wangenh.) K. Koch], a fruit tree native to North America, represents a promising option for Mediterranean orchards due to its productive potential and nutritional value. However, the agronomic and commercial success of this species also depends on a deeper understanding of its morphological and physiological traits, which remain poorly studied under Italian growing conditions. In the seasons 2019 and 2020, a study was conducted on 10 pecan cultivars grown at the repository of the Department of Soil, Plant and Food Sciences, University of Bari ‘Aldo Moro’ located at the ‘Martucci’ experimental and educational centre in Valenzano (Bari province), Puglia region (Italy). Two leaf parameters were analysed: stomatal density (SD) and leaf area (LA). Data were statistically evaluated using ANOVA followed by the REGWQ post hoc test. The cultivars Cherokee and Choctaw exhibited the largest leaf areas (454.13 mm²), while Cape Fear showed the smallest (215.56 mm²). Regarding stomatal density, Stuart and Cape Fear had the highest values (589.58 and 566.66 stomata/mm², respectively), whereas Peruque and Cherokee recorded the lowest (427.08 and 444.79 stomata/mm²). The combined analysis of these parameters suggests the existence of differentiated morphological strategies among pecan cultivars, potentially linked to variations in photosynthetic efficiency and water stress response. These findings provide valuable insights for selecting pecan cultivars best suited to sustainable cultivation under Mediterranean conditions, thus contributing to more efficient and climate-resilient orchard management. Further studies will be conducted to better understand the relationship between SD and physiological, yield and quality parameters.