Scalable Methods for Fruit Shape and Stomatal Phenotyping in Southern Highbush Blueberry

Fruit shape and stomatal distribution influence fruit water status and postharvest quality in southern highbush blueberry ( Vaccinium corymbosum hybrids). This study developed scalable phenotyping methods to quantify fruit morphology and stomatal traits in cultivars Colossus and Optimus across four developmental stages. Fruit volume was estimated using geometric models validated against three-dimensional (3D) scans, with the spheroid model offering the best compromise between accuracy and efficiency ( R 2 = 0.96). StoManager1 software was validated for automated stomatal phenotyping, showing strong concordance with manual counts ( R 2 = 0.96). Results revealed cultivar-specific differences in shape development and stomatal distribution. As fruits matured, both cultivars exhibited increases in volume and surface area with decreasing sphericity. Stomata were localized primarily to distal regions of the fruit, particularly the calyx, suggesting heterogeneous water loss pathways across the fruit surface. These findings establish a framework for integrating morphometric and anatomical traits into high-throughput phenotyping pipelines and future studies on fruit water relations.