Quantifying tree-level peach flowering dynamics using UAV imagery and an optimized instance segmentation model

Abstract

A timely and accurate assessment of flowering characteristics is vital for tracking floral phenology in agricultural management and peach breeding. In this study, an unmanned aerial vehicle (UAV) equipped with a high-resolution camera was integrated with deep learning techniques to monitor peach flowering across multiple varieties. An instance segmentation model, PeFloSEG, was proposed for the accurate detection of peach flowers and buds. Based on the YOLOv5-seg framework, PeFloSEG integrates an enhanced detection head for improved feature representation and a modified loss function—Focal Efficient Intersection over Union (Focal-EIoU)—to optimize bounding box regression. To boost model efficiency, a network slimming algorithm was applied, significantly reducing model size while maintaining high accuracy. PeFloSEG achieved strong results, with mean average precision (mAP@0.5) scores of 0.876 for detection and 0.825 for segmentation, outperforming state-of-the-art algorithms by 0.5 %–24.9 % in detection and 5.7 %–28.1 % in segmentation. Three flowering indices derived from PeFloSEG outputs—flowering intensity (FI) indices (FI1 and FI2) and single-tree flowering ratio (SFR)—were evaluated. Linear correlation analysis revealed strong relationships between these indices and ground truth values, with R² values of 0.964 (FI1), 0.961 (FI2), and 0.986 (SFR). These indices were further used to assess flowering dynamics over time and to distinguish phenological stages, achieving an overall classification accuracy of 91.7 %. They also enabled effective variety classification, facilitating the exploration of flowering characteristics across different peach varieties. Overall, the proposed approach offers a scalable and efficient solution for high-throughput phenotyping and provides valuable tools for peach breeding and germplasm resource evaluation.

Plant phenotyping relevance

UAV画像とインスタンスセグメンテーションモデルを開発し、花数・開花強度・単木開花率などの植物表現型を定量化することが研究の中心であるため。

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