Isotope Tracer Technique·Ecology and Environment·Physiology
ZHANG Bohan, HAN Tonghe, FEI Shuaipeng, LI Lei, JIA Yidan, XIAO Yonggui, GUO Lin, MENG Yaxiong
Current quantitative assessment methods are hindered by several critical limitations: inadequate characterization of lodging dynamics across growth stages, poor generalizability of conventional single-modal algorithms, and a lack of robust frameworks for multi-source data synergy and integration analysis. In this study, four deep learning models—U-Net, DeepLabV3+, PSP-Net, and HR-Net were employed to extract lodging regions from RGB images of 3 783 natural wheat populations. The multi-spectral data was integrated to calculate vegetation indices and a yield estimation model were constructed using four machine learning algorithms, including Support Vector Machine (SVM), Gradient Boosting Regression (GBR), Multilayer Perceptron (MLP), and Random Forest (RF). Yield loss was calculated by comparing predicted normal growth yield with the actual harvested yield after lodging. The results showed that for the task of lodging region extraction, U-Net achieved the highest recall and mean average precision, both exceeding 90.63%. However, its precision was slightly lower than that of the other three models. Under different growth conditions, there is significant variation in the accuracy of wheat lodging-region extraction. At the heading stage, the R² value ranged from 0.19 to 0.32, it increased to 0.84-0.88 in the early grain-filling stage, then decreased to 0.71-0.77 in the mid-grain-filling stage, and remained at 0.65-0.74 in the late grain-filling stage. It indicated that early grain-filling stage was the optimal period for lodging region extraction. During the heading and grain-filling stages of wheat, incorporating lodging features extracted by the U-Net algorithm into the yield estimation models resulted in an increase of R² value by 0-0.26. The model constructed by the MLP algorithm achieving the highest accuracy (R²=0.68) in the early grain-filling stage. For yield loss prediction, an ‘upright-lodging dual-track modeling’ strategy was adopted: first, upright-wheat yield models that did not incorporate lodging-area features were built separately using four algorithms SVM, GBR, MLP and RF to estimate the potential yield; second, lodging-wheat yield models were established, and the difference between the two predictions was taken as the actual yield loss caused by lodging. The MLP-MLP algorithm achieved the highest accuracy (R²=0.89) and the smallest error (RMSE=419.47 kg·hm-2) in estimating yield loss when predicting both lodged and normal wheat yields. In summary, the combination of multiple intelligent algorithms improved the accuracy of wheat lodging region extraction and yield loss estimation. This study provides theoretical basis and technical support for high-precision assessing the impact of lodging on wheat yield loss.