UAV-Based Yield Prediction Based on LAI Estimation in Winter Wheat ( Triticum aestivum L.) Under Different Nitrogen Fertilizer Types and Rates.

Abstract

The rapid and accurate prediction of crop yield and the construction of optimal yield prediction models are important for guiding field-scale agronomic management practices in precision agriculture. This study selected the leaf area index (LAI) of winter wheat ( Triticum aestivum L.) at four different stages, and collected canopy spectral information and extracted vegetation indexes through unmanned aerial vehicle (UAV) multi-spectral sensors to establish the yield prediction model under the condition of slow-release nitrogen fertilizer and proposed optimal fertilization strategies for sustainable yield increase in wheat. The prediction results were evaluated using random forest (RF), support vector machine (SVM) and back propagation neural network (BPNN) methods to select the optimal spectral index and establish yield prediction models. The results showed that LAI has a significantly positive correlation with yield across four growth stages of winter wheat, and the correlation coefficient at the anthesis stage reached 0.96 in 2018-2019 and 0.83 in 2019-2020. Therefore, yield prediction for winter wheat could be achieved through a remote sensing estimation of LAI at the anthesis stage. Six vegetation indexes calculated from UAV-derived reflectance data were modeled against LAI, demonstrating that the red-edge vegetation index (CI red edge ) achieved superior accuracy in estimating LAI for winter wheat yield prediction. RF, SVM and BPNN models were used to evaluate the accuracy and precision of CI red edge in predicting yield, respectively. It was found that RF outperformed both SVM and BPNN in predicting yield accuracy. The CI red edge of the anthesis stage was the best vegetation index and stage for estimating yield of winter wheat based on UAV remote sensing. Under different N application rates, both predicted and measured yields exhibited a consistent trend that followed the order of SRF (slow-release N fertilizer) > SRFU1 (mixed TU and SRF at a ratio of 2:8) > SRFU2 (mixed TU and SRF at a ratio of 3:7) > TU (traditional urea). The optimum N fertilizer rate and N fertilizer type for winter wheat in this study were 220 kg ha -1 and SRF, respectively. The results of this study will provide significant technical support for regional crop growth monitoring and yield prediction.

Plant phenotyping relevance

UAVマルチスペクトル画像からLAIを推定し、収量予測モデルを構築・比較しており、植物形質の取得・推定手法が中心的に扱われている。

Code and data availability

The paper's UAV multispectral imagery, LAI/yield measurements, and RF/SVM/BPNN analysis code are not publicly available: the Data Availability Statement states the supporting data are available only on request from the corresponding author. The only public supplement (MDPI s1 link) contains just 'Figure S1: Diagrams of

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