Hyperspectral Response to Leaf Nitrogen in Sugarcane: Dynamic Effects of Cultivar, Growth Stage, and Leaf Position with Model Inversion

Abstract

Abstract Rapid and non-destructive monitoring of leaf nitrogen (N) content (LNC) is essential for precision N management in sugarcane ( Saccharum officinarum L .). However, the accuracy of hyperspectral estimation is challenged by the dynamic interactions among cultivar, growth stage, and leaf position. This study systematically investigated the effects of these three factors on LNC and leaf hyperspectral reflectance (400–1000 nm) across six main sugarcane varieties. We identified sensitive spectral bands and developed LNC inversion models using Partial Least Squares Regression (PLSR) and Random Forest (RF). The results revealed highly significant interactive effects (P Context: Although previous studies has resulted in substantial knowledge on crop N monitoring via spectroscopy, systematic investigations into the "leaf N content–spectral characteristics" response mechanisms in sugarcane at the leaf level remain limited. Aims: This study was designed to address these critical research gaps. The specific objectives were to: (1) quantify the independent and interactive effects of cultivar, growth stage, and leaf position on sugarcane LNC and spectral reflectance; (2) identify the most sensitive spectral bands responsive to LNC changes across different varieties; and (3) construct and evaluate robust estimation models for sugarcane LNC using advanced machine learning algorithms. Our findings are expected to provide a solid theoretical foundation and technical support for developing remote sensing technologies tailored for precision N management in sugarcane fields.

Plant phenotyping relevance

サトウキビ葉の窒素含量という植物形質をハイパースペクトル反射から推定するモデルを開発・評価しており、表現型取得手法が研究の中心である。

Code and data availability

The paper's hyperspectral reflectance and leaf nitrogen measurements (648 leaf samples) and analysis code are not publicly deposited; the Data Availability Statement says data are available only upon request from the authors. No public URL, repository, or code deposit is provided.

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