Using crop intercepted solar radiation and vegetation index to estimate dry matter yield of Choy Sum

Abstract

An accurate assessment of vegetable yield is essential for agricultural production and management. One approach to estimate yield with remote sensing is via vegetation indices, which are selected in a statistical and empirical approach, rather than a mechanistic way. This study aimed to estimate the dry matter of Choy Sum by both a causality-guided intercepted radiation-based model and a spectral reflectance-based model and compare their performance. Moreover, the effect of nitrogen (N) rates on the radiation use efficiency ( RUE ) of Choy Sum was also evaluated. A 2-year field experiment was conducted with different N rate treatments (0 kg/ha, 25 kg/ha, 50 kg/ha, 100 kg/ha, 150 kg/ha, and 200 kg/ha). At different growth stages, canopy spectra, photosynthetic active radiation, and canopy coverage were measured by RapidScan CS-45, light quantum sensor, and camera, respectively. The results reveal that exponential models best match the connection between dry matter and vegetation indices, with coefficients of determination ( R 2 ) all below 0.80 for normalized difference red edge (NDRE), normalized difference vegetation index (NDVI), red edge ratio vegetation index (RERVI), and ratio vegetation index (RVI). In contrast, accumulated intercepted photosynthetic active radiation ( Aipar ) showed a significant linear correlation with the dry matter of Choy Sum, with root mean square error ( RMSE ) of 9.4 and R 2 values of 0.82, implying that the Aipar -based estimation model performed better than that of spectral-based ones. Moreover, the RUE of Choy Sum was significantly affected by the N rate, with 100 kg N/ha, 150 kg N/ha, and 200 kg N/ha having the highest RUE values. The study demonstrated the potential of Aipar -based models for precisely estimating the dry matter yield of vegetable crops and understanding the effect of N application on dry matter accumulation of Choy Sum.

Plant phenotyping relevance

植生指数および積算遮断光合成有効放射からチョイサムの乾物収量を推定するモデルを開発・比較し、RMSEやR²で性能評価しており、植物形質取得手法が中心である。

Code and data availability

The paper reports field-measured canopy spectra, PAR, canopy coverage images, and dry matter data, but no public dataset, code, or model deposit is provided. The data availability statement says raw data will be made available by the authors upon request, so access requires contacting the authors.

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