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

Yiyin He; Zhao Wang; Sashuang Sun; Lijun Zhu; Yu Li; Xiaoxiao Wang; Jiang Shi; Si Chen; Dunchang Qi; Junxiang Peng; Zhenjiang Zhou

doi:10.3389/fpls.2023.1208404

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

Front Plant Sci. 2023 Sep 18:14:1208404. doi: 10.3389/fpls.2023.1208404. eCollection 2023.

Authors

Yiyin He^{1

2}, Zhao Wang^{1

2}, Sashuang Sun^{1

2}, Lijun Zhu^{1

2}, Yu Li³, Xiaoxiao Wang³, Jiang Shi⁴, Si Chen⁵, Dunchang Qi¹, Junxiang Peng⁶, Zhenjiang Zhou^{1

2}

Affiliations

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, China.
² Huanan Industrial Technology Research Institute of Zhejiang University, Guangzhou, China.
³ Agricultural Experiment Station, Zhejiang University, Hangzhou, China.
⁴ Hangzhou Academy of Agricultural Sciences, Hangzhou, China.
⁵ College of Water Resources and Environmental Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, China.
⁶ Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences, Umeå, Sweden.

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 (R²) 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 R² 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.

Keywords: Choy Sum; N fertilization; canopy coverage; dry matter; radiation use efficiency.

Grants and funding

This research was funded by the Science and Technology Department of Guangdong Province (grant 2019B020216001), the National Key Research and Development Program of China (grant 2019YFE0125500-02), and the National Natural Science Foundation of China (grant 52109069).