Acta Agriculturae Zhejiangensis ›› 2023, Vol. 35 ›› Issue (6): 1265-1277.DOI: 10.3969/j.issn.1004-1524.2023.06.04

• Crop Science • Previous Articles     Next Articles

Estimation of rice leaf water content based on leaf reflectance spectrum and chlorophyll fluorescence

ZHANG Xuenan1(), WANG Lele1, NIU Mingxuan1, ZHAN Ni1, REN Haojie2, XU Haocong1, YANG Kun1, WU Liquan1,3, KE Jian1, YOU Cuicui1, HE Haibing1,*()   

  1. 1. College of Agronomy, Anhui Agricultural University, Hefei 230036, China
    2. Pujiwei Modern Agriculture Group Co., Ltd., Tongling 244071, Anhui, China
    3. Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing 210095, China
  • Received:2022-07-15 Online:2023-06-25 Published:2023-07-04

Abstract:

Rapid and non-destructive monitoring to leaf water content (LWC) in rice is of great significance for guiding precision irrigation of paddy fields and improving water use efficiency of rice plants. In this study, three different water treatments including traditional flooded irrigation, mild dry-wet alternation with-15 kPa supplementary irrigation critical value, severe dry-wet alternation with-30 kPa supplementary irrigation critical value were set in pot experiment to precisely regulate plant growth. The LWC of the canopy, single leaf spectral data and chlorophyll fluorescence parameters of the top 1 (L1), top 2 (L2), and top 3 (L3) leaves were continuously measured in the water-sensitive periods from heading to grain filling period. Water-sensitive bands were screened out through the full spectral bands to establish a new vegetation index. An accurate monitoring model for rice LWC based on leaf position combination was established in combination with the chlorophyll fluorescence parameters. It was found that: The sensitive water band is in the near-infrared band (1 000-1 400 nm), and a new vegetation index NDSII(1114,1387) was constructed. By screening the fluorescence parameters with a high correlation with LWC, the coupled monitoring model based on the actual photochemical efficiency Y(Ⅱ) and the vegetation index NDSII(1114,1387) was 71.807%-83.976% better accuracy than the single vegetation index NDSII(1114,1387) model. Compared with the single leaf, the Y(Ⅱ) and vegetation index NDSII(1114,1387) coupling model of L2and L3leaf position combination significantly improved the accuracy of LWC monitoring of rice canopy by 11.641% and 23.029% compared with L2and L3. This showed that the coupling of leaf reflectance spectrum and chlorophyll fluorescence could effectively monitor the LWC in the water-sensitive period of rice, providing a theoretical basis for optical instrument monitoring of rice LWC and theoretical support for future research on crop photosynthesis using the reflectance spectrum and fluorescence parameters.

Key words: leaf water content, Oryza sativa L., vegetation index, chlorophyll fluorescence parameter, model

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