Abstract
Abstract The spectral range <1,000 nm is commonly used for estimating the chlorophyll content of plants. However, the influence of the response band of leaf water content in the Short‐Wave InfraRed on the chlorophyll estimate model is uncertain. We measured the Visible‐Near InfraRed‐Short Wave InfraRed spectral reflectance and SPAD values of rice ( Oryza sativa L.) leaves at different growth stages. The vegetation indices (VIs), red edge positions (REPs), and spectral characteristic parameters (SCPs) were calculated. The correlation between the above parameters and SPAD was analyzed. The effects of chlorophyll and water content on the spectral reflectance absorption characteristics of rice leaves were analyzed by the PROSPECT model. SPAD spectral estimation models were established with different inputs using the Random Forest (RF) regression algorithm. Our results are described as follows: (a) The spectral reflectance after continuum removal of rice leaves was highly correlated with SPAD in 600–690, 720–760, 1,400–1,490, and 1,900–1,980 nm. (b) Compared with VIs and REPs, the SCPs after continuum removal including the Depth (D1) and Area (A1, A2) parameters had the highest correlation with SPAD. (c) By taking into account the influence of leaf water content (LWC), the accuracy of SPAD estimation may be enhanced. The RF SPAD estimate model with SCPs of all absorption valley as inputs performed the best. The findings reveal on the mechanism of the influence of LWC on the accuracy of chlorophyll spectra estimation. It provides technical support for estimating SPAD in rice leaves with high accuracy and for developing chlorophyll tachistoscopes.
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Claims 4
Claim · model-written summary
Continuum-removed rice leaf reflectance correlated highly with SPAD in four spectral ranges.
- Taxon
- rice
Oryza sativae0 - Outcome
- SPADe0
- Qualifier
- 600–690, 720–760, 1,400–1,490, and 1,900–1,980 nme0
Not reportedSettingDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The spectral reflectance after continuum removal of rice leaves was highly correlated with SPAD in 600–690, 720–760, 1,400–1,490, and 1,900–1,980 nm”
Claim · model-written summary
Continuum-removed depth D1 and area A1 and A2 parameters had the highest correlation with SPAD among the compared parameters.
- Taxon
- riceOryza sativat0
- Outcome
- correlation with SPADe0
- Comparator
- VIs and REPse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with VIs and REPs, the SCPs after continuum removal including the Depth (D1) and Area (A1, A2) parameters had the highest correlation with SPAD”
t0“rice leaves”
Claim · model-written summary
Accounting for leaf water content may enhance SPAD estimation accuracy.
- Taxon
- riceOryza sativat0
- Outcome
- accuracy of SPAD estimatione0
- Direction
- enhancede0
- Qualifier
- may be enhancede0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By taking into account the influence of leaf water content (LWC), the accuracy of SPAD estimation may be enhanced”
t0“rice leaves”
Claim · model-written summary
The random forest SPAD model using spectral characteristic parameters from all absorption valleys performed best.
- Taxon
- riceOryza sativat0
- Outcome
- performed the beste0
- Direction
- beste0
- Comparator
- SCPs of all absorption valleye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The RF SPAD estimate model with SCPs of all absorption valley as inputs performed the best”
t0“rice leaves”