Estimation of Chlorophyll Content in Maize Leaves Based on Optimized Area Spectral Index

Yu-zhe TANG; Mei HONG; Jia-yong HAO; Xu WANG; He-jing ZHANG; Wei-jian ZHANG; Fei LI

doi:10.3964/j.issn.1000-0593(2022)03-0924-09

Journals >Spectroscopy and Spectral Analysis >Volume 42 >Issue 3 >Page 924 > Article

Spectroscopy and Spectral Analysis
Vol. 42, Issue 3, 924 (2022)

Estimation of Chlorophyll Content in Maize Leaves Based on Optimized Area Spectral Index

Yu-zhe TANG^*, Mei HONG, Jia-yong HAO, Xu WANG, He-jing ZHANG, Wei-jian ZHANG, and Fei LI^*;

Author Affiliations

College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Inner Mongolia Key Laboratory of Soil Quality and Nutrient Resources, Inner Mongolia Agricultural University, Huhhot 010018, China

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DOI: 10.3964/j.issn.1000-0593(2022)03-0924-09 Cite this Article

Yu-zhe TANG, Mei HONG, Jia-yong HAO, Xu WANG, He-jing ZHANG, Wei-jian ZHANG, Fei LI. Estimation of Chlorophyll Content in Maize Leaves Based on Optimized Area Spectral Index[J]. Spectroscopy and Spectral Analysis, 2022, 42(3): 924 Copy Citation Text

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Fig. 1. Descriptive statistics of leaf SPAD values in different growth stages of maize

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Contour maps of the coefficient of determination (R2) between leaf chlorophyll content and OCAI index(a): V6 stage; (b): V12 stage; (c): VT stage; (d): R3 stage

Fig. 2. Contour maps of the coefficient of determination (R²) between leaf chlorophyll content and OCAI index
(a): V6 stage; (b): V12 stage; (c): VT stage; (d): R3 stage

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Fig. 3. Contour maps of the coefficient of determination (R²) between leaf chlorophyll content and OTVI index
(a): V6 stage; (b): V12 stage; (c): VT stage; (d): R3 stage

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Fig. 4. Contour maps of the coefficient of determination (R²) between leaf chlorophyll content and ONDDA index

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Fig. 5. The linear relationship between leaf chlorophyll contents in four growth stages and the top 6 spectral indices of estimation ability

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Fig. 6. Comparison between observed and predicted leaf chlorophyll contents based on six spectral indices

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Fig. 7. The sensitive bands of OCAI, OTVI and ONDDA at different growth stages

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光谱指数	算法	参考文献
三角形面积指数
Triangular greenness index (TGI)	-0.5[(670-480)(R₆₇₀-R₅₅₀)-(670-550)(R₆₇₀-R₄₈₀)]	Hunt et al. (2013)
Triangular chlorophyll index (TCI)	1.2(R₇₀₀-R₅₅₀)-1.5(R₆₇₀-R₅₅₀)(R₇₀₀/R₆₇₀)⁰^.⁵	Haboudane et al. (2008)
Triangle vegetation index (TVI)	0.5×[120×(R₇₅₀-R₅₅₀)-200×(R₆₇₀-R₅₅₀)]	Broge and Leblanc (2000)
Modified triangular vegetation index 1 (MTVI1)	1.2×[1.2×(R₈₀₀-R₅₅₀)-200×(R₆₇₀-R₅₅₀)]	Haboudane et al.(2004)
Modified triangular vegetation index 2 (MTVI2)	$\frac{1.5 \times [1.2 \times (R_{800} - R_{500}) - 2.5 \times (R_{670} - R_{550})]}{\sqrt[]{(2 \times R_{800} {+ 1)}^{2} - (6 \times R_{800} - 5 \times \sqrt[]{R_{670}}) - 0.5}}$	Haboudane et al. (2004)
Optimized triangle vegetation index(OTVI)	0.5×[(λ₂-550)×(Rλ₁-Rλ₂)-(Rλ₂-R₅₅₀)×(λ₁-λ₂)]^[1]	Li et al. (2013)
叶绿素吸收面积指数
Chlorophyll absorption ratio index (CARI)	[R₇₀₀×abs(a×670+R₆₇₀+b)]/R₆₇₀×(a²+1 ${)^{0.5}}^{[2]}$	Kim et al. (1994)
Modified chlorophyll absorption reflectance index (MCARI)	[(R₇₀₀-R₆₇₀)-0.2(R₇₀₀-R₅₅₀)](R₇₀₀/R₆₇₀)	Daughtry et al. (2000)
Modified chlorophyll absorption reflectance index 1 (MCARI1)	1.2×[2.5×(R₈₀₀-R₆₇₀)-1.3×(R₈₀₀-R₅₅₀)]	Haboudane et al. (2004)
Modified chlorophyll absorption reflectance index 2 (MCARI2)	$\frac{1.2 \times [2.5 \times (R_{800} - R_{670}) - 1.3 \times (R_{800} - R_{550})]}{\sqrt[]{(2 \times R_{800} {+ 1)}^{2} - (6 \times R_{800} - 5 \times \sqrt[]{R_{670}}) - 0.5}}$	Haboudane et al. (2004)
MCARI (705, 750)	[(R₇₅₀-R₇₀₅)-0.2(R₇₅₀-R₅₅₀)](R₇₅₀/R₇₀₅)	Wu et al. (2008)
Transformed chlorophyll absorption reflectance index (TCARI)	3×[(R₇₀₀-R₆₇₀)-0.2(R₇₀₀-R₅₅₀)(R₇₀₀/R₆₇₀)]	Haboudane et al. (2002)
TCARI (750, 705)	3×[(R₇₅₀-R₇₀₅)-0.2(R₇₅₀-R₅₅₀)(R₇₅₀/R₇₀₅)]	Wu et al. (2008)
Red-edge absorption chlorophyll area(RECA)	$\int_{680}^{780} \frac{R}{R_{780}}$	Ren et al. (2011)
Red-edge absorption valley area (REA)	$1 / 2 \times (R_{680 + Δ λ} - R_{680}) \times Δ λ^{[3]}$	Guo et al. (2017)
Optimized red-edge absorption valley area (OREA)	15×(3×R₇₆₀ -R₅₅₀)-20×(R₆₈₀+2R₇₂₀)	Wen et al. (2020)
Normalized area over reflectance curve (NAOC)	$1 - {\frac{\int_{a}^{b} ρ d λ}{ρ_{\max} (b - a)}}^{[4]}$	Delegido et al. (2010)
Chlorophyll absorption integral (CAI)	$\int_{600}^{735} {\frac{R_{si}}{R_{ei}}}^{[5]}$	N. Oppelt et al. (2007)
Optimized Chlorophyll absorption integral (OCAI)	$\int_{E}^{F} {\frac{R_{si}}{R_{ei}}}^{[6]}$	This study
波形变换指数
Area under curve Normamised to Maximal Band(ANMB)	AUC_500-800/MBD_500-800	Malenovsky et al. (2006)
Double-peak canopy nitrogen index (DCNI)	(R₇₂₀-R₇₀₀)/(R₇₀₀-R₆₇₀)/(R₇₂₀-R₆₇₀+0.03)	Chen et al. (2010)
Optimized double-peak canopy nitrogen index (ODCNI)	(R₇₂₀-R₇₀₀)/(R₇₀₀-R₆₇₀)/(R₇₂₀-R₆₇₀+n); n=[-1∶1]	This study
Difference index of the double-peak areas(DIDA)	(R₇₅₅+R₆₈₀-3×R₇₁₈)/(R₇₅₅-R₆₈₀)	Feng et al. (2014)
Ratio index of the double-peak areas(RIDA)	$\frac{RSDR}{LSDR}$	Feng et al. (2014)
Double-peak areas based on REP division(NDDA)	(R₇₅₅+R₆₈₀-2×R_REPig)/(R₇₅₅-R₆₈₀)	Feng et al. (2014)
Optimized double-peak areas based on REP division(ONDDA)	$(\int_{D}^{675} - \int_{D}^{721}) / \int_{D}^{675}$	This study

Table 1. Spectral indices

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	EXP.1					EXP.2				EXP.3
	V6	V12	VT	R3	All	V12	VT	R3	All	VT	All
基于三角形面积的光谱指数
TGI	0.83	0.90	0.95	0.95	0.92	0.95	0.93	0.95	0.94	0.95	0.94
TCI	0.81	0.87	0.91	0.92	0.88	0.95	0.90	0.92	0.91	0.89	0.89
TVI	0.35	0.62	0.86	0.74	0.59	0.59	0.56	0.74	0.61	0.83	0.60
MTVI1	0.37	0.65	0.85	0.75	0.62	0.61	0.55	0.78	0.63	0.84	0.63
MTVI2	0.65	0.91	0.94	0.94	0.85	0.88	0.92	0.93	0.91	0.93	0.87
OTVI	0.85	0.94	0.98	0.95	0.95	0.90	0.95	0.97	0.94	0.95	0.95
基于叶绿素吸收面积的光谱指数
CARI	0.70	0.35	0.90	0.93	0.65	0.92	0.92	0.93	0.91	0.89	0.87
MCARI	0.80	0.87	0.87	0.89	0.85	0.94	0.88	0.91	0.90	0.86	0.87
MCARI1	0.57	0.66	0.85	0.75	0.62	0.61	0.55	0.79	0.63	0.84	0.63
MCARI2	0.65	0.91	0.94	0.95	0.85	0.88	0.92	0.93	0.91	0.93	0.87
MCARI(705, 750)	0.67	0.83	0.96	0.93	0.86	0.83	0.90	0.95	0.88	0.95	0.87
TCARI	0.80	0.87	0.94	0.94	0.90	0.95	0.92	0.94	0.93	0.92	0.92
TCARI(750, 705)	0.37	0.56	0.89	0.71	0.67	0.81	0.85	0.71	0.79	0.86	0.73
RECA	0.58	0.73	0.93	0.93	0.81	0.85	0.88	0.94	0.88	0.93	0.84
CAI	0.38	0.56	0.82	0.88	0.63	0.93	0.89	0.89	0.88	0.88	0.67
REA	0.76	0.88	0.95	0.92	0.89	0.86	0.92	0.90	0.89	0.93	0.89
NAOC	0.81	0.90	0.97	0.95	0.93	0.92	0.95	0.96	0.94	0.94	0.91
OREA	0.81	0.89	0.97	0.95	0.92	0.89	0.83	0.96	0.92	0.95	0.92
OCAI	0.82	0.91	0.96	0.95	0.92	0.94	0.95	0.96	0.94	0.95	0.93
基于波形变换的光谱指数
ANMB	0.69	0.80	0.94	0.95	0.86	0.69	0.88	0.94	0.94	0.93	0.89
DCNI	0.64	0.75	0.93	0.91	0.83	0.86	0.93	0.80	0.85	0.92	0.84
DIDA	0.79	0.88	0.97	0.96	0.92	0.92	0.95	0.95	0.94	0.96	0.85
RIDA	0.80	0.87	0.96	0.93	0.89	0.87	0.93	0.88	0.89	0.97	0.93
NDDA	0.82	0.89	0.95	0.95	0.92	0.95	0.91	0.92	0.91	0.92	0.88
ODCNI	0.65	0.77	0.94	0.92	0.84	0.87	0.94	0.81	0.86	0.93	0.85
ONNDA	0.88	0.94	0.99	0.98	0.96	0.97	0.97	0.97	0.96	0.98	0.96

Table 2. Coefficient of determination (R²) of the linear relationships between leaf chlorophyll content and spectral indices in different growth stages

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Spectral index	R²	RMSE	NRMSE/%	Slope
TGI	0.928	2.543	4.585	0.917
TCARI	0.912	2.794	5.077	0.907
ANMB	0.845	3.951	7.099	0.951
OTVI	0.936	2.403	4.116	0.973
OCAI	0.939	2.359	4.012	0.922
ONDDA	0.943	2.285	3.938	0.996

Table 3. Characteristics of the regression between observed and estimated SPAD values

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