Abstract
Based on the field experiments with different rice varieties and nitrogen application rates,a comprehensive analysis was made on the quantitative relationships between hyperspectral vegetation indices of rice canopy and its leaf nitrogen concentration(LNC) at different rice growth stages.The wave bands most sensitive to the canopy LNC were in red region(665-675 nm),blue region(490-500 nm),and red edge region(680-760 nm).Within the range of 400-2500 nm,the wave bands showing the best relationships between rice canopy vegetation indices and LNC were 550-600 nm and 500-550 nm in green region,and the ratio index SR(533,565) had the highest value of determination coefficient(R2).However,the spectral parameter established with three wavelengths in blue region,i.e.,blue nitrogen index R434/(R496 + R401),had a significant linear relationship with the canopy LNC,and made the prediction accuracy of the canopy LNC promoted significantly,compared with SR(533,565).The tests with independent datasets showed that R434/(R496 + R401) was a reliable indicator of rice canopy LNC,with the RMSE and RE values between measured and estimated LNC being 9.67% and 8%,respectively.Therefore,the newly developed blue nitrogen index R434/(R496 + R401) was recommended as a good indicator of rice canopy LNC.
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Claims 8
Claim · model-written summary
In rice, wave bands most sensitive to canopy leaf nitrogen concentration lay in the red, blue and red edge regions.
- Taxon
- rice
Oryza sativat0 - Outcome
- wave bands most sensitive to the canopy LNCe1
- Value
- red region(665-675 nm),blue region(490-500 nm),and red edge region(680-760 nm)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The wave bands most sensitive to the canopy LNC were in red region(665-675 nm),blue region(490-500 nm),and red edge region(680-760 nm)”
t0“rice”
Claim · model-written summary
Wave bands with the best relationships between rice canopy vegetation indices and LNC were 550-600 nm and 500-550 nm in the green region.
- Taxon
- riceOryza sativae1
- Outcome
- wave bands showing the best relationshipse1
- Value
- 550-600 nm and 500-550 nme1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the wave bands showing the best relationships between rice canopy vegetation indices and LNC were 550-600 nm and 500-550 nm in green region”
Claim · model-written summary
The ratio index SR(533,565) had the highest determination coefficient (R2) with rice canopy LNC.
- Taxon
- riceOryza sativat0
- Outcome
- highest value of determination coefficient(R2)e1
- Qualifier
- ratio index SR(533,565)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the ratio index SR(533,565) had the highest value of determination coefficient(R2)”
t0“rice”
Claim · model-written summary
The blue nitrogen index R434/(R496 + R401) had a significant linear relationship with rice canopy LNC.
- Taxon
- riceOryza sativat0
- Organ / stage
- canopye1
- Outcome
- canopy LNCe1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“had a significant linear relationship with the canopy LNC”
t0“rice”
Claim · model-written summary
The blue nitrogen index significantly improved prediction accuracy of rice canopy LNC compared with SR(533,565).
- Taxon
- riceOryza sativat0
- Outcome
- prediction accuracy of the canopy LNCe1
- Direction
- promoted significantlye1
- Comparator
- SR(533,565)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“made the prediction accuracy of the canopy LNC promoted significantly,compared with SR(533,565)”
t0“rice”
Claim · model-written summary
In tests with independent datasets, R434/(R496 + R401) estimated rice canopy LNC with an RMSE of 9.67%.
- Taxon
- riceOryza sativae1
- Outcome
- RMSEe1
- Value
- 9.67%e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“R434/(R496 + R401) was a reliable indicator of rice canopy LNC,with the RMSE and RE values between measured and estimated LNC being 9.67% and 8%”
Claim · model-written summary
In tests with independent datasets, R434/(R496 + R401) estimated rice canopy LNC with an RE of 8%.
- Taxon
- riceOryza sativae1
- Outcome
- REe1
- Value
- 8%e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“R434/(R496 + R401) was a reliable indicator of rice canopy LNC,with the RMSE and RE values between measured and estimated LNC being 9.67% and 8%”
Claim · model-written summary
The authors recommend the blue nitrogen index R434/(R496 + R401) as a good indicator of rice canopy LNC.
- Taxon
- riceOryza sativat0
- Outcome
- good indicator of rice canopy LNCe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“was recommended as a good indicator of rice canopy LNC”
t0“rice”