Threshold values of canopy reflectance indices and chlorophyll meter readings for optimal nitrogen nutrition of tomato

2014 ◽  
Vol 166 (2) ◽  
pp. 271-285 ◽  
Author(s):  
F.M. Padilla ◽  
M.T. Peña-Fleitas ◽  
M. Gallardo ◽  
R.B. Thompson
Keyword(s):  
Nitrogen Nutrition ◽  
Canopy Reflectance ◽  
Threshold Values ◽  
Chlorophyll Meter ◽  
Reflectance Indices

scholarly journals Leaf Canopy Layers Affect Spectral Reflectance in Silver Birch

2019 ◽  
Vol 11 (24) ◽  
pp. 2884 ◽  
Author(s):  
Maya Deepak ◽  
Sarita Keski-Saari ◽  
Laure Fauch ◽  
Lars Granlund ◽  
Elina Oksanen ◽  
...  
Keyword(s):  
Principal Component ◽  
Common Garden ◽  
Dry Weight ◽  
Leaf Traits ◽  
Tree Canopy ◽  
Canopy Reflectance ◽  
Canopy Layer ◽  
Leaf Reflectance ◽  
Individual Trees ◽  
Reflectance Indices

The availability of light within the tree canopy affects various leaf traits and leaf reflectance. We determined the leaf reflectance variation from 400 nm to 2500 nm among three canopy layers and cardinal directions of three genetically identical cloned silver birches growing at the same common garden site. The variation in the canopy layer was evident in the principal component analysis (PCA), and the influential wavelengths responsible for variation were identified using the variable importance in projection (VIP) based on partial least squares discriminant analysis (PLS-DA). Leaf traits, such as chlorophyll, nitrogen, dry weight, and specific leaf area (SLA), also showed significant variation among the canopy layers. We found a shift in the red edge inflection point (REIP) for the canopy layers. The canopy layers contribute to the variability in the reflectance indices. We conclude that the largest variation was among the canopy layers, whereas the differences among individual trees to the leaf reflectance were relatively small. This implies that within-tree variation due to the canopy layer should be taken into account in the estimation of intraspecific variation in the canopy reflectance.

scholarly journals Differentiating between Nitrogen and Water Deficiency in Irrigated Maize Using a UAV-Based Multi-Spectral Camera

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1671
Author(s):  
Taylor Becker ◽  
Taylor S. Nelsen ◽  
Michelle Leinfelder-Miles ◽  
Mark E. Lundy
Keyword(s):  
Cropping System ◽  
Canopy Reflectance ◽  
Maize Crop ◽  
Maize Productivity ◽  
Crop Water Demand ◽  
Aerial Vehicle ◽  
N Deficiency ◽  
Experimental Treatments ◽  
Reflectance Indices ◽  
Blue Reflectance

The objective of this research was to determine if canopy reflectance measured by an Unmanned Aerial Vehicle (UAV) equipped with a 5-band multi-spectral camera can differentiate between water and nitrogen (N) deficiency in irrigated maize. Crop reflectance was used to generate a Normalized Difference Red Edge (NDRE), Green Leaf Index (GLI), and a Blue Reflectance Index (BRI). These indices were then used in combination to categorize N and water stressed experimental units into a Combined Index (CI) indicating water-stressed, N-stressed, or non-stressed crops. The CI generated at blister (R2) successfully identified 90% of experimental treatments to the correct group but only identified 60% of treatments when generated at the 14th leaf stage (V14). The CI methodology was subsequently applied to two independent site-years where only N deficiency gradients were imposed. The CI was not successful at separating treatments at the validation sites, incorrectly identifying water stress where there was none. Among individual indices investigated, NDRE had the strongest relationship to grain yields (r2 = 0.62, p < 0.001) but a weaker linear relationship compared to the CI (r2 = 0.68, p < 0.005) where deficit irrigation treatments were imposed. At sites where irrigation was sufficient to meet crop water demand, NDRE (r2 = 0.63, p < 0.05) had a stronger relationship to grain yield compared to the CI (r2 = 0.41, p = 0.31). This study found that, under narrow cropping system circumstances, N and irrigation-induced differences in maize productivity can be differentiated in-season by a combination of reflectance indices, but that NDRE alone provides superior information under broader contexts.

scholarly journals Simple Assessment of Nitrogen Nutrition Index in Summer Maize by Using Chlorophyll Meter Readings

2018 ◽  
Vol 9 ◽  
Author(s):  
Ben Zhao ◽  
Syed Tahir Ata-Ul-Karim ◽  
Zhandong Liu ◽  
Jiyang Zhang ◽  
Junfu Xiao ◽  
...  
Keyword(s):  
Nitrogen Nutrition ◽  
Summer Maize ◽  
Chlorophyll Meter ◽  
Nitrogen Nutrition Index

SEASONAL VARIATION AND THRESHOLD VALUES FOR CHLOROPHYLL METER READINGS ON LEAVES OF POTATO CULTIVARS

2010 ◽  
Vol 33 (14) ◽  
pp. 2148-2156 ◽  
Author(s):  
Camilo Busato ◽  
Paulo Cezar Rezende Fontes ◽  
Heder Braun ◽  
Paulo Roberto Cecon
Keyword(s):  
Seasonal Variation ◽  
Potato Cultivars ◽  
Threshold Values ◽  
Chlorophyll Meter
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