Articles
Estimating radiation interception and canopy size in pecan orchards using aerial and ground-based images
Article number
1409_9
Pages
59 – 66
Language
English
Abstract
Accurate estimation of photosynthetically active radiation (PAR) interception by pecan trees is crucial, as it significantly influences orchard water use and yield.
However, estimates of fractional PAR interception (FIPAR) in pecan orchards are complex due to the polynomial canopy growth as a function of time, suggesting the need for multiple measurements of FIPAR and model input parameters.
This limits the practical use of PAR interception models as a management tool in orchards.
A study was therefore conducted to calibrate and validate a radiation interception model that estimates PAR based on the area of the shadow projected on the ground surface.
The study was conducted on ‘Wichita’ and ‘Choctaw’ cultivars with varying canopy sizes, grown in subtropical and semi-arid regions of South Africa.
Both aerial images and smartphone applications (VitiCanopy, Canopeo app) were used to estimate the inputs for the model, which included the proportion of sunflecks within the shaded area of the tree, referred to as canopy porosity (Cp). Measured Cp (using VitiCanopy and PAR sensors) was regressed with fractional ground cover estimated using the Canopeo App (fccanopeo) to develop a practical method of estimating Cp.
A strong negative correlation was observed between fccanopeo and both measures of Cp, with a R2 of >0.77. In addition, acceptable statistical indices, with Wilmott index of agreement (D) >0.87, mean absolute percentage error (MAPE) <10.4%, root mean square error (RMSE) <0.14 and R2>0.82, were observed when using the developed relationships to estimate FIPAR, suggesting that FIPAR and ultimately canopy size of pecan trees can be practically estimated using the Canopeo App, thereby providing a simple tool to estimate radiation interception of pecan trees to aid in orchard management practices such as irrigation scheduling and pruning.
However, estimates of fractional PAR interception (FIPAR) in pecan orchards are complex due to the polynomial canopy growth as a function of time, suggesting the need for multiple measurements of FIPAR and model input parameters.
This limits the practical use of PAR interception models as a management tool in orchards.
A study was therefore conducted to calibrate and validate a radiation interception model that estimates PAR based on the area of the shadow projected on the ground surface.
The study was conducted on ‘Wichita’ and ‘Choctaw’ cultivars with varying canopy sizes, grown in subtropical and semi-arid regions of South Africa.
Both aerial images and smartphone applications (VitiCanopy, Canopeo app) were used to estimate the inputs for the model, which included the proportion of sunflecks within the shaded area of the tree, referred to as canopy porosity (Cp). Measured Cp (using VitiCanopy and PAR sensors) was regressed with fractional ground cover estimated using the Canopeo App (fccanopeo) to develop a practical method of estimating Cp.
A strong negative correlation was observed between fccanopeo and both measures of Cp, with a R2 of >0.77. In addition, acceptable statistical indices, with Wilmott index of agreement (D) >0.87, mean absolute percentage error (MAPE) <10.4%, root mean square error (RMSE) <0.14 and R2>0.82, were observed when using the developed relationships to estimate FIPAR, suggesting that FIPAR and ultimately canopy size of pecan trees can be practically estimated using the Canopeo App, thereby providing a simple tool to estimate radiation interception of pecan trees to aid in orchard management practices such as irrigation scheduling and pruning.
Authors
N. Shongwe, N.J. Taylor, J.G. Annandale
Keywords
Canopeo, fractional interception of PAR, irrigation water management, Viticanopy
Online Articles (64)