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Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment

Leaf area index (LAI) is an important parameter for characterizing the canopy structure ofa crop. The LAI, which is often used as a critical variable to simulate different ecosystem models, is difficult to measure directly in oil palm. In this study, optical methods for quantifYing variation in LAI...

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Main Authors: Awal, Md Abdul, Wan Ismail, Wan Ishak, Endan, Johari, Harun, Mohd Haniff
Format: Article
Language:English
Published: Universiti Putra Malaysia Press 2006
Online Access:http://psasir.upm.edu.my/id/eprint/3672/1/Measurements_of_Leaf_Area_Index_Using_Optical_Method_%28IAI-2000%29.pdf
http://psasir.upm.edu.my/id/eprint/3672/
http://www.pertanika.upm.edu.my/Pertanika%20PAPERS/JTAS%20Vol.%2029%20(1&2)%20Mar.%202006/03%20JTAS%20Vol.29%20(1&2)%202006%20(Pg%2015-24).pdf
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spelling my.upm.eprints.36722015-09-17T00:54:48Z http://psasir.upm.edu.my/id/eprint/3672/ Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment Awal, Md Abdul Wan Ismail, Wan Ishak Endan, Johari Harun, Mohd Haniff Leaf area index (LAI) is an important parameter for characterizing the canopy structure ofa crop. The LAI, which is often used as a critical variable to simulate different ecosystem models, is difficult to measure directly in oil palm. In this study, optical methods for quantifYing variation in LAI under different conditions were evaluated. It was found that the accuracy of the readings depended on different factors, such as measuring technique, view cap angle, spatial variability, and height of the measuring point. The measuring technique had an effect on the LAI measurement. Results showed that the Zigzag method underestimated the LAI compared to other methods. The LAI by the Zigzag method was 11.6% less than the LAI by the "one above and four below" technique and 5.7% less than the LAI by the "one above and eight below" technique. The LAI obtained I7y the "one above eight below" technique was 6.2% less than the LAI obtained with the "one abovefour below" technique. Results from the investigation ofthe effect of view cap on LAI measurement showed that the view cap strongly influenced the LAI calculation and LAI decreased with increase in the view cap angle. PCA LAI values were also affected by spatial variability and height of the sensor. PCA LAI values increased with increase in sensor height above ground with a maximum LAI value (2.77) at 2.5-meter height above ground and mzmmum LAI value (0.932) at O-meter height from ground. Maximum values of LAI were obtained for all dIrectIOns at 0.5-meter dtstance from the trunk and minimum LA1 values were obtained near the tip of the frond. The PCA LAI values increased by about 5%- 50% with increase in distance from the frond tip to frond base. Universiti Putra Malaysia Press 2006-03 Article PeerReviewed application/pdf en http://psasir.upm.edu.my/id/eprint/3672/1/Measurements_of_Leaf_Area_Index_Using_Optical_Method_%28IAI-2000%29.pdf Awal, Md Abdul and Wan Ismail, Wan Ishak and Endan, Johari and Harun, Mohd Haniff (2006) Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment. Pertanika Journal of Tropical Agricultural Science, 29 (1&2). pp. 15-24. ISSN 1511-3701; ESSN: 2231-8542 http://www.pertanika.upm.edu.my/Pertanika%20PAPERS/JTAS%20Vol.%2029%20(1&2)%20Mar.%202006/03%20JTAS%20Vol.29%20(1&2)%202006%20(Pg%2015-24).pdf
institution Universiti Putra Malaysia
building UPM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Putra Malaysia
content_source UPM Institutional Repository
url_provider http://psasir.upm.edu.my/
language English
description Leaf area index (LAI) is an important parameter for characterizing the canopy structure ofa crop. The LAI, which is often used as a critical variable to simulate different ecosystem models, is difficult to measure directly in oil palm. In this study, optical methods for quantifYing variation in LAI under different conditions were evaluated. It was found that the accuracy of the readings depended on different factors, such as measuring technique, view cap angle, spatial variability, and height of the measuring point. The measuring technique had an effect on the LAI measurement. Results showed that the Zigzag method underestimated the LAI compared to other methods. The LAI by the Zigzag method was 11.6% less than the LAI by the "one above and four below" technique and 5.7% less than the LAI by the "one above and eight below" technique. The LAI obtained I7y the "one above eight below" technique was 6.2% less than the LAI obtained with the "one abovefour below" technique. Results from the investigation ofthe effect of view cap on LAI measurement showed that the view cap strongly influenced the LAI calculation and LAI decreased with increase in the view cap angle. PCA LAI values were also affected by spatial variability and height of the sensor. PCA LAI values increased with increase in sensor height above ground with a maximum LAI value (2.77) at 2.5-meter height above ground and mzmmum LAI value (0.932) at O-meter height from ground. Maximum values of LAI were obtained for all dIrectIOns at 0.5-meter dtstance from the trunk and minimum LA1 values were obtained near the tip of the frond. The PCA LAI values increased by about 5%- 50% with increase in distance from the frond tip to frond base.
format Article
author Awal, Md Abdul
Wan Ismail, Wan Ishak
Endan, Johari
Harun, Mohd Haniff
spellingShingle Awal, Md Abdul
Wan Ismail, Wan Ishak
Endan, Johari
Harun, Mohd Haniff
Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment
author_facet Awal, Md Abdul
Wan Ismail, Wan Ishak
Endan, Johari
Harun, Mohd Haniff
author_sort Awal, Md Abdul
title Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment
title_short Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment
title_full Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment
title_fullStr Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment
title_full_unstemmed Measurements of leaf area index using optical method (IAI-2000) in oil palm plantation: accuracy and limitation assessment
title_sort measurements of leaf area index using optical method (iai-2000) in oil palm plantation: accuracy and limitation assessment
publisher Universiti Putra Malaysia Press
publishDate 2006
url http://psasir.upm.edu.my/id/eprint/3672/1/Measurements_of_Leaf_Area_Index_Using_Optical_Method_%28IAI-2000%29.pdf
http://psasir.upm.edu.my/id/eprint/3672/
http://www.pertanika.upm.edu.my/Pertanika%20PAPERS/JTAS%20Vol.%2029%20(1&2)%20Mar.%202006/03%20JTAS%20Vol.29%20(1&2)%202006%20(Pg%2015-24).pdf
_version_ 1643822678992224256
score 13.211869

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