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United States Department of Agriculture

Agricultural Research Service

Research Project: PLANT VARIATION IN CD, PB, ZN AND AS ACCUMULATION AND BIOAVAILABILITY AND METHODS TO LIMIT RISK Title: Quantifying arsenic-induced morphological changes in spinach leaves: implications for remote sensing

Authors
item Varaprasad, Bandaru -
item Hansen, David -
item Codling, Eton
item Daughtry, Craig
item White-Hansen, Susan -
item Green, Carrie

Submitted to: International Journal of Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2010
Publication Date: August 10, 2010
Citation: Varaprasad, B., Hansen, D.J., Codling, E.E., Daughtry, C.S., White-Hansen, S., Green, C.E. 2010. Quantifying arsenic-induced morphological changes in spinach leaves: implications for remote sensing. International Journal of Remote Sensing. 31:4163-4177.

Interpretive Summary: Many orchard soils are contaminated by arsenic, a heavy metal that was used as a pesticide that can be taken up by plants. Some old orchard soils are being used for vegetable crop production. The ability to detect arsenic contaminated plants in the field will reduce the potential health risks. The use of remote sensing of plant metal toxicity has been studied. The spectral properties in near infrared spectra are strongly affected by leaf structural characteristics. Therefore, quantitative analyses of structural changes in the arrangement of mesophyll cells caused by As will help to explain spectral responses to As. The objectives of this study were to use stereological methods to quantify internal structural changes in leaves with As treatment in spinach plants, and to relate these changes to leaf spectral properties in near infrared spectra. Hydroponically-grown spinach was treated with 0, 5, 10 and 20 µmol L-1 As for four weeks in a growth chamber. Leaf structural properties such as mesophyll thickness and mesophyll surface area were measured using stereological methods. Quantitative analysis of leaf structure showed that total leaf thickness and intercellular spaces in spongy mesophyll cells decreased with increasing As treatment. Results from this study support hypothesis that relationships between leaf structure and reflectance may be useful in the interpretation of spectral data to detect leaf As concentration.

Technical Abstract: Arsenic (As) is a widely spread soil contaminant which can be accumulated into plant parts. The ability to detect As in contaminated plants is an important tool to minimize As induced health risks. Remote sensing of plant metal toxicity has been the subject of numerous studies. The spectral properties in near infrared spectra are strongly affected by leaf structural characteristics. Therefore, quantitative analyses of structural changes in the arrangement of mesophyll cells caused by As will help to explain spectral responses to As. The objectives of this study were to use stereological methods to quantify internal structural changes in leaves with As treatment in spinach plants, and to relate these changes to leaf spectral properties in near infrared spectra. Hydroponically-grown spinach was treated with 0, 5, 10 and 20 µmol L-1 As for four weeks in a growth chamber. Spectral properties of leaves were obtained for visible and infrared frequencies. Leaf structural properties such as mesophyll thickness and mesophyll surface area were measured using stereological methods. Quantitative analysis of leaf structure showed that total leaf thickness and intercellular spaces in spongy mesophyll cells decreased with increasing As treatment. Changes in leaf reflectance (LR) in near infrared wavelengths were strongly correlated with leaf As concentration and leaf structural changes. Multi linear regression of LR values at the highest correlated wavelengths (1048, 1098, 1081, and 1080 nm) generated an R2 value of 0.68. Results from this study support hypothesis that relationships between leaf structure and reflectance may be useful in the interpretation of spectral data to detect leaf As concentration.

Last Modified: 10/20/2014
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