Ground penetrating radar (GPR) detects fine roots of agricultural crops in the field
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Ground penetrating radar (GPR) as a non-invasive technique is widely used in coarse root detection. However, the applicability of the technique to detect fine roots of agricultural crops is unknown. The objective of this study was to assess the feasibility of utilizing GPR to detect fine roots in the field.
This study was conducted in four locations with different soil types and soil moisture conditions in Texas. Several varieties of winter wheat and energy cane were scanned with GPR (1600 MHz). Soil cores were collected immediately after scanning to measure root parameters. Using an image analysis software, four pixel indices with or without intensity threshold were used to assess the relationships between GPR signal and root parameters.
There were significant relations between GPR indices and root parameters depending on soil conditions. The accuracy of root estimation was higher in wet clay soils than in dry sandy soils. Estimated root parameters from GPR had lower variation than measured roots. Average GPR pixel intensity without intensity threshold may be better to reflect root information than pixel indices with intensity threshold.
This study demonstrates that GPR has the potential to predict bulk root biomass and diameter in winter wheat and energy cane.
KeywordsGround penetrating radar Fine roots Average pixel intensity Triticum aestivum Saccharum
Ground penetrating radar
Normalized root mean square error
Geophysical Survey Systems, Inc.
The authors express thanks to Mr. Shane Sieckenius and Mr. Dalton Thompson at the Uvalde Research Center and Mr. Kirk Jessup at the Amarillo Research Center for assistance in carrying out much of the field work, as well as Dr. Subas Malla for internal review. We also thank Mr. Jaime Lopez at the Frio County Extension Service for help in identifying field sampling locations. Support for this study was provided in part by the Texas A&M AgriLife Research cropping system seed grant entitled “Root-shoot phenotyping and water balance characterization to improve water use efficiency and productivity of cropping systems in Texas” and also by an Agriculture and Food Research Initiative Competitive Grant # 2013-67009-21353 titled “A Water and Risk Management Tool for Sustainable Production of Bioenergy Feed stocks” from the USDA National Institute of Food and Agriculture.
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