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Poster Presentations


Poster Presentations


Utility of vegetation indices in assessing soybean canopy leaf area

Presenter: Joe Omielan

Other authors and affiliations: Elena Prior, Saratha Kumudini, Jason Sarver, Chad Lee. University of Kentucky, Plant & Soil Sciences, Lexington, KY 40546-0312, U.S.A.

The yield potential of a soybean crop is related to its canopy leaf area. The leaf area increases during crop development and declines after R5. Defoliation due to soybean rust can rapidly decrease the canopy’s ability to intercept solar radiation. Vegetation indices (VIs), such as normalize difference vegetation index (NDVI), wide dynamic range vegetation index (WDRVI), and simple ratio (SR), quantify the amount of green leaf area. However, they have difficulty detecting differences in leaf area indices (LAIs) after canopy closure. Our objective was to compare how well the VIs measured differences in canopy leaf area. For this study, plots were established with different row widths (7.5", 15", and 30"), which had different times of canopy closure. Vegetation indices, LAI, and light interception (LI) were measured at weekly intervals from R1 to R5. Relationships between VIs and LAI were developed and then used to calculate LAIs for another set of plots. The calculated LAIs were compared with measured values for those plots to assess the utility of the VIs.

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