Estimating Canopy Light Interception, Leaf Area Index, and Yield in Peanut Using Remote Sensing.

Leaf area index (LAI) and ground cover (GC) are important parameters as they are directly related light interception, plant growth, and yield.  However determination of LAI and GC are often tedious processes and, for LAI require destructive sampling.  Hence, remote sensing can be a tool for determining LAI and GC non-destructively.  Numerous spectral-based models are available in the literature for estimating LAI.  Many of these spectral-based models depend on the empirical relationships between LAI and vegetation indices, which sometimes make them site- and sensor-specific.  We have conducted a study in a peanut field in Brownfield, TX to develop a procedure based on the Perpendicular Vegetation Index (PVI) to estimate GC and LAI.  Aerial images were collected three times during the growing season using the Texas Tech Airborne Multispectral Remote Sensing System (TTAMRSS) at an altitude of approximately 3000 m.  As the first step, vegetation cover is estimated from the ratio of the PVI for an image pixel to the PVI of full vegetation canopy (100% ground cover).  In the second step, vegetation cover is converted to LAI using a model relating GC to LAI.  The major advantages of using PVI compared to other indices such as Normalized Difference Vegetation Index (NDVI) is that that this method does not rely on empirical relationships.