A Technique to Determine which Crop Development Stages Can be Estimated from Spectral Data

Estimates of crop development stage by remote sensing techniques are potentially more cost effective for large areas than present labor intensive estimates. Here, discriminant analysis fo: identi~ying crop aevelopment stage uS1ng mult1spectral data is discussed. The data analyzed were Exotech 100 measurements in four wavelenqth bands (.5-.6, .6-.7, .7-.8, .8-1.1 urn) over field plots of soybeans and corn in West Lafayette, Indiana. Different row spacings, soils, plant populations, planting dates, soybean cultivars and crop years (1978, 1979, 1980) increased the generality of the data set. Results show that development stage classes at the beginning and end of the growi~g, se~son have relatively high class1f1cat10n accuracy. Midseason classes have moderate to low classification accuracies. Overall accuracy increases as development stages are ,pooled to form fewer classes per grow1ng season. Applying discriminant analysis ~o a subset of development stages 1n a season increases classification accuracy.