Spring Wheat Yield Estimates from Spectral Reflectance Measurements

The purpose of our investigation was twofold: 1) to relate spectral reflectance measurements to spring wheat grain yield and total dry matter production, and 2) to establish whether or not a relationship between grain and total dry matter can be useful for residue management decisions. The field experiment was located on a Williams loam soil (fine-loamy mixed, typic Argiborolls) 11 km northwest of Sidney, MT. Seven rates-from 0 to 100 percent-of "Olaf," a semidwarf, hard red spring wheat (Triticum aestivum L.) cultivar, were seeded to stand. On clear mornings, a handheld radiometer was used to measure spectral band reflectances corresponding to the LANDSAT multispectral scanner bands. In addition, grain and straw yield data were collected from a number of sources in order to try to define a general relationship between grain and dry matter yields. A relationship between the normalized difference vegetation index (ND7 = (MSS7 - MSS5)/(MSS7 + MSS5)), as determined any time between the tillering and watery ripe growth stages, and grain and total dry matter yields clearly established the potential of remote sensing for predicting grain and total dry matter yields. The potential use of such predictions for residue management is also important. The strong relationship between grain and total dry matter production suggested that the approach described deserves further testing to determine its potential wide-area applicability in predicting spring wheat grain and dry matter yields.