Thesis (Ph.D., Plant, Soil and Entomological Sciences) -- University of Idaho, 2015 | This study was designed to assess spring wheat accessions found in the USDA-ARS National Small Grains Collection using a combination of genetic markers, agronomic characteristic, and a novel spectrometer based high-throughput phenotyping platform. The panel of spring wheat accessions selected for this study originated from six continents and 81 countries. This panel included wheat accessions classified by the USDA as `Cultivars', `Breeding lines', `Landraces' and `Uncertain'. Cultivars and breeding lines were developed through modern breeding techniques, while landraces developed through farmer selections. In the present study, the following measurements were made in irrigated and water stressed environments: yield, grain protein, grain volume by weight (test weight), plant heights, and days to heading. Spectrometer readings were made throughout the growing season and markers were used to map genes influencing traits of interest. Selection of accessions using genetic markers and spectral reflectance found that each of these methods was able to identify a significant proportion of the highest yielding accessions. Several of the landrace accessions selected by markers, spectral reflectance and yield, were found to have relatively high yields that were consistent across both years and irrigations regimes. The accessions identified here may contain novel genes not currently found in modern cultivars and could be used to introduce genetic variation into current breeding programs.