Reflectance Based Characterization of Wheat Cultivars for Identifying Drought Tolerance.

In the US Southern Great Plains (SGP), drought stress is the single most important factor for reducing yield in winter wheat. Selection of drought tolerant wheat cultivars has been and will continue to be a critical strategy for wheat management under water-limited conditions. Currently, yield is still the primary trait used in cultivar selection. It is largely unknown as to which other traits contribute to drought tolerance in wheat genotypes in the SGP.  Spectral reflectance indices have been used to differentiate genotypes for yield potential and water relations. However, little information is known for the genotypic differences in spectral indices and their relations to drought tolerance in the SGP. The objective of this study is to characterize genotypic variation in various spectral reflectance indices and their relations to drought tolerance in wheat cultivars. Field experiments have been conducting using twenty wheat cultivars with a wide genetic background. The cultivars are growing under different soil water regimes from drylant to limited irrigation to full irrigation. Measurements include spectral reflectance, canopy temperature, leaf area index, biomass and yield.  The results will help us to identify drought tolerant wheat genotypes and develop useful screening tools.