Breeding for Nitrogen Use Efficiency in Hard Winter Wheat Using Canopy Spectral Reflectance and Genomic Selection

Nitrogen use efficient (NUE) crops are needed to reduce increasing nitrogen costs and environmental concerns. However, traditional phenotyping methods for NUE are labor intensive and destructive. Canopy spectral reflectance (CSR) is non-destructive, quick, and less labor intensive phenotyping method that measures incident light reflected by the plant canopy. Reflectance values for specific wavelengths are selected and used to calculate vegetation indices that estimate traits such as chlorophyll content and biomass. During the 2012 and 2013 growing season, the USDA-NIFA Triticeace Coordinated Agricultural Project (TCAP) supported proximally based CSR phenotyping in the 299-genotype hard winter wheat association mapping panel grown near Ithaca, NE. CSR data was collected weekly from anthesis to physiological maturity using a dual-fiber optic system allows for adjustment to incident light. Entry mean heritability of vegetation indices was calculated, and the most heritable indices were used in a G-BLUP genomic selection model using SNP markers. Prediction accuracy was estimated using 10 fold cross validation replicated 100 times. In 2012, accuracy for EVI phenotypes ranged from 0.38 for week 1 EVI to 0.57 for week 5 EVI showing that genomic selection combined with CSR data was successful in predicting unphenotyped lines within same year. Analysis for 2013 and testing the prediction accuracy of genomic selection and CSR data across years/environments is ongoing.