Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2016
Publication Date: 7/21/2016
Citation: Gizaw, S.A., Garland Campbell, K.A., Carter, A.H. 2016. Use of spectral reflectance for indirect selection of yield potential and stability in Pacific Northwest winter wheat. Field Crops Research. doi: 10.1016/j.fcr.2016.06.022. Interpretive Summary: Drought events constrain wheat production in the Pacific Northwest of the US and are expected to play an even greater role in the future. This study was undertaken to see if the use of spectral reflectance indices together with grain yield could improve the response to selection for better performance of wheat genotypes in drought conditions. In the dryest environments, the use of spectral reflectance indices improved the expected response to selection. These indices can be measured with more accuracy than measuring yield per se in drought environments and will be a useful tool for breeders to select for better performance under drought.
Technical Abstract: Indirect selection approaches have been recommended to augment genetic gain from yield based selection in highly variable environments. We evaluated the potential use of spectral reflectance indices (SRIs) to select for grain yield in Pacific Northwest Winter wheat (Triticum aestivum L.) in wide range of moisture regimes. The objectives of this study were to estimate genotypic correlations between (SRIs) and grain yield, and to estimate heritability, expected response to selection, relative efficiency of indirect selection, and accuracy of predictive models for yield. A winter wheat diversity panel of 402 genotypes (87 hard and 315 soft) was grown in drought, irrigated, and moist-cool conditions in 2012 and 2013. Canopy spectral reflectance measured at heading, milking, soft dough and hard dough were used to derive six SRIs. Grain yield had generally lower broad sense heritability (H2) than SRIs. Efficiency of indirect selection for yield using SRIs was generally high in drought environments and exceeded selection efficiency of grain yield per se in the soft winter subgroup. Normalized water band index (NWI) showed generally higher genetic correlation (0.51- 0.80, p < 0.001), consistent response to selection across environments, and the highest indirect selection efficiency for grain yield (up to 143%). A yield predictive model with one or more SRIs explained 41-82% of total variation in grain yield (p < 0.001). The repeatability of genotypic performance between years increased when selection was conducted based on both SRIs and grain yield compared to selection based on yield or SRI alone. The generally high heritability of SRIs along with their significant genotypic correlation with grain yield indicates the possibility to improve yield and yield stability in the PNW winter wheat through remotely sensed phenotyping approach.