Adoption of no-till systems in Eastern Washington has been slow due to the difficulty of managing wheat (Triticum aestivum L.) straw residue and the unknown decomposition potential of cultivars. We hypothesize that by analyzing wheat straw with near-infrared spectroscopy (NIRS), calibration models can be developed to accurately predict fiber and chemical constituents of wheat, determining straw decomposition potential. Straw from a panel of 480 soft winter wheat cultivars adapted to the Pacific Northwest are analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), cellulose, hemicellulose, carbon (C), and nitrogen (N). Using modified partial least squares regression and cross validation techniques, specific environment and broad-based NIRS models are calibrated and predictive ability is validated. R2cal values from broad models are better than the specific models, and are 0.85 (NDF), 0.86 (ADF), 0.65 (ADL), 0.88 (cellulose), 0.42 (hemicellulose), 0.67 (C), and 0.73 (N). The corresponding SEP values are 1.68% (NDF), 1.54% (ADF), 0.62% (ADL), 1.14% (cellulose), 1.11% (hemicellulose), 1.23% (C), and 0.06% (N). A Finch × Eltan breeding population is used to further validate models and prediction accuracies for variety selection within a breeding program scenario. The broad NIRS models prove useful for estimating high and low ranges of NDF, ADF, and cellulose in wheat cultivars which translate into characteristics of slow and fast decomposition potential.

The Finch-Eltan winter wheat (Triticum aestivum L.) recombinant inbred line (RIL) population (Reg. No. MP-11, NSL 528074 MAP) was developed by Washington State University from soft white winter wheat cultivars 'Finch' and 'Eltan'. This population of 155 RILs was developed by single seed descent from the F 2 generation to the F 5 generation. It was genotyped using the 9k iSelect single nucleotide polymorphism (SNP) chip, simple sequence repeat markers, and 90k iSelect SNPs. A total of 1258 markers were polymorphic and were mapped to 21 linkage groups that locate to 15 of the wheat chromosomes. The population has been phenotyped to study the genetics of freezing tolerance, snow mold tolerance, stripe rust resistance, straw residue breakdown, and Cephalosporium (Cephalosporium gramineum) stripe resistance. Markers were identiied that are closely linked to quantitative trait loci (QTL) that inluence these traits, and there is potential for this population to be used to detect QTL for other traits. Because the parents are elite breeding lines developed for the US Paciic Northwest, this population is particularly well-suited to facilitating breeding eforts in this region.