Thesis
Rapid estimation of wheat (Triticum aestivum L.) straw decomposition potential through a genome-wide association study and near-infrared spectroscopy
Washington State University
Master of Science (MS), Washington State University
2019
Handle:
https://hdl.handle.net/2376/101566
Abstract
Adoption of no-till farming in the dryland regions of Eastern Washington has been slow due to difficulties managing straw residue in no-till systems. To address these complications, both fast and slow decomposing crop cultivars will be needed in different precipitation zones. We hypothesize that by analyzing wheat straw after harvest with near-infrared spectroscopy (NIRS) and molecular markers, we can better understand the genetic architecture of straw decomposition and quickly estimate decomposition potential of cultivars. The straw from a panel of 480 soft white winter wheat cultivars in the Pacific Northwest was harvested over two years at three locations throughout Eastern Washington. The samples were analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), cellulose, and hemicellulose using a wet chemistry procedure while carbon (C) and nitrogen (N) were determined using dry combustion. Average NDF, ADF, ADL, and cellulose were correlated with precipitation zones. Increases were observed as precipitation increased. Hemicellulose, C, and N did not display the same trend. The samples were analyzed with NIRS and calibration equations were developed. NIRS was successful in predicting NDF (R2=0.85), ADF (R2=0.86), and cellulose (R2=0.88) of a validation set but was less successful when predicting a breeding population (R2 range for NDF=0.32-0.77, ADF=0.40-0.64, cellulose=0.44-0.70). Although NIRS predicted external validation sets with lower accuracy than anticipated, the calibration equations should still be useful for estimating if NDF, ADF, and cellulose values fit into a low or high range for any given cultivar. A genome-wide association study (GWAS) was performed using statistical package FarmCPU implemented in R to find associations between the fiber and chemical constituents of decomposition and molecular markers previously identified in this panel. Through GWAS, 23 marker-trait associations were identified across 12 wheat chromosomes. Five chromosomal loci of interest, all of which had affiliation with cellulose, NDF, or ADF, were identified on chromosomes 1B, 2B, 4B, 5B, and 6B. This is a good initiative for understanding the genetic architecture of straw decomposition, but a different approach will be required to assist in selection for these traits.
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Details
- Title
- Rapid estimation of wheat (Triticum aestivum L.) straw decomposition potential through a genome-wide association study and near-infrared spectroscopy
- Creators
- Nathan Scott Nielsen
- Contributors
- Arron H. Carter (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525292501842
- Language
- English
- Resource Type
- Thesis