Enhancing Economic and Environmental Value in Soybean Production through Value-Added Innovation

This dissertation examines three interconnected dimensions of soybean value enhancement. First, we evaluated 218 diverse soybean plant introductions across multiple environments, revealing significant genotype-by-environment interactions affecting fatty acid profiles. A metabolite-based genome-wide association study identified 20 single nucleotide polymorphisms (SNPs) significantly associated with 21 fatty acid ratios. These SNPs were linked to genes involved in phytohormone-mediated stress responses and offer potential targets for breeding climate-resilient varieties. Second, laboratory incubation studies with soils from 11 Virginia agricultural fields demonstrated moisture-dependent greenhouse gas dynamics: nitrous oxide (N₂O) emissions peaked at 80% water-filled pore space (WFPS), carbon dioxide (CO₂) emissions remained substantial across moisture gradients, and methane (CH₄) exhibited complex production-consumption patterns. Microbial community analysis through 16S rRNA sequencing identified specific taxa associated with each gas. Overall, soil carbon, nitrogen, and base cations showed positive relationships with GHG-positive microbes, while iron and several micronutrients correlated with GHG-negative taxa. Additionally, recent cereal crop rotations supported lower-emitting communities than leguminous crops. Finally, a survey of 208 Virginia gardeners revealed a substantial gap between edamame consumption (88.94%) and cultivation (7.7%), with adoption significantly associated with prior consumption, gardening innovativeness, and seed sources. Together, these findings advance genetic, agronomic, and market strategies to improve soybean's economic and environmental sustainability while addressing critical challenges in agricultural systems.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Crop and Soil Environmental Sciences

Department dc:contributor.department

Crop and Soil Environmental Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2025

Author dc:creator

• Bewick, Patrick William

Chair dc:contributor.committeechair

• Zhang, Bo

Committee members dc:contributor.committeemember

• Williams, Mark A.
• Stewart, Ryan Daniel
• Larochelle, Catherine
• Colla'kova', Eva
• Morota, Gota

• soybean
• GWAS
• fatty acids
• greenhouse gas emissions
• soil microbiome
• 16S rRNA
• edamame

Statement dc:rights

• Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

en

Dc Identifier Other

vt_gsexam:43713

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/134250