Author ORCID Identifier

https://orcid.org/0000-0001-7676-6326

Date Available

12-15-2023

Year of Publication

2023

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department/School/Program

Plant and Soil Sciences

First Advisor

Dr. David A. Van Sanford

Abstract

Soft Red Winter (SRW) wheat is an important crop grown on about 400,000 acres in Kentucky as a pivotal cash crop in the 3-crops-in-2-years rotation of corn, wheat, and soybean. The humid environment of Kentucky generates a high yielding wheat crop, with low protein concentration and weak gluten strength. This wheat is mainly sold to millers and used by the industry for cakes, pastries, cookies, and crackers. Conversely, there is a rapidly growing interest in identifying other value-added markets for this wheat different to commodity commercialization, such as artisan-baked goods and craft-distilled beverages. Evaluating the quality characteristics of wheat grown in Kentucky is essential if growers and other stakeholders are to access those specialized markets and recover the added value in the system. Unfortunately, there is an expressed concern that modern wheat selection programs have narrowed the genetic basis of newer wheat varieties through propagation of successful varieties that are genetically related. In this scenario, introducing sensorial and baking quality parameters as new breeding criteria could possibly contribute to broadening the genetic diversity of modern bread wheat. Furthermore, wheat quality is mainly defined by its protein concentration and composition. Since sulfur (S) and nitrogen (N) are central components of proteins, management practices such as fertilization could improve wheat quality and interact with genotype selection to produce a high-quality crop suitable for bread baking. Given this background, the aims of the present work are: 1) to quantify and characterize genetic variation in sensory and dough functionality characteristics among breeding lines from the University of Kentucky Wheat Breeding Program, 2) to estimate heritability of these traits to understand if we can incorporate them as selection criteria, 3) to determine growing conditions under which S fertilization is limiting to grain protein concentration and grain yield through a meta-analysis; and 4) to determine the effects of S and N fertilization on grain yield, grain quality, and baking quality of several wheat varieties grown in Kentucky. The results showed that heritability of several bread-baking quality parameters were high to moderate and could be useful parameters to incorporate in a breeding program (i.e., loaf volume, sedimentation volume, HMW-GS, LMW-GS, gliadin to glutenin ratio, texture of the crumb and the crust, dough extensibility). Moreover, a genome wide association study (GWAS) identified six SNPs significantly associated with loaf volume located on the 1D chromosome in a region that could be linked to the Glu-1D gene. Regarding growing conditions to improve grain protein concentration and yield, the meta-analysis revealed that S fertilization increased protein concentration by 5.4% and grain yield by 16.2%, but the co-application of N fertilizer is needed to get a response to S fertilizer. Moreover, we found that the effect of S fertilizer is greater when wheat is grown under no-till and following a legume. Finally, the field study evaluating S and N fertilization strategies on several wheat varieties grown in Kentucky showed that cultivar selection (i.e., genotype) is the main determinant of baking quality parameters such as sedimentation volume, dough elasticity and loaf volume. The co-application of S along with N increased yield compared to the treatments without S, but decreased protein concentration. Nonetheless, applying N without the addition of S increased the N:S ratio over the recommended threshold to get the best baking quality. Interestingly, there was a significant effect of the environment in most of the parameters under study, which could be driven by differences in S and N content in the soil. The findings of our work supports the idea that we can select and improve SRW wheat lines through breeding to achieve high quality bread baking characteristics, that Kentucky’s growing conditions can be S-limiting for wheat (i.e., wheat in rotation with soybeans, no tillage practices), and that fertilization with S along with N can improve grain quality for bread baking purposes.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2023.463

Funding Information

Funds awarded directly to the author, e.g., scholarship(s):

  • Student Opportunity Grant

  • Funder: The Food Connection (https://foodconnection.ca.uky.edu/students/student-opportunity-grants)

  • Title: Identifying Wheat Breeding Lines and Cultivars with Flavor and Dough Functionality for Use in Local Artisan Bakeries

  • Awarded in 2020

Funds awarded to a research lab, team, or project in which the author was officially recognized as a member or contributor, e.g., research grant(s):

  • Title: Breeding Agronomically Superior Soft Red Winter Wheat Varieties with Outstanding Milling Quality for Kentucky

  • Funder: Siemer Miling (https://www.siemermilling.com/)

  • Awarded to research team 2021 and 2022

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