Author ORCID Identifier

Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Agriculture, Food and Environment


Plant and Soil Sciences

First Advisor

Dr. Krista Jacobsen

Second Advisor

Dr. Mark Williams


In Kentucky, there is growing interest among farmers to produce high protein and strong gluten wheat that is suitable for bread baking to meet the demand of local artisanal bakers. Soft red winter wheat (SRW) is the most commonly wheat grown in the state and throughout the Southeastern US. Flours produced from SRW are relatively low in grain nitrogen (N) due to the region’s moderate winters and warm humid conditions during grain filling. As such, SRW is used in baking products where lower protein flours are preferred, such as cookies, cakes, pastries and crackers. Unlike SRW, hard red winter wheat (HRW) is known for high protein content and primarily used in bread baking. The objective of this dissertation was to evaluate the effect of N management on bread baking quality and agronomic traits in winter wheat cultivars grown in conventional and organic farming systems.

This work was conducted through three field experiments. The first experiment focused on the variable effects of N fertilizer level on various SRW cultivars. Five SRW cultivars were grown using two levels of N input (high and low) in both conventional and organic systems over two years. The second experiment evaluated the effect of split N application on cultivars selected for their agronomic or bread baking quality potential. In this experiment, two cultivars of SRW were grown under three split N application treatments in both organic and conventional systems for two years. The final study evaluated the effect of combined N fertilizer and biofertilizer N on HRW bred for the southeastern US. One HRW cultivar was grown with three levels of fertilizer N input and two biofertilizer application regimes in both conventional and organic systems over two years.

In general, the first experiment showed that yields and protein content were greater in wheat grown in the conventional system at the low N rate compared to wheat grown at the high N rate in the same system. Similarly, in the second experiment, yields and protein content were consistently greater than in the organic system. In the third experiment, results were inconsistent between years. Yields were greater in the organic system in the second year, while the protein content was greater in the conventional system in the first year. Biofertilizer application had a negative or neutral effect on grain yield. Future research to improve understanding of N dynamics in organic farming systems, specifically the interaction between soil N levels and plant uptake, is needed to improve bread baking quality in organic systems.

Digital Object Identifier (DOI)

Funding Information

  • This research was awarded directly to the author as a scholarship by Dr. Krista Jacobsen - Horticulture department
  • years of funding were: 2017- 2022.