Plant Health Program, Doctor of


First Advisor

Gary Hein

Document Type

Doctoral Document

Second Advisor

Sam Wortman

Date of this Version


Third Advisor

Gerard Adams


Blecha, Sarah, "Addressing the Challenges Facing Wheat Production: Nebraska and International Breeding Efforts" (2019)


A Doctoral Document Presented to the Faculty of The College of Agricultural Sciences and Natural Resources, University of Nebraska-Lincoln, In Partial Fulfillment of Requirements For the Degree of Doctor of Plant Health, Under the Supervision of Professor Gary L. Hein, Lincoln, Nebraska: May, 2019

Copyright 2019 Sarah Blecha


Bread wheat, Triticum aestivum L., provides 20 percent of the global daily calorie intake. It is the third most important food crop, after rice and corn. Biotic challenges significantly reduce wheat yield; chemical control can be a solution but can be cost prohibitive for subsistence farmers. For many farmers, genetic resistance to biotic stresses can be the most cost effective solution.

The International Center for Agricultural Research in the Dry Areas (ICARDA) and the Nebraska Small Grains Breeding Program have been addressing these wheat production challenges. ICARDA is part of an international research consortium to increase wheat yield and tolerance to abiotic and biotic stresses. It focuses on wheat development in the Middle East, Africa, and Asia. Chapter 1 provides a brief overview of how ICARDA breeds for wheat using mega environments, shuttle breeding, and multi-location yield trials.

Many abiotic and biotic stresses decrease wheat yield around the world. Some of the major wheat diseases and incest pests in the ICARDA region include: Septoria tritici blotch, stem rust, stripe rust, Hessian fly, and Sunn pest. A brief review of each of these wheat pests and diseases are provided in Chapter 2.

Currently, there is a less than 1.0 percent annual increase in wheat yield. But to feed the growing population, the annual increase of wheat needs to improve to 1.6 percent. Hybrid wheat could address this yield gap through heterosis. Heterosis, hybrid vigor, in wheat has been estimated to be 3.5 to 15 percent. As hybrid wheat research continues, a transparent and robust SNP panel for hybrid purity testing is required (Chapter 3). Because wheat has a compact floral architecture, researchers and regulators must be able to run a molecular test to confirm if seed is a true hybrid or a female-self. To address this problem, we plan to develop a robust panel of 42 SNPs (two SNPs per chromosome) by finding highly polymorphic regions among parents and breeding lines and testing them within our Nebraska-Texas hybrid genotypes. This study validates two KASP markers (Sr6_1 and Sr6_3) used in the Nebraska and Texas hybrid breeding program. These markers provide KASP markers for both stem rust resistance and hybrid purity testing.