Graduate Studies


First Advisor

P. Stephen Baenziger

Date of this Version



Stoll, Hannah Kay, "Unraveling the Influence of Female Flowering Characteristics and Chemical Hybridizing Agent Formulations on Hybrid Wheat (Triticum aestivum L.) Seed Production" (2019).


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agronomy, Under the Supervision of Professor P. Stephen Baenziger. Lincoln, Nebraska: December, 2019

Copyright 2019 Hannah Kay Stoll


The success of hybrid wheat (Triticum aestivum L.) is largely limited by inefficiencies in seed production. This research aims to address these inefficiencies by examining various Chemical Hybridizing Agent (CHA) formulations using the chemical Croisor®100 on sterility, CHA damage, and female flowering characteristics. In addition, an efficient method of phenotyping female flowering characteristics (contributing factors in hybrid production seed yield) were identified using Stepwise Regression, ANCOVA, and Pearson R-Correlations, and duration of stigma receptivity in the cytoplasmic male sterile (CMS; Triticum timopheevii Zhuk.) background was determined. At an optimally timed spray application, including a moderate rate of CHA with a few wetting, sticking and spreading adjuvants induced the best sterility with minimal CHA damage and effects on female flowering characteristics. Moreover, significant genotypic differences for female flowering characteristics (Gape Angle, Stigma Exsertion) were detected, and traits were moderately to highly heritable in the broad-sense (2018: 0.41- 0.88; 2019: 0.60- 0.86). Out of the four female traits measured, Gape Angle 100% and Stigma Exsertion 100% (both rated 1-9, three days after flowering) were sufficient for phenotyping efforts of the female. Anther Extrusion (male trait), CHA Damage, Sterility, and Gape Angle 100% (female trait) all played a role in determining hybrid seed yield, some to a lesser extent depending on environmental conditions. Stigma receptivity in the CMS background declined after four or five days of gaping and genotype also affected the duration of stigma receptivity (α=.05). Overall, this research demonstrated that female traits are largely genetically controlled, but are influenced by CHA application and environmental conditions.

Advisor: P. Stephen Baenziger