Graduate Studies, UNL
Embargoed Master's Theses
First Advisor
Joseph A. Turner
Committee Members
Mehrdad Negahban, Wen Qian
Date of this Version
12-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillments of the requirements for the degree of Master of Science
Major: Mechanical Engineering and Applied Mechanics
Under the supervision of Professor Joseph A. Turner
Lincoln, Nebraska, December 2025
Abstract
Plant cell walls are complex composite structures whose mechanics govern stomatal opening and closing. As plant cells are exposed to environmental stimuli, the cell walls undergo deformations which allow the stomatal pore to widen in response to stimuli. As the pore widens, gas exchanges occur with the atmosphere—oxygen is released and carbon dioxide is taken in through the pore. As this process occurs, water vapor is naturally lost through the open pore. As drought conditions shift globally, excessive water loss through the stomatal pore becomes a risk of failure to staple crops. Given that grasses make up most of the global caloric intake, there a need to understand the cell wall mechanics that influence pore dynamics for plant adaptation to the changing climate. In this thesis, nanoindentation methods are used to study the mechanical and material properties of grass cell walls. Three nanoindentation methods that were used for measurements on grass cell walls are first introduced. Normal and lateral indentation methods are used to characterize the wall stiffness values at various depths to study the bulk wall properties and turgor pressure effects on cell wall stiffness then compared to Arabidopsis, another common research plant model. Following this, time dependent behavior of the cell wall is studied using nanoDMA. The characterization of viscoelastic properties of pavement cell walls in comparison to stomatal cell walls in subsidiary cells of grasses in two species reveal that viscoelastic behavior is inherent to grass stomata and may be necessary for pore dynamics. Finally, the results reveal that the increased wall stiffness and viscoelastic behavior seen in grasses are influencing factors in grass cell wall mechanics when compared to Arabidopsis cell wall mechanics. However, more work is needed to fully understand the origin and effects of viscoelasticity on grass stomatal cell wall mechanics.
Advisor: Joseph Turner
Comments
Copyright 2025, Magdalene M. Peklo. Used by permission