Evaluation of Barley (Hordeum vulgare L.) Stem and Root Traits that Influence Lodging

Barley (Hordeum vulgare L.) lodging is a detrimental phenomenon that occurs globally and causes several hundred million dollars in financial losses annually to the industry due to reduced yield, downgraded quality, and increased disease load. While lodging can be managed through agronomic practices, such as reduced seeding and nitrogen rates or via the application of plant growth regulators, developing lodging resistant varieties is an important aspect of lodging management that allows producers to maximize yield and quality potential. Plant breeders will typically assess lodging in field trials when suitable environmental conditions (e.g. storm events) and management techniques (e.g. higher nitrogen application) promote lodging. However, developing new methods to help breeders assess specific traits which promote lodging resistance is important and facilitates consistent evaluation of breeding lines over time, especially through years and environments where no visual lodging is observed. As such, this thesis had two main objectives: 1) to identify and evaluate traits within a set of field-based plant, stem and root mechanical and architectural traits that were well correlated to lodging, and 2) to identify and evaluate traits within a set of lab-based root architecture traits that were well correlated to lodging. To address the first objective, 13 spring barley genotypes adapted to western Canada and representing a diversity of classes, height and lodging scores were grown at six site-years with data related to plant height, plant and head density, whole plant bending resistance, stem strength, stem cross-section features, root anchorage strength, root architecture features, and lodging scores collected. Plant height, crown root angle and whole plant bending resistance were best correlated to lodging score (r = 0.61, -0.30 and 0.36, respectively). Decision trees and structural equation modelling (SEM) confirmed the importance of these traits, in addition to influences from other traits. Imaging of field-collected root systems revealed that solidity, the ratio of network area to convex area, also had a strong correlation to lodging score (r = 0.47). The SEM demonstrated that solidity was a central trait that encapsulated information from numerous other root traits. To address the second objective, 32 genotypes (which included the 13 genotypes from objective 1) were grown to 17-days in a laboratory setting and 22 root architecture-related traits were measured over the course of root system development. Seminal root angle obtained from 3-day-old seedlings displayed the highest correlation to field lodging score at r = -0.82. This relationship persisted throughout plant development with a correlation of r = -0.52 observed between lodging score and root angle of 11-week-old plants. Root angle was also consistent through the lifespan of the plant with a correlation of r = 0.75 between 3-day seminal root angles and 11-week crown root angles. Root system solidity from 17-day-old seedling root systems was also well correlated to lodging resistance (r = 0.50). The importance of root angle and solidity were confirmed with both SEM and decision trees. It appears that root angle is established early and sets the foundation for root angle throughout the life of the barley plant. Root angle also appears to be an important factor determining overall root system architecture which can be represented by the solidity trait. Seminal root angle demonstrates potential as an effective trait for high-throughput phenotyping to predict lodging tolerance because of its correlation to lodging score, it can be evaluated in early generations in a laboratory setting and it is amenable to screening thousands of genotypes on an annual basis due to the ability to assess the trait on very young seedlings. To complement indoor root phenotyping, assessments of height and whole plant bending resistance in the field also contribute to evaluating lodging risk in a simple, large-scale manner at any generation. Collectively, this thesis has provided insight into key traits that influence barley lodging in diverse prairie environments and offers several screening tools to help breeders select for, and improve, lodging resistance.

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Plant Sciences

Grantor

University of Saskatchewan

Year dc:date.issued

2023

Author dc:creator

• Taylor, Michael Warren

Advisors dc:contributor.advisor

• Beattie, Aaron
• Feurtado, Allan

Committee members dc:contributor.committeemember

• Beattie, Aaron
• Noble , Scott
• Warkentin, Thomas
• Badea, Ana

• Barley
• Lodging
• Root imaging
• Stem strength
• Root anchorage
• Stem
• Root
• Structural equation model
• Decision tree
• Cereal

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/15311

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/15311