1 AN ABSTRACT OF THE THESIS OF Elif Sahin for the degree of Master of Science in Crop Science presented on March 12, 2020. Title: Breeding for Improved Forage Yield Potential and Digestibility in Tall Fescue (Schedonorus arundinaceus (Schreb.) Dumort.) Abstract approved: ______________________________________________________ David B. Hannaway Tall fescue is a perennial forage grass widely used in areas not well-suited to perennial ryegrass due to climatic or edaphic stressors including drought and low or high pH. Although tall fescue has many agronomic attributes that make it well suited to a wide range of environments, it is lower in palatability and digestibility than Lolium species. To take full advantage of tall fescue, genetic improvements in digestibility are needed to increase animal performance. The goal of this study was to improve fiber digestibility and yield of early and medium maturing tall fescue genotypes through recurrent phenotypic selection. Improving fiber digestibility and yield concurrently is a challenge because yield and fiber content are positively correlated. Sixteen plants were selected from both an early maturity source population of 1600 plants and from a medium maturity source population of 1700 plants. Selected plants from each maturity group were placed in separate polycross blocks. Using resulting half-sib seeds, two spaced-plant nurseries were established in Philomath, Oregon to evaluate forage and seed yield and agro-morphological characteristics including plant height, tiller number, and heading date. In 2 addition, small plot trials were established in Boyd, Kentucky in 2018 to quantify forage yield and estimate forage quality. In the Oregon spaced-plant nurseries, forage yield, seed yield, heading date, tiller number, and plant height were significantly different (P<0.05) among genotypes. In the Kentucky small plot trials, significant differences were found for forage yield, NDF, ADF, TDN, RFV, and RFQ in the first cutting while only forage yields were significantly different for second and third cuttings. Thus, although there is a positive correlation between forage yield and fiber (NDF and ADF), concurrent improvements can be obtained for yield and digestibility through recurrent phenotypic selection. Since tall fescue does not produce culmed (jointed) vegetative shoots in regrowth, quality evaluation from the first cutting is most critical in selecting for improved digestibility. 3 ©Copyright by Elif Sahin March 12, 2020 All Rights Reserved 4 Breeding for Improved Forage Yield Potential and Digestibility in Tall Fescue (Schedonorus arundinaceus (Schreb.) Dumort.) by Elif Sahin A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Presented March 12, 2020 Commencement June 2020 5 Master of Science thesis of Elif Sahin presented on March 12, 2020 APPROVED: Major Professor, Representing Crop Science Head of the Department of Crop and Soil Science Dean of the Graduate School I understand that my thesis will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my thesis to any reader upon request. Elif Sahin, Author 6 ACKNOWLEDGEMENTS First, I would like to express my sincere thanks to my supervisor Dr. David B. Hannaway, for his invaluable guidance, wisdom, support, and patience during this research. I have been so lucky to have a supervisor who cared so much about my work, and who responded to my questions and queries all of the time. I will never forget the experiences that I have benefited from him throughout my life. Thank you, my almost joint supervisor, Dr. Serkan Ates, and his lovely family members. I always felt like they are my family. I would also like to thank Dr. Sabry Elias for serving on my committee and for making the time to listen to me about all my concerns and questions about this project. I would like to also thank Dr. Marcelo Moretti for his continuous encouragement, understanding, and motivation. In addition, I would like to thank Steve Reid for teaching me all the aspects of the field breeding study. He always answered my questions with great patience, even when he had limited free time. I would like to thank Barbara Hints-Cook for helping me transfer the data that I collected from the field, and for answering my numerous questions for this project. I would like to thank DLF Pickseed USA for supplying all equipment, materials, and staff. Your kindness, wisdom, and free spirit humbles me. Muhammet Sahin, who is my husband, was always there with all his love for me when I needed a warm-hearted hand. He always provided full support and helped me when I felt tired, upset, and depressed through my master’s program. My special thanks go to my beloved parents; my mother Ayse, my father Yusuf, and my sisters Sevilay, Sabriye, Eda, Seyda, Gulseren, and Gulsah. I also would like to thank my second 7 parents, mother-in-law Gursun and father-in-law Recep for their endless support and encouragement in my every decision I have made throughout my whole life. I would like to thank Ramazan Tuzen; I am sure that I would not have been at this point if you had not helped push me along. I learned that I should never give up on my way. I also thank Tuncay Guzel for his support and belief in me. Last, but not least, I am thankful for the great two and a half years of my life here in Oregon, where I have met the wonderful people in my life. I have always felt I am fortunate to have met these people. Ayse and Merve were always there for me like sisters when I need a warm-hearted hand. Also, Yunus, thank you for the countless ways you have helped me throughout this process. I am genuinely grateful for the impact each of you has had on my life and career. TABLE OF CONTENTS Page Chapter 1: General Introduction and Literature Review ................................................................. 1 1.1 Tall Fescue .................................................................................................................... 1 1.1.1 Origin and Distribution of Tall Fescue .......................................................... 1 1.1.2 Systematics, Physiology, and Morphology .................................................... 2 1.1.3 Usage of Tall Fescue ...................................................................................... 3 1.1.4 Endophytic Fungus Association .................................................................... 5 1.1.5 Cultivars ......................................................................................................... 7 1.1.6 Climatic and Soil Tolerances ......................................................................... 8 1.1.7 Forage Yield and Quality ............................................................................... 9 1.1.8 Recurrent Phenotypic Selection ................................................................... 12 1.2 Project Description ...................................................................................................... 14 1.3 Project Overview ........................................................................................................ 14 1.4 Anticipated Impact ...................................................................................................... 15 Chapter 2: Breeding for improved forage yield potential and digestibility of tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) .......................................................................... 16 Abstract ......................................................................................................................................... 16 2.1 Introduction ................................................................................................................. 17 2.2 Materials and Methods ................................................................................................ 18 2.2.1 Development of Populations and Selection Criteria .................................... 18 2.2.2 Field Planting and Evaluation ...................................................................... 22 2.2.2.1 Small Plot Trial (Experiments A1 and A2) ................................... 22 2.2.2.2 Spaced-Plant Nurseries (Experiments B1 and B2) ....................... 23 2.2.3 Measurements and Data Collection ............................................................. 25 9 2.2.3.1 Dry Matter Yield and Forage Quality ........................................... 25 2.2.3.2 Agro-morphological Characteristics ......................................................... 25 2.2.5 Experimental Design and Statistical Analysis ............................................. 27 2.3 Results ......................................................................................................................... 28 2.3.1 Phenotypical Traits ...................................................................................... 28 2.3.1.1 Dry Matter Yield (DM) and Spring Growth Indices (1st, 2nd, 3rd SGI) ........................................................................................................... 28 2.3.1.2 Heading Date, Seed Yield, Tiller Number and Plant Height ........ 30 2.3.1.6 Flag Leaf Length-Height-Width and Panicle Length ................... 32 2.3.2 Forage Yield and Quality ............................................................................. 33 2.3.2.1 First Cutting .................................................................................. 33