University of Kentucky UKnowledge University of Kentucky Doctoral Dissertations Graduate School 2008 COMPARATIVE BIOLOGY OF SEED DORMANCY-BREAK AND GERMINATION IN CONVOLVULACEAE (ASTERIDS, SOLANALES) Kariyawasam Marthinna Gamage Gehan Jayasuriya University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Jayasuriya, Kariyawasam Marthinna Gamage Gehan, "COMPARATIVE BIOLOGY OF SEED DORMANCY- BREAK AND GERMINATION IN CONVOLVULACEAE (ASTERIDS, SOLANALES)" (2008). University of Kentucky Doctoral Dissertations. 639. https://uknowledge.uky.edu/gradschool_diss/639 This Dissertation is brought to you for free and open access by the Graduate School at UKnowledge. It has been accepted for inclusion in University of Kentucky Doctoral Dissertations by an authorized administrator of UKnowledge. For more information, please contact [email protected]. ABSTRACT OF DISSERTATION Kariyawasam Marthinna Gamage Gehan Jayasuriya Graduate School University of Kentucky 2008 COMPARATIVE BIOLOGY OF SEED DORMANCY-BREAK AND GERMINATION IN CONVOLVULACEAE (ASTERIDS, SOLANALES) ABSRACT OF DISSERTATION A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Art and Sciences at the University of Kentucky By Kariyawasam Marthinna Gamage Gehan Jayasuriya Lexington, Kentucky Co-Directors: Dr. Jerry M. Baskin, Professor of Biology Dr. Carol C. Baskin, Professor of Biology and of Plant and Soil Sciences Lexington, Kentucky 2008 Copyright © Gehan Jayasuriya 2008 ABSTRACT OF DISSERTATION COMPARATIVE BIOLOGY OF SEED DORMANCY-BREAK AND GERMINATION IN CONVOLVULACEAE (ASTERIDS, SOLANALES) The biology of seed dormancy and germination of 46 species representing 11 of the 12 tribes in Convolvulaceae were compared in laboratory (mostly), field and greenhouse experiments. Seeds were tested for kind of dormancy and storage behavior; artificial or simulated natural treatments were applied to break physical dormancy (PY); the initial route of water entry (“water gap”) into seeds was identified; the morpho- anatomy of the water gap was compared in seeds of 17 species; ontogenetical differences between water gap and seed coat away from the hilum were described in Ipomoea lacunosa seeds; cycling of sensitivity to dormancy break was elucidated in seeds of I. lacunosa, I. hederacea, Cuscuta australis and Jaquemontia ovalifolia; and mechanism of opening of the water gap was determined for seeds of I. lacunosa and of I hederacea. Seeds of only three of the 46 species were nondormant. Two of these were recalcitrant (Maripa panamensis and Erycibe henryi), and the other one was orthodox (Bonamia menziesii). Seeds of the other 43 species were orthodox and had PY except those of Cuscuta europea, which also had physiological dormancy (PD) i.e. combinational dormancy (PY + PD). Two bulges adjacent to the micropyle were identified as the water gap in all seeds with PY except those of Cuscuta, in which the hilar fissure is the water gap. Anatomy of the bulges (water gap) adjacent to the micropyle differs from that of seed coat away from the bulges. A different sequence and phase of anticlinal and periclinal cell divisions during development created weak transitional zones between bulge - hilum and bulge - seed coat away from hilum. Water vapor pressure changes below the bulges caused formation of the opening(s) in water gap. Seeds of I. lacunosa I. hederacea, C. australis and J. ovalifolia cycle between sensitive and insensitive states to dormancy break, but not between PY and nondormancy. Seed dormancy and storage characteristics and anatomy and morphology of dormancy of seeds of Convolvulaceae closely follow the molecular phylogeny of the family. I suggest that PY in seeds of subfamily Convolvuloideae evolved from nondormant recalcitrant seeds of an ancestor closely related to Erycibeae. KEY WORDS, Convolvulaceae, phylogeny of seed dormancy, physical dormancy, seed dormancy breaking mechanism, sensitivity cycling to dormancy break Gehan Jayasuriya July 23, 2008 COMPARATIVE BIOLOGY OF SEED DORMANCY-BREAK AND GERMINATION IN CONVOLVULACEAE (ASTERIDS, SOLANALES) By Kariyawasam Marthinna Gamage Gehan Jayasuriya Jerry M. Baskin Co-Director of Dissertation Carol C. Baskin Co-Director of Dissertation Brian C. Rymond Director of Graduate Studies July 23, 2008 RULES FOR THE USE OF DISSERTATIONS Unpublished dissertations submitted for the Doctor's degree and deposited in the University of Kentucky Library are as a rule open for inspection, but are to be used only with due regard to the rights of the authors. Bibliographical references may be noted, but quotations or summaries of parts may be published only with the permission of the author, and with the usual scholarly acknowledgments. Extensive copying or publication of the dissertation in whole or in part also requires the consent of the Dean of the Graduate School of the University of Kentucky. A library that borrows this dissertation for use by its patrons is expected to secure the signature of each user. Name Date _______________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ DISSERTATION Kariyawasam Marthinna Gamage Gehan Jayasuriya The Graduate School University of Kentucky 2008 COMPARATIVE BIOLOGY OF SEED DORMANCY-BREAK AND GERMINATION IN CONVOLVULACEAE (ASTERIDS, SOLANALES) DISSERTATION A Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Art and Sciences at the University of Kentucky By Kariyawasam Marthinna Gamage Gehan Jayasuriya Lexington, Kentucky Co-Directors: Dr. Jerry M. Baskin, Professor of Biology Dr. Carol C. Baskin, Professor of Biology and of Plant and Soil Sciences Lexington, Kentucky Copyright© Gehan Jayasuriya 2008 ACKNOWLEDGEMENTS The following dissertation, while an individual work, benefited from the insights and direction of several people. First and foremost, I thank my co-major Professors, Jerry Baskin and Carol Baskin, for their guidance, encouragement and friendship throughout my graduate studies. They recognized and developed my interest and ability to do research in biology, and their influence will be a light for the rest of my career as a scientist. I thank Prof. Robert L. Geneve and Prof. Dennis M. TeKrony for serving on my graduate committee and for their assistance and guidance in my research. Especially without the assistance of Prof. Robert L. Geneve, some parts of my research would not have been possible. I thank Prof. Willam W. Witt for representing the UK Graduate School at my dissertation defense, and Drs. Bruce Downie and Sharyn Perry for allowing me to use their laboratory facilities. Mr. Henry H. Southgate and Mr. Larry Rice provided valuable assistance with SEM and Mrs. Sharon T. Kester with sectioning and staining. I thank Dr. John Dickie and the Millennium Seed Bank Project, Royal Botanical Gardens, UK; Mr. Alvin Yoshinaga; Dr. Ching-Te Chein; Dr. Shun-Ying Chen; Mr. Carl Weekley; Dr. Jeff Walck; Dr. Siti Nur Hidiati; Dr. Julissa Roncal, Mr. John Geiger; and Mrs. Adriana Sautau and the Smithsonian Tropical Research Institute for collecting and sending me seeds for experiments reported in my dissertation. I thank Prof. NKB Adikaram and Dr. GAD Perera for allowing me to use the experimental facilities in the Department of Botany, University of Peradeniya, Sri Lanka, during my summer vacation in 2006. I thank the editors of Annals of Botany for permitting me to use data and figures, from papers I published in Annals of Botany, in my dissertation and the editors of Systematic Botany and Botanical Journal of the Linnean Society for permitting me to use, in modified from, figures published in their journals that helped to improve the quality of my dissertation. I thank Beverly Taulbee and other administrative staff members in the UK Biology Department for taking care of my administrative needs during my whole stay in the USA. I was fortunate to have a supportive and helpful fellow graduate student Miss. ii Xiaoxia Qu in my lab. This project would not have been possible without funding from the UK Graduate School and Biology Department, including a teaching assistantship and Ribble research funds. I received equally important assistance from my family and my friends. My wife, Isuru M. Gunathilaka, provided on-going support throughout the dissertation process. She has taken care of our son and my parents in Sri Lanka and given me inspiration during my stay in the USA. My father and mother, Mr. S.A. Jayasuriya & Mrs. A.P.B.I. Jayasuriya, instilled in me, from an early age, the desire and skills to obtain the Ph.D. iii TABLE OF CONTENTS Acknowledgements………………………………………………………………….…...ii