EVALUATION of the DOMESTICATION STATUS of COW COCKLE (Vaccaria Hispanica [P

EVALUATION OF THE DOMESTICATION STATUS OF COW COCKLE (Vaccaria hispanica [P. Mill.] Rauschert) POPULATIONS A Thesis Submitted to the College of Graduate Studies and Research In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy In the Department of Plant Sciences University of Saskatchewan Saskatoon By Hema Sudhakar Naidu Duddu © Copyright Hema S. N. Duddu, April 2014. All rights reserved. PERMISSION TO USE In presenting this thesis in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying, publication, or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or to make other use of materials in this thesis, in whole or part, should be addressed to: Head of the Department of Plant Sciences University of Saskatchewan 51 Campus Drive Saskatoon, Saskatchewan S7N 5A8 Canada OR Dean College of Graduate Studies and Research University of Saskatchewan 107 Administration Place Saskatoon, Saskatchewan S7N 5A2 Canada i ABSTRACT Cow cockle (Vaccaria hispanica [P. Mill.] Rauschert) is a summer annual species introduced to North America from Europe. It has been investigated as a potential crop for the Canadian prairies because of its ultra–fine starch, cyclo–peptides, and saponins. However, cow cockle has a long history of being a weed in Canada and may need additional scrutiny of its weediness potential before initiating commercial production. In addition, cultivating poorly domesticated species may lead to further environmental and weed management risks; hence, an understanding of the domestication status is required. The objectives of this research were to evaluate available cow cockle germplasm i) to identify populations that are best adapted to cultivation as well as the traits responsible for such adaptation, ii) to determine seed dormancy levels in cow cockle populations and to determine how temperature and light affect seed dormancy and germination, and iii) to determine whether cow cockle populations are persistent and form a seed bank. A total of 15 cultivated, weedy, and wild cow cockle populations from different parts of the world were compared for agro–morphological, seed dormancy and seed persistence characters from 2009 to 2011. In the field persistence study, two populations including weedy (Scott weedy) and cultivated (Scott) lines were included. Cluster analysis revealed three main groups among the populations based on the traits studied. Physiological maturity, seed size, plant height and seed yield differed most among populations. The cultivated populations, Pink Beauty, Turkey, PB–87, Scott and a weedy population, UMan–89 had higher seed yield, larger seeds, and greater biomass compared to the other populations. Although weedy populations showed some adaptation to cultivation, characters relating to plant architecture, seed size and yield suggested a weedy habit. Freshly matured seeds of all the populations showed high levels of primary conditional dormancy except “Mongolia”. At optimum temperature conditions for germination (10 C), the effect of temperature regime (alternating and constant) and light on seed dormancy were insignificant. The variation in optimum temperature, light, and their interactions among the cow cockle populations may be due to the plants evolving to adapt to their local environments. In the field persistence study, the weedy population had higher seedling emergence at two out of three locations and a larger residual seed bank at all the locations. Despite the differences in seed ii persistence between the populations, considerable numbers of seed of both weedy and cultivated lines were recovered from the soil seed bank at the end of the study. This concurs with the results of the laboratory persistence study, as both the populations had greater seed longevity (p50 values > 50 days) which suggests a field persistence of over three years. In conclusion, higher seed yield, larger seeds, and greater biomass in cultivated populations may result from certain pre– adaptation towards domestication, which may have been acquired during the process of pre– domestication cultivation. From a domestication perspective, if cow cockle were grown as a crop, the conditional dormancy may not be considered a barrier to domestication and can be viewed as a physiological mechanism to avoid germination at harvest. The major concern in cow cockle domestication would be seed persistence, as it can form a reasonably long–term seed bank. This may pose some concerns for the production of cow cockle as a crop in the Canadian Prairies. The current research suggests that cow cockle populations from Canada, although they showed some adaptation to cultivation; are largely weedy and can be considered as variants of an early introduced species which might have evolved to adapt to non–native conditions. iii ACKNOWLEDGEMENT First, I wish to express my deep and sincere appreciation to my supervisor on this project, Dr. Steve Shirtliffe, whose patience and support through this project has been enormous–obviously without him I would not be where I am today. Steve has put great trust and confidence in me and has withstanded my inexperience. Thank you Dr. Shirtliffe. I am extremely thankful to Drs. Yuguang Bai, Pierre Hucl and Angela Bedard–Haughn for their valuable time and constructive input as advisory committee members. I extend my special thanks to Dr. B. Coulman, Eric Johnson at Agriculture and Agri–Food Canada in Scott, Dr. Robert Blackshaw at Lethbridge Research Centre, AB, Dr. Christian Willenborg, Dr. John Balsevich and Dr. Yongsheng Wei for their support and cooperation. I sincerely acknowledge the financial support provided by Agriculture Development Fund (ADF), Natural Science and Engineering Research Council (NSERC), the Saskatchewan Ministry of Agriculture and Department of Plant Sciences, University of Saskatchewan for funding this research project. I also thank L.H. Hantelman Post Graduate Scholarship and Rene Vandeveld Postgraduate Scholarships in Crop Science. Furthermore, a special thanks to Agronomy/Weed Ecology technical staff: Shaun Campbell and Matthew Leisle as well as all summer students for their help and support during this research. I would like to extend my acknowledgement to the graduate students: Dilshan Benaragama, Teketel Haile, Jay Anderson, Angelena Syrovy and Colleen Redlick for their support and friendship. On a more personal note, I would like to express my appreciation for the love and support of my Father (Madeen Naidu Duddu), Mother (Ramanamma Duddu), as well as my siblings and the entire family, thank–you for always being there for me. Last, but certainly not least, a warm thanks to all my friends for providing help and company throughout the whole process. iv TABLE OF CONTENTS PERMISSION TO USE ................................................................................................................... i ABSTRACT .................................................................................................................................... ii ACKNOWLEDGEMENT ............................................................................................................. iv TABLE OF CONTENTS ................................................................................................................ v LIST OF TABLES ....................................................................................................................... viii LIST OF FIGURES ........................................................................................................................ x LIST OF ABBREVIATIONS ....................................................................................................... xii 1.0 INTRODUCTION .................................................................................................................... 1 2.0 REVIEW OF LITERATURE ................................................................................................... 6 2.1 Cow cockle.......................................................................................................................................... 6 2.1.1 Distribution and Taxonomy ......................................................................................................... 6 2.1.2 Cow cockle as a weed .................................................................................................................. 7 2.1.3 Utilization .................................................................................................................................... 8 2.2 Domestication ..................................................................................................................................... 9 2.2.1 Significance of domestication .....................................................................................................

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