ABSTRACT CAREY, DENNIS JOHN. the Effects Of
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ABSTRACT CAREY, DENNIS JOHN. The Effects of Benzyladenine on Ornamental Crops. (Under the direction of Drs. Brian Whipker and Wayne Buhler). A synthetic cytokinin, benzyladenine (BA), has recently been released in the U.S. as Configure® (2% liquid solution) for use on ornamental plants. Experiments were conducted to determine the efficacy of BA on various ornamental crops and to determine the optimal concentrations. BA was trialed on petunias, succulents, Paeonia, Salvia ’Caradonna’, and Helleborus ×hybridus and resulted in an increase in shoot number. Succulents (Sempervivum, Echeveria, Jovibarba, Agave, and Aloe) were the most reactive. The ideal foliar spray concentrations of 200 to 400 mg•L-1 applied one time increased offset formation by two times in five Sempervivum cultivars and in Echeveria. The ideal foliar spray concentration of 1600 mg•L-1 applied one time increased offset formation by two times in one cultivar of Jovibarba. BA foliar sprays applied two times were ineffective on three Agave cultivars and three Aloe cultivars. Foliar sprays, drenches, fertigations, bulb soaks and plug dips in a range of concentrations, application numbers and timings were evaluated on an additional 48 annual and perennial species. Applications of BA had minor positive effects, no effects, or negative effects and the most promising commercial applications will be presented. The Effects of Benzyladenine on Ornamental Crops. by Dennis John Carey Jr. A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science Horticultural Science Raleigh, North Carolina 2008 APPROVED BY: Wayne Buhler, Ph.D. Brian E. Whipker, Ph.D. Co-Chair of Advisory Committee Co-Chair of Advisory Committee Mark Kistler, Ph.D DEDICATION To my wife Eileen who has supported me through my career change, who has read every single paper I have ever written, and, inserted, commas, in, the, right, places. ii BIOGRAPHY Dennis John Carey Jr. was born on 13 June, 1969 in Rockford, Illinois to Dennis and Kathryn Carey. In 1976 he moved to Cary, North Carolina. Dennis graduated from Cary High School in 1987. He went on to attend North Carolina State University and received a Bachelor of Science Degree in Electrical Engineering in December 1992 and a Bachelor of Science Degree in Computer Engineering in August 1993. He worked as a software engineer at Nortel Networks in RTP, NC until he was laid off in December 2002. He decided to change careers into Horticulture and went back to North Carolina State University and received a Bachelor of Science Degree in Horticulture Science in December 2004. He then worked at Plantworks Nursery in Rougemont, NC as a Section Grower until December 2006. In January 2007 he began a program of graduate study at North Carolina State University in Horticulture under the direction of Dr. Brian Whipker. Following the completion of the requirements for the degree of Master of Science in the floriculture program Dennis will find a job in the field of ornamental horticulture. iii ACKNOWLEDGMENTS I would like to thank a number of people for their help and guidance throughout my gradate studies. I would like to thank Dr. Brian E. Whipker for his guidance and encouragement. Thank you to Eileen Carey for her time spent editing everything that I have ever written. Thanks to Ingram McCall for her help setting up experiments and taking data. iv TABLE OF CONTENTS LIST OF TABLES xii LIST OF FIGURES xvi Chapter 1.................................................................................................................................1 Literature Review and Introduction........................................................................................1 1.1 The Need for Plant Growth Regulators ........................................................................1 1.2 History of Plant Growth Regulators .............................................................................2 1.3 Overview of Plant Growth Regulators..........................................................................3 1.3.1 Growth Inhibition...................................................................................................4 1.3.1.1 Anti-Gibberellins...................................................................................................................... 4 1.3.1.2 Anti-Auxins.............................................................................................................................. 6 1.3.2 Branching Agents...................................................................................................8 1.3.2.1 Ethylene Promoters .................................................................................................................. 8 1.3.2.1.1 Ethephon........................................................................................................................... 9 1.3.2.2 Methyl Esters of Fatty Acids.................................................................................................... 9 1.3.2.3 Dikegulac-sodium .................................................................................................................... 9 1.3.2.4 Cytokinins .............................................................................................................................. 10 1.3.2.5 Anti-Auxins............................................................................................................................ 11 1.3.3 Growth Enhancers................................................................................................12 1.3.3.1 Gibberellins............................................................................................................................ 12 1.3.3.2 Auxins .................................................................................................................................... 12 1.3.4 Flowering Enhancers ...........................................................................................13 1.3.4.1 Gibberellins............................................................................................................................ 13 1.3.4.2 Cytokinins .............................................................................................................................. 13 1.3.5 Senescence Interruption.......................................................................................14 1.3.5.1 Cytokinins .............................................................................................................................. 15 1.3.5.2 Anti-Ethylene Compounds..................................................................................................... 15 1.3.5.2.1 1-MCP ............................................................................................................................ 16 1.3.5.2.2 Silver Thiosulfate (STS)................................................................................................. 16 1.3.6 Stop Water Loss...................................................................................................16 1.3.7 Research Focus of this Thesis..............................................................................16 1.4 Overview of Cytokinins..............................................................................................17 1.4.1 Description of Cytokinins....................................................................................17 1.4.1.1 Cytokinin Effects in Plants..................................................................................................... 18 1.4.1.1.1 Cell Division................................................................................................................... 19 1.4.1.1.2 Morphogenesis ............................................................................................................... 19 1.4.1.1.3 Lateral Bud Growth / Apical Dominance....................................................................... 19 1.4.1.1.4 Flower Promotion or Inhibition...................................................................................... 22 1.4.1.1.5 Leaf Expansion............................................................................................................... 23 1.4.1.1.6 Delay Senescence ........................................................................................................... 23 1.4.1.1.7 Stomatal Opening ........................................................................................................... 24 1.4.1.1.8 Chlorophyll Biosynthesis ............................................................................................... 25 1.4.1.1.9 Flower Sex Ratios........................................................................................................... 25 v 1.4.1.1.10 Vernalization ................................................................................................................ 26 1.4.1.1.11 Parthenocarpy............................................................................................................... 26 1.4.1.1.12 Nutrient Signaling and Photosynthate Partitioning....................................................... 26 1.4.1.1.13 Seed Development and Germination............................................................................ 27 1.4.1.1.14 Cellular Differentiation................................................................................................. 28 1.4.1.1.15 Maturation ...................................................................................................................