Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1992 Physiological Studies on Postharvest Leaf Blackening in Cut Flower Protea Species. Margaret Robyn Mcconchie Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Mcconchie, Margaret Robyn, "Physiological Studies on Postharvest Leaf Blackening in Cut Flower Protea Species." (1992). LSU Historical Dissertations and Theses. 5451. https://digitalcommons.lsu.edu/gradschool_disstheses/5451 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. 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Ann Arbor, MI 48106 PHYSIOLOGICAL STUDIES ON POSTIIARVEST LEAF BLACKENING IN CUT FLOWER PROTEA SPECIES A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Horticulture by M. Robyn McConchie B.Sc., University of London, UK, 1979 M .A ., Macquarie University, Australia, 1988 December 1992 DEDICATION Dedicated to my parents, Margaret and Angus McConchie ACKNOWLEDGEMENTS I wish to express my gratitude and appreciation to Dr. Suzanne Lang, who served as the major professor during the course of this study. Her guidance, advice and encouragement were invaluable to me. The willing and constructive advice of the examining committee, Dr. Gregory Lang, Dr. James Moroney, Dr. David Picha and Dr. Paul Wilson was greatly appreciated. I am also indebted to my colleague, Ms. Gloria McClure, for her tremendous support and friendship, and all the members, staff and graduate students of the Horticulture Department. Thank you to my coauthors Dr. Ken Gross (Chapter 2), Dr. Alan Lax and Dr. Greg Lang (Chapter 5). I would like to especially thank my husband, Dr. Ben Oldroyd, for his wonderful support, guidance and patience during this study. TABLE OF CONTENTS DEDICATION ..................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................. iii LIST OF TABLES ............................................................................................................ vi LIST OF FIGURES ........................................................................................................... vii ABSTRACT ........................................................................................................................ ix CHAPTER 1 INTRODUCTION ................................................................................................ 1 2 CARBOHYDRATE DEPLETION AND LEAF BLACKENING IN PROTEA NERIIFOLIA...................................................................................... 14 Introduction............................................................................................................ 15 Materials and Methods ....................................................................................... 17 Results ..................................................................................................................... 21 D isc u ssio n............................................................................................................... 32 References to Chapter 2 ....................................................................................... 35 3 COMPARISON OF POSTHARVEST LEAF BLACKENING AND PREHARVEST CARBOHYDRATE STATUS IN THREE PROTEA SPECIES........................................................................... 37 Introduction............................................................................................................ 38 Materials and Methods ....................................................................................... 40 Results and Discussion ....................................................................................... 42 References to Chapter 3 ....................................................................................... 54 4 CARBOHYDRATE METABOLISM AND POSSIBLE MECHANISMS OF LEAF BLACKENING IN PROTEA NERIIFOLIA UNDER DARK POSTHARVEST CONDITIONS.......................................... 56 Introduction ............................................................................................................ 57 Materials and Methods ....................................................................................... 60 Results ..................................................................................................................... 65 D iscu ssio n............................................................................................................ 75 References to Chapter 4 .................................................................................... 80 5 POLYPHENOL OXIDASE AND PEROXIDASE ACTIVITY IN PROTEA SUSANNAE x COMPACTA ’PINK ICE’ UNDER LIGHT AND DARK POSTHARVEST CONDITIONS............................. 83 Introduction........................................................................................................ 84 Materials and Methods .................................................................................... 86 Results ................................................................................................................. 92 D iscu ssio n............................................................................................................ 101 References to Chapter 5 ..................................................................................... 107 6 SUMMARY AND PROSPECTUS ............................................................. I l l A PPEN D IX .................................................................................................................... 118 VITA ................................................................................................................................. 119 v LIST OF TABLES Table 1. Relative abundance (%) from gas chromatograph/mass spectral analysis of the alditol acetate derivatives of a xylose standard and the unknown monosaccharide from Protea neriifolia leaves................. 25 Table 2. Carbon exchange rate, assimilate export rate and % fixed carbon exported for leaves of Protea neriifolia under 12 hr photoperiod (120 jumol• m'2• s'1) with 0% or 0.5% sugar in the vase solution............................................................................................................. 27 Table 3. Average Protea neriifolia leaf concentrations of total glutathione and oxidized glutathione at preharvest (Day 0), after a 24-hr dark shipping period (Day 1), and each day thereafter for 6 days while held in 24 h darkness (25C ± 1C)................... 72 Table 4. Average Protea neriifolia leaf malionaldehyde concentrations at preharvest (Day 0), after a 24-h dark shipping period (Day 1) and each day thereafter for 6 days while held in 24 h darkness (25C ± 1C)........................................................................................................... 74 Table 5. Changes in total leaf chlorophyll and total leaf protein concentration (mg • g fresh weight'1) from Protea Susannae x compacta cut flower stems at harvest (day 0), after a 24-h shipping period (day 1) and held at 25C (± 1C) (days 2-8) . 100 vi LIST OF FIGURES Figure 1. Percentage of leaves with at least 10% blackened leaf area in P. neriifolia ..............................................................................................................