Pollination Effects On Strawberry Fruit Quality

Pollination effects on strawberry fruit quality CAO DINH DUNG i Pollination effects on strawberry fruit quality By CAO DINH DUNG Bachelor of Science (Honours) in Horticulture Master of Science in Horticulture ii This thesis is submitted in fulfilment of the requirements for the completion of the degree of Doctor of Philosophy University of the Sunshine Coast Maroochydore DC, Queensland 4558, Australia June 2021 iii Abstract Cross-pollination affects the fruit characteristics of many crops, but little was known previously about the effects of cross-pollination on strawberry fruit quality This thesis aimed to evaluate the effects of cross-pollination on yield and fruit quality of the strawberry cultivar, Redlands Joy The thesis also evaluated the potential of hyperspectral imaging to estimate plant nutrient status and predict fruit yield In particular, the thesis aimed to: (1) evaluate the effects of manual cross-pollination with either Rubygem or Sugarbaby pollen, when compared with manual self-pollination or unassisted selfpollination (autogamy), on fruit yield and fruit quality when all flowers on each plant received either cross-pollen or self-pollen; (2) evaluate the effects of cross-pollination on fruit mass and fruit quality when both cross-pollinated and self-pollinated fruit developed on the same plant; (3) determine the consistency of cross-pollination effects on fruit mass and fruit quality across different levels of plant calcium nutrition; (4) identify at what developmental stages cross-pollinated fruit differ in mass and quality from self-pollinated fruit, and whether differences in the mass of fruit are caused by differential accumulation of mineral nutrients; and (5) assess hyperspectral imaging as a technique to rapidly estimate macronutrient concentrations in strawberry leaves, flowers and fruit and to predict yield Cross-pollination by either Rubygem or Sugarbaby did not affect Redlands Joy fruit yield or individual fruit mass significantly when cross-pollinated fruit and selfpollinated fruit developed on different plants However, cross-pollinated fruit were 4.2– 7.5 % heavier than self-pollinated fruit when both types of fruit competed for resources on the same plant Differences in mass and size between cross-pollinated and selfpollinated fruit occurred temporarily during early fruit development but emerged mainly during the final week of fruit ripening The effects of cross-pollination on fruit mass and size were not the result of differences in mineral nutrient accumulation between crosspollinated and self-pollinated fruit iv Cross-pollination had major impacts on fruit appearance, taste attributes, firmness and shelf life Cross-pollinated fruit were darker red and sometimes had lower °Brix or lower acidity than self-pollinated fruit, with the effect on °Brix:acid ratio depending on the calcium level Cross-pollinated fruit sometimes had approximately days’ longer shelf life than self-pollinated fruit Many of these effects of cross-pollination on fruit quality were amplified when calcium was in shortest supply In addition, manually crosspollinated or manually self-pollinated fruit were darker, redder and firmer and had longer shelf life than autogamously pollinated fruit Cross-pollinated fruit contained higher concentrations of some mineral nutrients than self-pollinated fruit Cross-pollination by Sugarbaby increased fruit calcium, iron, manganese, phosphorus and potassium concentrations by 10–41 %, but decreased boron, copper and zinc concentrations by 12–31 % Cross-pollination by Rubygem increased fruit manganese concentration by 11 %, but decreased potassium and sodium concentrations by % and 23 %, respectively In addition, hand-pollinated fruit had 20– 24 % higher protein concentration, 30–45 % lower aluminium concentration and 37–79 % lower sodium concentration than fruit arising from autogamy Hyperspectral imaging showed potential for estimating nitrogen, phosphorus, potassium and calcium concentrations in strawberry leaves, flowers or fruitlets, and for predicting plant yield and fruit mass Prediction accuracies were R2P = 0.64, 0.60 and 0.81 for nitrogen concentrations, R2P = 0.49, 0.34 and 0.81 for phosphorus concentrations, R2P = 0.68, 0.49 and 0.46 for potassium concentrations, and R2P = 0.70, 0.62 and 0.61 for calcium concentrations of leaves, flowers and unripe fruit, respectively Hyperspectral imaging based on the foliar Difference Vegetation Index, DVI [800, 670] had potential for predicting plant yield and fruit mass with r2 = 0.256 and 0.226, respectively In conclusion, cross-pollination had major impacts on the quality and mineral nutrient concentrations of strawberry fruit Strawberry growers could consider inter-planting different cultivars more closely and managing insect pollinators to maximize the transfer of cross-pollen across farms and ensure the highest possible fruit quality Growers could manage calcium fertilizer regimes to help decrease variability in fruit mass and improve fruit appearance Growers could also consider the use of hyperspectral imaging for estimating plant nutrient status, which could assist them to amend nutrients rapidly for optimizing yield and fruit quality v Declaration of originality The thesis is my own account of research undertaken by me, and the thesis has been wholly completed during candidature, and where work has been done conjointly with other persons, my contribution is clearly stated and the contribution of other persons is clearly acknowledged and recognised The thesis does not contain as its main content any work or material which is embodied in a thesis or dissertation previously submitted by me or any other person for a university degree or other similar qualification at this or other higher education institution, except where approval has previously been granted by the Committee ……… ………………………………………… 30th June 2021 Cao Dinh Dung, CANDIDATE ……… ………………………………………… Steven M Ogbourne, PRINCIPAL SUPERVISOR vi 30th June 2021 Dedication I dedicate this thesis to my wife Nguyen Thuy Hang and our son Cao Dinh Thien Nhan (Kenny Cao) whose inspiration kept me going during my PhD journey vii Acknowledgements The success of this thesis is a result of a collective effort and contributions from many people, whom I would like to acknowledge My special thanks go to my principal supervisor Associate Professor Steven Ogbourne and my co-supervisor Dr Gabriel Conroy for making this journey possible It is immeasurable how much I have learnt from them and I am extremely grateful for having worked with them during these formative years I also acknowledge Associate Professor Steven Ogbourne for his mentoring and support I acknowledge my consultant supervisors Professor Stephen Trueman, Professor Helen Wallace and Dr Shahla Hosseini Bai from Griffith University for their persistence and patience in guiding me through to the thesis’ completion More than assisting with the practical, technical and theoretical aspects of my research, which has been instrumental, they encouraged me, challenged me, treated me with respect and as an equal, provided opportunities, promoted me and my work, and fostered enormous growth in me as an early career academic I give sincere thanks to Professor Stephen Trueman and Professor Helen Wallace Working collaboratively with them has shaped my work to be something more meaningful and shaped me to be a more skilled and knowledgeable researcher with a better understanding of the professional and societal context in which my research sits Many thanks also go to Dr Shahla Hosseini Bai for all her patience throughout my entire journey, her timely feedback and her rapid responses to my emails I thank Dr Wiebke Kämper, Bruce Randall, Tracey McMahon and Joel Nichols for helping me with ordering of my consumables for my laboratory work and Ian Darby, Darren Morrow and Michael Nielsen for providing me with laboratory and nursery equipment My thanks also go to Michael Farrar, Tsvakai Gama and Dr Iman Tahmasbian for their assistance with hyperspectral imaging I thank my other friends for remaining interested and supportive, and for giving me many, many things to enjoy outside of the PhD I acknowledge the University of the Sunshine Coast (USC) and the GeneCology Research Centre for providing me funding and facilities to finish my PhD course viii I thank the Hort Frontiers Pollination Fund (Horticulture Innovation Australia) for providing project funding Perhaps the biggest thank you belongs to the Vietnamese Ministry of Education and Training (Moet), International Cooperation Department (Vied) and Vietnamese Agriculture and Rural Development Ministry which participated in my research by funding my PhD study Finally, I give biggest thanks to my family, Nguyen Thuy Hang and Cao Dinh Thien Nhan (Kenny Cao), for their love, support and inspiration I acknowledge Dr Cao Dinh Hung who had introduced me to Professor Stephen Trueman And for my parents, if I am proud of this work and my achievements, that does not compare to how proud I am to be their son I thank them for allowing me to be everything of which I am capable ix Table of contents Abstract iv Declaration of originality vi Dedication vii Acknowledgements viii Table of contents x List of figures xiv List of tables xviii List of manuscripts xx Chapter Introduction Chapter Literature review: The role of pollination and calcium in fruit quality 10 2.1 Introduction 10 2.2 Effects of pollination on fruit quality 11 2.2.1 Effects of cross-pollination versus self-pollination on fruit quality 11 2.2.2 Effects of pollination on strawberry fruit quality 11 2.3 Effects of calcium on fruit quality 12 2.3.1 Influences of calcium on fruit quality 12 2.3.2 Effects of calcium application method on fruit quality 13 2.4 Indicators of strawberry fruit quality 13 2.5 Visible/near-infrared (Vis/NIR) hyperspectral imaging as a tool to predict leaf and flower nutrient status and fruit quality 15 2.5.1 Potential of hyperspectral imaging for predicting leaf and flower nutrient status 15 2.5.2 Potential of hyperspectral imaging for predicting fruit quality 16 2.6 Conclusion 16 2.7 Research objectives 17 x Chapter Cross-pollination affects fruit colour, taste attributes, firmness, shelf life and mineral nutrient concentrations of selfcompatible strawberry 29 Statement of contribution 29 3.1 Abstract 30 3.2 Introduction 31 3.3 Materials and Methods 32 3.3.1 Plant material 32 3.3.2 Experimental design and pollination method 34 3.3.3 Yield, fruit characteristics and shelf life 34 3.3.4 Data analysis 36 3.4 Results 37 3.4.1 Pollination effects on fruit yield, fruit quality and seed fertilization 37 3.4.2 Relationships between fertilized seeds and fruit quality 42 3.5 Discussion 44 3.6 Conclusion 47 Acknowledgments 47 Chapter Fruit size, shape, colour, taste and shelf life differ between competing self-pollinated and cross-pollinated fruit on self-compatible strawberry plants 54 Statement of contribution 54 4.1 Abstract 55 4.2 Introduction 56 4.3 Material and Methods 58 4.3.1 Plant material 58 4.3.2 Experimental design 58 4.3.3 Fruit measurements 59 4.3.4 Statistical analysis 60 4.4 Results 61 4.4.1 Fruit size and shape 61 4.4.2 Fruit colour and taste attributes 63 4.4.3 Fruit firmness and shelf life 64 4.5 Discussion 65 xi 4.6 Conclusion 67 Acknowledgements 68 Chapter Biomass and mineral nutrient partitioning among selfpollinated and cross-pollinated fruit on the same strawberry plant 73 Statement of contribution 73 5.1 Abstract 74 5.2 Introduction 75 5.3 Material and methods 76 5.3.1 Plant material 76 5.3.2 Experimental design 76 5.3.3 Fruit quality 77 5.3.4 Leaf mineral nutrient concentrations across the three experiments 78 5.3.5 Data analysis 78 5.4 Results 79 5.4.1 Biomass and leaf mineral nutrient concentrations across experiments 79 5.4.2 Cross-pollination effects on fruit growth and colour 80 5.4.3 Cross-pollination effects on fruit mineral-nutrient accumulation 82 5.5 Discussion 85 5.6 Conclusion 88 Acknowledgements 88 Chapter Hyperspectral imaging for estimating leaf, flower and fruit macronutrient concentrations and predicting yield of strawberry 93 Statement of contribution 93 6.1 Abstract 94 6.2 Introduction 95 6.3 Material and Methods 97 6.3.1 Sample preparation 97 6.3.2 Hyperspectral imaging 98 6.3.3 Nutrient analyses of the samples 99 6.3.4 Data analysis and model development 99 6.3.5 Predicting yield and fruit mass 101 6.4 Results 102 6.4.1 Descriptive statistics 102 6.4.2 Estimating nitrogen (N) concentrations 103 xii 6.4.3 Estimating phosphorus (P) concentrations 106 6.4.4 Estimating potassium (K) concentrations 109 6.4.5 Estimating calcium (Ca) concentrations 112 6.4.6 Predicting fruit mass and yield 115 6.5 Discussion 117 6.6 Conclusion 120 Acknowledgements 120 Supplementary materials 130 Chapter Summary and Conclusions 133 7.1 Introduction 133 7.2 Cross-pollination impacted strawberry fruit colour, taste attributes, firmness, shelf life and mineral nutrient concentrations 134 7.3 More xenia effects were apparent when cross-pollinated fruit competed with selfpollinated fruit on the same plant 135 7.4 Xenia effects on fruit growth were evident temporally at early developmental stages but the differences in mass were not caused by differences in accumulation of mineral nutrients 136 7.5 Hyperspectral imaging has potential for estimating leaf, flower and fruitlet macronutrient concentrations and predicting yield of strawberry 137 7.6 Conclusions 138 7.7 Recommendations 139 7.8 Knowledge gaps 139 xiii ... self -pollination on fruit quality 11 2.2.2 Effects of pollination on strawberry fruit quality 11 2.3 Effects of calcium on fruit quality 12 2.3.1 Influences of calcium on fruit quality. .. pollination and calcium in fruit quality 10 2.1 Introduction 10 2.2 Effects of pollination on fruit quality 11 2.2.1 Effects of cross -pollination versus self -pollination. .. previously about the effects of cross -pollination on strawberry fruit quality This thesis aimed to evaluate the effects of cross -pollination on yield and fruit quality of the strawberry cultivar,