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The effects of soil water deficit on physiological, morphological and chemical traits of Eucalyptus by Adam B. McKiernan B.Sc. (Hons) Submitted in fulfilment of the requirements for the Degree of Doctorate of Philosophy University of Tasmania August 2015 Declaration This thesis contains no material which has been accepted for a degree or diploma by the University or any other institution, and to the best of my knowledge and belief no material previously published or written by another person except where due acknowledgement is made in the text of the thesis. The publisher of the paper comprising Chapter 2 holds the copyright for that content, and access to the material should be sought from the journal. The remaining non-published content of the thesis may be made available for loan and limited copying and communication in accordance with the Copyright Act 1968. Signed Adam B McKiernan B.Sc Date 27.8.2015 2 The following people contributed to the publication of work undertaken as part of this thesis: Adam B. McKiernan, School of Biological Sciences, University of Tasmania, Hobart, Australia = Candidate Julianne M, O’Reilly-Wapstra (supervisor), School of Biological Sciences, University of Tasmania, Hobart, Australia = Author 2 Mark J. Hovenden (co-supervisor), School of Biological Sciences, University of Tasmania, Hobart, Australia = Author 3 Bradley M. Potts (co-supervisor), School of Biological Sciences, University of Tasmania, Hobart, Australia = Author 4 Timothy J. Brodribb (co-supervisor), School of Biological Sciences, University of Tasmania, Hobart, Australia = Author 5 Noel W. Davies, Central Science Laboratory, University of Tasmania, Hobart, Australia = Author 6 Thomas Rodemann, Central Science Laboratory, University of Tasmania, Hobart, Australia = Author 7 Scott A. M. McAdam, School of Biological Sciences, University of Tasmania, Hobart, Australia = Author 8 John J. Ross, School of Biological Sciences, University of Tasmania, Hobart, Australia = Author 9 The details of which papers the co-authors contributed to, the contributions they made, and where the papers can be found are listed below: Chapter 2 is published: McKiernan AB, Hovenden MJ, Brodribb TJ, Potts BM, Davies NW, O’Reilly Wapstra JM. 2014. Effect of limited water availability on foliar plant secondary metabolites of two Eucalyptus species. Environmental and Experimental Botany 105: 55-64. Candidate was the primary author. Candidate, Authors 2-4 contributed to developing the idea. Author 6 undertook some sample analysis. Candidate and Authors 2-5 assisted with refining the text. 3 Chapter 3 is accepted: McKiernan AB, Potts BM, Brodribb TJ, Hovenden MJ, Davies NW, McAdam SAM, Ross JJ, Rodemann T, O’Reilly-Wapstra JM. Responses to soil water deficit and re-watering differ among secondary metabolites but are similar among provenances within Eucalyptus species. Tree Physiology This paper was conceived by the Candidate and Authors 2 -5. Candidate conducted the experiment, analysed data and wrote the manuscript. Author 6 analysed some samples. Authors 8 and 9 developed the foliar ABA assay and provided guidance on foliar ABA sample preparation, extraction and data interpretation. Authors 3 and 5 provided guidance with treatments. Modelling of chemical data using Near Infrared Spectroscopy (NIRS) was completed by the Candidate in association with Author 7. Supervision, guidance and corrections were provided by Authors 2–5. Author 9 also provided feedback on the manuscript. Chapter 4 has been reviewed: McKiernan AB, Hovenden MJ, Brodribb TJ, Potts BM, Davies NW, Rodemann T, O’Reilly-Wapstra JM. Trait changes in juvenile eucalypt leaves due to ontogeny, soil water deficit and recovery: Links to leaf flammability Annals of Botany This paper was conceived by the Candidate and Authors 2 -5. Candidate conducted the experiment, analysed data and wrote the manuscript. Author 6 analysed some samples. Authors 8 provided guidance on foliar ABA sample preparation, extraction and data interpretation. Authors 3 and 5 provided guidance with treatments. Modelling of chemical data using Near Infrared Spectroscopy (NIRS) was completed by the Candidate in association with Author 7. Supervision, guidance and corrections were provided by Authors 2–5. Chapter 5 has been reviewed: McKiernan AB, Brodribb TJ, Potts BM, Davies NW, Rodemann T, McAdam SAM, Hovenden MJ, O’Reilly-Wapstra JM. Limits to trait stability in potted juvenile Eucalyptus across decreasing levels of soil water availability. Functional Plant Biology This paper was conceived by the Candidate and Authors 2 -5. Candidate conducted the experiment, analysed data and wrote the manuscript. Author 6 analysed some samples. Authors 8 provided guidance on foliar ABA sample preparation, extraction and data interpretation. Authors 3 and 5 provided guidance with treatments. Modelling of chemical data using Near Infrared Spectroscopy (NIRS) was completed by the Candidate in association with Author 7. Supervision, guidance and corrections were provided by Authors 2–5. 4 We the undersigned agree with the above stated “proportion of work undertaken” for each of the above published (or submitted) peer-reviewed manuscripts contributing to this thesis: Signed: __________________ Signed: __________________ Julianne M. O’Reilly-Wapstra Anthony Koutoulis Supervisor Head of School School of Biological Sciences School of Biological Sciences University of Tasmania University of Tasmania Date: 28.8.2015 Date: 28.8.2015 5 Thesis abstract Abstract Drought periods leading to soil water deficit can fundamentally affect plant growth and survival, and alter plant traits such as leaf chemistry. Predictions of increased drought periods in many regions means that widespread plant species may experience soil water deficit that differs in duration and severity over the species natural range. Glasshouse experiments were used to test the effect of water deficit level, water deficit duration and re-watering on juveniles from genetically-distinct Eucalyptus globulus and E. viminalis provenances by quantifying plant morphological, physiological and chemical traits. Eucalyptus globulus provenances vary in genetic-based drought tolerance, and provenances are located across a rainfall gradient. I hypothesised that juveniles of provenances from wet locations would be affected by water deficit to a larger degree than those from dry locations due to intra- specific adaptation to local rainfall patterns. Both species and all provenances responded similarly to all water deficit treatments and to re-watering regardless of genetic-based constitutive trait variation, local rainfall patterns, or in the case of adult E. globulus, field drought susceptibility. The only response to water deficit which varied between provenances was foliar abscisic acid (ABA) levels, and the response pattern was similar for both species at each paired locality, indicating parallel evolution and local adaptation. While many E. viminalis constitutive chemical and morphological traits changed over time due to plant development, the duration of moderate (50%) water deficit had no impact on any trait. Eucalyptus globulus leaf water potential, foliar ABA levels, plant biomass and C:N were affected by different levels of water availability ranging from 90 – 0% of control evapotranspiration. Plant secondary metabolite (PSM) responses to water deficit varied between experiments, and also between the selected PSM traits. Overall, concentrations of individual terpenes and total oil were not influenced by water deficit. Concentrations of phenols were more plastic in response to water deficit than terpenes, as condensed tannin concentrations increased in some 6 Thesis abstract experiments and total phenolic and formylated phloroglucinol compound (FPC) concentrations decreased in some experiments. A short re-watering period reversed the effects of water deficit on some chemical traits, but also decreased phenol concentrations. Variation in responses to water deficit between experiments is discussed. Overall, genetic-based quantitative PSM variation was high between species and provenances, with comparably low levels of plasticity due to water deficit. While responses to soil water deficit may largely be similar in juveniles across each species range, the ecological impact of modest changes to Eucalyptus PSM concentrations during drought may be equally modest, and the effect on mature trees is unknown. 7 Acknowledgments Acknowledgments First and foremost my thanks go to my supervisors, Julianne O’Reilly- Wapstra, Brad Potts, Mark Hovenden and Tim Brodribb. Without your expertise in your respective fields I could not have put the various elements of this PhD together into a cohesive piece of work. Brad’s experience and energy helped keep the research detailed in this thesis progressing smoothly. Special thanks go to Julianne, who has been my primary supervisor over the last 5 ½ years, beginning with my little undergraduate research project. Your commitment to your students is phenomenal, your door was always open, and you are an exceptional researcher, teacher and mentor. The expertise of Thomas Rodemann and Noel Davies made this work possible. Thank-you for all the work you put in, as well as for taking the time to explain the equipment, theory, methodology and software used in your laboratories. The analytical parts of this thesis were able to be completed due to funding from the National Centre for Future Forest Industries (NCFFI). Thanks to Mark Hunt for providing financial support when it was