Testing, advancing, and applying an isotope mass balance model to investigate nitrogen uptake and assimilation in poplar and willow
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Hu, Yi
issued: 2022-05-27T19:05:56Z
issued: 2022
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Poplars and willows are widely distributed in temperate ecosystems and are important woody crops, but their growth depends on adequate (and often replete) supplies of water and nitrogen. Nitrogen isotope discrimination (∆¹⁵N) have utility as an indicator of nitrogen-use in plants, and an isotope mass balance (IMB) model has been proposed to estimate the fluxes across root plasma membranes (E/I), the proportion of inorganic nitrogen assimilated in roots (Proot) and translocation of inorganic nitrogen to shoots (Ti/Tt) under steady-state conditions. Good correspondence between model-estimated E/I and compartmental analysis of tracer efflux has been demonstrated. In this thesis, the IMB model was further validated and then, after adjusting the ∆¹⁵N value of nitrate reductase (∆enzyme), used to explore intraspecific variation in nitrogen-use in black cottonwood (Populus trichocarpa Torr. & Gray) and heart-leaved willow (Salix eriocephala Michx.). To test the IMB model, I measured concentrations and δ¹⁵N of inorganic and organic nitrogen in xylem sap extracted from stems of black cottonwood provisioned hydroponically with nitrate. Direct determinations of Ti/Tt and Proot compared very favorably with IMB model-derived estimates. The difference in δ¹⁵N between organic-N and NO3̄ -N fractions in xylem sap (24.9‰) suggests a ∆enzyme of 25.1‰, which is higher than previously assumed by the IMB model, but close to recent estimates that average ~22‰. There was significant variation in nitrogen-use related traits in both poplar and willow. In heart-leaved willow, variation in δ¹⁵N, δ¹³C and C/N ratios indicated differences in nitrogen uptake and assimilation, WUE, and NUE. Clinal variation in δ¹⁵N was found in field and hydroponic experiments, possibly related to water availability. The absence of a trade-off between E/I, WUE, and NUE in willow suggests that additive variation in these traits can be captured without compromise. Variation in growth, R:S ratio, ∆¹⁵N, and C/N ratio…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/81646
note: Testing, advancing, and applying an isotope mass balance model to investigate nitrogen uptake and assimilation in poplar and willow by Yi Hu B.S.F. Sichuan Agricultural University, 2013 M.Sc. Sichuan Agricultural University, 2015 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The Faculty of Graduate and Postdoctoral Studies (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) May 2022 ©Yi Hu, 2022 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Testing, advancing, and applying an isotope mass balance model to investigate nitrogen uptake and assimilation in poplar and willow submitted by Yi Hu in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Forestry Examining Committee: Robert D. Guy, Professor, Department of Forest and Conservation Sciences, UBC Supervisor Shawn D. Mansfield, Professor, Department of Wood Science, UBC Supervisory Committee Member Barbara J. Hawkins, Professor, Department of Biology, University of Victoria Supervisory Committee Member Andrew Riseman, Professor, Centre for Sustainable Food Systems at UBC Farm, UBC University Examiner Christopher Chanway, Professor, Department of Forest and Conservation Sciences, UBC University Examiner Additional Supervisory Committee Member: Lee A. Kalcsits, Associate Professor, Department of Horticulture, Washington State University Supervisory Committee Member iii Abstract Poplars and willows are widely distributed in temperate ecosystems and are important woody crops, but their growth depends on adequate (and often replete) supplies of water and nitrogen. Nitrogen isotope discrimination (15N) have utility as an indicator of nitrogen-use in plants, and an isotope mass balance (IMB) model has been proposed to estimate the fluxes across root plasma membranes (E/I), the proportion of inorganic nitrogen …
has type: Thesis/Dissertation
date issued: 2022-11
is shown at: 10.14288/1.0413712
language: eng
degree discipline: Forestry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Guy, Robert D.
type: Text
type: Still Image
identifier URI: http://hdl.handle.net/2429/81646