dc.contributor.advisor |
Singhal, Naresh |
|
dc.contributor.advisor |
David, Karine |
|
dc.contributor.author |
Borker, Aditi |
|
dc.date.accessioned |
2021-01-12T00:43:24Z |
|
dc.date.available |
2021-01-12T00:43:24Z |
|
dc.date.issued |
2020 |
en |
dc.identifier.uri |
https://hdl.handle.net/2292/54153 |
|
dc.description.abstract |
Contamination of the environment by metal ions poses a threat to human and ecosystem health.
In the past few years, concern has shifted to metal oxide nanoparticles due to the rapid rise in
nanomaterial usage, resulting in their release into the environment. Despite an abundance of
literature on metal uptake by plants and the use of amendments to enhance it, information on
processes by which plants take up metal ions and nanoparticles and the changes over time from
the use of one or more ions and amendments and translocation from roots to shoots is limited.
Metal chelate complexes are known to transport from the roots to the shoots through breaks in
the casparian strip, or through damaged physiological barriers. Plant hormones can also affect
metal uptake as they regulate plant development and some hormones can activate plant
defence mechanisms under adverse environmental conditions, thus alleviating stress. Presence
of chelate-plant hormone in combination can cause a competition between plant damage and
growth, thereby either allowing or restricting metal mobility in plant tissues. This thesis aimed
at studying temporal translocation trends of Cu and Zn as ions and nanoparticles in the
presence and absence of amendments and investigating the processes influencing this
behaviour in Lolium perenne. A two-stage investigation process was designed to build on the
understanding of the plant damage and growth that would allow the translocation of metals as
ions and nanoparticles into ryegrass shoots. 1) Investigation of the combined effects of a
commercially available plant growth regulator, gibberellic acid (GA), and a biodegradable
chelating agent, ethylene diamine-disuccinic acid (EDDS), on the translocation of free ions
(Cu, Zn) alone and in combination in a hydroponic solution; 2) Explaining the behaviour and
translocation trends of hydroponically grown perennial ryegrass (Lolium perenne) plants when
metals were supplied as copper oxide (CuO) and zinc oxide (ZnO) nanoparticles and Cu and
Zn ions with different amendment combinations.
Translocation of Cu and Zn ions varied over time when added individually and in
combinations. Cu applied individually caused less damage with little translocation from roots
to shoots. In contrast, Zn accumulation and damage in roots increased translocation over time
to shoots. Cu concentration in shoots was enhanced by the co-application of Zn, while the
application of EDDS and GA-EDDS, by themselves or with Cu and Zn, lowered transpiration
and increased damage and translocation, while GA increased transpiration but decreased
translocation. Metal ions and nanoparticles in mixtures increased the translocation patterns of both copper
and zinc through increased membrane damage. EDDS affected the two nanoparticles very
differently, with increased copper translocation, but decreased zinc translocation, either by
increasing damage or plant growth. GA slightly increased translocation of both copper and zinc
ions influenced by an increase in plant transpiration. Competition between GA and EDDS
subsequently led to ion uptake through breached membrane barriers in GA-EDDS treatments.
This shows that the increase in metal uptake was typically increased by EDDS that enhanced
membrane damage and stress, while GA promoted plant growth and transpiration, lowering ion
uptake.
Overall, the results of this study demonstrate that several plant processes can affect the
temporal translocation trends of Cu and Zn as ions and nanoparticles in Lolium perenne. EDDS
application typically increased metal ion uptake by causing more cell damage, while GA
typically lowered the damage and decreased metal uptake, even though the transpiration
increased over time and plant growth occurred. Variability in toxicity of metal ions and
nanoparticles in mixtures and several plant processes acting either simultaneously or
individually are responsible for change in accumulation and translocation in perennial ryegrass.
Such information may well be important as release of both forms of metals, ions and
nanoparticles, will continue to intensify in the future. |
|
dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
PhD Thesis - University of Auckland |
en |
dc.relation.isreferencedby |
UoA |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
|
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.rights.uri |
http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ |
|
dc.title |
Temporal patterns of metal ion and nanoparticle uptake by Lolium perenne in hydroponic systems in the presence of amendments ethylene diamine disuccinic acid (EDDS) and gibberellic acid |
|
dc.type |
Thesis |
en |
thesis.degree.discipline |
Civil and Environmental Engineering |
|
thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Doctoral |
en |
thesis.degree.name |
PhD |
en |
dc.date.updated |
2020-12-17T20:55:05Z |
|
dc.rights.holder |
Copyright: The author |
en |
dc.rights.accessrights |
http://purl.org/eprint/accessRights/OpenAccess |
en |
dc.identifier.wikidata |
Q112951438 |
|