Abstract
An integrated approach to the study of the distribution of resources in the clonal grassAgrostis stolonifera L. is described. Paired, connected ramets of A. stolonifera were
grown hydroponically with high (+P) or low (-P) phosphate treatments. Ramets in -P
had a lower dry weight than +P with fewer leaves, branches and tillers and longer,
less-branched roots. The length of the main stolons, the rates of production and
elongation of leaves, photosynthesis and stomata! conductance were unaffected.
Paired ramets given heterogeneous phosphate environments, with younger ramets
given +P, were heavier than those grown in homogeneous +P. Vascular connections,
investigated using contrasting dyes, revealed a bidirectional flow between ramets in
the xylem of different vascular bundles. The rate of flow was greatest in the direction
of the transpiration stream and shading the parent ramet had no effect on this. When
Ol!e partner in a pair of ramets was given a P-treatment and the other either high, low
or no water, droughted +P ramets showed reduced rate of stomata! conductance
whereas droughted -P ramets did not. The uptake of 32P, within paired ramets given
contrasting phosphate treatments, was greatest by the roots of high P ramets. Transfer
of P was faster towards +P than to -P ramets. P was carried in the xylem, circulated
out of the leaves and translocated basipetally in the phloem. Approximately 95% P
was in the vacuoles and 5% in the cytoplasm with the ratio of cytoplasmic to vacuolar
P higher in the oldest leaves. The allocation of 14C assimilate showed that little was
translocated from a fed shoot but more was allocated to -P than to +P roots. The
results show that adjacent ramets are physiologically integrated as regards water and
phosphate but have independent carbon economies.
| Date of Award | 2000 |
|---|---|
| Original language | English |
| Awarding Institution |
|
| Supervisor | John Farrar (Supervisor) & Chris Marshall (Supervisor) |
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