St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Hormonal control of growth of freshwater aquatic plants

Thumbnail
View/Open
AlastairCWebsterPhDThesis.pdf (83.58Mb)
Date
1975
Author
Webster, Alastair C.
Supervisor
Spence, David Hugh Neven
Metadata
Show full item record
Altmetrics Handle Statistics
Abstract
1. The life cycle of this rosette aquatic plant was discussed in detail. 2. Anatomical differences between terrestrial and submerged forms of the rosettes were found. Terrestrial rosettes were induced very rapidly by exposure of previously submerged rosettes to air. Laminal development was greatly reduced in the leaves and roots of the terrestrial rosettes. 3. Two main aspects of the life cycle were considered in detail propagation of the rosettes; and leaf elongation. 4. Propagation: In nature the rosettes have the ability to propagate by (a) stolon formation or (b) by a less efficient means where the rosette elongates vertically. (a) Experimental evidence presented indicates that stolon initiation is controlled by gibberellic acid, although cytokinins may be involved. In nature, stolons from similar rosettes may be of varying lengths, and so the elongation phase of stolon development was considered. It was found that gibberellic acid may bring about a protraction of this elongation phase of growth of the stolon, at the expense of the development of the terminal plantlet. Ethylene supplied as ETHREL E inhibited further elongation of the stolons, and furthermore, promoted accumulation of starch. Starch grains in stolons of rosettes treated with gibberellic acid were limited to a central ring of cells. Some radial growth in response to supplied ETHREL E was noted. Stolons may persist in some cases, thus interconnecting many rosettes, but in some cases the stolons senesce. Evidence presented above suggests that gibbarellic acid and ethylene may control senescence. Where gibberellins levels are low in the stolons, accumulated ethylene will rapidly effect the senescence of the stolon, thus making the rosetts independent. (b) Where rosettes are partially and repeatedly buried by sediment, they have the ability to perennate themselves vertically by means of an elongated stem axis. Various rooting levels on the same rosette reflect the sequential nature of the deposition of the sediment. This was found experimentally where rosettes were grown under different conditions of deposition of sediment, and rosettes similar to those experimentally induced were found on a silt fan, near the inflow in Loch Drumore, near Glenshee, in Perthshire. The ability of the plant to propagate so rapidly by stolon formation on eroded shores, or by altering its rooting level and then forming stolons, explains to a great extent the ubiquity of this species throughout Great Britain, and thus implicitly explains the persistence of this species through many of the stages in hydrosere formation.
Type
Thesis, PhD Doctor of Philosophy
Collections
  • Biology Theses
URI
http://hdl.handle.net/10023/14419

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter