Edinburgh Research Archive

View Item 
  •   DSpace Home
  • Biological Sciences, School of
  • Biological Sciences thesis and dissertation collection
  • View Item
  •   DSpace Home
  • Biological Sciences, School of
  • Biological Sciences thesis and dissertation collection
  • View Item
    • Login
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Physiological and anatomical studies in seed coat regulation of water uptake in soybeans (Glycine max L. Merril)

    Download
    HahalisD_1997redux.pdf (30.39Mb)
    Date
    1997
    Author
    Hahalis, Demosthenis
    Metadata
    Show full item record
    Abstract
     
     
    This study examined i) the imbibition behaviour of a wide range of genotypes with different seed coat characteristics; ii) the use of a polymer to regulate the rate of water uptake and iii) the mechanism of regulation of water uptake by the seed coat in soybeans (Glycine max L. Merril.). Seed coat structure was studied by using light, fluorescence and scanning electron microscopy. The effects of different methanol and chloroform pre-treatments on seed coat permeability to water were also assessed. In this study, imbibition damage due to rapid water uptake was well documented in a wide range of soybean genotypes. In addition a line (VLS-1) was identified that possessed a delayed-permeability seed coat characteristic that offered protection against imbibition damage. This characteristic was likely to be due to a lack of pits in the abaxial region of the seed. In contrast, genotypes with a high proportion of deep and wide open pits in the abaxial region of the seed offered minimal protection against imbibition damage.
     
    Coating seeds (24 mg per seed) with a polymer containing vinyl acetate, vinyl chloride, ethylene and acrylate regulated the rate of water uptake, and offered protection against imbibition damage. Seedling emergence from polymer coated seeds was also improved.
     
    Deposits and pits occurred in the surface of the seed coat in most genotypes. Deposits were shown to be composed of hydrophilic polysaccharide material, since staining with calcofluor was observed. Water permeability mapping indicated that pits were the sites o f the initial water penetration. However, in hard seeds, pits appeared to function in a different way to soft seeds and this is fully discussed within the thesis. Prolonged methanol pre-treatments were highly effective in increasing the water uptake when seeds were imbibed immediately after the pre-treatments. However, drying of seeds after the organic solvent pre-treatments restored permeability to water to untreated control levels. Results from the absorption spectrum of the methanol and chloroform supernatants, indicated that the effect of the pre-treatments were not due to the extraction of UV-absorbed material from the seed coat. In hard seeds, the location of the water impermeability barrier was near the outermost part of the palisade cell layer. The nature of the barrier was not identified by comparative anatomical and histochemical studies between hard and soft seeds. A mechanism for the water uptake regulation by the soybean seed coat was proposed. The proposed mechanism involved: i) a diminished role of the cuticle and its components (epicuticular and intracuticular waxes), ii) a key role for pits as initial sites of water penetration, and iii) swelling or collapse of the cellulosic and/or pectic material in the subcuticular and palisade cell layer that could regulate water penetration through the seed coat. The common behaviour of a wide range of genotypes tested indicated that the above mechanism of regulation of water uptake by the seed coat is likely to be universal in soybeans.
     
    URI
    http://hdl.handle.net/1842/28179
    Collections
    • Biological Sciences thesis and dissertation collection

    Privacy & Cookies | Takedown Policy | Accessibility | Contact
    Privacy & Cookies
    Takedown Policy
    Accessibility
    Contact
     

     

    Browse

    All of DSpaceCommunities & CollectionsIssue DateAuthorsTitlesSubjectsPublication TypeSponsorThis CollectionIssue DateAuthorsTitlesSubjectsPublication TypeSponsor

    My Account

    LoginRegister

    Privacy & Cookies | Takedown Policy | Accessibility | Contact
    Privacy & Cookies
    Takedown Policy
    Accessibility
    Contact