• Login
    View Item 
    •   Home
    • Theses and Dissertations
    • Theses
    • View Item
    •   Home
    • Theses and Dissertations
    • Theses
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of KAUSTCommunitiesIssue DateSubmit DateThis CollectionIssue DateSubmit Date

    My Account

    Login

    Quick Links

    Open Access PolicyORCID LibguidePlumX LibguideSubmit an Item

    Statistics

    Display statistics

    ‘Allelofertile’ soil islands self-conditioned by Welwitschia mirabilis in the Namib Desert

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    Dalia Shabaan Thesis.pdf
    Size:
    2.467Mb
    Format:
    PDF
    Description:
    Dalia Shabaan Thesis
    Download
    View more filesView fewer files
    Type
    Thesis
    Authors
    Shabaan, Dalia H. cc
    Advisors
    Daffonchio, Daniele cc
    Committee members
    Pain, Arnab cc
    Hong, Pei-Ying cc
    Program
    Bioscience
    KAUST Department
    Biological and Environmental Sciences and Engineering (BESE) Division
    Date
    2019-07
    Embargo End Date
    2020-07-31
    Permanent link to this record
    http://hdl.handle.net/10754/656256
    
    Metadata
    Show full item record
    Access Restrictions
    At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2020-07-31.
    Abstract
    Under the extreme arid conditions of deserts, long periods of drought, nutrient-poor soils and high temperatures severely challenge the primary productivity of the ecosystem. Desert plants have evolved morphological and physiological adaptations against abiotic stresses. Along with these adaptation strategies they can recondition their surrounding soil, which will result in the enrichment of nutrients and moisture in the soil surrounding the plant. Although such self-fertilization may support the growth of other sympatric plant species under the plant, competitive exclusion mechanisms (i.e., allelopathy) reduce this possibility. Consequently, this will affect the diversity and functionality of the edaphic microbial communities. I hypothesize that desert xerophytes recondition the soils surrounding their body along with combining the ‘fertility’ and ‘allelopathy’ mechanisms to create a favorable new niche in desert ecosystem. I tested this hypothesis on the soil reconditioned by Welwitschia mirabilis growing in its native environment, the Namib Desert, Namibia. The collected soils were first used to confirm that Welwitschia manipulates the surrounding soil creating a ‘fertile’ but ‘exclusive’ soil area around the plant. Along with evaluating the effect of the reconditioned soil on the germination and plant development under normal irrigation and controlled drought condition, using barley as phytometer. The physio-chemical (i.e., WHC and WP) and microbial community analyses demonstrate that W. mirabilis reconditions the surrounding soil creating an environmental gradient around itself, in which the fertility is increased, through the accumulation and incorporation of shed reproductive parts of the plants (i.e., cones) in the surrounding soil, that will stimulate the plant growth under drought stress. Along with the fertilization effect, soil reconditioning also favor the antagonist effect (i.e., allelopathy) against plant competitors (e.g., new germinating seeds) to protect its ecological niche. Furthermore, the microorganisms and/or soluble/thermolabile molecules contribute to the allelopathic effect activated by the soil-reconditioning around W. mirabilis. The interactions among W. mirabilis, soil and microbes highlight an adaptive strategy that combines soil fertilization and allelopathy that I defined as “Alleolofertility” strategy. This allelofertility island surrounding the W. mirabilis may contributes to explain the evolutionary success of such a ‘living fossil’.
    Citation
    Shabaan, D. H. (2019). ‘Allelofertile’ soil islands self-conditioned by Welwitschia mirabilis in the Namib Desert. KAUST Research Repository. https://doi.org/10.25781/KAUST-Q7750
    DOI
    10.25781/KAUST-Q7750
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-Q7750
    Scopus Count
    Collections
    Biological and Environmental Sciences and Engineering (BESE) Division; Bioscience Program; Theses

    entitlement

     
    DSpace software copyright © 2002-2021  DuraSpace
    Quick Guide | Contact Us | KAUST University Library
    Open Repository is a service hosted by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items. For anonymous users the allowed maximum amount is 50 search results.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.