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dc.contributor.advisorDaffonchio, Daniele
dc.contributor.authorShabaan, Dalia H.
dc.date.accessioned2019-07-31T07:37:06Z
dc.date.available2020-07-31T00:00:00Z
dc.date.issued2019-07
dc.identifier.citationShabaan, 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
dc.identifier.doi10.25781/KAUST-Q7750
dc.identifier.urihttp://hdl.handle.net/10754/656256
dc.description.abstractUnder 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’.
dc.language.isoen
dc.subjectNamib Desert
dc.subjectWelwitschia mirabilis
dc.subjectAllelofertile soil
dc.subjectMicrobiome
dc.subjectPolyextreme Condition
dc.subjectPlant-soil-microbe interacttion
dc.title‘Allelofertile’ soil islands self-conditioned by Welwitschia mirabilis in the Namib Desert
dc.typeThesis
dc.contributor.departmentBiological and Environmental Science and Engineering (BESE) Division
dc.rights.embargodate2020-07-31
thesis.degree.grantorKing Abdullah University of Science and Technology
dc.contributor.committeememberPain, Arnab
dc.contributor.committeememberHong, Pei-Ying
thesis.degree.disciplineBioscience
thesis.degree.nameMaster of Science
dc.rights.accessrightsAt 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.
refterms.dateFOA2020-07-31T00:00:00Z
kaust.request.doiyes


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