{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/35307"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/35307","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Will Nitrogen fixers benefit from rising Atmospheric CO2? The response of Podalyria Sericea to elevated CO2","abstract":"To predict the response of communities and ecosystems to rising levels of atmospheric CO2, the response of individual plants under natural conditions needs to be determined. Podalyria sericea, a fynbos legume, was grown in a greenhouse under ambient (35 Pa) and elevated (70 Pa) CO2 partial pressure for 18 months. Growth, leaf 615N and leaf gas exchange was measured to determine whether this N2-fixer could maintain a positive growth response under conditions of high competition. Results revealed a lack of positive growth response to elevated CO2, although far more flowers were produced in the elevated treatment. Allocation patterns were slightly different, with relatively higher shoot mass for plants exposed to elevated CO2. Leaf 61 5N and N concentrations were unaffected. Photosynthetic capacity was greatly reduced and maximum rates of Rubisco carboxylation (V cmaJ and light saturated electron transport (Jniax) were lower for plants exposed to elevated CO2. Net CO2 assimilation (A) at growth CO2 was higher for the plants from the ambient treatment. Shading appears to have been an important constraint on growth response to elevated CO2, and plants which received more light had significantly more biomass in the elevated treatment. The potential effect of restricted root growth and low soil nutrient availability are discussed as additional factors which may have negated a positive growth response.","abstract_html":"To predict the response of communities and ecosystems to rising levels of atmospheric CO2, the response of individual plants under natural conditions needs to be determined. Podalyria sericea, a fynbos legume, was grown in a greenhouse under ambient (35 Pa) and elevated (70 Pa) CO2 partial pressure for 18 months. Growth, leaf 615N and leaf gas exchange was measured to determine whether this N2-fixer could maintain a positive growth response under conditions of high competition. Results revealed a lack of positive growth response to elevated CO2, although far more flowers were produced in the elevated treatment. Allocation patterns were slightly different, with relatively higher shoot mass for plants exposed to elevated CO2. Leaf 61 5N and N concentrations were unaffected. Photosynthetic capacity was greatly reduced and maximum rates of Rubisco carboxylation (V cmaJ and light saturated electron transport (Jniax) were lower for plants exposed to elevated CO2. Net CO2 assimilation (A) at growth CO2 was higher for the plants from the ambient treatment. Shading appears to have been an important constraint on growth response to elevated CO2, and plants which received more light had significantly more biomass in the elevated treatment. The potential effect of restricted root growth and low soil nutrient availability are discussed as additional factors which may have negated a positive growth response.","abstract_has_math":false,"creators":["Swemmer, Tony"],"institution":"Department of Environmental and Geographical Science","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Stock, Willy"],"committee_chairs":[],"committee_members":[],"year":1998,"date_issued":"1998","date_published":"1998","updated_at":"2026-07-22T22:23:16Z","subjects":["eco-systems","natural conditions","woody legume"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/35307","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Stock, Willy"]},{"key":"dc:creator","label":"Author","values":["Swemmer, Tony"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2021-11-02T14:04:11Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2021-11-02T14:04:11Z"]},{"key":"dc:date.issued","label":"Date","values":["1998"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Environmental and Geographical Science"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University Of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Thesis / Dissertation"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Honours Project"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["eco-systems","natural conditions","woody legume"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/35307"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["To predict the response of communities and ecosystems to rising levels of atmospheric CO2, the response of individual plants under natural conditions needs to be determined. Podalyria sericea, a fynbos legume, was grown in a greenhouse under ambient (35 Pa) and elevated (70 Pa) CO2 partial pressure for 18 months. Growth, leaf 615N and leaf gas exchange was measured to determine whether this N2-fixer could maintain a positive growth response under conditions of high competition. Results revealed a lack of positive growth response to elevated CO2, although far more flowers were produced in the elevated treatment. Allocation patterns were slightly different, with relatively higher shoot mass for plants exposed to elevated CO2. Leaf 61 5N and N concentrations were unaffected. Photosynthetic capacity was greatly reduced and maximum rates of Rubisco carboxylation (V cmaJ and light saturated electron transport (Jniax) were lower for plants exposed to elevated CO2. Net CO2 assimilation (A) at growth CO2 was higher for the plants from the ambient treatment. Shading appears to have been an important constraint on growth response to elevated CO2, and plants which received more light had significantly more biomass in the elevated treatment. The potential effect of restricted root growth and low soil nutrient availability are discussed as additional factors which may have negated a positive growth response."]},{"key":"dc:title","label":"Title","values":["Will Nitrogen fixers benefit from rising Atmospheric CO2? The response of Podalyria Sericea to elevated CO2"]}]}],"canonical_facts":{"dc:contributor.advisor":["Stock, Willy"],"dc:creator":["Swemmer, Tony"],"dc:date.accessioned":["2021-11-02T14:04:11Z"],"dc:date.available":["2021-11-02T14:04:11Z"],"dc:date.issued":["1998"],"dc:description.abstract":["To predict the response of communities and ecosystems to rising levels of atmospheric CO2, the response of individual plants under natural conditions needs to be determined. Podalyria sericea, a fynbos legume, was grown in a greenhouse under ambient (35 Pa) and elevated (70 Pa) CO2 partial pressure for 18 months. Growth, leaf 615N and leaf gas exchange was measured to determine whether this N2-fixer could maintain a positive growth response under conditions of high competition. Results revealed a lack of positive growth response to elevated CO2, although far more flowers were produced in the elevated treatment. Allocation patterns were slightly different, with relatively higher shoot mass for plants exposed to elevated CO2. Leaf 61 5N and N concentrations were unaffected. Photosynthetic capacity was greatly reduced and maximum rates of Rubisco carboxylation (V cmaJ and light saturated electron transport (Jniax) were lower for plants exposed to elevated CO2. Net CO2 assimilation (A) at growth CO2 was higher for the plants from the ambient treatment. Shading appears to have been an important constraint on growth response to elevated CO2, and plants which received more light had significantly more biomass in the elevated treatment. The potential effect of restricted root growth and low soil nutrient availability are discussed as additional factors which may have negated a positive growth response."],"dc:identifier.uri":["http://hdl.handle.net/11427/35307"],"dc:language.iso":["en"],"dc:publisher.department":["Department of Environmental and Geographical Science"],"dc:publisher.institution":["University Of Cape Town"],"dc:subject":["eco-systems","natural conditions","woody legume"],"dc:title":["Will Nitrogen fixers benefit from rising Atmospheric CO2? The response of Podalyria Sericea to elevated CO2"],"dc:type":["Thesis / Dissertation"],"dc:type.qualificationlevel":["Honours Project"]},"updated_at":"2026-07-22T22:23:16Z"}