{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/22610"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/22610","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Effects of elevated atmospheric carbon dioxide concentration and drought on soybean leaf photosynthesis","abstract":"Soybean (Glycine max (L.) Merr. cv. Jack) was grown in the field in rain-protected plots to study effects of drought and atmospheric CO$\\sb2$ enrichment on leaf gas exchange. Midday depressions in net leaf photosynthetic CO$\\sb2$ exchange rates (Pn) were found in drought-stressed plants and the diurnal changes were mostly stomatal regulated, although accumulated drought stress eventually resulted in some non-stomatal limitations. However, seasonal changes in Pn were mostly limited by non-stomatal factors. Water use efficiency was always higher for drought stressed plants and depended on the severity of stress and associated stomatal or nonstomatal limitations. At enriched atmospheric CO$\\sb2$ levels, stomatal limitations to Pn under drought stress were less important than at ambient atmospheric CO$\\sb2$ levels. Morning and afternoon leaf starch levels were enhanced in both irrigated and nonirrigated plants in enriched CO$\\sb2$. Afternoon starch levels were higher in stressed leaves than in non-stressed leaves at normal CO$\\sb2$ levels.","abstract_html":"Soybean (Glycine max (L.) Merr. cv. Jack) was grown in the field in rain-protected plots to study effects of drought and atmospheric CO$\\sb2$ enrichment on leaf gas exchange. Midday depressions in net leaf photosynthetic CO$\\sb2$ exchange rates (Pn) were found in drought-stressed plants and the diurnal changes were mostly stomatal regulated, although accumulated drought stress eventually resulted in some non-stomatal limitations. However, seasonal changes in Pn were mostly limited by non-stomatal factors. Water use efficiency was always higher for drought stressed plants and depended on the severity of stress and associated stomatal or nonstomatal limitations. At enriched atmospheric CO$\\sb2$ levels, stomatal limitations to Pn under drought stress were less important than at ambient atmospheric CO$\\sb2$ levels. Morning and afternoon leaf starch levels were enhanced in both irrigated and nonirrigated plants in enriched CO$\\sb2$. Afternoon starch levels were higher in stressed leaves than in non-stressed leaves at normal CO$\\sb2$ levels.","abstract_has_math":true,"creators":["Chen, Xiaoming"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Agronomy","degree_department":null,"school":null,"contributors":["Hesketh, John D."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:45:26Z","date_published":"2011-05-07T13:45:26Z","updated_at":"2026-07-22T22:25:20Z","subjects":["Agriculture, Agronomy","Biology, Ecology","Biology, Plant Physiology"],"languages":["eng"],"rights":["Copyright 1994 Chen, Xiaoming"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9503163","(UMI)AAI9503163"],"render_values":[{"text":"AAI9503163","href":null,"code":true},{"text":"(UMI)AAI9503163","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/22610","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hesketh, John D."]},{"key":"dc:creator","label":"Author","values":["Chen, Xiaoming"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:45:26Z","10000-01-01","1994"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Agronomy"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Agriculture, Agronomy","Biology, Ecology","Biology, Plant Physiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1994 Chen, Xiaoming"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9503163","(UMI)AAI9503163","http://hdl.handle.net/2142/22610"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Soybean (Glycine max (L.) Merr. cv. Jack) was grown in the field in rain-protected plots to study effects of drought and atmospheric CO$\\sb2$ enrichment on leaf gas exchange. Midday depressions in net leaf photosynthetic CO$\\sb2$ exchange rates (Pn) were found in drought-stressed plants and the diurnal changes were mostly stomatal regulated, although accumulated drought stress eventually resulted in some non-stomatal limitations. However, seasonal changes in Pn were mostly limited by non-stomatal factors. Water use efficiency was always higher for drought stressed plants and depended on the severity of stress and associated stomatal or nonstomatal limitations. At enriched atmospheric CO$\\sb2$ levels, stomatal limitations to Pn under drought stress were less important than at ambient atmospheric CO$\\sb2$ levels. Morning and afternoon leaf starch levels were enhanced in both irrigated and nonirrigated plants in enriched CO$\\sb2$. Afternoon starch levels were higher in stressed leaves than in non-stressed leaves at normal CO$\\sb2$ levels.","Soybean (Glycine max (L.) Merr. cv. Jack) grown under both controlled environment and field conditions was used to study acclimation of leaf photosynthesis to long-term atmospheric CO$\\sb2$ enrichment. Plants grown at 350-400 $\\mu$L CO$\\sb2$/L air and at 700-800 $\\mu$L/L were switched back and forth between treatments to follow dynamic changes in Pn and Gs. Pn of enriched plants was less than that of ambient-grown plants when measured at the ambient CO$\\sb2$ level, but it was higher than that of ambient-grown plants when measured at elevated CO$\\sb2$ levels, in both controlled environment and field studies. Stomatal conductance (Gs) of leaves on field-grown plants and pot-grown plants responded similarly to changes in air CO$\\sb2$ level; although the timing and extent of response differed, the general response pattern was identical. Gs values in plants grown in an enriched CO$\\sb2$ environment responded differently to rapid changes in CO$\\sb2$ than Gs values in ambient-grown plants; such behavior suggested stomatal acclimation to long-term exposure to an CO$\\sb2$-enriched atmosphere.","Leaf non-structural carbohydrate levels were greater in plants exposed to long-term atmospheric CO$\\sb2$ enrichment, but we could not prove that this was the main cause for lower photosynthetic performance when such plants were placed in ambient air. Pn of CO$\\sb2$-enriched plants in ambient air did recover to that of ambient-grown plants after 15 days of exposure to ambient air.","Both field-grown and pot-grown plants in controlled environments acclimated similarly to CO$\\sb2$-enrichment.","Made available in DSpace on 2011-05-07T13:45:26Z (GMT). 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Merr. cv. Jack) was grown in the field in rain-protected plots to study effects of drought and atmospheric CO$\\sb2$ enrichment on leaf gas exchange. Midday depressions in net leaf photosynthetic CO$\\sb2$ exchange rates (Pn) were found in drought-stressed plants and the diurnal changes were mostly stomatal regulated, although accumulated drought stress eventually resulted in some non-stomatal limitations. However, seasonal changes in Pn were mostly limited by non-stomatal factors. Water use efficiency was always higher for drought stressed plants and depended on the severity of stress and associated stomatal or nonstomatal limitations. At enriched atmospheric CO$\\sb2$ levels, stomatal limitations to Pn under drought stress were less important than at ambient atmospheric CO$\\sb2$ levels. Morning and afternoon leaf starch levels were enhanced in both irrigated and nonirrigated plants in enriched CO$\\sb2$. Afternoon starch levels were higher in stressed leaves than in non-stressed leaves at normal CO$\\sb2$ levels.","Soybean (Glycine max (L.) Merr. cv. Jack) grown under both controlled environment and field conditions was used to study acclimation of leaf photosynthesis to long-term atmospheric CO$\\sb2$ enrichment. Plants grown at 350-400 $\\mu$L CO$\\sb2$/L air and at 700-800 $\\mu$L/L were switched back and forth between treatments to follow dynamic changes in Pn and Gs. Pn of enriched plants was less than that of ambient-grown plants when measured at the ambient CO$\\sb2$ level, but it was higher than that of ambient-grown plants when measured at elevated CO$\\sb2$ levels, in both controlled environment and field studies. Stomatal conductance (Gs) of leaves on field-grown plants and pot-grown plants responded similarly to changes in air CO$\\sb2$ level; although the timing and extent of response differed, the general response pattern was identical. Gs values in plants grown in an enriched CO$\\sb2$ environment responded differently to rapid changes in CO$\\sb2$ than Gs values in ambient-grown plants; such behavior suggested stomatal acclimation to long-term exposure to an CO$\\sb2$-enriched atmosphere.","Leaf non-structural carbohydrate levels were greater in plants exposed to long-term atmospheric CO$\\sb2$ enrichment, but we could not prove that this was the main cause for lower photosynthetic performance when such plants were placed in ambient air. Pn of CO$\\sb2$-enriched plants in ambient air did recover to that of ambient-grown plants after 15 days of exposure to ambient air.","Both field-grown and pot-grown plants in controlled environments acclimated similarly to CO$\\sb2$-enrichment.","Made available in DSpace on 2011-05-07T13:45:26Z (GMT). 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