title: Responses of Gmelina arborea, a tropical deciduous tree species, to elevated atmospheric CO2: growth, biomass productivity and carbon sequestration efficacy.
abstract: The photosynthetic response of trees to rising CO(2) concentrations largely depends on source-sink relations, in addition to differences in responsiveness by species, genotype, and functional group. Previous studies on elevated CO(2) responses in trees have either doubled the gas concentration (>700 μmol mol(-1)) or used single large addition of CO(2) (500-600 μmol mol(-1)). In this study, Gmelina arborea, a fast growing tropical deciduous tree species, was selected to determine the photosynthetic efficiency, growth response and overall source-sink relations under near elevated atmospheric CO(2) concentration (460 μmol mol(-1)). Net photosynthetic rate of Gmelina was ~30% higher in plants grown in elevated CO(2) compared with ambient CO(2)-grown plants. The elevated CO(2) concentration also had significant effect on photochemical and biochemical capacities evidenced by changes in F(V)/F(M), ABS/CSm, ET(0)/CSm and RuBPcase activity. The study also revealed that elevated CO(2) conditions significantly increased absolute growth rate, above ground biomass and carbon sequestration potential in Gmelina which sequestered ~2100 g tree(-1) carbon after 120 days of treatment when compared to ambient CO(2)-grown plants. Our data indicate that young Gmelina could accumulate significant biomass and escape acclimatory down-regulation of photosynthesis due to high source-sink capacity even with an increase of 100 μmo lmol(-1) CO(2).
authors: Photosynthesis and Plant Stress Biology Laboratory, Department of Plant Sciences, University of Hyderabad, Hyderabad, India.
authors: Girish K
authors: GK
authors: Rasineni
authors: Anirban
authors: A
authors: Guha
authors: Attipalli R
authors: AR
authors: Reddy
mesh_terms: D000383:Agriculture; D001272:Atmosphere / Q000737:chemistry*; D018533:Biomass; D002245:Carbon Dioxide / Q000494:pharmacology*; D057965:Carbon Sequestration / Q000187:drug effects*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D005453:Fluorescence; D019686:Lamiaceae / Q000187:drug effects* / Q000254:growth & development*; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013045:Species Specificity; D014197:Trees / Q000187:drug effects / Q000254:growth & development*; D014329:Tropical Climate
chemical_list: D002734:Chlorophyll; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D000077194:Chlorophyll A