title: Elevated atmospheric CO₂ mitigated photoinhibition in a tropical tree species, Gmelina arborea.
abstract: Effects of elevated CO₂ on photosynthetic CO₂ assimilation, PSII photochemistry and photoinhibition were investigated in the leaves of a fast growing tropical tree species, Gmelina arborea (Verbenaceae) during summer days of peak growth season under natural light. Elevated CO₂ had a significant effect on CO₂ assimilation rates and maximal efficiency of PSII photochemistry. Chlorophyll a fluorescence induction kinetics were measured to determine the influence of elevated CO₂ on PSII efficiency. During midday, elevated CO₂-grown Gmelina showed significantly higher net photosynthesis (p<0.001) and greater F(V)/F(M) (p<0.001) than those grown under ambient CO₂. The impact of elevated CO₂ on photosynthetic rates and Chl a fluorescence were more pronounced during midday depression where the impact of high irradiance decreased in plants grown under elevated CO₂ compared to ambient CO₂-grown plants. Our results clearly demonstrate that decreased susceptibility to photoinhibition in elevated CO₂ grown plants was associated with increased accumulation of active PSII reaction centers and efficient photochemical quenching. We conclude that elevated CO₂ treatment resulted in easy diminution of midday photosynthetic depression.
authors: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors: Girish Kumar
authors: GK
authors: Rasineni
authors: Anirban
authors: A
authors: Guha
authors: Attipalli Ramachandra
authors: AR
authors: Reddy
mesh_terms: D001272:Atmosphere; D002245:Carbon Dioxide / Q000494:pharmacology; D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D014197:Trees / Q000378:metabolism; D029648:Verbenaceae / Q000187:drug effects / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D002245:Carbon Dioxide; D000077194:Chlorophyll A