Acclimation of photosynthesis and stimulated respiration in tomato under carbon dioxide enrichment
Xin Li, Guanqun Zhang, Kai Shi*
Department of Horticulture, Zhejiang University, Hangzhou, 310058 .
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This study investigated the molecular, biochemical and physiological changes in tomato exposed to ambient [CO2] and elevated [CO2]. We measured CO2-efflux rates of whole leaves and O2-uptake rates of leaf segments for 18 days after the treatment with CO2 enrichment. CO2 enrichment had significant effects on the leaf, shoot and root growth since the 5th day. For their grown environment, CO2 enrichment greatly increased Pn from the 2nd day to the end of the experiment. However, the plants for CO2 enrichment showed significant reductions in Vc,max and in Jmax at 10th day, which leads to photosynthetic acclimation. Analysis of leaf respiration showed that the CO2 enrichment exhibited a significant increase in the total respiration after two days of treatment. Meanwhile, CO2 enrichment also resulted in significant increase of Cyt pathway capacity and COX activity from the 2nd day and the 4th day. Our results suggest that stimulation of respiration to elevated CO2 has also been related to adjustments in mitochondrial enzymes, including the number of active mitochondria.
Key Words: CO2 enrichment; photosynthesis; respiration