Photosynthesis and carbohydrate partitioning of a C{sub 3} species Encelia Farinosa grown under current and doubled CO{sub 2} concentrations

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · Bulletin of the Ecological Society of America

OSTI ID:107159

Zhang, H; S, Nobel P ^[1]

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1. Univ. of California, Los Angeles, CA (United States)

A daily course of photosynthesis and carbohydrate (glucose, fructose, sucrose, and starch) content was determined for Encelia farinosa, a common shrub in arid regions of southwestern United States, grown under 370 {mu}l 1{sup {minus}1} CO{sub 2} concentrations. Photosynthesis was higher for plants grown under the doubled than for those under the current CO{sub 2} concentration; it decreased during the day for the doubled CO{sub 2} treatment but remained unchanged for the ambient CO{sub 2} treatment. Both sucrose and starch contents increased during the day but more so for the doubled CO{sub 2} treatment. Similarly, osmolality of leaf sap increased during the day for both CO{sub 2} treatments, but to a greater extent for the doubled CO{sub 2} treatment. Glucose and fructose contents were similar for both treatments. To help interpret the daily decline of photosynthesis under doubled CO{sub 2}, Rubisco activity was determined. K{sub m} was not significantly different between the two treatments, yet both initial and fully-activated Rubisco activities were higher for the ambient CO{sub 2} treatment and generally decreased during the day. The fraction of Rubisco in the activated state was higher for the doubled CO{sub 2} treatment and decreased slightly in the afternoon. These results may indicate that photosynthesis of E.farinosa grown under doubled CO{sub 2} concentration was inhibited by end-products and that the fraction of Rubisco activated appeared not to be the cause of the daily decline of photosynthesis under doubled CO{sub 2}.

• OSTI ID: 107159
• Report Number(s): CONF-9507129--
• Journal Information: Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 3 Vol. 76; ISSN BECLAG; ISSN 0012-9623
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL EFFECTS
CARBON DIOXIDE
PHOTOSYNTHESIS
PLANTS