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Interdependence of CO 2 and inorganic nitrogen on crassulacean acid metabolism and efficiency of nitrogen use by Littorella uniflora (L.) Aschers
Author(s) -
BAATTRUPPEDERSEN A.,
MADSEN T. V.
Publication year - 1999
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1999.00413.x
Subject(s) - crassulacean acid metabolism , nitrogen , photosynthesis , botany , nitrogen cycle , eutrophication , biology , chemistry , nutrient , ecology , organic chemistry
The hypothesis is tested that crassulacean acid metabolism (CAM) in isoetids is a mechanism which not only conserves inorganic carbon but also plays a role in nitrogen economy of the plants. This hypothesis was tested in an outdoor experiment, where Littorella uniflora (L.) Aschers. were grown at two CO 2 and five inorganic nitrogen concentrations in a crossed factorial design. The growth of Littorella responded positively to enhanced nitrogen availability at high but not at low CO 2 indicating that growth was limited by nitrogen at high CO 2 only. For the nitrogen‐limited plants, the capacity for CAM (CAM cap ) increased with the degree of nitrogen limitation of growth and an inverse coupling between CAM and tissue‐N was found. Although this might indicate a role of CAM in economizing on nitrogen in Littorella , the hypothesis was rejected for the following reasons: (1) although CAM cap was related to tissue‐N no relationship between tissue‐N and ambient CAM activity (CAM ambient ) was found whereas a close relationship would be expected if CAM was regulated by nitrogen availability; (2) the photosynthetic nitrogen use efficiency for high CO 2 ‐grown plants declined with increased CAM ambient and with CAM cap ; and (3) growth per unit tissue‐N per unit time declined with increased CAM ambient and CAM cap .