Relations between K+ uptake and photosynthetic uptake of inorganic carbon by aquatic plants |
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Authors: | L. Adamec |
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Affiliation: | (1) Section of Plant Ecology, Institute of Botany of the Academy of Sciences of the Czech Republic, Dukelská 145, CZ-379 82 Třeboň, Czech Republic |
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Abstract: | The uptake of K+ by the leafy shoots of four submersed higher aquatic plants (Elodea canadensis, Ranunculus aquatilis, R. trichophyllus, and Callitriche hamulata) with different HCO3 - affinity was measured in successive 2-h periods under the conditions of high or low photosynthetic rates (i.e. at pH 7.5 or 10). At pH 7.5 the uptake of K+ by species with the higher HCO3 - affinity (E. canadensis, R. trichophyllus) was significantly faster than that by species with a lower HCO3 - affinity (R. aquatilis, C. hamulata). In the former group of species, the K+ uptake rate at pH 7.5 was 1.7 - 3.5 times higher than at pH 10. At pH 10, the soft-water species, R. aquatilis, had the lowest net photosynthetic rate (PN) of the three HCO3 - users but, in contrast to the relative hard-water species, R. trichophyllus, showed a small K+ efflux (47 nmol kg-1 s-1). Thus, K+ uptake by shoots was not strictly correlated with PN. A significant K+ efflux (73 - 86 nmol kg-1 s-1) occurred from all HCO3 - users in darkness. The relatively low K+ uptake by the strict CO2 user, C. hamulata, was quite independent of PN and light or darkness. It may be suggested that uptake of K+ by shoots of submersed plants depends on their HCO3 - affinity. This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Callitriche hamulata Elodea canadensis HCO3- affinity hard- and soft-water species leafy shoots R. aquatilis R. trichophyllus |
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