Carbon Isotope Composition of the Halophyte Disphyma clavellatum (Haw.) Chinnock (Aizoaceae), as Affected by Salinity

1983 ◽  
Vol 10 (5) ◽  
pp. 437 ◽  
Author(s):  
TF Neales ◽  
MS Fraser ◽  
Z Roksandic
Keyword(s):  
Acid Metabolism ◽  
Diffusion Processes ◽  
Isotope Composition ◽  
Titratable Acidity ◽  
Co2 Assimilation ◽  
Carbon Isotope Composition ◽  
Diurnal Pattern ◽  
Δ13c Values ◽  
Net Co2 Assimilation ◽  
Appreciable Increase

The δ13C values of the leaves of Disphyma clavellatum (Aizoaceae) systematically became less negative as the salinity in the root environment increased from 0 to 500 mol m-3 NaCl. The maximum shift of δ13C was from -26.1‰ to -20.0‰. Similar increases in salinity did not, however, result either in a change in the diurnal pattern of net CO2 assimilation or in an appreciable increase in the fluctuations of titratable acidity. It is suggested that salinity induced the observed shift in δ13C values, not by effecting change in the mode of carboxylation towards that of crassulacean acid metabolism (CAM), but by affecting the degree of limitation of CO2 assimilation by diffusion processes. It is concluded therefore that, in D. clavellatum, CAM is not induced by salinity, as it is in Mesembryanthemum crystallinum.

The evolution of crassulacean acid metabolism inAeonium inferred from carbon isotope composition and enzyme activities

Oecologia ◽  
1992 ◽  
Vol 91 (4) ◽  
pp. 548-553 ◽  
Author(s):  
E. A. H. Pilon-Smits ◽  
H. 't Hart ◽  
J. W. Maas ◽  
J. A. N. Meesterburrie ◽  
R. Kreuler ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Enzyme Activities ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Isotope Composition ◽  
Carbon Isotope Composition

Carbon Isotope Discrimination measured Concurrently with Gas Exchange to Investigate CO2 Diffusion in Leaves of Higher Plants

1986 ◽  
Vol 13 (2) ◽  
pp. 281 ◽  
Author(s):  
JR Evans ◽  
TD Sharkey ◽  
JA Berry ◽  
GD Farquhar
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Isotope ◽  
Higher Plants ◽  
Isotope Composition ◽  
Co2 Assimilation ◽  
Carbon Isotope Composition ◽  
C3 Plants ◽  
Isotopic Discrimination ◽  
Co2 Diffusion

Conventional gas-exchange techniques that measure the stomatal conductance and rate of CO2 assimilation of leaves were combined with measurements of the carbon isotope composition of CO2 in air passing over a leaf. Isotopic discrimination during uptake was determined from the difference in the carbon isotope composition of air entering and leaving the leaf chamber. Isotopic discrimination measured over the short term correlated strongly with that determined from combusted leaf material. Environmental conditions were manipulated to alter the relative influences of stomatal conductance and carboxylation on the discrimination of carbon isotopes by intact leaves. With C3 plants, discrimination increased as the gradient in partial pressure of CO2 across the stomata decreased. For C4 plants there was little change in discrimination despite substantial changes in the diffusion gradient across the sto- mata. These results are consistent with, and provide the first direct experimental support for, theoretical equations describing discrimination during photosynthesis. Despite uncertainties about various processes affecting carbon isotope composition, the resistance to the transfer of CO2 from the intercellular airspaces to the sites of carboxylation in the mesophyll chloroplasts was estimated using this technique. For wheat the estimated resistance was 1.2-2.4 m2 s bar mol -1.

scholarly journals Carbon Isotopes of Riparian Forests Trees in the Savannas of the Volta Sub-Basin of Ghana Reveal Contrasting Responses to Climatic and Environmental Variations

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 251 ◽  
Author(s):  
Emmanuel Boakye ◽  
Aster Gebrekirstos ◽  
Dibi Hyppolite ◽  
Victor Barnes ◽  
Stefan Porembski ◽  
...  
Keyword(s):  
Climate Change ◽  
Stable Isotopes ◽  
Carbon Isotope ◽  
Tree Ring ◽  
Isotope Composition ◽  
Carbon Isotope Composition ◽  
Riparian Forests ◽  
Δ13c Values ◽  
Riparian Trees ◽  
Species Specific

Stable isotopes of tree rings are frequently used as proxies in climate change studies. However, species-specific relationships between climate and tree-ring stable isotopes have not yet been studied in riparian forests in the savannas of West Africa. Four cross-dated discs, each of Afzelia africana Sm. (evergreen) and Anogeissus leiocarpus (DC.) Guill. & Perr. (deciduous) in the humid (HSZ) and dry (DSZ) savanna zones of the Volta basin in Ghana were selected from a larger tree-ring dataset to assess the relationships between the tree-ring carbon isotope composition (δ13C values) and climatic parameters. The atmospherically corrected δ13C values of both studied species showed that A. africana was enriched in 13C compared to A. leiocarpus. Strong correlations were found between δ13C values of A. africana and A. leiocarpus with temperature, but weak correlations with precipitation. Spatial correlation analysis revealed significant relationships between δ13C values of both tree species and Sea Surface Temperatures in the Gulf of Guinea in the southern Atlantic Ocean. The results suggest that the carbon isotope composition of riparian trees in the Volta river basin has a potential to reconstruct climate variability and to assess tree ecological responses to climate change.

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