scholarly journals Variability in growth, carbon isotope composition, leaf gas exchange and hydraulic traits in the eastern Mediterranean cedars Cedrus libani and C. brevifolia

2008 ◽  
Vol 28 (5) ◽  
pp. 689-701 ◽  
Author(s):  
M. Ducrey ◽  
R. Huc ◽  
M. Ladjal ◽  
J.-M. Guehl
Keyword(s):  
Gas Exchange ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Eastern Mediterranean ◽  
Leaf Gas Exchange ◽  
Carbon Isotope Composition ◽  
Cedrus Libani

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 Rootstocks induce functional differences that affect carbon isotope discrimination and water relations in the apple scion

2021 ◽  
Author(s):  
Erica Casagrande Biasuz ◽  
Lee Kalcsits
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Carbon Isotope ◽  
Hydraulic Resistance ◽  
Water Relations ◽  
Water Movement ◽  
Isotope Composition ◽  
Leaf Gas Exchange ◽  
Stem Water Potential ◽  
Stem Water

Composite trees combine traits from both the rootstock and scion. Dwarfing rootstocks are used to reduce shoot vigor and improve fruit quality and productivity. Although differences in rootstock vigour have been clearly described, the underlying physiological mechanisms regulating scion vigor are not well understood. Plant water status is strongly influenced by stem hydraulic resistance to water movement. In the scion, stomata regulate transpiration rates and are essential to prevent hydraulic failure. Lower stomatal conductance contributes to enriched leaf carbon isotope composition (δ13C). Combined, the effects of increased hydraulic resistance, limited stomatal control, and subsequently, limited gas exchange can affect tree growth. These differences may also correspond to differences in scion vigor. Here, vegetative growth, gas exchange, stem water potential, and leaf δ13C were compared to determine how rootstocks affect scion water relations. B.9 had the lowest shoot vigor compared to the more vigorous rootstock, G.890. Similarly, photosynthetic rates were also lower. Rootstock vigor was closely associated with leaf gas exchange and stem water potential in the scion and were reflected in leaf δ13C signatures. Dwarfing was strongly related to hydraulic limitations induced by rootstock genotype and these changes are distinguishable when measuring leaf and stem δ13C composition.

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