Environmental Effects on Oxygen Isotope Enrichment of Leaf Water in Cotton Leaves

Abstract

The oxygen isotope enrichment of bulk leaf water (D b ) was measured in cotton (Gossypium hirsutum) leaves to test the CraigGordon and Farquhar-Gan models under different environmental conditions. D b increased with increasing leaf-to-air vapor pressure difference (VPd) as an overall result of the responses to the ratio of ambient to intercellular vapor pressures (e a /e i ) and to stomatal conductance (g s ). The oxygen isotope enrichment of lamina water relative to source water ð D 1 Þ; which increased with increasing VPd, was estimated by mass balance between less enriched water in primary veins and enriched water in the leaf. Recently, the analysis of the oxygen isotope composition (d 18 O) of leaf water became of increased interest as a result of efforts to obtain information on the global carbon cycle Gillon and Yakir, 2001) and because of applications in agriculture (Barbour et al., 2000a). These and other applications were recently updated (Barbour, 2007;Farquhar et al., 2007). The d 18O of atmospheric CO 2 and of plant organic matter depends strongly on the extent of leaf water enrichment that occurs during transpiration (Barbour et al., 2000b) because the diffusivity and vapor pressure of heavier H 2 18O are less than that of lighter H 2 16 O (Craig and Gordon, 1965). A large portion of the CO 2 that enters the leaf equilibrates with evaporatively enriched leaf water via the catalytic activity of carbonic anhydrase, then retrodiffuses out of the leaf, increasing the d

Influence of salinity on hydrogen isotope fractionation in Rhizophora mangroves from Micronesia

“…With the exception of nC 29 -alkane from Pohnpei, there were not significant correlations between salinity and α Lipid-LW (Table 2). These weak relationships may be due to the inherent noise in leaf water isotopes, which change significantly with meteorological conditions and the time of day (Kahmen et al, 2008;Ripullone et al, 2008). We attempted to avoid some of this temporal noise by modeling leaf water for climatological average conditions at each site ( Figure 3).…”

Combining carbon-13 and oxygen-18 to unravel triticale grain yield and physiological response to water stress

“…The assumption was based on theories described in a review by Yakir (1992) and explored further by many other authors (Farquhar et al, 2007;Ripullone et al, 2008). This assumption was duly met by the measured data of 2014 ( Fig.…”

The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

“…The δ 18 O LW is commonly modelled as a function of the isotope composition of absorbed water, the isotope composition of water vapor, and RH (Craig and Gordon, 1965). The Craig and Gordon simple approach overestimates δ 18 O LW and different corrections have been proposed to take into account the diffusion of the evaporating water back to the leaf lamina and the advection of less evaporated stem water (i.e., the Péclet effect, Buhay et al, 1996;Helliker and Ehleringer, 2000;Roden et al, 2000;Farquhar and Gan, 2003;Farquhar and Cernusak, 2005;Ripullone et al, 2008;Treydte et al, 2014). In the growth chamber experiment, where water availability, relative humidity, and temperature were kept constant, we assume that transpiration rapidly reached a steady state and that the isotope composition of transpired water was the same as that of the irrigation water entering the plant (e.g., Welp et al, 2008 (2000) proposed, for monocotyledonous species characterized by a vertical parallel veinal structure, to use instead of the Craig and Gordon model the Gat and Bowser (1991) Table S3 was either higher or lower than the observed 17 O-excess e LW−IW .…”