On the progressive enrichment of the oxygen isotopic composition of water along a leaf

Farquhar, Graham D.; Gan, Kim Suan

doi:10.1046/j.1365-3040.2003.01013.x

Cited by 66 publications

(40 citation statements)

References 25 publications

(40 reference statements)

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“…Instead, we found that the primary driver of greater progressive enrichment was seasonal decreases in RH, consistent with the ‘desert river’ type model that focuses on atmospheric humidity and needle transpiration rates as drivers of progressive enrichment (e.g. Farquhar & Gan, 2003; Ogée et al, 2007).…”

Section: Discussionsupporting

confidence: 85%

“…The maximum enrichment observed in the leaf, located at l m , has an isotope ratio of Δ C /h′. When integrated over the whole leaf, this model yields an average value equivalent to C–G prediction (Farquhar & Gan, 2003).…”

Section: Methodsmentioning

confidence: 95%

“…To account for this, Farquhar and Gan (2003) described enrichment along the length of a leaf in a continuous fashion as a ‘desert river’, where water evaporates continuously along a path until it is completely evaporated. In this formulation (Equation ) from Farquhar & Gan, 2003), the isotope ratio at any point along the leaf can be expressed as:

Δ_{L} ((), l) = \frac{{normalΔ}_{C}}{h^{'}} ([], 1 - {(1 - \frac{l}{l_{m}})}^{\frac{h^{'}}{1 - h^{'}}}),

where Δ C is the predicted bulk leaf water isotope ratio from the standard C–G equation, l is the position along the leaf, l m is the length of the leaf, and h ′ = 1 − α eq α k (1 − h ). The maximum enrichment observed in the leaf, located at l m , has an isotope ratio of Δ C /h′.…”

Section: Methodsmentioning

confidence: 99%

“…Beyond this fundamental mechanism, however, each of the models differs in their predictions regarding what causes variability in the magnitude of the progressive isotope enrichment effect. For this process to occur, it has been suggested that radial advection of water towards the evaporation site (the normal flow in a transpiring leaf) needs to be slow enough to not overwhelm back‐diffusion of the heavy isotopologue, leading to predictions that this phenomenon should only be present in species with small interveinal distances (Helliker & Ehleringer, 2000) and/or large mesophyll tortuosity (Farquhar & Gan, 2003; Ogée et al, 2007). Other factors have been suggested to increase the strength of longitudinal progressive enrichment, such as a longer leaf length (Helliker & Ehleringer, 2000; Roden, Kahmen, Buchmann, & Siegwolf, 2015), low humidity and high transpiration rates (Farquhar & Gan, 2003; Gan et al, 2002, 2003; Šantrůček et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal and diurnal trends in progressive isotope enrichment along needles in two pine species

Kannenberg

Fiorella

Anderegg

et al. 2020

Plant Cell & Environment

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The Craig-Gordon type (C-G) leaf water isotope enrichment models assume a homogeneous distribution of enriched water across the leaf surface, despite observations that Δ 18 O can become increasingly enriched from leaf base to tip. Datasets of this 'progressive isotope enrichment' are limited, precluding a comprehensive understanding of (a) the magnitude and variability of progressive isotope enrichment, and (b) how progressive enrichment impacts the accuracy of C-G leaf water model predictions. Here, we present observations of progressive enrichment in two conifer species that capture seasonal and diurnal variability in environmental conditions. We further examine which leaf water isotope models best capture the influence of progressive enrichment on bulk needle water Δ 18 O. Observed progressive enrichment was large and equal in magnitude across both species. The magnitude of this effect fluctuated seasonally in concert with vapour pressure deficit, but was static in the face of diurnal cycles in meteorological conditions. Despite large progressive enrichment, three variants of the C-G model reasonably successfully predicted bulk needle Δ 18 O. Our results thus suggest that the presence of progressive enrichment does not impact the predictive success of C-G models, and instead yields new insight regarding the physiological and anatomical mechanisms that cause progressive isotope enrichment.

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Section: Discussionsupporting

confidence: 85%

Section: Methodsmentioning

confidence: 95%

Δ_{L} ((), l) = \frac{{normalΔ}_{C}}{h^{'}} ([], 1 - {(1 - \frac{l}{l_{m}})}^{\frac{h^{'}}{1 - h^{'}}}),

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Seasonal and diurnal trends in progressive isotope enrichment along needles in two pine species

Kannenberg

Fiorella

Anderegg

et al. 2020

Plant Cell & Environment

View full text Add to dashboard Cite

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“…The genotype QUP2529 showed the highest leaf WC, the lowest leaf δ 18 O and δ 2 H values, and the lowest evaporative enrichment ( 18 O, 2 H). These results can be attributed to lower leaf temperatures and higher transpiration rates (Farquhar and Gan, 2003;Sheshshayee et al, 2005;Cabrera-Bosquet et al, 2009;Ferrio et al, 2009Ferrio et al, , 2012. The response of QUP2529 partly relies on more effective water uptake, which would allow this genotype to maintain higher transpiration rates under mild water stress.…”

Section: Isotope Composition Of the Soil And Plant Water Usementioning

confidence: 99%

Root Architecture and Functional Traits of Spring Wheat Under Contrasting Water Regimes

et al. 2020

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Wheat roots are known to play an important role in the yield performance under water-limited (WL) conditions. Three consecutive year trials (2015, 2016, and 2017) were conducted in a glasshouse in 160 cm length tubes on a set of spring wheat ( Triticum aestivum L.) genotypes under contrasting water regimes (1) to assess genotypic variability in root weight density (RWD) distribution in the soil profile, biomass partitioning, and total water used; and (2) to determine the oxygen and hydrogen isotopic signatures of plant and soil water in order to evaluate the contribution of shallow and deep soil water to plant water uptake and the evaporative enrichment of these isotopes in the leaf as a surrogate for plant transpiration. In the 2015 trial under well-watered (WW) conditions, the aerial biomass (AB) was not significantly different among 15 wheat genotypes, while the total root biomass and the RWD distribution in the soil profile were significantly different. In the 2016 and 2017 trials, a subset of five genotypes from the 2015 trial was grown under WW and WL regimes. The water deficit significantly reduced AB only in 2016. The water regimes did not significantly affect the root biomass and root biomass distribution in the soil depths for both the 2016 and 2017 trials. The study results highlighted that under a WL regime, the production of thinner roots with low biomass is more beneficial for increasing the water uptake than the production of large thick roots. The models applied to estimate the relative contribution of the plant’s primary water sources (shallow or deep soil water) showed large interindividual variability in soil, and plant water isotopic composition resulted in large uncertainties in the model estimates. On the other side, the combined information of root architecture and the leaf stable isotope signatures could explain plant water status.

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Leaf transition from heterotrophy to autotrophy is recorded in the intraleaf C, H and O isotope patterns of leaf organic matter

Zhu

Yin

Song

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale Quantitatively relating 13C/12C, 2H/1H and 18O/16O ratios of plant α‐cellulose and 2H/1H of n‐alkanes to environmental conditions and metabolic status should ideally be based on the leaf, the plant organ most sensitive to environmental change. The fact that leaf organic matter is composed of isotopically different heterotrophic and autotrophic components means that it is imperative that one be able to disentangle the relative heterotrophic and autotrophic contributions to leaf organic matter. Methods We tackled this issue by two‐dimensional sampling of leaf water and α‐cellulose, and specific n‐alkanes from greenhouse‐grown immature and mature and field‐grown mature banana leaves, taking advantage of their large areas and thick waxy layers. Leaf water, α‐cellulose and n‐alkane isotope ratios were then characterized using elemental analysis isotope ratio mass spectrometry (IRMS) or gas chromatography IRMS. A three‐member (heterotrophy, autotrophy and photoheterotrophy) conceptual linear mixing model was then proposed for disentangling the relative contributions of the three trophic modes. Results We discovered distinct spatial leaf water, α‐cellulose and n‐alkane isotope ratio patterns that varied with leaf developmental stages. We inferred from the conceptual model that, averaged over the leaf blade, only 20% of α‐cellulose in banana leaf is autotrophically laid down in both greenhouse‐grown and field‐grown banana leaves, while approximately 60% and 100% of n‐alkanes are produced autotrophically in greenhouse‐grown and field‐grown banana leaves, respectively. There exist distinct lateral (edge to midrib) gradients in autotrophic contributions of α‐cellulose and n‐alkanes. Conclusions Efforts to establish quantitative isotope–environment relationships should take into account the fact that the evaporative leaf water 18O and 2H enrichment signal recorded in autotrophically laid down α‐cellulose is significantly diluted by the heterotrophically formed α‐cellulose. The δ2H value of field‐grown mature banana leaf n‐alkanes is much more sensitive than α‐cellulose as a recorder of the growth environment. Quantitative isotope–environment relationship based on greenhouse‐grown n‐alkane δ2H values may not be reliable.

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On the progressive enrichment of the oxygen isotopic composition of water along a leaf

Cited by 66 publications

References 25 publications

Seasonal and diurnal trends in progressive isotope enrichment along needles in two pine species

Seasonal and diurnal trends in progressive isotope enrichment along needles in two pine species

Root Architecture and Functional Traits of Spring Wheat Under Contrasting Water Regimes

Leaf transition from heterotrophy to autotrophy is recorded in the intraleaf C, H and O isotope patterns of leaf organic matter

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