Graham D Farquhar

Graham D Farquhar
Australian National University | ANU · Research School of Biology (RSB)

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439
Publications
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Publications

Publications (439)
Preprint
Photosynthetic manipulation provides new opportunities for enhancing crop yield. However, understanding and quantifying effectively how the seasonal growth and yield dynamics of target crops might be affected over a wide range of environments is limited. Using a state-of-the-art cross-scale model we predicted crop-level impacts of a broad list of p...
Article
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Canola varieties exhibit discernible variation in drought avoidance and drought escape traits, reflecting adaptation to water‐deficit environments. Our understanding of underlying genes and their interaction across environments in improving crop productivity is limited. A doubled haploid (DH) population was analysed to identify QTL associated with...
Chapter
Absorption of water from seawater with its high osmotic pressure is costly to mangroves and requires the plants to use water conservatively. Indeed, measurements of gas exchange, growth rate and carbon isotope composition have shown that mangrove species operate with higher water-use efficiency (WUE) than do most C3 species. These characteristics o...
Article
The prevalence of phylogenetic constraints in Rubisco evolution has been emphasised recently by (Bouvier et al., 2021), who argued that phylogenetic inheritance limits Rubisco adaptation much more than the biochemical trade-off between specificity, CO2 affinity and turn-over. In this Opinion, we have critically examined how a phylogenetic signal ca...
Article
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Food production must increase significantly to sustain a growing global population. Reducing plant water loss may help achieve this goal and is especially relevant in a time of climate change. The plant cuticle defends leaves against drought, and so understanding water movement through the cuticle could help future proof our crops and better unders...
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Cuticular conductance to water (gcw ) is difficult to quantify for stomatous surfaces due to the complexity of separating cuticular and stomatal transpiration, and additional complications arise for determining adaxial and abaxial gcw . This has led to the neglect of gcw as a separate parameter in most common gas exchange measurements. Here, we des...
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A Correction to this paper has been published: https://doi.org/10.1038/s41477-021-00899-w.
Article
An expression was earlier derived for the non-steady state isotopic composition of a leaf when the composition of the water entering the leaf was not necessarily the same as that of the water being transpired (Farquhar and Cernusak 2005). This was relevant to natural conditions because the associated time constant is typically sufficiently long to...
Article
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The widely used theory for gas exchange proposed by von Caemmerer and Farquhar (vCF) integrates molar fluxes, mole fraction gradients and ternary effects but does not account for cuticular fluxes, for separation of the leaf surface conditions or for ternary effects within the boundary layer. The magnitude of cuticular conductance to water (gcw) is...
Preprint
Full-text available
Food production needs to increase significantly in 30 years, and water loss from plants may hold one key, especially relevant in a time of climate change. The plant leaf cuticle is the final defence of leaves in drought and at night, and so by understanding water movement in the leaf with mathematical modelling techniques, we can move towards futur...
Article
H218 O enrichment develops when leaves transpire, but an accurate generalized mechanistic model has proven elusive. We hypothesized that leaf hydraulic architecture may affect the degree to which gradients in H218 O develop within leaves, influencing bulk leaf stable oxygen isotope enrichment (ΔL ) and the degree to which the Péclet effect is relev...
Article
Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the cornerstone of atmospheric CO2 fixation by the biosphere. It catalyzes the addition of CO2 onto enolized ribulose 1,5-bisphosphate (RuBP), producing 3-phosphoglycerate which is then converted to sugars. The major problem of this reaction is competitive O2 addition, which forms a phosp...
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Tight coordination in the photosynthetic, gas exchange and water supply capacities of leaves is a globally conserved trend across land plants. Strong selective constraints on leaf carbon gain create the opportunity to use quantitative optimization theory to understand the connected evolution of leaf photosynthesis and water relations. We developed...
Article
Atmospheric carbon dioxide concentration ([CO2]) is increasing, which increases leaf‐scale photosynthesis and intrinsic water‐use efficiency. These direct responses have the potential to increase plant growth, vegetation biomass, and soil organic matter; transferring carbon from the atmosphere into terrestrial ecosystems (a carbon sink). A substant...
Article
Background and aims: The stable carbon isotope ratio of leaf dry matter (γ13Cp) is generally a reliable recorder of intrinsic water-use efficiency in C3 plants. Here, we investigated a previously reported pattern of developmental change in leaf δ13Cp during leaf expansion, whereby emerging leaves are initially 13C-enriched compared to mature leave...
Article
Drought is a major constraint to canola production around the world. There is potential for improving crop performance in dry environments by selecting for transpiration efficiency (TE). In this work we investigated TE by studying its genetic association with carbon isotope discrimination (Δ) and other traits, e.g. specific leaf weight (SLW) and le...
Article
Full-text available
Stable isotopes are commonly used to study the diffusion of CO2 within photosynthetic plant tissues. The standard method used to interpret the observed preference for the lighter carbon isotope in C3 photosynthesis involves the model of Farquhar et al., which relates carbon isotope discrimination to physical and biochemical processes within the lea...
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Several lines of evidence point to an increase in the activity of the terrestrial biosphere over recent decades, impacting the global net land carbon sink (NLS) and its control on the growth of atmospheric carbon dioxide (ca). Global terrestrial gross primary production (GPP)—the rate of carbon fixation by photosynthesis—is estimated to have risen...
Article
Ralph Slatyer (16 April 1929–26 July 2012) had a distinguished career in the Commonwealth Scientific and Industrial Research Organisation and the Australian National University, in plant-water relations and plant succession, leading the development of physiological plant ecology. He was the founding Professor of Environmental Biology at the Researc...
Article
Theoretical models of photosynthetic isotopic discrimination of CO2 (13C and 18O) are commonly used to estimate mesophyll conductance (gm). This requires making simplifying assumptions and assigning parameter values so that gm can be solved for as the residual term. Uncertainties in gm estimation occur due to measurement noise and assumptions not h...
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The arrangement of mitochondria and chloroplasts, together with the relative resistances of cell wall and chloroplast, determine the path of diffusion out of the leaf for (photo)respired CO2. Traditional photosynthesis models have assumed a tight arrangement of chloroplasts packed together against the cell wall with mitochondria located behind the...
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Understanding stomatal and biochemical components that limit photosynthesis under different conditions is important for both the targeted improvement of photosynthesis and the elucidation of how stomata and biochemistry affect plant performance in an ecological context. Limitation analyses have not yet been extensively applied to conditions of phot...
Article
Rice quantitative trait locus (QTL) qDTY 12.1 is a major-effect drought yield QTL that was identified from a cross of Vandana (recipient parent) and Way Rarem (donor parent) through breeding efforts to improve rice yield under upland drought stress conditions. The two main physiological effects previously observed to be related to the presence of q...
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Enhancing photosynthesis is widely accepted as critical to advancing crop yield. However, yield consequences of photosynthetic manipulation are confounded by feedback effects arising from interactions with crop growth, development dynamics and the prevailing environment. Here, we developed a cross-scale modelling capability that connects leaf photo...
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This work aims at developing an adequate theoretical basis for comparing assimilation of the ancestral C3 pathway with CO2 concentrating mechanisms (CCM) that have evolved to reduce photorespiratory yield losses. We present a novel model for C3, C2, C2+C4 and C4 photosynthesis simulating assimilatory metabolism, energetics, and metabolite traffic a...
Article
Leaves are a nexus for the exchange of water, carbon, and energy between terrestrial plants and the atmosphere. Research in recent decades has highlighted the critical importance of the underlying biophysical and anatomical determinants of CO2 and H2O transport, but a quantitative understanding of how detailed 3D leaf anatomy mediates within-leaf t...
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More efficient gas exchange strategies under dynamic light environments have been hypothesised to contribute to the dominance of angiosperms in the vascular plant flora. However, we still lack a clear understanding of how stomatal dynamics affect photosynthetic dynamics and whether differences exist between lineages. Stomatal and photosynthetic dyn...
Article
Aim Within C3 plants, photosynthesis is a balance between CO2 supply from the atmosphere via stomata and demand by enzymes within chloroplasts. This process is dynamic and a complex but crucial aspect of photosynthesis. We sought to understand the spatial pattern in CO2 supply–demand balance on a global scale, via analysis of stable isotopes of car...
Chapter
Stable carbon isotopes are a powerful tool to study photosynthesis. Initial applications consisted of determining isotope ratios of plant biomass using mass spectrometry. Subsequently, theoretical models relating C-isotope values to gas exchange characteristics were introduced and tested against instantaneous online measurements of 13C photosynthet...
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Stomatal conductance (gs) impacts both photosynthesis and transpiration, and is therefore fundamental to the global carbon and water cycles, food production, and ecosystem services. Mathematical models provide the primary means of analysing this important leaf gas exchange parameter. A nearly universal assumption in such models is that the vapour p...
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There is a growing research interest in the detection of changes in hydrologic and climatic time series. Stationarity can be assessed using the autocorrelation function, but this is not yet common practice in hydrology and climate. Here, we use a global land-based gridded annual precipitation (hereafter P) database (1940–2009) and find that the lag...
Article
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the most widespread carboxylating enzyme in autotrophic organisms. Its kinetic and structural properties have been intensively studied for more than half a century. Yet important aspects of the catalytic mechanism remain poorly understood, especially the oxygenase reaction. Because of its...
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Photorespiration is a major bioengineering target for increasing crop yields as it is often considered a wasteful process. Photorespiratory metabolism is integrated into leaf metabolism and thus may have certain benefits. Here, we show that plants can increase their rate of photosynthetic CO2 uptake when assimilating nitrogen de novo via the photor...
Article
Elevated atmospheric CO2 concentration (e[CO2]) can stimulate the photosynthesis and productivity of C3 species including food and forest crops. Intraspecific variation in responsiveness to e[CO2] can be exploited to increase productivity under e[CO2]. However, active selection of genotypes to increase productivity under e[CO2] is rarely performed...
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Compartmentation of C4 photosynthetic biochemistry into bundle sheath (BS) and mesophyll (M) cells, and photorespiration in C3 plants is predicted to have hydrogen isotopic consequences for metabolites at both molecular and site-specific levels. Molecular-level evidence was recently reported (Zhou et al., 2016), but evidence at the site-specific le...
Article
Photosynthetic manipulation is seen as a promising avenue for advancing field crop productivity. However, progress is constrained by the lack of connection between leaf-level photosynthetic manipulation and crop performance. Here we report on the development of a model of diurnal canopy photosynthesis for well watered conditions by using biochemica...
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Contents I. II. III. IV. V. VI. VII. VIII. References SUMMARY: It has been 75 yr since leaf respiratory metabolism in the light (day respiration) was identified as a low-flux metabolic pathway that accompanies photosynthesis. In principle, it provides carbon backbones for nitrogen assimilation and evolves CO2 and thus impacts on plant carbon and ni...
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Mitochondrial respiration often appears to be inhibited in the light when compared with measurements in the dark. This inhibition is inferred from the response of the net CO2 assimilation rate (A) to absorbed irradiance (I), changing slope around the light compensation point (Ic). We suggest a model that provides a plausible mechanistic explanation...
Article
How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the va...
Article
It was shown over 40 years ago that plants maximize carbon gain for a given rate of water loss if stomatal conductance, gs , varies in response to external and internal conditions such that the marginal carbon revenue of water, ∂A/∂E, remains constant over time. This theory has long held promise for understanding the physiological ecology of water...
Article
The 2H/1H ratio of carbon-bound H in biolipids holds potential for probing plant lipid biosynthesis and metabolism. The biochemical mechanism underlying the isotopic differences between lipids from C3 and C4 plants is still poorly understood. GC-pyrolysis-IRMS measurement of the 2H/1H ratio of leaf lipids from controlled and field grown plants indi...
Article
The process of evaporation results in the fractionation of water isotopes such that the lighter (16) O isotope preferentially escapes the gas phase leaving the heavier (18) O isotope to accumulate at the sites of evaporation. This applies to transpiration from a leaf with the degree of fractionation dependent on a number of environmental and physio...
Article
In the context of changing climate, global pan evaporation records have shown a spatially-averaged trend of ∼−2 to ∼−3 mm a⁻² over the past 30–50 years. This global phenomenon has motivated the development of the “PenPan” model (Rotstayn et al., 2006). However, the original PenPan model has yet to receive an independent experimental evaluation. Hen...
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Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals inco...
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Background: The flag leaf of a wheat (Triticum aestivum L.) plant rolls up into a cylinder in response to drought conditions and then unrolls when leaf water relations improve. This is a desirable trait for extending leaf area duration and improving grain size particularly under drought. But how do we quantify this phenotype so that different vari...
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A recent interpretation of climate model projections concluded that “warmer is more arid.” In contrast, dust records and other evidence have led the geoscience community to conclude that “warmer is less arid” leading to an aridity paradox. The “warmer is more arid” interpretation is based on a projected increase in the vapour pressure deficit (∼ 7–...
Article
We present a combined 3-D model of light propagation, CO2 diffusion and photosynthesis in tomato (Solanum lycopersicum L.) leaves. The model incorporates a geometrical representation of the actual leaf microstructure that we obtained with synchrotron radiation X-ray laminography, and was evaluated using measurements of gas exchange and leaf optical...
Article
The two-pool and Péclet effect models represent two theories describing mechanistic controls underlying leaf water oxygen isotope composition at the whole-leaf level (δ18OL).To test these models, we used a laser spectrometer coupled to a gas-exchange cuvette to make online measurements of δ18O of transpiration (δ18Otrans) and transpiration rate (E)...
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Halophytic eudicots are characterized by enhanced growth under saline conditions. This study combines physiological and anatomical analyses to identify processes underlying growth responses of the mangrove Avicennia marina to salinities ranging from fresh- to seawater conditions. Following pre-exhaustion of cotyledonary reserves under optimal condi...
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Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. M...
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Forest and savanna are the two dominant vegetation types of the tropical regions with very few tree species common to both. Aside from precipitation patterns, boundaries between these two vegetation types are strongly determined by soil characteristics and nutrient availability. For tree species drawn from a range of forest and savanna sites in tro...
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Forest and savanna are the two dominant vegetation types of the tropical regions with very few tree species common to both. At a broad scale, it has long been recognised that the distributions of these two biomes are principally governed by precipitation and its seasonality, but with soil physical and chemical properties also potentially important....
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Inoculation with Rhizobium strain IC3342 induces in pigeonpea (Cajanus cajan (L) Millsp.) a leaf curl syndrome and elevated cytokinin levels in the xylem sap. High N nutrition was found to inhibit onset of the syndrome which could then be induced by N-free nutrient after development of 7 trifoliate leaves. This provided a new system to study the ro...
Article
We present a conceptual model linking dry-mass allocational allometry, hydraulic limitation, and vertical stratification of environmental conditions to patterns in vertical tree growth and tree height. Maximum tree height should increase with relative moisture supply and both should drive variation in apparent stomatal limitation. Carbon isotope di...
Conference Paper
Full-text available
The rising atmospheric CO2 concentration is altering global temperature and precipitation patterns, which could challenge agricultural productivity. Mesophyll conductance (gm) is now recognized as an important limiting process for photosynthesis and has been found to respond to both environmental conditions and leaf anatomical traits. To understand...
Article
Tropical soils are often characterised by low phosphorus availability and tropical forest trees typically exhibit lower area-based rates of photosynthesis (A(a)) for a given area-based leaf nitrogen concentration ([N](a)) compared with plants growing in higher-latitude, N-limited ecosystems. Nevertheless, to date, very few studies have assessed the...
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Climate models project increases in globally averaged atmospheric specific humidity that are close to the Clausius–Clapeyron (CC) value of around 7% K−1 whilst projections for mean annual global precipitation (P) and evaporation (E) are somewhat muted at around 2% K−1. Such global projections are useful summaries but do not provide guidance at loca...
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CO2 diffusion from substomatal intercellular cavities to sites of carboxylation in chloroplasts (mesophyll conductance; g(m)) limits photosynthetic rate and influences leaf intrinsic water-use efficiency (A/g(sw)). We investigated genotypic variability of g(m) and effects of g(m) on A/g(sw) among eleven wheat (Triticum aestivum L.) genotypes under...
Article
Certainty regarding the degree to which organic molecules exchange oxygen with local water during plant cellulose synthesis (pex ) is necessary for cellulose oxygen isotope (δ(18) Ocell ) based applications in environmental and ecological studies. However, the currently accepted notion that pex is a constant of ca. 0.42 appears inconsistent with bi...