scholarly journals Where in the leaf is intercellular CO2 (Ci)? Considerations and recommendations for assessing gaseous diffusion in leaves

2020 ◽  
Author(s):  
Joseph R. Stinziano ◽  
Jun Tominaga ◽  
David T. Hanson
Keyword(s):  
Water Vapor ◽  
High Temperature ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Loss ◽  
Leaf Water ◽  
Marginal Effect ◽  
Photosynthetic Gas Exchange ◽  
Gaseous Diffusion ◽  
Intercellular Co2

AbstractThe assumptions that water vapor exchange occurs exclusively through stomata, that the intercellular airspace is fully saturated with water vapor, and that CO2 gradients are negligible between stomata and the intercellular airspace have enabled significant advancements in photosynthetic gas exchange research for nearly 60 years via calculation of intercellular CO2 (Ci). However, available evidence suggests that these assumptions may be overused. Here we review the literature surrounding evidence for and against the assumptions made by Moss & Rawlins (1963). We reinterpret data from the literature by propagating different rates of cuticular water loss, CO2 gradients, and unsaturation through the data. We find that in general, when cuticle conductance is less than 1% of stomatal conductance, the assumption that water vapor exchange occurs exclusively through stomata has a marginal effect on gas exchange calculations, but this is not true when cuticle conductance exceeds 5% of stomatal conductance. Our analyses further suggest that CO2 and water vapor gradients have stronger impacts at higher stomatal conductance, while cuticle conductance has a greater impact at lower stomatal conductance. Therefore, we recommend directly measuring Ci whenever possible, measuring apoplastic water potentials to estimate humidity inside the leaf, and exercising caution when interpreting data under conditions of high temperature and/or low stomatal conductance, and when a species is known to have high cuticular conductance.HighlightLeaf water vapor and CO2 exchange have been successfully used to model photosynthetic biochemistry. We review critical assumptions in these models and make recommendations about which need to be re-assessed.

Leaf-scale quantification of the effect of photosynthetic gas exchange on Δ17O of atmospheric CO2

2020 ◽  
Author(s):  
Getachew Adnew ◽  
Thijs Pons ◽  
Gerbrand Koren ◽  
Wouter Peters ◽  
Thomas Röckmann
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Photosynthetic Capacity ◽  
Isotope Composition ◽  
Diffusion Flux ◽  
Relative Difference ◽  
Leaf Water ◽  
Back Diffusion ◽  
Photosynthetic Gas Exchange ◽  
High Photosynthetic Capacity

<p> </p><p> </p><p>Understanding the processes affecting the triple oxygen isotope composition of atmospheric CO<sub>2</sub> during photosynthesis can help to constrain the interaction and fluxes between the atmosphere and the biosphere. We conducted leaf cuvette experiments under controlled conditions, using sunflower (<em>Helianthus annuus</em>), an annual C<sub>3</sub> species with high photosynthetic capacity and stomatal conductance for CO<sub>2</sub>, an evergreen C<sub>3</sub> species, ivy (<em>Hedera hybernica</em>) with lower values for these traits, and a C<sub>4</sub> species maize (<em>Zea mays)</em> that has a high photosynthetic capacity and low stomatal conductance. The experiments were conducted at different light intensities and using CO<sub>2</sub> with different <sup>17</sup>O- excess. Our results demonstrate that two key factors determine the effect of photosynthetic gas exchange on Δ<sup>17</sup>O of atmospheric CO<sub>2</sub>: The relative difference in Δ<sup>17</sup>O of the CO<sub>2</sub> entering the leaf and Δ<sup>17</sup>O of leaf water, and the back-diffusion flux from the leaf to the atmosphere, which can be quantified by the c<sub>m</sub>/c<sub>a</sub> ratio.  At low c<sub>m</sub>/c<sub>a</sub> the discrimination is governed by diffusion into the leaf, and at high c<sub>m</sub>/c<sub>a</sub> by back-diffusion of CO<sub>2</sub> that has equilibrated with the leaf water. Plants with a higher c<sub>m</sub>/c<sub>a</sub> ratio modify the Δ<sup>17</sup>O of atmospheric CO<sub>2</sub> more strongly than plants with lower c<sub>m</sub>/c<sub>a</sub>. </p><p>Based on the leaf cuvette experiments using both C<sub>4</sub> and C<sub>3</sub> plants, the global discrimination in <sup>17</sup>O-excess of atmospheric CO<sub>2</sub> due to assimilation is estimated to be -0.6±0.2‰. The main uncertainty in the global estimation is due to the uncertainty in the c<sub>m</sub>/c<sub>a</sub> ratio.</p><p> </p><p> </p><p> </p>

scholarly journals Effects of shading on the growth, development and yield of winged bean (Psophocarpus tetragonolobus)

2020 ◽  
Vol 50 (2) ◽  
Author(s):  
Murthazar Naim Raai ◽  
Nurul Amalina Mohd Zain ◽  
Normaniza Osman ◽  
Nur Ardiyana Rejab ◽  
Nurul Amylia Sahruzaini ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Physiological Responses ◽  
Canopy Cover ◽  
Winged Bean ◽  
Psophocarpus Tetragonolobus ◽  
Photosynthetic Gas Exchange ◽  
Growth Development ◽  
The Tropics ◽  
Protein Rich

ABSTRACT: An experiment was conducted to investigate the effects of different shading regimes [i.e., 60% (heavy), 30% (moderate), and 0% (control)] on 25 traits associated with the morphological features, photosynthetic gas exchange and agronomic characteristics of winged bean (Psophocarpus tetragonolobus), an underutilized protein-rich legume from the tropics. Collectively, 80% of the studied variables displayed significant differences (P<0.05) between at least two shade treatments. Shading generally showed most pronounced effect on the physiological traits of the legume, whereby the stomatal conductance, photosynthetic and transpiration rate differed significantly among plants for all treatments. The non-shaded plants were observed to have superior growth and physiological responses than the shaded plants. Interestingly, the moderately shaded plants exhibited the highest yield per plant, which significantly differed from the non-shaded and heavily shaded plants. This indicated that winged bean can adapt to partial canopy cover, making it a potential nitrogen-fixing cash crop which can be planted together with fruit or oil trees in commercial plantations.

Seasonal and diurnal variation in the stomatal conductance and paraheliotropism of tedera (Bituminaria bituminosa var. albomarginata) in the field

2013 ◽  
Vol 40 (7) ◽  
pp. 719 ◽  
Author(s):  
Kevin Foster ◽  
Megan H. Ryan ◽  
Daniel Real ◽  
Padmaja Ramankutty ◽  
Hans Lambers
Keyword(s):  
Stomatal Conductance ◽  
Drought Resistance ◽  
Water Loss ◽  
Incident Light ◽  
Leaf Water ◽  
Leaf Angle ◽  
Leaf Water Content ◽  
Bituminaria Bituminosa ◽  
Pasture Plant ◽  
Perennial Legumes

The mechanisms of drought resistance in perennial legumes are poorly understood. We explored the diurnal and seasonal variation (May, August, February) in stomatal conductance (gs) and paraheliotropism of three tedera accessions (Bituminaria bituminosa (L.) C.H. Stirton var. albomarginata) and lucerne (Medicago sativa L.), both perennial legumes, grown in the field. For the tedera accessions, there was a significant reduction in gs during the day in May (late autumn) and February (summer), but there was little reduction for lucerne. The peak leaf angle in the tedera accessions ranged from <40° to 70°, whereas for lucerne, the leaf angle was nearly parallel to incident light at 85°. Leaf water-use efficiency, relative leaf water content and leaf retention were higher for the tedera accessions than for lucerne in February. These results highlight the superior drought resistance of tedera compared with lucerne. The reduction in gs over the day in tedera shows the capacity of this species to reduce water loss quickly when conditions for CO2 fixation relative to water loss are highly unfavourable. The high retention of leaves in summer by tedera is a valuable trait for a perennial pasture plant in Mediterranean environments. Leaf folding, combined with effective stomatal control in summer, provides tedera with a set of physiological responses that confer high drought resistance.

The leaf miner Phyllocnistis populiella negatively impacts water relations in aspen

2019 ◽  
Vol 40 (5) ◽  
pp. 580-590 ◽  
Author(s):  
Diane Wagner ◽  
Jenifer M Wheeler ◽  
Stephen J Burr
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Water Loss ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Leaf Miner ◽  
Phyllocnistis Populiella

Abstract Within the North American boreal forest, a widespread outbreak of the epidermal leaf miner Phyllocnistis populiella Cham. has damaged quaking aspen (Populus tremuloides Michx.) for nearly 20 years. In a series of experiments, we tested the effects of feeding damage by P. populiella on leaf water relations and gas exchange. Relative to insecticide-treated trees, the leaves of naturally mined trees had lower photosynthesis, stomatal conductance to water vapor, transpiration, water-use efficiency, predawn water potential and water content, as well as more enriched foliar δ13C. The magnitude of the difference between naturally mined and insecticide-treated trees did not change significantly throughout the growing season, suggesting that the effect is not caused by accumulation of incidental damage to mined portions of the epidermis over time. The contributions of mining-related stomatal malfunction and cuticular transpiration to these overall effects were investigated by restricting mining damage to stomatous abaxial and astomatous adaxial leaf surfaces. Mining of the abaxial epidermis decreased photosynthesis and enriched leaf δ13C, while increasing leaf water potential and water content relative to unmined leaves, effects consistent with stomatal closure due to disfunction of mined guard cells. Mining of the adaxial epidermis also reduced photosynthesis but had different effects on water relations, reducing midday leaf water potential and water content relative to unmined leaves, and did not affect δ13C. In the laboratory, extent of mining damage to the adaxial surface was positively related to the rate of water loss by leaves treated to prevent water loss through stomata. We conclude that overall, despite water savings due to closure of mined stomata, natural levels of damage by P. populiella negatively impact water relations due to increased cuticular permeability to water vapor across the mined portions of the epidermis. Leaf mining by P. populiella could exacerbate the negative effects of climate warming and water deficit in interior Alaska.

Effect of Changes in Leaf Water Oxygen Isotopic Composition on Discrimination Against C18O16O During Photosynthetic Gas Exchange

1994 ◽  
Vol 21 (2) ◽  
pp. 221 ◽  
Author(s):  
LB Flanagan ◽  
SL Phillips ◽  
JR Ehleringer ◽  
J Lloyd ◽  
GD Farquhar
Keyword(s):  
Gas Exchange ◽  
Isotopic Composition ◽  
Vapour Pressure ◽  
Mechanistic Model ◽  
Isotopic Fractionation ◽  
Oxygen Isotopic Composition ◽  
Leaf Water ◽  
Photosynthetic Gas Exchange ◽  
Oxygen Isotopic ◽  
Environment Chamber

Photosynthetic gas exchange measurements were combined with measurements of the carbon and oxygen stable isotopic composition of CO2 after it passed over a leaf of Phaseolus vulgaris or Senecio spp. plants held in a controlled environment chamber. Calculations were then made of discrimination by the leaf against 13CO2 and C18O16O. Leaves were maintained at different vapour pressure gradients in order to generate a range of leaf water 18CO/16CO ratios. The 18CO content of leaf water increased when plants were exposed to higher vapour pressure deficits. The observed C18O16O discrimination values also increased with an increase in the leaf-air vapour pressure gradient and the associated change in leaf water 18/CO16CO values. In addition, the observed C18O16O discrimination values were strongly correlated with values predicted by a mechanistic model of isotopic fractionation.

How stomata resolve the dilemma of opposing priorities

1976 ◽  
Vol 273 (927) ◽  
pp. 551-560 ◽  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Loss ◽  
Stomatal Closure ◽  
Guard Cells ◽  
Xanthium Strumarium ◽  
Solute Content ◽  
Stomatal Responses ◽  
Saturation Kinetics ◽  
Use Efficiency

Satisfaction of a leaf’s need for CO 2 requires an intensive gas exchange between mesophyll and atmosphere; prevention of excessive water loss demands that gas exchange be kept low. Stomata open when a low CO 2 concentration in the guard cells triggers ( a ) uptake of K + in exchange of H + , ( b ) production of organic acids, and ( c ) import of Cl - . ‘Hydropassive’ stomatal closure (i.e. turgor loss without reduction of the solute content of the guard cell) appears insufficient to protect the plant from desiccation. An additional ‘hydroactive’ solute loss is necessary; it is brought about by (+)-abscisic acid (ABA) acting as feedback messenger between mesophyll and epidermis. Stomatal closure not only curbs water loss but improves water-use efficiency because transpiration is proportional to stomatal conductance (at constant temperature). In contrast, assimilation, following saturation kinetics with respect to intercellular CO 2 , is relatively insensitive to changes in stomatal conductance (as long as stomata are wide open). In Xanthium strumarium , the amplitude of stomatal responses to ABA depends on the concentration of CO 2 in the guard cells; the opposite statement is also true. These interactions cause stomata to behave like ‘adjustable control systems’ capable of giving priority either to CO 2 assimilation or to water husbandry.

scholarly journals Leaf scale quantification of the effect of photosynthetic gas exchange on Δ47 of CO2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Getachew Agmuas Adnew ◽  
Magdalena E. G. Hofmann ◽  
Thijs L. Pons ◽  
Gerbrand Koren ◽  
Martin Ziegler ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Isotope Composition ◽  
Diffusion Flux ◽  
Leaf Water ◽  
Back Diffusion ◽  
Ambient Conditions ◽  
Photosynthetic Gas Exchange ◽  
O Isotope ◽  
Clumped Isotope ◽  
Kinetic Fractionation

AbstractThe clumped isotope composition (Δ47, the anomaly of the mass 47 isotopologue relative to the abundance expected from a random isotope distribution) of CO2 has been suggested as an additional tracer for gross CO2 fluxes. However, the effect of photosynthetic gas exchange on Δ47 has not been directly determined and two indirect/conceptual studies reported contradicting results. In this study, we quantify the effect of photosynthetic gas exchange on Δ47 of CO2 using leaf cuvette experiments with one C4 and two C3 plants. The experimental results are supported by calculations with a leaf cuvette model. Our results demonstrate the important roles of the Δ47 value of CO2 entering the leaf, kinetic fractionation as CO2 diffuses into, and out of the leaf and CO2–H2O isotope exchange with leaf water. We experimentally confirm the previously suggested dependence of Δ47 of CO2 in the air surrounding a leaf on the stomatal conductance and back-diffusion flux. Gas exchange can enrich or deplete the Δ47 of CO2 depending on the Δ47 of CO2 entering the leaf and the fraction of CO2 exchanged with leaf water and diffused back to the atmosphere, but under typical ambient conditions, it will lead to a decrease in Δ47.

scholarly journals Water status and gas exchange of umbu plants (Spondias tuberosa Arr. Cam.) propagated by seeds and stem cuttings

2007 ◽  
Vol 29 (2) ◽  
pp. 355-358 ◽  
Author(s):  
José Moacir Pinheiro Lima Filho
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Leaf Gas Exchange ◽  
Leaf Water ◽  
Soil Water Deficit ◽  
Stem Cuttings

The experiment was carried out at the Embrapa Semi-Árido, Petrolina-PE, Brazil, in order to study the physiological responses of umbu plants propagated by seeds and by stem cuttings under water stress conditions, based on leaf water potential and gas exchange measurements. Data were collected in one-year plants established in pots containing 30 kg of a sandy soil and submitted to twenty-day progressive soil water deficit. The evaluations were based on leaf water potential and gas exchange data collection using psychrometric chambers and a portable infra-red gas analyzer, respectively. Plants propagated by seeds maintained a significantly higher water potential, stomatal conductance, transpiration and photosynthesis under decreasing soil water availability. However, plants propagated by stem cuttings were unable to maintain a favorable internal water balance, reflecting negatively on stomatal conductance and leaf gas exchange. This fact is probably because umbu plants propagated by stem cuttings are not prone to formation of root tubers which are reservoirs for water and solutes. Thus, the establishing of umbu plants propagated by stem cuttings must be avoided in areas subjected to soil water deficit.

scholarly journals Petroleum Spray Oil Effects on Net Gas Exchange of Grapefruit Leaves at Various Vapor Pressures

HortScience ◽  
1991 ◽  
Vol 26 (2) ◽  
pp. 168-170 ◽  
Author(s):  
J.P. Syvertsen ◽  
M. Salyani
Keyword(s):  
Water Vapor ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Vapor Pressure ◽  
Citrus Paradisi ◽  
Vapor Pressures ◽  
Vapor Pressure Difference ◽  
Oil Mixtures ◽  
Oil Emulsions ◽  
Petroleum Spray Oil

The effects of three highly refined petroleum spray oils and of ambient vapor pressure on net CO2 assimilation (A) and stomatal conductance of water vapor (gs) of single grapefruit (Citrus paradisi Macf.) leaves were investigated. Overall, gs of various-aged leaves was decreased by a large leaf-to-air vapor pressure difference (VPD). In the first experiment, oils with midpoint distillation temperatures (50% DT) of 224, 235, and 247C were applied with a hand atomizer at concentrations of 0, 1%, and 4% oil emulsions in water and 100% oil, all with 0.82% surfactant (by volume). There was a tendency for oils of the two higher DT to decrease net gas exchange during a subsequent 12 days, but significant differences could not be attributed to oil DT. Both A and gs were reduced by the two higher concentrations of oil mixtures. In the second experiment, a commercial airblast sprayer was used to apply the 224C oil at 4% or the 235C oil at 2% and 4% mixtures plus surfactant under field conditions. There were no significant effects of oil treatments on net gas exchange of leaves either measured under moderate VPD outdoors 1 day after spraying or under low VPD in the laboratory 2 days after spraying. No visible phytotoxic symptoms were observed in either experiment.

scholarly journals Physiological effects of water deficit on two oil palm (Elaeis guineensis Jacq.) genotypes

2015 ◽  
Vol 33 (2) ◽  
pp. 164-173 ◽  
Author(s):  
Seyed Mehdi Jazayeri ◽  
Yurany Dayanna Rivera ◽  
Jhonatan Eduardo Camperos-Reyes ◽  
Hernán Mauricio Romero
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Oil Palm ◽  
Photosynthetic Capacity ◽  
Elaeis Guineensis ◽  
Leaf Water ◽  
Physiological Effects

Water supply is the main limiting factor that affects oil palm (Elaeis guineensis Jacq.) yield. This study aimed to evaluate the gas exchange and photosynthetic capacity, determine the physiological effects and assess the tolerance potential of oil palm genotypes under water-deficit conditions. The two oil palm commercial genotypes IRHO1001 and IRHO7010 were exposed to soil water potentials of -0.042 MPa (field capacity or well-watered) or -1.5 MPa (drought-stressed). The leaf water potential and gas exchange parameters, including photosynthesis, stomatal conductance, transpiration and water use efficiency (WUE), as well as the photosynthesis reduction rate were monitored at 4 and 8 weeks after treatment. The IRHO7010 genotype showed fewer photosynthesis changes and a smaller photosynthetic reduction under the prolonged water deficit conditions of 23% at 4 weeks after the treatment as compared to 53% at 8 weeks after treatment, but the IRHO1001 genotype showed 46% and 74% reduction at the two sampling times. 'IRHO7010' had a higher stomatal conductance and transpiration potential than 'IRHO1001' during the water shortage. The WUE and leaf water potential were not different between the genotypes during dehydration. The data suggested that 'IRHO7010' had a higher photosynthetic capacity during the drought stress and was more drought-tolerant than 'IRHO1001'.

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