An Empirical Model of Net Photosynthesis and Leaf Conductance for the Simulation of Diurnal Courses of CO2 and H2O Exchange

1985 ◽  
Vol 12 (5) ◽  
pp. 513 ◽  
Author(s):  
M Kuppers ◽  
ED Schulze
Keyword(s):  
Gas Exchange ◽  
Empirical Model ◽  
Climatic Factors ◽  
Net Photosynthesis ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Uptake ◽  
Diurnal Courses ◽  
Humidity Response ◽  
Steady State Responses

An empirical model of CO2 uptake and water loss of leaves is established using steady-state responses of gas exchange to climatic factors as input. From the model the response surface of net CO2 assimilation and leaf conductance to climate can be derived. The model consists of two submodels, one describing the response of CO2 uptake to light and temperature, the other describing the response of leaf conductance to temperature and humidity. Both submodels are joined via the linear relationship between CO2 uptake and leaf conductance at short-term (minutes) variation of irradiance. From the humidity response of leaf conductance and the 'demand function' (Raschke 1979) of CO2 uptake in the mesophyll, the effect of stomata on the diffusion of CO2 between leaf and air is determined. The model is tested by comparing measured and calculated diurnal courses of gas exchange for two plants of Pinus silvestris, differing in photosynthetic capacity due to different levels of magnesium nutrition. Applications and limitations of the model are discussed.

Design and testing of twig chambers for ozone fumigation and gas exchange measurements in mature trees

1994 ◽  
Vol 102 ◽  
pp. 541-546 ◽  
Author(s):  
Wilhelm M. Havranek ◽  
Gerhard Wieser
Keyword(s):  
Gas Exchange ◽  
Net Photosynthesis ◽  
Ambient Air ◽  
Field Conditions ◽  
Chamber System ◽  
Mature Trees ◽  
Diurnal Courses ◽  
Controlled Conditions ◽  
Design And Testing

SynopsisA twig chamber system was developed for the exposure of mature trees to ozone (O3) under field conditions. The fumigation system allowed the exact control of O3 concentrations in the chambers, the measurement of O3 uptake as well as gas exchange measurements under ambient and controlled conditions during and after O3 fumigation. Because of differences in individual twigs the system should provide the exposure of replicates to different O3 treatments. Tests showed that temperature, humidity and O3 concentrations inside the chambers were comparable with diurnal courses observed in the field. Comparative gas exchange measurements indicated that there were no differences in net photosynthesis and conductance of twigs outside the chambers and twigs which remained within the chambers for 23 weeks receiving ambient air.

scholarly journals Limitations to leaf photosynthesis in field-grown grapevine under drought — metabolic and modelling approaches

2002 ◽  
Vol 29 (4) ◽  
pp. 451 ◽  
Author(s):  
João P. Maroco ◽  
M. Lucília Rodrigues ◽  
Carlos Lopes ◽  
M. Manuela Chaves
Keyword(s):  
Gas Exchange ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Co2 Assimilation ◽  
Quantum Yields ◽  
Vitis Vinifera L ◽  
Lower Efficiency ◽  
Photosynthetic Rates ◽  
Fructose 1,6 Bisphosphate

The effects of a slowly-imposed drought stress on gas-exchange, chlorophyll a fluorescence, biochemical and physiological parameters of Vitis vinifera L. leaves (cv. Aragonez, syn. Tempranillo) growing in a commercial vineyard (South Portugal) were evaluated. Relative to well-watered plants (predawn water potential, ΨPD = –0.13 ± 0.01 MPa), drought-stressed plants (ΨPD = –0.97 ± 0.01 MPa) had lower photosynthetic rates (ca 70%), stomatal conductance, and PSII activity (associated with a higher reduction of the quinone A pool and lower efficiency of PSII open centres). Stomatal limitation to photosynthesis was increased in drought-stressed plants relative to well-watered plants by ca 44%. Modelled responses of net photosynthesis to internal CO2 indicated that drought-stressed plants had significant reductions in maximum Rubisco carboxylation activity (ca 32%), ribulose-1,5-bisphosphate regeneration (ca 27%), and triose phosphate (triose-P) utilization rates (ca 37%) relative to well-watered plants. There was good agreement between the effects of drought on modelled biochemical parameters, and in vitro activities of key enzymes of carbon metabolism, namely Rubisco, glyceraldehyde-3-phosphate dehydrogenase, ribulose-5-phosphate kinase and fructose-1,6-bisphosphate phosphatase. Quantum yields measured under both ambient (35 Pa) and saturating CO2 (100 Pa) for drought-stressed plants were decreased relative to well-watered plants, as well as maximum photosynthetic rates measured at light and CO2 saturating conditions (three times ambient CO2 levels). Although stomatal closure was a strong limitation to CO2 assimilation under drought, comparable reductions in electron transport, CO2 carboxylation, and utilization of triose-P capacities were also adaptations of the photosynthetic machinery to dehydration that slowly developed under field conditions. Results presented in this study confirm that modelling photosynthetic responses based on gas-exchange data can be successfully used to predict metabolic limitations to photosynthesis.

Seasonal ecophysiology and leaf morphology of four successional Pennsylvania barrens species in open versus understory environments

1993 ◽  
Vol 23 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Brian D. Kloeppel ◽  
Marc D. Abrams ◽  
Mark E. Kubiske
Keyword(s):  
Gas Exchange ◽  
Stomatal Density ◽  
Net Photosynthesis ◽  
Leaf Conductance ◽  
Response Curves ◽  
Tissue Water ◽  
Specific Leaf Mass ◽  
Leaf Mass ◽  
Quercus Spp ◽  
Open Versus

Seasonal net photosynthesis, water relations, and leaf structure were measured in co-occurring saplings of Quercusvelutina Lam., Quercusprinus L., Sassafrasalbidum (Nutt.) Nees, and Acerrubrwn L. from adjacent open and understory sites in the central Pennsylvania barrens, United States. Saplings of all species exhibited significant physiological and morphological plasticity, which included greater area-based photosynthesis, leaf conductance, water-use efficiency, stomatal density, specific leaf mass, and leaf thickness on the open site. However, only Q. velutina had greater net photosynthesis in the open versus understory when photosynthesis was expressed on a mass basis. The earlier successional Quercus spp. and S. albidum exhibited higher diurnal and seasonal gas exchange in the open than the later successional A. rubrum, although all species exhibited significant diurnal declines in photosynthesis. Quercus spp. exhibited a 56–62% greater decrease in diurnal water potential compared with S. albidum and A. rubrum in both the open and understory. Sassafras maintained high gas-exchange rates in the open without experiencing large diurnal tissue water deficits. Seasonal variations in net photosynthesis and leaf conductance were significantly correlated with each other and with specific leaf mass. Light-response curves predicted greater saturating light levels and greater rates of maximum photosynthesis in the early successional species versus A. rubrum, but similar light compensation values in all species. The results of this study suggest that each species displayed many similar and unique adaptations and responses to varying light and water availability in the barrens environment.

Photosynthesis in the Aquatic Macrophyte Egeria densa. III. Gas Exchange Studies

1979 ◽  
Vol 6 (4) ◽  
pp. 499 ◽  
Author(s):  
JA Browse ◽  
FI Dromgoole ◽  
JMA Brown
Keyword(s):  
Gas Exchange ◽  
Aquatic Macrophyte ◽  
Ambient Medium ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Open Circuit ◽  
Co2 Uptake ◽  
Total Resistance ◽  
Egeria Densa ◽  
Co2 Response

When free CO2 alone was present in the ambient medium, photosynthesis by Egeria densa Planch displayed an apparent Km of 77 μM. A light- and CO2-saturated rate of 100 μmol C (mg Chl)-1 h-1 was achieved only in 400 μM CO2(aq) [c. 1% CO2(g)]. The CO2 response data and other considerations suggest that, although the carboxylation and mesophyll resistances (3800 s m-1 and <9000 s m-1 respectively) are considerably higher than in aerial plant leaves, the boundary layer is the highest component (> 27 000 s m-1) of the total resistance. An increase in the total resistance of 7200 s m-1 between 0.02 and 0.21 atm O2 (2 and 21 kPa O2) is attributed to photorespiration. Closed and open circuit gas exchange experiments demonstrated that bicarbonate is taken up by the plant cells and does not act merely as a reservoir of inorganic carbon for production of CO2 at the plasmalemma. Bicarbonate stimulated photosynthesis, even when the free CO2 concentration was below the CO2 compensation point. The total resistance to bicarbonate uptake appears to be 8-12 times that for CO2 uptake presumably due to the processes of active uptake, transport and/or conversion to CO2 involved in bicarbonate but not CO2 assimilation.

The interplay between limiting processes in C3 photosynthesis studied by rapid-response gas exchange using transgenic tobacco impaired in photosynthesis

1998 ◽  
Vol 25 (8) ◽  
pp. 859 ◽  
Author(s):  
Sari Ruuska ◽  
T. John Andrews ◽  
Murray R. Badger ◽  
Graham S. Hudson ◽  
Agu Laisk ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Co2 Assimilation ◽  
Small Subunit ◽  
Rapid Response ◽  
Co2 Uptake ◽  
Wild Type ◽  
Gapdh Activity ◽  
Nicotiana Tabacum L ◽  
C3 Photosynthesis ◽  
Gas Exchange System

A gas-exchange system with a rapid response time was used to study the interplay between rate-limiting processes of C3 photosynthesis in wild-type tobacco (Nicotiana tabacum L. cv. W38) and transgenic tobaccos with antisense DNAs directed against the Rubisco small subunit (anti-SSu plants) or the chloroplast glyceraldehyde-3-phosphate dehydrogenase (anti-GAPDH plants). High ribulosebisphos-phate (RuBP) pools were generated in leaves by exposing them briefly to very low CO2, after which they were transferred to varying CO2 concentrations, and transient CO2 assimilation rates were measured within the first 2–3 s. Comparison of the transient (RuBP-saturated) and steady-state rates confirmed that the CO2 assimilation rate in anti-SSu plants was RuBP-saturated (i.e. Rubisco limited) at all intercellular CO2 partial pressures (Ci), and that, in anti-GAPDH plants, the transition from RuBP-saturation to RuBP-limitation occurred at lower assimilation rates and lower Ci as GAPDH activity was decreased. In addition, we investigated whether the integrated post-illumination CO2 uptake could be used as a non-destructive means of estimating RuBP pools in leaves. In wild-type plants there was generally a good agreement between RuBP pools extracted from leaves after rapid freeze-clamping and estimates made from post-illumination CO2 uptake. However, in the anti-SSu plants, the post- illumination CO2 uptake underestimated the actual RuBP content and the discrepancy became larger as the Rubisco content decreased. Possible explanations for this are discussed.

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

Photosynthesis and Transpiration in Damaged and Undamaged Spruce Trees

1996 ◽  
Vol 51 (3-4) ◽  
pp. 200-210 ◽  
Author(s):  
Aloysius Wild ◽  
Peter Sabel ◽  
Lucia Wild-Peters ◽  
Ursula Schmieden
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Natural Habitat ◽  
Late Summer ◽  
Net Photosynthesis ◽  
Diurnal Course ◽  
Physiological Homeostasis ◽  
Use Efficiency ◽  
Needle Loss ◽  
Light Saturation Curves

Abstract The investigations presented here focus on the CO2/H2O gas exchange in damaged and undamaged spruce trees while using open-air measurements as well as measurements under defined conditions in the laboratory. The studies were performed at two different sites in the Hunsrück and the Westerwald mountains. In the laboratory the CO2/H2O gas exchange was measured on detached branches under controlled conditions in the course of two years. CO2 saturation curves were also generated. In addition CO2 compensation points were deter­ mined employing a closed system. In the natural habitat diurnal course measurements of photosynthesis and transpiration as well as light-saturation curves for photosynthesis were performed. In parallel with the photosynthesis and transpiration measurements, measurements of the water potential were taken at both locations. The photosynthetic capacity and transpiration rate show a typical annual course with pronounced maxima in spring and late summer and minima in summer and winter. The needles of the damaged trees exhibit higher transpiration rates and a distinct reduction in photosyn­ thesis than the needles of the undamaged trees during two seasons. The diurnal course measurements of net photosynthesis and transpiration show a maximum in photosynthesis and transpiration in the afternoon in May and September, but a characteristic midday depression in July. Photosynthesis was markedly lower and transpiration higher in the needles of the damaged trees. The damaged trees show a lower increase in the light and CO2 saturation curves and higher CO2 compensation points as compared to the undamaged trees. The water potential reaches much lower values during the course of the day in needles of the dam­ aged trees. The reduction of the photosynthetic rate on one hand and the increase in transpiration on the other hand result in an extreme lowering of the water use efficiency in photosynthesis. The damage to the thylakoid membranes and to the guard cells obviously results in a pro­ found disturbance of the physiological homeostasis of the needles and could thus lead to premature needle loss.

scholarly journals Salt tolerance and regulation of gas exchange and hormonal homeostasis by auxin-priming in wheat

2013 ◽  
Vol 48 (9) ◽  
pp. 1210-1219 ◽  
Author(s):  
Muhammad Iqbal ◽  
Muhammad Ashraf
Keyword(s):  
Abscisic Acid ◽  
Gas Exchange ◽  
Acid Concentration ◽  
Spring Wheat ◽  
Indoleacetic Acid ◽  
Co2 Assimilation ◽  
Assimilation Rate ◽  
Co2 Assimilation Rate ◽  
Net Co2 Assimilation Rate ◽  
Net Co2 Assimilation

The objective of this work was to assess the regulatory effects of auxin-priming on gas exchange and hormonal homeostasis in spring wheat subjected to saline conditions. Seeds of MH-97 (salt-intolerant) and Inqlab-91 (salt-tolerant) cultivars were subjected to 11 priming treatments (three hormones x three concentrations + two controls) and evaluated under saline (15 dS m-1) and nonsaline (2.84 dS m-1) conditions. The priming treatments consisted of: 5.71, 8.56, and 11.42 × 10-4 mol L-1 indoleacetic acid; 4.92, 7.38, and 9.84 × 10-4 mol L-1 indolebutyric acid; 4.89, 7.34, and 9.79 × 10-4 mol L-1 tryptophan; and a control with hydroprimed seeds. A negative control with nonprimed seeds was also evaluated. All priming agents diminished the effects of salinity on endogenous abscisic acid concentration in the salt-intolerant cultivar. Grain yield was positively correlated with net CO2 assimilation rate and endogenous indoleacetic acid concentration, and it was negatively correlated with abscisic acid and free polyamine concentrations. In general, the priming treatment with tryptophan at 4.89 × 10-4 mol L-1 was the most effective in minimizing yield losses and reductions in net CO2 assimilation rate, under salt stress conditions. Hormonal homeostasis increases net CO2 assimilation rate and confers tolerance to salinity on spring wheat.

scholarly journals Physiological responses of beet plants irrigated with saline water and silicon application

2020 ◽  
Vol 11 ◽  
pp. E3113
Author(s):  
José Sebastião de Melo Filho ◽  
Toshik Iarley da Silva ◽  
Anderson Carlos de Melo Gonçalves ◽  
Leonardo Vieira de Sousa ◽  
Mario Leno Martins Véras ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Concentration ◽  
Saline Water ◽  
Block Design ◽  
Essential Element ◽  
Net Photosynthesis ◽  
Crop Productivity ◽  
Experimental Unit ◽  
Randomized Block Design

Although not considered an essential element, silicon can be used to increase crop productivity, especially under stress conditions. In this sense, the objective was to evaluate the gas exchange of beet plants irrigated with saline water depending on the application of silicon. The experiment was conducted in a randomized block design, in a 5 x 5 factorial, referring to five levels of electrical conductivity of irrigation water (ECw): (0.5; 1.3; 3.25; 5.2 and 6.0 dS m-1) and five doses of silicon (0.00; 2.64; 9.08; 15.52 and 18.16 mL L-1), with six beet plants as an experimental unit. The effect of treatments on beet culture was evaluated at 30 and 60 days after irrigation with saline water from measurements of internal carbon concentration, stomatal conductance, net photosynthesis rate, instantaneous water use efficiency and instantaneous carboxylation efficiency using the LCpro+Sistem infrared gas analyzer (IRGA). Irrigation with saline water reduced the gas exchange of beet plants at 60 days after irrigation, but at 30 days after irrigation, the use of saline water increased stomatal conductance, transpiration rate and internal carbon concentration. The application of silicon decreased stomatal conductance, internal carbon concentration and efficiency in the use of water, but increased the rate of net photosynthesis, the rate of transpiration and instantaneous efficiency of carboxylation at 30 and 60 days after irrigation.

scholarly journals GAS EXCHANGE, CHLOROPLAST PIGMENTS AND GROWTH OF PASSION FRUIT CULTIVATED WITH SALINE WATER AND POTASSIUM FERTILIZATION 1

2020 ◽  
Vol 33 (1) ◽  
pp. 184-194
Author(s):  
GEOVANI SOARES DE LIMA ◽  
COSMO GUSTAVO JACOME FERNANDES ◽  
LAURIANE ALMEIDA DOS ANJOS SOARES ◽  
HANS RAJ GHEYI ◽  
PEDRO DANTAS FERNANDES
Keyword(s):  
Gas Exchange ◽  
Saline Water ◽  
Block Design ◽  
Co2 Assimilation ◽  
Passion Fruit ◽  
Water Salinity ◽  
Chloroplast Pigments ◽  
Potassium Fertilization ◽  
Randomized Block Design ◽  
Fruit Plants

ABSTRACT The objective of this study was to evaluate the gas exchange, chloroplast pigments and growth of ‘BRS Rubi do Cerrado’ passion fruit as a function of irrigation with saline water and potassium fertilization in the seedling formation stage. The experiment was conducted under greenhouse conditions in the municipality of Pombal-PB, Brazil. A randomized block design was used in 5 x 2 factorial scheme, corresponding to five levels of water electrical conductivity - ECw (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and two doses of potassium - KD (50 and 100% of the recommendation), with four replicates and two plants per plot. Water salinity from 0.3 dS m-1 reduced the stomatal opening, transpiration, CO2 assimilation and inhibited the growth of ‘BRS Rubi do Cerrado’ passion fruit plants, at 40 days after sowing. There was no CO2 restriction in the substomatal cavity of passion fruit plants grown under water salinity from 0.3 dS m-1. Potassium dose of 150 mg kg-1 of soil, corresponding to 100%, intensified the effect of salt stress on the assimilation rate and instantaneous carboxylation efficiency in 'BRS Rubi do Cerrado' passion fruit. There was interaction between water salinity levels and potassium doses for the chlorophyll a and b contents of 'BRS Rubi do Cerrado' passion fruit.

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