Assimilation, Stomatal Conductance, Specific Leaf Area and Chlorophyll Responses to Elevated CO2 of Maranthes corymbosa, a Tropical Monsoon Rain Forest Species

1993 ◽  
Vol 20 (6) ◽  
pp. 741 ◽  
Author(s):  
D Eamus ◽  
CA Berryman ◽  
GA Duff
Keyword(s):  
Stomatal Conductance ◽  
Elevated Co2 ◽  
Rain Forest ◽  
Stomatal Density ◽  
Significant Decline ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Data Sets ◽  
Forest Species ◽  
Apparent Quantum Yield

Seeds of Maranthes corymbosa Blume, a monsoon rain forest species of northern Australia, were sown under ambient or elevated CO2 concentrations in tropical Australia. Seedlings were grown under conditions of photon flux density, temperature and atmospheric vapour pressure deficit which followed ambient variations as closely as possible. Specific leaf area, chlorophyll, stomatal density, stomatal conductance and assimilation responses to photon flux density were measured after 30 weeks growth. Gas exchange characteristics were divided into morning and afternoon data sets and analysed separately. Stomatal density decreased and leaf area:dry weight ratio decreased in response to elevated CO2. In contrast there was no effect of elevated CO2 upon chlorophyll (total or ratio of a:b). Apparent quantum yield and rates of light saturated assimilation (Amax) increased in response to elevated CO2. There was a significant decline in apparent quantum yield for both treatments between morning and afternoon. Stomatal conductance (gs) declined in response to elevated CO2. There was no significant difference in gs between morning and afternoon for ambient grown trees, but gs declined significantly between morning and afternoon for elevated CO2 grown trees. Instantaneous transpiration efficiency (ITE) was higher for elevated CO2 grown trees compared with control trees. There was a significant increase in ITE between morning and afternoon data for ambient grown trees; in contrast a significant decline in ITE was observed for elevated CO2 grown trees between morning anf afternoon data sets. The slope of the regression between assimilation rate and stomatal conductance increased for plants grown under elevated CO2. These data are discussed and compared with the responses of plants adapting to different photon flux densities.

scholarly journals Light Quality Affects Water Use of Sweet Basil by Changing Its Stomatal Development

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 303
Author(s):  
Sungeun Lim ◽  
Jongyun Kim
Keyword(s):  
Stomatal Conductance ◽  
Blue Light ◽  
Water Use ◽  
Growth Parameters ◽  
Stomatal Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Stomatal Development ◽  
Sweet Basil ◽  
Stomatal Responses

Different light qualities affect plant growth and physiological responses, including stomatal openings. However, most researchers have focused on stomatal responses to red and blue light only, and the direct measurement of evapotranspiration has not been examined. Therefore, we quantified the evapotranspiration of sweet basil under various red (R), green (G), and blue (B) combinations using light-emitting diodes (LEDs) and investigated its stomatal responses. Seedlings were subjected to five different spectral treatments for two weeks at a photosynthetic photon flux density of 200 µmol m−2 s−1. The ratios of the RGB light intensities were as follows: R 100% (R100), R:G = 75:25 (R75G25), R:B = 75:25 (R75B25), R:G:B = 60:20:20 (R60G20B20), and R:G:B = 31:42:27 (R31G42B27). During the experiment, the evapotranspiration of the plants was measured using load cells. Although there were no significant differences in growth parameters among the treatments, the photosynthetic rate and stomatal conductance were higher in plants grown under blue LEDs (R75B25, R60G20B20, and R31G42B27) than in the R100 treatment. The amount of water used was different among the treatments (663.5, 726.5, 728.7, 778.0, and 782.1 mL for the R100, R75G25, R60G20B20, R75B25, and R31G42B27 treatments, respectively). The stomatal density was correlated with the blue light intensity (p = 0.0024) and with the combined intensity of green and blue light (p = 0.0029); therefore, green light was considered to promote the stomatal development of plants together with blue light. Overall, different light qualities affected the water use of plants by regulating stomatal conductance, including changes in stomatal density.

scholarly journals Environmental controls over methanol emission from leaves

2007 ◽  
Vol 4 (4) ◽  
pp. 2593-2640 ◽  
Author(s):  
P. Harley ◽  
J. Greenberg ◽  
Ü. Niinemets ◽  
A. Guenther
Keyword(s):  
Stomatal Conductance ◽  
Leaf Growth ◽  
Dry Mass ◽  
Leaf Temperature ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Emission Model ◽  
Production Term ◽  
Methanol Production ◽  
Environmental Controls

Abstract. Methanol is found throughout the troposphere, with average concentrations second only to methane among atmospheric hydrocarbons. Proposed global methanol budgets are highly uncertain, but all agree that at least 60% of the total source arises from the terrestrial biosphere and primary emissions from plants. However, the magnitude of these emissions is also highly uncertain, and the environmental factors which control them require further elucidation. Using a temperature-controlled leaf enclosure, we measured methanol emissions from leaves of six plant species by proton transfer reaction mass spectrometry, with simultaneous measurements of leaf evapotranspiration and stomatal conductance. Rates of emission at 30°C varied from 0.3 to 38 μg g (dry mass)−1 h−1, with higher rates measured on young leaves, consistent with the production of methanol via pectin demethylation in expanding foliage. On average, emissions increased by a factor of 2.4 for each 10°C increase in leaf temperature. At constant temperature, emissions were also correlated with co-varying incident photosynthetic photon flux density and rates of stomatal conductance. The data were analyzed using the emission model developed by Niinemets and Reichstein (2003a, b), with the incorporation of a methanol production term that increased exponentially with temperature. It was concluded that control of emissions, during daytime, was shared by leaf temperature and stomatal conductance, although rates of production may also vary diurnally in response to variations in leaf growth rate in expanding leaves. The model, which generally provided reasonable simulations of the measured data during the day, significantly overestimated emissions on two sets of measurements made through the night, suggesting that production rates of methanol were reduced at night, perhaps because leaf growth was reduced or possibly through a direct effect of light on production. Although the short-term dynamics of methanol emissions can be successfully modeled only if stomatal conductance and compound solubility are taken into account, emissions on longer time scales will be determined by rates of methanol production, controls over which remain to be investigated.

The Optimal Allocation of Nitrogen Within the C3 Photosynthetic System at Elevated CO2

1996 ◽  
Vol 23 (5) ◽  
pp. 593 ◽  
Author(s):  
BE Medlyn
Keyword(s):  
Elevated Co2 ◽  
Optimal Allocation ◽  
Co2 Concentration ◽  
Leaf Nitrogen ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Nitrogen Distribution ◽  
Photosynthetic System ◽  
Light Regimes ◽  
Nitrogen Contents

The distribution of nitrogen among compounds involved in photosynthesis varies in response to changes in environmental conditions such as photon flux density. However, the extent to which the nitrogen distribution within leaves adjusts in response to increased atmospheric CO2 is unclear. A model was used to determine the nitrogen distribution which maximises photosynthesis under realistic light regimes at both current and elevated levels of CO2, and a comparison was made with observed leaf nitrogen distributions reported in the literature. The model accurately predicted the distribution of nitrogen within the photosynthetic system for leaves grown at current levels of CO2, except at very high leaf nitrogen contents. The model predicted that, under a doubling of CO2 concentration from its current level, the ratio of electron transport capacity to Rubisco activity (Jmax : Vcmax) should increase by 40%. In contrast, measurements of Jmax : Vcmax taken from the literature show a slight but non-significant increase in response to an increase in CO2. The discrepancy between predicted and observed Jmax : Vcmax suggests that leaf nitrogen distribution does not acclimate optimally to elevated CO2. Alternatively, the discrepancy may be due to effects of CO2 which the model fails to take into account, such as a possible decrease in the conductance to CO2 transfer between the intercellular spaces and the sites of carboxylation at elevated CO2.

Growth, yield and plant-water relations of four cowpea (Vigna unguiculata) cultivars in the Sahel

1996 ◽  
Vol 126 (2) ◽  
pp. 183-190 ◽  
Author(s):  
M. V. K. Sivakumar ◽  
B. R. Ntare ◽  
J. M. Roberts
Keyword(s):  
Stomatal Conductance ◽  
Water Use ◽  
Vigna Unguiculata ◽  
Growth Yield ◽  
Net Photosynthesis ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Dual Purpose ◽  
Area Index ◽  
Photosynthetic Rates

SUMMARYThe response of four cowpea (Vigna unguiculata(L.) Walp.) cultivars to the warm, semi-arid tropical environment at the ICRISAT Sahelian Center at Sadore, Niger was studied during 1985 and 1986 interms of leaf area index (LAI), dry matter (DM) accumulation, net photosynthesis, stomatal conductance, total water use and yield. Among the three improved cultivars, IT82D–716 is early and erect, cv. IT83S–947 is early and spreading and cv. TVX4659–03E is a medium-duration, highyielding, dual-purpose type. The local cv. Sadore Local is a long-duration, photosensitive, spreading type used mainly for fodder. In both years, Sadore Local recorded the highest LAI. IT82D–716 and IT83S–947 produced < 1·3 t/ha of DM in both years, whereas TVX 4659–03E produced > 2 t/ha of DM and proved superior to Sadore Local in partitioning DM into pods. The four cultivars did not differ significantly either in stomatal conductance or in net phytosynthetic rates. Observed maximum photosynthetic rates of c. 20 μmol/m2/s lie at the bottom of the range 21–38 μmol/m2/s reported for 31 cowpea genotypes in an earlier study. Photosynthetic rates increased with increasing photon flux density. TVX4659–03E had an advantage in total seed plus fodder yields while the local cultivar gave significantly greater fodder yields in both years. Seed and fodder yields, as well as water-use efficiency, confirmed the advantages offered by the dual-purpose cultivar TVX4659–03E. Future breeding efforts in the Sahel should focus on dual-purpose (grain/fodder) cowpea types.

scholarly journals Environmental controls over methanol emission from leaves

2007 ◽  
Vol 4 (6) ◽  
pp. 1083-1099 ◽  
Author(s):  
P. Harley ◽  
J. Greenberg ◽  
Ü. Niinemets ◽  
A. Guenther
Keyword(s):  
Stomatal Conductance ◽  
Leaf Growth ◽  
Dry Mass ◽  
Leaf Temperature ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Emission Model ◽  
Production Term ◽  
Methanol Production ◽  
Environmental Controls

Abstract. Methanol is found throughout the troposphere, with average concentrations second only to methane among atmospheric hydrocarbons. Proposed global methanol budgets are highly uncertain, but all agree that at least 60% of the total source arises from the terrestrial biosphere and primary emissions from plants. However, the magnitude of these emissions is also highly uncertain, and the environmental factors which control them require further elucidation. Using a temperature-controlled leaf enclosure, we measured methanol emissions from leaves of six plant species by proton transfer reaction mass spectrometry, with simultaneous measurements of leaf evapotranspiration and stomatal conductance. Rates of emission at 30°C varied from 0.2 to 38 μg g (dry mass)−1 h−1, with higher rates measured on young leaves, consistent with the production of methanol via pectin demethylation in expanding foliage. On average, emissions increased by a factor of 2.3 for each 10°C increase in leaf temperature. At constant temperature, emissions were also correlated with co-varying incident photosynthetic photon flux density and rates of stomatal conductance. The data were analyzed using the emission model developed by Niinemets and Reichstein (2003a, b), with the incorporation of a methanol production term that increased exponentially with temperature. It was concluded that control of emissions, during daytime, was shared by leaf temperature and stomatal conductance, although rates of production may also vary diurnally in response to variations in leaf growth rate in expanding leaves. The model, which generally provided reasonable simulations of the measured data during the day, significantly overestimated emissions on two sets of measurements made through the night, suggesting that production rates of methanol were reduced at night, perhaps because leaf growth was reduced or possibly through a direct effect of light on production. Although the short-term dynamics of methanol emissions can be successfully modeled only if stomatal conductance and compound solubility are taken into account, emissions on longer time scales will be determined by rates of methanol production, controls over which remain to be investigated.

Leaf gas exchange processes and related characteristics of seven poplar clones under laboratory conditions

1980 ◽  
Vol 10 (3) ◽  
pp. 429-435 ◽  
Author(s):  
R. Ceulemans ◽  
I. Impens
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Leaf Gas Exchange ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Apparent Quantum Yield ◽  
Uptake Rates ◽  
Use Efficiency

Different ecophysiological characteristics of various Populus clones (maximum net CO2 uptake rate, apparent quantum yield, photon flux density compensation point, boundary layer resistance, and stomatal and internal resistances to carbon dioxide and water use efficiency) were studied using a gas exchange method. Most significant differences were found in the water use efficiency ratios, the internal resistances to carbon dioxide and the maximum net CO2 uptake rates. Recently selected interamerican Populustrichocarpa crossings (Populus clones Unal, Beaupré, and Trichobel) showed high water use efficiency, high maximum net CO2 uptake rates, and low internal resistances.

Influence of gibberellin A3 and ancymidol on sunflower leaf anatomy

1990 ◽  
Vol 68 (1) ◽  
pp. 159-162 ◽  
Author(s):  
T. W. Starman ◽  
J. W. Kelly ◽  
H. B. Pemberton
Keyword(s):  
Leaf Anatomy ◽  
Leaf Surface ◽  
Stomatal Density ◽  
Unit Length ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Palisade Cell ◽  
Leaf Surface Area

The plant growth retardant ancymidol (α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol), when sprayed at 132 mg/L of active ingredient, increased leaf thickness, palisade cell length, and number of cells per unit length, and decreased intercellular space percentage in developing Helianthus annuus L. (sunflower) cv. Mammoth Russian leaves when plants were grown under 400 or 1500 μmol∙s−1∙m−2 photosynthetic photon flux density. Foliar sprays of gibberellic acid at 10–40 mg/L reversed the effects of ancymidol on leaf anatomy. Stomatal density and total stomata per adaxial leaf surface area were increased by ancymidol sprays.

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