Photosynthesis and transpiration in large forest-grown Douglas-fir: diurnal variation

1981 ◽  
Vol 59 (3) ◽  
pp. 349-356 ◽  
Author(s):  
Jerry W. Leverenz
Keyword(s):  
Stomatal Conductance ◽  
Vapor Pressure ◽  
Diurnal Variation ◽  
Pressure Difference ◽  
Intercellular Space ◽  
Net Photosynthesis ◽  
Douglas Fir ◽  
Leaf Temperature ◽  
Photon Flux ◽  
Vapor Pressure Difference

Net photosynthesis, transpiration, and stomatal conductance of terminal shoots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were measured using an open gas exchange system. Correlations between these physiological parameters and environmental variables on an overcast day, a cool partly sunny day, and a day of high temperature and leaf–air vapor pressure difference are presented. Diurnal variation in shoot water potential and intercellular space CO2 concentration had little effect on the physiological parameters. Leaf–air vapor pressure difference and (or) leaf temperature had considerable influence on days of high temperatures. Net photosynthetic rate was strongly correlated with photon flux density on completely overcast days.Stomatal conductance exerted little control on diurnal variation of net photosynthetic rates on overcast days because stomatal conductance saturated at lower photon flux densities than net photosynthesis. When net photosynthesis was light saturated parallel responses of stomatal and residual conductances to vapor pressure difference and (or) leaf temperature occurred. Intercellular space CO2 concentration remained fairly constant when net photosynthesis was light saturated.

scholarly journals Gas Exchange and Growth of Two Transplanted, Field-grown Tree Species in an Arid Climate

HortScience ◽  
2000 ◽  
Vol 35 (4) ◽  
pp. 763-768
Author(s):  
Thayne Montague ◽  
Roger Kjelgren ◽  
Larry Rupp
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Vapor Pressure ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Pressure Difference ◽  
Leaf Water ◽  
Arid Climate ◽  
Vapor Pressure Difference ◽  
Predawn Leaf Water Potential

Gas exchange and growth of transplanted and nontransplanted, field-grown Norway maple (Acer platanoides L. `Schwedleri') and littleleaf linden (Tilia cordata Mill. `Greenspire') trees were investigated in an arid climate. In the spring of 1995, three trees of each species were moved with a tree spade to a new location within a field nursery and three nontransplanted trees were selected as controls. Predawn leaf water potential, morning-to-evening stomatal conductance and leaf temperature, leaf-to-air vapor pressure difference, midday stomatal conductance and photosynthetic rate, and growth data were collected over a 2-year period. After transplanting, weekly predawn leaf water potential indicated that transplanted trees were under greater water stress than were nontransplanted (control) trees. However, predawn leaf water potential of maple trees recovered to control levels 18 weeks after transplanting, while that of transplanted linden trees remained more negative than that of controls. In 1995, stomatal conductance and photosynthetic rates were lower throughout the day for transplanted trees. In 1996, gas exchange rates of transplanted maple trees recovered to near control levels while rates for transplanted linden trees did not. Sensitivity of stomata to leaf-to-air vapor pressure difference varied with species and with transplant treatment. Each year transplanted trees of both species had less apical growth than did control trees. Although gas exchange and apical growth of transplanted trees was reduced following transplanting, recovery of gas exchange to control rates differed with species.

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.

Setting Realistic Design Indoor Conditions for Residential Buildings by Vapor Pressure Difference

2009 ◽  
Vol 6 (9) ◽  
pp. 102052 ◽  
Author(s):  
Patrick Roppel ◽  
Mark Lawton ◽  
William C. Brown ◽  
Phalguni Mukhopadhyaya ◽  
Mavinkal K. Kumaran ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Pressure Difference ◽  
Residential Buildings ◽  
Vapor Pressure Difference ◽  
Indoor Conditions

Photosynthesis in an open field for exotic versus native vines of the southeastern United States

1989 ◽  
Vol 67 (2) ◽  
pp. 443-446 ◽  
Author(s):  
Gregory A. Carter ◽  
Alan H. Teramura ◽  
Irwin N. Forseth
Keyword(s):  
Vapor Pressure ◽  
Pressure Difference ◽  
Native Species ◽  
Leaf Gas Exchange ◽  
Water Vapor Pressure ◽  
High Irradiance ◽  
Pueraria Lobata ◽  
Vapor Pressure Difference ◽  
High Vapor ◽  
Parthenocissus Quinquefolia

The potential importance of leaf gas exchange to the prolific growth characteristics of the exotic vines Pueraria lobata and Lonicera japonica versus the native vines Rhus radicans, Parthenocissus quinquefolia, Vitis vulpina, and Clematis virginiana was evaluated. Under high irradiance and low leaf-air water vapor pressure difference, photosynthesis was similar (23 – 27 μmol∙m−2∙s−1) among species with the exception of R. radicans (16 μmol∙m−2∙s−1). Conductance and transpiration were greater in Pueraria lobata than in the other species. When the leaf-air vapor pressure difference was high (4.0 kPa) photosynthesis in the exotic vines decreased more than in several of the native species. Photosynthesis in L. japonica and Parthenocissus quinquefolia, and to a lesser extent in Pueraria lobata, was reduced by high vapor pressure differences even though internal CO2 partial pressures remained relatively high, suggesting a nonstomatal reduction of photosynthetic capacity. Thus, the highly prolific growth typical of the exotic vines may not be attributable to greater steady-state photosynthesis.

Osmosis: Characteristics of Liquid at an Interface

2006 ◽  
Author(s):  
Larry D. Howlett
Keyword(s):  
Kinetic Energy ◽  
Kinetic Theory ◽  
Vapor Pressure ◽  
Pressure Difference ◽  
Total Kinetic Energy ◽  
Universal Model ◽  
Vapor Pressure Difference ◽  
Water Ice ◽  
Speed Distribution

Many explanations for the movement of water across a membrane have been presented. One idea proposes that osmosis is the movement of water in response to a vapor pressure difference. It is difficult to accept this model for osmosis without a good understanding of the existence of a vapor in a liquid. We propose a model for a vapor in a liquid. The model is based upon the kinetic theory of gas and Maxwell's predicted speed distribution. Since vapor pressure and total kinetic energy are both expressions of the energy of a gas, we compare the model to published values of vapor pressure for water, ice, and several other liquids. Based upon this limited comparison, it appears that this model may be a universal model for the continuous existence of a vapor in a liquid or a solid.

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.

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