Stomatal Responses to Environmental Variables in Shade and Sun Grown Coffee Plants in Mexico

1985 ◽  
Vol 21 (3) ◽  
pp. 249-258 ◽  
Author(s):  
Luis Fanjul ◽  
R. Arreola-Rodriguez ◽  
M. P. Mendez-Castrejon
Keyword(s):  
Stomatal Conductance ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Vapour Pressure ◽  
Environmental Variables ◽  
Vapour Pressure Deficit ◽  
Net Photosynthesis ◽  
Stomatal Movement ◽  
Stomatal Responses ◽  
Coffee Plants

SUMMARYThe influence of air temperature (T), vapour pressure deficit (vpd), irradiance (Q) and leaf water potential (ψ) on diurnal stomatal movement of coffee plants was examined under field and controlled environmental conditions. Leaves of plants grown under shade had larger stomatal conductance (g) values than plants grown in open sun. Stomatal responses to vpd under constant temperature conditions were very strong, indicating that ambient humidity could play a major role in controlling stomatal aperture. Changes in g as vpd increased probably contributed to observed reductions in the rate of net photosynthesis (Pn), though the effect of vpd on Pn was smaller.

Stomatal characteristics and transpiration of three species of conifer seedlings planted on a high elevation south-facing clear-cut

1987 ◽  
Vol 17 (10) ◽  
pp. 1273-1282 ◽  
Author(s):  
N. J. Livingston ◽  
T. A. Black
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
High Elevation ◽  
Boundary Line ◽  
Silver Fir ◽  
Clear Cut ◽  
Physiological Variables ◽  
Stomatal Responses

Douglas-fir (Pseudotsugamenziessi (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabalis (Doug.) Forbes) seedlings were planted in the spring as 1-0 container-grown plugs on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia, and their stomatal responses to environmental and physiological variables were determined over two successive growing seasons. The stomatal responses of all three species to changes in environmental variables and time did not differ over the 2 years nor were there differences in response between seedlings planted a year apart. A simple multiplicative boundary-line model that related seedling stomatal conductance (gs) to measurements of hourly average solar irradiance, air temperature, vapour pressure deficit, and average root zone soil water potential accounted for over 70% of the variability in gs. When the number of hours from sunrise was included as an independent variable, over 85% of the variability in gs could be explained. Daily seedlings transpiration rates on a projected leaf area basis were successfully estimated by summing the product of the calculated average gs and D/(RvT′) where D is the vapour pressure deficit, Rv is the gas constant for water vapour, and T′ is the absolute air temperature.

The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field

1976 ◽  
Vol 273 (927) ◽  
pp. 593-610 ◽  
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Vapour Pressure ◽  
Environmental Variables ◽  
Turgor Pressure ◽  
Radiant Energy ◽  
Vapour Pressure Deficit ◽  
Leaf Water ◽  
Scatter Diagram

Attempts to correlate values of stomatal conductance and leaf water potential with particular environmental variables in the field are generally of only limited success because they are simultaneously affected by a number of environmental variables. For example, correlations between leaf water potential and either flux of radiant energy or vapour pressure deficit show a diurnal hysteresis which leads to a scatter diagram if many values are plotted. However, a simple model may be adequate to relate leaf water potential to the flow of water through the plant. The stomatal conductance of illuminated leaves is a function of current levels of temperature, vapour pressure deficit, leaf water potential (really turgor pressure) and ambient CO 2 concentration. Consequently, when plotted against any one of these variables a scatter diagram results. Physiological knowledge of stomatal functioning is not adequate to provide a mechanistic model linking stomatal conductance to all these variables. None the less, the parameters describing the relationships with the variables can be conveniently estimated from field data by a technique of non-linear least squares, for predictive purposes and to describe variations in response from season to season and plant to plant.

Stomatal Responses to Leaf-to-Air Vapour Pressure Deficit in Sahelian Species

1997 ◽  
Vol 24 (3) ◽  
pp. 381 ◽  
Author(s):  
João P. Maroco ◽  
João S. Pereira ◽  
M. Manuela Chaves
Keyword(s):  
Stomatal Conductance ◽  
Vapour Pressure ◽  
Arid Zone ◽  
Stomatal Closure ◽  
Vapour Pressure Deficit ◽  
Survival Strategies ◽  
Evaporative Demand ◽  
Resistant Species ◽  
Stomatal Responses ◽  
Negative Effect

Stomatal response to leaf-to-air vapour pressure deficit (LAVPD) was studied in the annual arid zone C4 grasses Schoenefeldia gracilis, Dactyloctenium aegyptium and Eragrostis tremula and in the C3 species, convolvulus, Ipomoea pes-tigridis and Ipomoea vagans. Stomatal responses to LAVPD were consistent with the drought survival strategies adopted by the different species. In drought resistant species (S. gracilis, I. vagansand I. pes-tigridis) stomatal conductance showed a negative response to increasing LAVPD whereas, in drought escaping species (D. aegyptium and E. tremula), stomatal conductance was independent of LAVPD. These observations suggest that resistance to drought was associated with stomatal closure as LAVPD increased, thus reducing the negative effect of a higher evaporative demand on water use efficiency, whereas in drought escaping species stomata showed no response to increasing evaporative demand in the atmosphere.

Modelling stomatal conductance in a northern deciduous forest, Chalk River, Ontario

1994 ◽  
Vol 24 (5) ◽  
pp. 904-910 ◽  
Author(s):  
J. Harry McCaughey ◽  
Antonio Iacobelli
Keyword(s):  
Stomatal Conductance ◽  
Least Squares ◽  
Environmental Variables ◽  
Deciduous Forest ◽  
Vapour Pressure Deficit ◽  
Multiple Linear Regression Model ◽  
Nonlinear Least Squares ◽  
Global Solar Radiation ◽  
White Birch ◽  
Conductance Data

Modelling results of stomatal conductance of trembling aspen (Populustremuloides Michx.) and white birch (Betulapapyrifera Marsh.) are reported. Stomatal conductance for the two species was related to global solar radiation, vapour pressure deficit, and air temperature using both linear and nonlinear least squares approaches. Both approaches provided an equally poor fit when relating the large scatter of stomatal conductance data to each of the environmental variables separately. However, an additive, multiple linear regression model and a multiplicative, nonlinear least squares model were able to explain between 50 and 62% of the variability in stomatal conductance when all three environmental variables were included in the models. The two models were able to track changes in stomatal conductance from one half-hour period to the next.

Gas exchange processes of yellow-cedar (Chamaecyparis nootkatensis) in response to environmental variables

1991 ◽  
Vol 69 (12) ◽  
pp. 2684-2691 ◽  
Author(s):  
Steven C. Grossnickle ◽  
John H. Russell
Keyword(s):  
Stomatal Conductance ◽  
Response Surface ◽  
Photosynthetically Active Radiation ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Surface Model ◽  
Root Temperature ◽  
Active Radiation ◽  
Chamaecyparis Nootkatensis ◽  
Exchange Processes

Yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) gas exchange processes were measured in response to the following primary environmental variables: photosynthetically active radiation, vapour pressure deficit, root temperature, and soil moisture. Under nonlimiting edaphic conditions, maximum stomatal conductance and maximum CO2 assimilation increased rapidly as photosynthetically active radiation increased from 0 to 200 μmol∙m−2∙s−1 and from 0 to 500 μmol∙m−2∙s−1, respectively. Thereafter, greater photosynthetically active radiation levels only resulted in minor increases in stomatal conductance and CO2 assimilation. Maximum stomatal conductance and maximum CO2 assimilation declined in a concave manner as vapour pressure deficit increased from 1 to 5 kPa. Response surface model for stomatal conductance showed vapour pressure deficit was the primary influence after light had caused initial stomatal opening. Response surface modeling approach showed CO2 assimilation increased as photosynthetically active radiation increased, but increased vapour pressure deficit resulted in a suppression of CO2 assimilation. Response surface model showed internal CO2 concentration declined sharply as photosynthetically active radiation increased from 0 to 500 μmol∙m−2∙s−1, but it remained constant with increasing vapour pressure deficit. Decreasing root temperature resulted in a continual decline in CO2 assimilation and stomatal conductance from 22 to 1 °C, while internal CO2 concentration declined from 22 to 13 °C with little change between 13 and 1 °C. As predawn shoot water potential decreased from −0.5 to −2.0 MPa, CO2 assimilation declined in a linear manner, while stomatal conductance and internal CO2 concentration declined in a concave manner. Key words: Chamaecyparis nootkatensis, CO2 assimilation, stomatal conductance, internal CO2 concentration, photosynthetically active radiation, vapour pressure deficit, root temperature, predawn shoot water potential.

scholarly journals Influence of season, drought and xylem ABA on stomatal responses to leaf-to-air vapour pressure difference of trees of the Australian wet-dry tropics

2000 ◽  
Vol 48 (2) ◽  
pp. 143 ◽  
Author(s):  
D. S. Thomas ◽  
D. Eamus ◽  
S. Shanahan
Keyword(s):  
Stomatal Conductance ◽  
Vapour Pressure ◽  
Pressure Difference ◽  
Dry Season ◽  
Wet Season ◽  
Stomatal Responses ◽  
Dry Seasons ◽  
Stomatal Sensitivity ◽  
Vapour Pressure Difference ◽  
Wet And Dry Seasons

This paper reports the results of two experiments undertaken to investigate the influence of season and soil drying on stomatal responses to leaf-to-air vapour pressure differences. We examined the response of stomatal conductance to increasing leaf-to-air vapour pressure difference, in the wet and dry seasons, of five tropical tree species. We also examined leaves of these species for anatomical differences to determine whether this could explain differences in stomatal sensitivity to leaf-to-air vapour pressure differences. Finally, we conducted a split-root experiment with one of those species to look for interactions between xylem abscisic acid concentration, predawn water potential, leaf area to root mass ratio and stomatal responses to leaf-to-air vapour pressure differences. Stomatal conductance declined linearly with increasing leaf-to-air vapour pressure difference in all species. Leaves that expanded in the ‘dry’ season were more sensitive to leaf-to-air vapour pressure differences than those that had expanded in the ‘wet’ season. The value of leaf-to-air vapour pressure difference where 50% of extrapolated maximum stomatal conductance would occur was 5.5 kPa for wet season but only 3.4 kPa for dry season leaves. In the wet season, transpiration rate increased with increasing leaf-to-air vapour pressure difference in most example species. However, in the dry season, transpiration was constant as leaf-to-air vapour pressure differences increased in most cases. There were significant changes in the proportion of cell wall exposed to air space in leaves, between wet and dry seasons, in three of four species examined. In the split-root experiment, a very mild water stress increased stomatal sensitivity to leaf-to-air vapour pressure differences, and stomatal conductivity declined linearly with decreasing predawn water potential. However, levels of ABA in the xylem did not change, and stomatal sensitivity to exogenous ABA did not change. The ratio of leaf area to root mass declined during water stress and was correlated to changes in stomatal sensitivity to leaf-to-air vapour pressure differences.

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