scholarly journals Osmotic adjustment and hormonal regulation of stomatal responses to vapour pressure deficit in sunflower

AoB Plants ◽  
2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Amanda A Cardoso ◽  
Timothy J Brodribb ◽  
Cade N Kane ◽  
Fábio M DaMatta ◽  
Scott A M McAdam
Keyword(s):  
Vapour Pressure ◽  
Hormonal Regulation ◽  
Vapour Pressure Deficit ◽  
Hormonal Control ◽  
Stomatal Response ◽  
Wild Type ◽  
Dynamic Variation ◽  
Stomatal Responses ◽  
Vapour Pressure Difference ◽  
Osmotic Potentials

Abstract Dynamic variation of the stomatal pore in response to changes in leaf–air vapour pressure difference (VPD) constitutes a critical regulation of daytime gas exchange. The stomatal response to VPD has been associated with both foliage abscisic acid (ABA) and leaf water potential (Ψ l); however, causation remains a matter of debate. Here, we seek to separate hydraulic and hormonal control of stomatal aperture by manipulating the osmotic potential of sunflower leaves. In addition, we test whether stomatal responses to VPD in an ABA-deficient mutant (w-1) of sunflower are similar to the wild type. Stomatal apertures during VPD transitions were closely linked with foliage ABA levels in sunflower plants with contrasting osmotic potentials. In addition, we observed that the inability to synthesize ABA at high VPD in w-1 plants was associated with no dynamic or steady-state stomatal response to VPD. These results for sunflower are consistent with a hormonal, ABA-mediated stomatal responses to VPD rather than a hydraulic-driven stomatal response to VPD.

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.

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.

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.

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