Comparing model predictions and experimental data for the response of stomatal conductance and guard cell turgor to manipulations of cuticular conductance, leaf-to-air vapour pressure difference and temperature: feedback mechanisms are able to account for all observations

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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Photosynthesis and Transpiration of Pinus Radiata D. Don Under Plantation Conditions in Southern Australia. Ii. First-Year Seedlings and 5-Year-Old Trees on Aeolian Sands at Rennick (South-Western Victoria).

Functional Plant Biology ◽

10.1071/pp9820761 ◽

1982 ◽

Vol 9 (6) ◽

pp. 761 ◽

Cited By ~ 10

Author(s):

PM Attiwill ◽

RO Squire ◽

TF Neales

Keyword(s):

Pinus Radiata ◽

Vapour Pressure ◽

Pressure Difference ◽

Net Photosynthesis ◽

Co2 Assimilation ◽

First Year ◽

Assimilation Rate ◽

Old Trees ◽

Vapour Pressure Difference ◽

Very High

Measurements of net CO2 assimilation and transpiration rates were made over 4 days in the field in February 1980, on first-year seedlings and 5-year-old trees of Pinus radiata growing in plantation conditions in SW. Victoria. Gas exchange, enclosure, methods were used. Very high needle temperatures (to 45�C) and vapour pressure differences (to 70 mbar) were encountered. Watering treatments allowed estimates to be made of the effect of existing soil water deficits. The maximum rates of assimilation observed were 3.78 �mol CO2 m-� s-� in the watered seedlings and 3.15 �mol m-� s-� in the unwatered tree. These values are 40% less than has been recently reported for P. radiata in New Zealand but agree with other data for P. radiata and other conifers. The light saturation of net photosynthesis occurred at c. 350 W m-�. Increase in needle-air vapour pressure difference reduced needle conductance. Decrease of needle temperature and of vapour pressure difference from very high values, due to a rapid drop in air temperature, was accompanied by an increase of assimilation rate and of needle conductance, confirming that needle temperatures above about 30�C are supraoptimal for P. radiata. Watering increased assimilation rate, needle water potential and needle conductance. This was most apparent in the seedlings; the responses of the older trees were much less marked.

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Leaf anatomical adaptations have central roles in photosynthetic acclimation to humidity

Journal of Experimental Botany ◽

10.1093/jxb/erz238 ◽

2019 ◽

Vol 70 (18) ◽

pp. 4949-4962 ◽

Cited By ~ 7

Author(s):

Qingjie Du ◽

Tao Liu ◽

Xiaocong Jiao ◽

Xiaoming Song ◽

Jiayu Zhang ◽

...

Keyword(s):

Cell Size ◽

Vapour Pressure ◽

Pressure Difference ◽

Mesophyll Cell ◽

Photosynthetic Acclimation ◽

Anatomical Adaptations ◽

Tomato Cultivars ◽

Vapour Pressure Difference

Examination of long-term photosynthetic acclimation of two tomato cultivars (Jinpeng and Zhongza) to leaf-to-air vapour pressure difference reveals that independent changes in epidermal and mesophyll cell size maintain photosynthetic homeostasis in Jinpeng.

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Stomatal response to humidity in sugarcane and soybean: effect of vapour pressure difference on the kinetics of the blue light response

Plant Cell & Environment ◽

10.1111/j.1365-3040.1990.tb01288.x ◽

1990 ◽

Vol 13 (2) ◽

pp. 163-169 ◽

Cited By ~ 38

Author(s):

S. M. ASSMANN ◽

D. A. GRANTZ

Keyword(s):

Blue Light ◽

Vapour Pressure ◽

Pressure Difference ◽

Light Response ◽

Stomatal Response ◽

Blue Light Response ◽

Kinetics Of ◽

Vapour Pressure Difference

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The Croonian Lecture - Transport of substances in plants

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1938.0010 ◽

1938 ◽

Vol 125 (838) ◽

pp. 1-25 ◽

Cited By ~ 9

Keyword(s):

Vapour Pressure ◽

Pressure Difference ◽

Royal Society ◽

Driving Force ◽

Energy Conditions ◽

First Approximation ◽

Vapour Pressure Difference

When the Royal Society—now many years ago—did the late Dr Joly and me the honour of publishing our first paper on the ascent of sap (Dixon and Joly 1894, 1895), it was not difficult to make a first approximation as to the mechanism, and the energy conditions, availed of by plants in lifting water from the soil to their leaves. The driving force was to be sought in the vapour-pressure difference obtaining in the spaces surrounding the roots and the leaves (Dixon 1897).

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Stomatal and Mesophyll Resistances in Two Clones of Pinus radiata D.don Known to Differ in Transpiration and Survival Rate

Functional Plant Biology ◽

10.1071/pp9780231 ◽

1978 ◽

Vol 5 (3) ◽

pp. 231 ◽

Cited By ~ 14

Author(s):

KJ Bennett ◽

DA Rook

Keyword(s):

Survival Rate ◽

Vapour Pressure ◽

Pressure Difference ◽

Relative Survival ◽

Co2 Concentration ◽

Stomatal Resistance ◽

High Survival ◽

Experimental Conditions ◽

Vapour Pressure Difference ◽

Mesophyll Resistance

The gaseous exchange characteristics of two clones of P. radiata were compared. Clone 457, which had a low survival rate in the field, showed a transpiration rate up to twice that of clone 456, which had a high survival rate. Transpiration in both clones was not markedly affected by leaf-air vapour pressure differences varying between 0.4 and 1.4 kPa. The stomatal resistance of clone 457 was almost half that measured for clone 456 under all experimental conditions; however, increasing the leaf-air vapour pressure difference resulted in increased stomatal resistances in both clones. The photosynthetic response to CO2 concentration was also determined. The measured rates for clone 457 were twice those of clone 456 and both clones gave maximum rates of apparent photosynthesis above about 700 ng cm-3 internal CO2 concentration (corresponding to about 1400 ng cm-3 external concentration). The differences in photosynthetic rate could be accounted for by the greater than twofold difference in mesophyll resistance between the clones. Mesophyll resistance was not affected by altering the leaf-air vapour pressure difference. It is suggested that a factor in determining the relative survival rate of the two clones is the greater ability of clone 456 to limit transpiration water loss and that this more than compensates for the reduced rate of photosynthesis of this clone compared with clone 457.

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Water Exchange in the Mantle of a Terrestrial Snail During Periods of Reduced Evaporative Loss

Journal of Experimental Biology ◽

10.1242/jeb.57.1.103 ◽

1972 ◽

Vol 57 (1) ◽

pp. 103-111

Author(s):

J. MACHIN

Keyword(s):

Steady State ◽

Relative Humidity ◽

Surface Temperature ◽

Vapour Pressure ◽

Pressure Difference ◽

Water Exchange ◽

Impermeable Barrier ◽

Humidity Change ◽

Evaporative Loss ◽

Vapour Pressure Difference

1. Based on surface temperature, steady-state rates of evaporation of the mantle of inactive Otala lactea are very low even down to 1.5% relative humidity. 2. Mantle permeability is 0.016 mg/cm2/h per mmHg vapour pressure difference. 3. Marked peaks in surface temperature following humidity change are interpreted as net gain or loss of water to the mantle. 4. Smaller flucations in surface temperature are interpreted as limited mucusgland activity. 5. The existence of a superficial hygroscopic layer overlying an impermeable barrier in the mantle is discussed.

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Sweating in cattle. III. Mechanism of water transportation through the skin

The Journal of Agricultural Science ◽

10.1017/s002185960003567x ◽

1959 ◽

Vol 52 (1) ◽

pp. 62-65 ◽

Cited By ~ 3

Author(s):

G. C. Taneja

Keyword(s):

Water Vapour ◽

Vapour Pressure ◽

Pressure Difference ◽

Water Vapour Pressure ◽

Atmospheric Conditions ◽

Water Transportation ◽

Saturated Water ◽

The Difference ◽

Cutaneous Evaporation ◽

Vapour Pressure Difference

Two calves (Zebu × Australian Illawara Shorthorn and Shorthorn) of about 7–8 months of age were exposed to controlled atmospheric conditions. Cutaneous evaporation from the belly area of these calves was measured by the capsule method. Records of the temperature of the skin under test and that of the air passed over the skin was also maintained.The amount of water passing through the cattle skin was proportional to the difference between the saturated water-vapour pressure at skin temperature and the water-vapour pressure in the air. Tests were made for the water-vapour pressure difference varying from 9 to 25 mm. Hg.

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