Showing papers on "Transpiration published in 1969"
TL;DR: In this paper, it was shown that (RS)-abscisic acid induces stomatal closure and inhibits transpiration in excised leaves, and it was further shown that ABSCISIC acid affects several physiological and biochemical processes including abscission2,3, senescence3,4, flowering3, dormancy3 and enzyme activity.
Abstract: (RS)-ABSCISIC acid1 affects several physiological and biochemical processes including abscission2,3, senescence3,4, flowering3, dormancy3 and enzyme activity5. It now is shown that (RS)-abscisic acid induces stomatal closure and inhibits transpiration in excised leaves.
259 citations
TL;DR: In this paper, three analytic and two emperic methods are described to calculate the surface resistance rs of crops transpiring at a measured rate, which is applicable when detailed temperature, humidity, and wind profiles are measured; for the residual method, measurements of surface temperature, wind, and humidity are enough; the calculation is based on the ratio of potential to actual evaporation.
Abstract: Three analytic and two emperic methods are described to calculate the surface resistance rs of crops transpiring at a measured rate. The profile method is applicable when detailed temperature, humidity, and wind profiles are measured; for the residual method, measurements of surface temperature, wind, and humidity are enough; for the heat balance method, the calculation is based on the ratio of potential to actual evaporation. For rough estimates, an empiric equation of Monteith or a relation between leaf area and surface resistance can be used. In southern England and in California all three analytic methods agree closely. Hourly values of rs in California demonstrate the effect of water stress on an irrigated grass canopy by midday, whereas in England the rs of a barley crop is maintained constant for almost the whole day. From Aslyng's measurements of evaporation, the relation of rs to soil-water potential is calculated and used to show how relative rates of transpiration and photosynthesis may change in response to water stress. For an equatorial rain forest in Kenya, mean monthly rs varied systematically with soil moisture deficit, ranging between 0.3 and 1.1, sec cm−1.
170 citations
TL;DR: Ozone induced partial stomatal closure and a reduction in apparent photosynthesis and transpiration in plants as mentioned in this paper, but the effect was reversible and plants frequently recovered within a few hours.
Abstract: Little is known regarding the cause of plant growth suppression resulting from photochemical pollution. Studies with ozone indicate that elevated ozone concentrations may be involved. Ozone induced partial stomatal closure and a reduction in apparent photosynthesis and transpiration. High concentrations of ozone caused a temporary reduction in apparent photosynthesis of many species, often with little or no injury developing. The effect was reversible and plants frequently recovered within a few hours. Ozone concentrations as low as 10 pphm for several hours caused partial stomatal closure of oats. A comparison of the effects of ozone under sunlight and artificial lighting showed that photosynthesis was reduced most in sunlight.
170 citations
TL;DR: In this paper, the aerodynamic properties of pine forest, lucerne, and potatoes are combined with British records and with those of Tanner and Pelton, permitting the following generalizations: for pliable agricultural crops the roughness length decreases with increasing wind speed (to ½ for 1 to 3 m sec−1), and in this range, Zo ≅ crop height/10.
Abstract: Measurements of Zo and other aerodynamic qualities of three crops in Germany (pine forest, lucerne, potatoes) are combined with British records and with those of Tanner and Pelton, permitting the following generalizations. For pliable agricultural crops the roughness length decreases with increasing wind speed (to ½ for 1 to 3 m sec−1), and in this range, Zo ≅ crop height/10. Calculations of eddy conductivity (1/ra) give values 3 times that of open water for the farm crops, and 30 times that of open water for the trees. From measured components of the energy balance the surface resistances of the crops are calculated using Monteith's empirical relation. Values of rs for the trees-between 1.0 and 1.5 sec cm−1- are always 2 to 4 times as great as for the farm crops, indicating very effective stomatal control of transpiration by pine leaves. Including the two specific crop parameters in Penman's combination formula gives estimates of evaporation for open water, pine forest, potatoes, and lucerne that agree within 5–15% with measurements in southern England and in California.
129 citations
TL;DR: The measurement of transpiration and leaf temperature indicated that latentHeat loss was much more important in wheat, and sensible heat loss was more importantIn sorghum as means of dissipating excess energy absorbed.
Abstract: Two experiments were conducted to determine the transpiration rates of tropical and temperate grasses under a range of environmental conditions. In dense populations, three temperate grasses lost considerably more water per unit leaf area than did four tropical grasses, though tropical grasses tended to produce more dry matter per unit leaf area. The efficiency of production in relation to water use was thus greater in tropical than in temperate grasses. Wheat, a temperate grass, lost water at an average rate 2.25 times that of sorghum, a tropical grass, on a unit leaf area basis when single leaves were exposed to temperatures from 17 to 32° and light intensities from 1.7 to 4.4×10(4) ergs cm(-2) sec(-1) at 0.55 μ (1,100 to 2,800 ft.-c.). The measurement of transpiration and leaf temperature indicated that latent heat loss was much more important in wheat, and sensible heat loss was more important in sorghum as means of dissipating excess energy absorbed. These findings were attributed to the greater resistance to gas diffusion offered by sorghum than by wheat stomata in each environment.
113 citations
110 citations
TL;DR: Water content of foliage and moisture stress of twigs associated with stomatal closure were determined for 3-year-old seedlings of ponderosa pine, lodgepole pine, grand fir, Douglas-fir, and Engelmann spruce, indicating that the stomata of these species were more sensitive to increasing leaf moisture stress than those of the firs.
Abstract: The water content of foliage and moisture stress of twigs associated with stomatal closure were determined for 3-year-old seedlings of ponderosa pine, lodgepole pine, grand fir, Douglas-fir, and Engelmann spruce. Stomatal behavior during increasing soil drought was interpreted from transpiration trends of potted seedlings kept under controlled conditions, and relative degree of stomatal opening was determined with a pressure infiltration technique. In grand fir and Douglas-fir, a decline in transpiration rate in response to drought was associated with a relatively small reduction in size of stomatal aperture as compared with the pines and spruce, indicating that mesophyll resistance may have been a significant factor limiting transpiration in the firs. At stomatal closure, or end of the transpiration decline, needle water contents ranged from 122.5% to 162.5% and were lowest in Engelmann spruce and Douglas-fir, intermediate in the pines, and highest in grand fir. Needle relative turgidities ranged from 81...
92 citations
TL;DR: In this article, the transpiration rates of root-pruned and unpruned wheat plants at various soil moisture contents were discussed with the aid of further data, and the matric potential drop across the rhizosphere and the relative magnitude of the rhizo-sphere and plant resistances were calculated for the unpruning plants at different soil matric levels.
Abstract: Summary
Two experiments described in an earlier paper, on the transpiration rates of root-pruned and unpruned wheat plants at various soil moisture contents, are discussed with the aid of further data.
The matric potential drop across the rhizosphere, and the relative magnitude of the rhizo-sphere and plant resistances are calculated for the unpruned plants at various soil matric potentials. Even at −15 bars soil matric potential the estimated drop was only 0.02 bar, and the rhizosphere resistance was less than 2% of the plant resistance.
The amount of water made available to the plant by root extension was only a small fraction of that lost by transpiration. We suggest that root interception is unlikely to be important in the field, as long as new roots are growing among existing ones.
Reasons are considered for the declining influence of root pruning on transpiration as the soil dried. It can be partly explained by the soil resistance remaining very small and by the relationship between transpiration rate and leaf water potential. However, there was evidently some other factor involved, possibly change in plant resistance or influence of root kinins on transpiration rate. The effects of root pruning on transpiration are too complex to provide satisfactory evidence on the magnitude of the rhizosphere resistance, but the experimental results are at any rate in agreement with the calculated prediction that it remained very small.
85 citations
TL;DR: Continuous transpiration and beta-guage measurements were made on cotton plants, the stomatal apertures of which had been induced to oscillate, thus allowing a water balance and leaf potential to be measured as functions of time.
Abstract: Continuous transpiration and beta-guage measurements were made on cotton plants, the stomatal apertures of which had been induced to oscillate, thus allowing a water balance to be made, and leaf potential to be measured as functions of time.Analyses showed phase differences between the water entering and leaving the leaf. Also, from the phase relationship between the flow into the leaf and the water potential in the leaf it was shown that the water potential in the xylem of the plant also oscillated. This is proposed as a necessary condition for the stomates of all the leaves of a plant to oscillate in phase.It is convenient to describe the dynamics of the phenomena using a simple electrical analogue, and the usefulness and limitations of the model are discussed.
69 citations
01 Jan 1969
66 citations
TL;DR: Diurnal variations in the pattern of movement of sugars, water, and ions into developing tubers of the potato were investigated and it was demonstrated using a recording balance that large increases in the fresh weight of tubers occur during a dark period of reduced transpiration.
01 Jan 1969
TL;DR: In this paper, the uptake of monosilicic acid by crimson clover (Trifolium incarnatum L) was investigated using solution cultures in which the level ranged from 0.4 to 60 ppm SiO2, and in soils with the level in solution ranged from 7 to 67 ppm SIO2.
Abstract: The uptake of monosilicic acid by crimson clover (Trifolium incarnatum L.) was investigated using solution cultures in which the level ranged from 0.4 to 60 ppm SiO2, and soils in which the level in solution ranged from 7 to 67 ppm SiO2. With increasing levels of silica in the external solution there were systematic increases in uptake, but the quantities of silica in the tops were always less than those which were theoretically carried to the roots in the mass flow of water. The silica content of the roots was higher than in the corresponding tops and seemed to be largely associated with the epidermis. These findings and the observation that the concentration of monosilicic acid in the xylem sap is lower than that in the external solution, are regarded as evidence that the plant excludes a proportion of the monosilicic acid from the transpiration stream. This exclusion is attributed to a barrier in the root through which monosilicic acid passes at a slower rate than water.
[...]
TL;DR: In this article, a corn crop was wetted to simulate dewfall and the evaporation from the wetted and unwetted areas was measured simultaneously with a pair of accurate weighing lysimeters.
TL;DR: In Betula papyrifera stomata of various size classes were considered as physiologically different populations, which influenced stomatal response only slightly and did not cause evident browning of leaves.
Abstract: Effects of 10(-3)m, 10(-4)m, and 10(-5)m phenylmercuric acetate (PMA) on stomatal movement and transpiration of excised Betula papyrifera leaves were investigated. Duco cement leaf prints and transpiration decline curves were used for the analysis of stomatal condition. PMA induced stomatal closure and decreased transpiration. Stomata of leaves treated with any of the 3 PMA concentrations closed earlier and at a higher relative water content than did stomata of untreated leaves. As determined from transpiration decline curves, PMA at 10(-3)m caused an increase in apparent "cuticular" transpiration. However, the increase appeared to result largely from some PMA-poisoned stomata which remained open for prolonged periods. Considerable PMA toxicity was observed, with 10(-3)m and 10(-4)m concentrations causing browning of leaves. PMA treatment caused a decrease in chlorophyll content, even at a low PMA concentration (10(-5)m) which influenced stomatal response only slightly and did not cause evident browning of leaves. The time and degree of stomatal opening varied with stomatal size. Large stomata tended to open earlier and close later than small stomata. Hence, in Betula papyrifera stomata of various size classes were considered as physiologically different populations.
TL;DR: It was concluded that the leaf boundary layer resistance under field conditions is small compared with the total CO2 diffusion resistance.
Abstract: In upland cotton (Gossypium hirsutum L.) certain varieties are available with the mutant character “okra” leaves. These deeply lobed leaves were found to have thinner boundary layers than their normal analogues. Apparent photosynthesis and transpiration measurements were made in field-grown stands under a variety of light intensities and carbon dioxide levels to assess the effect of leaf boundary layer diffusion resistance on photosynthetic efficiency. The thinner boundary layers associated with deeply lobed “okra” cotton failed to euhance carbon fixation rates per unit land area. It was concluded that the leaf boundary layer resistance under field conditions is small compared with the total CO2 diffusion resistance.
01 Jan 1969
TL;DR: The transpiration rate of P. jannonei is lower than that of M. pruinosus, and low even compared to that of the desert woodlouse, H. reaumuri of North Africa, but both species show quick acclimation to high and low temperature.
Abstract: The transpiration rate of P. jannonei is lower than that of M. pruinosus, and low even compared to that of the desert woodlouse, H. reaumuri of North Africa. Different populations of the same species of woodlouse may have transpiration rates which are related to the xeric nature of their environment, but rapid acclimation in the rate of water-loss does occur. Both species, however, show quick acclimation to high and low temperature, not only as regards their time of survival in saturated air at 41·5°C (L.T. 50 for exposure of 30 minutes) but also in their metabolic rates.
01 Apr 1969
TL;DR: In this paper, the effect of soil water stress on transpiration, photosynthesis, stomatal aperture and relative turgidity of coffee plants was investigated and it was shown that at midday with moderate soil moisture stress a closure of stomates results in a decrease in CO2 internal.
Abstract: SUMMARY
A study was made on the effect of soil water stress on transpiration, photosynthesis, stomatal aperture and relative turgidity of coffee plants.
The decrease in turgidity as a consequence of soil moisture depletion was only small, due to the closing of stomatas and hence a decrease in transpiration. This means that an efficient water control is present in coffee plants. The reduction in photosynthesis, however, was much more pronounced than that in transpiration. This could be ascribed, apart from an increase in stomatal resistance, to the large effect of increasing leaf temperature on the internal CO2 concentration. The diurnal variation in stomatal resistance and internal CO2 concentration shows that at midday with a moderate soil moisture stress a closure of stomates results in a decrease in CO2 internal. Net photosynthesis almost recovers in a period of five days when rewatering after drought.
TL;DR: It is concluded that the ion concentration in the xylem vessels, which is directly determined by the transpiration rate, limits the rate of transfer of K ions from the cytoplasmatic constituents of the root tissue to the xylesm vessels.
Abstract: The influence of the transpiration rate on uptake and transport of K+ in intact barley plants was investigated The results indicate that both components of K absorption by the root, that is, accumulation into the vacuoles and binding in the cytoplasm, proceed independently of the transpiration rate, nor is there any influence on the length of the lag phase in K translocation to the shoot It is concluded that the ion concentration in the xylem vessels, which is directly determined by the transpiration rate, limits the rate of transfer of K ions from the cytoplasmatic constituents of the root tissue to the xylem vessels
Journal Article•
TL;DR: The leaves of Primula palinuri and Zea mays are amphistomatic and the distribution of stomata and the portion of CO2-uptake of both leaf surfaces correspond well, and the significance of this property of amphistsomatic leaves in relation to transpiration and CO2 assimilation is discussed.
Abstract: The leaves of Primula palinuri and Zea mays are amphistomatic. The CO2-exchange of both leaf surfaces was measured separately. The distribution of stomata and the portion of CO2-uptake of both leaf surfaces correspond well. In Primula the greater part diffuses through the upper surface of the leaf, in Zea through the lower surface. Stripping of the Primula epidermis does not change the total CO2-uptake but the greater part now diffuses through the lower stripped surface of the leaf. The CO2-uptake of the upper surface alone, as well as of the lower surface alone and of both surfaces together was measured. The quantities of CO2 transported through the leaf surfaces are not independent of each other: if CO2-uptake is only possible through one surface of the leaf the CO2 flux on this side increases. The significance of this property of amphistomatic leaves in relation to transpiration and CO2 assimilation is discussed.
TL;DR: The results indicate that higher plant photosynthesis in normal air and saturating light is not determined by physical barriers to gas diffusion alone but that it is markedly limited by biochemical processes.
Abstract: Transpiration rate was unaffected by O2 concentration in the range 1–80% when illuminated leaves ofAtriplex patula andA. rosea were kept at low CO2 concentrations. Moreover, the marked increase in the rate of light-saturated photosynthesis that takes place in many plant species when O2 concentration is reduced from 21% to a few percent was not accompanied by any change in transpiration rate inA. patula andSolanum dulcamara. The results indicate that higher plant photosynthesis in normal air and saturating light is not determined by physical barriers to gas diffusion alone but that it is markedly limited by biochemical processes.
TL;DR: In this article, the authors used the theory of porometers to obtain estimates of diffusive conductivity from readings taken with a portable porometer, and determinations made with an infiltration technique on leaves of both species.
TL;DR: Simultaneous measurements of leaf resistance to gaseous flow, rate of transpiration and rate of carbon dioxide exchange were made with the main object of investigating the effects of severing the petiole on stomatal movements andgaseous exchange of leaves of Vicia faba of differing initial water content.
Abstract: Summary
Simultaneous measurements of leaf resistance to gaseous flow, rate of transpiration and rate of carbon dioxide exchange were made with the main object of investigating the effects of severing the petiole on stomatal movements and gaseous exchange of leaves of Vicia faba of differing initial water content.
Extensive stomatal changes occurred on cutting the petioles of illuminated leaves in air. The magnitude and direction of the stomatal movements were strongly influenced by the water relations of the leaf at the time of excision. When the water deficit was small there was a substantial temporary stomiatal opening and corresponding temporary increases in rates of transpiration and photosynthesis. In leaves of moderate water deficit the stomatal opening on leaf excision was much less pronounced and, in leaves under severe water stress at he time of cutting, there was little evidence of any immediate stomatal response. Preliminary stomatal opening and a temporary increase in transpiration rate were also observed in leaves excised in air from plants kept in darkness. In experiments in which the illuminated leaves were severed under water, however, a temporary increase of leaf resistance to gaseous flow was found on leaf excision, and associated declines in rates of transpiration and of photosynthesis.
The changes in transpiration rate resulting from leaf severance are clearly associated with stomatal behaviour, and there is evidence of close stomatal control, under these conditions, of rates of transpiration and of photosynthesis. The phenomena involved in leaf excision both in air and under water are discussed and stomatal behaviour shown to depend to a considerable extent on the water relations of the leaf; stomatal movements are interpreted largely in terms of differential turgor changes in the guard cells and neighbouring epidermal cells.
TL;DR: Antitranspirants are most effective in decreasing transpiration when other resistances in the passage of water to the roots, through the plant, and to the atmosphere are not great, when there is good coverage of the stomatal bearing leaf surfaces (except for reflecting materials), when new foliar growth following treatment is minimal, and when optimum concentrations and application rates are used.
Abstract: Research on antitranspirants may have application in increasing the yield of water from watersheds by reducing transpirational losses from vegetation under certain environmental conditions. There are three broad groups of antitranspirants: (1) reflecting materials that decrease the heat load on the leaf. (2) film-forming materials that hinder the escape of water vapor from the leaf, and (3) stomata-closing materials that increase stomatal resistance. Antitranspirants are most effective in decreasing transpiration when other resistances in the passage of water to the roots, through the plant, and to the atmosphere are not great, when there is good coverage of the stomatal bearing leaf surfaces (except for reflecting materials), when new foliar growth following treatment is minimal, and when optimum concentrations and application rates are used.
TL;DR: In this paper, the authors investigated the intensity of transpiration, intensity of water absorption, water saturation deficit, and rate of water transport in samples from leaf tissue of fodder cabbage and banana-tree.
Abstract: Intensity of transpiration, intensity of water absorption, water saturation deficit (wsd) in different parts of samples and rate of water transport was investigated in samples from leaf tissue of fodder cabbage and banana-tree
TL;DR: The only substance found to be an effective transpiration suppressant was Acropol, which reduced water consumption by an average of 50% when applied as a leaf spray.
Abstract: A range of antitranspirants has been tested under glasshouse conditions for their effectiveness In reducing the water consumption of grapevines (Vitis vinifera cv. Sultana). The substances tested included three that form plastic films, Polycote J (Tag), Polycote S720, and Acropol (S789, a silicone type compound), and the inhibitor phenyl mercurrc acetate which 1s known to be effective at suppressing transpiration In cotton. The only substance found to be an effective transpiration suppressant was Acropol, which reduced water consumption by an average of 50% when applied as a leaf spray. Repeated applications at 12-day intervals were necessary and the substance had a morphogenetic effect, bringing about a significant increase In the leaf area but a decrease in dry matter production, especially evident In the lower root weight of treated plants. (Similar morphogenetic effects were shown with Polycote S720, where the increased leaf area was shown to be a result of increased leaf number despite a slightly lower mean leaf area ) In short-term experiments both Acropol and Polycote S720 reduced carbon dioxide uptake in the light and carbon dioxide output in the dark. When Acropol was applied to plants in the field it did not affect the rate of sugar accumulation In grapes.
TL;DR: In this paper, a plexiglass chamber consisting of three parts was used to measure the intensity of transpiration and water saturation deficit in a sample of 14 cm2 leaf tissue, and a positive correlation between the ratio of water absorption to transpiration was found.
Abstract: Samples of the leaf tissue (14cm2) were placed in a plexiglass chamber which consisted of three parts. Water absorbed by the leaf tissue on one side of the sample was transported through the middle part of the sample to the opposite side and was transpirated there. The intensity of transpiration the intensity of water absorption and water saturation deficit (w.s.d.) were determined simultaneously in this tissue by gravimetry. Water balance was studied either in saturated samples of leaf tissue or in tissue where w.s.d. (10%, 20%, 30%, 40%) was established in advance. Although conditions for water absorption in leaf segments were optimal, w.s.d. originated in the saturated leaf tissue under all given external conditions (evaporation from 41.7 to 17.8 mg cm−2 h−1). W.s.d. which was established in advance for the most part increased during the experiment and reached even high values (more than 60%). the equilibration was reached only under conditions of low evaporation and initial w.s.d. higher than 20% in young leaves and higher than 30% in adult leaves. A positive correlation between the ratio of the intensity of water absorption to the intensity of transpiration and w.s.d. was found only under conditions of lower evaporation (17.8 and 23.2mg cm−2h−1). The maximal values of w.s.d. were limited in this way.