COMPARISON BETWEEN TWO INBRED CORN LINES FOR DIFFUSIVE RESISTANCES, PHOTOSYNTHESIS AND TRANSPIRATION AS A FUNCTION OF LEAF WATER POTENTIAL

1974 ◽  
Vol 54 (4) ◽  
pp. 765-770 ◽  
Author(s):  
P. A. DUBÉ ◽  
K. R. STEVENSON ◽  
G. W. THURTELL
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Potentials ◽  
Diffusive Resistance ◽  
Response To Water ◽  
Mesophyll Resistance

Relationships between (1) photosynthesis (2) transpiration (3) total diffusive resistance to water vapor and (4) mesophyll resistance and leaf water potential were examined in two lines of corn (Zea mays L.) differing in phenotypic response to water stress. One line (Q-188) was a wilting inbred and the other (DR-1) was an inbred known to have at least some heat and drought resistance under field conditions. No differences were found between inbred lines in net photosynthetic rate, transpiration rate and total diffusive resistance to water vapor at high or low leaf water potentials in the light. In both lines, stomatal closure began to occur between − 8.5 to − 9.5 bars. Similarly, rapid increases in both total resistance to water vapor diffusion and mesophyll resistance to carbon dioxide diffusion occurred within a narrow range of water potentials. However, leaf water potential, and thus all other parameters, differed markedly between lines when considered on a time scale. The early wilting of Q-188 suggested that high resistances to water flow were present in the xylem system.

scholarly journals DIFFUSIVE RESISTANCE, TRANSPIRATION, AND PHOTOSYNTHESIS IN SINGLE LEAVES OF CORN AND SORGHUM IN RELATION TO LEAF WATER POTENTIAL

1973 ◽  
Vol 53 (3) ◽  
pp. 537-544 ◽  
Author(s):  
C. L. BEADLE ◽  
K. R. STEVENSON ◽  
H. H. NEUMANN ◽  
G. W. THURTELL ◽  
K. M. KING
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Narrow Range ◽  
Light Flux ◽  
Leaf Water ◽  
Diffusive Resistance ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Mesophyll Resistance

Growth chamber studies were conducted to determine the relationships between leaf water potential and diffusive resistance, transpiration rate, and photosynthesis in corn (Zea mays L.) and sorghum (Sorghum vulgare L.). Few differences were apparent between species in response to leaf water potentials above −8 to −6 bars at all light flux densities used. At lower potentials their ability to withstand water stress differed. Rapid increases in both total resistance to water vapor and mesophyll resistance to carbon dioxide within a narrow range of water potential were observed in corn with simultaneous decreases in transpiration and photosynthesis. More gradual changes occurred in sorghum, with little increase in mesophyll resistance except at the highest light flux density. Photosynthetic rate of sorghum was still 25% of maximum at −11.5 bars whereas corn was severely wilted and photosynthesis had ceased at a similar water potential.

The leaf miner Phyllocnistis populiella negatively impacts water relations in aspen

2019 ◽  
Vol 40 (5) ◽  
pp. 580-590 ◽  
Author(s):  
Diane Wagner ◽  
Jenifer M Wheeler ◽  
Stephen J Burr
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Water Loss ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Leaf Miner ◽  
Phyllocnistis Populiella

Abstract Within the North American boreal forest, a widespread outbreak of the epidermal leaf miner Phyllocnistis populiella Cham. has damaged quaking aspen (Populus tremuloides Michx.) for nearly 20 years. In a series of experiments, we tested the effects of feeding damage by P. populiella on leaf water relations and gas exchange. Relative to insecticide-treated trees, the leaves of naturally mined trees had lower photosynthesis, stomatal conductance to water vapor, transpiration, water-use efficiency, predawn water potential and water content, as well as more enriched foliar δ13C. The magnitude of the difference between naturally mined and insecticide-treated trees did not change significantly throughout the growing season, suggesting that the effect is not caused by accumulation of incidental damage to mined portions of the epidermis over time. The contributions of mining-related stomatal malfunction and cuticular transpiration to these overall effects were investigated by restricting mining damage to stomatous abaxial and astomatous adaxial leaf surfaces. Mining of the abaxial epidermis decreased photosynthesis and enriched leaf δ13C, while increasing leaf water potential and water content relative to unmined leaves, effects consistent with stomatal closure due to disfunction of mined guard cells. Mining of the adaxial epidermis also reduced photosynthesis but had different effects on water relations, reducing midday leaf water potential and water content relative to unmined leaves, and did not affect δ13C. In the laboratory, extent of mining damage to the adaxial surface was positively related to the rate of water loss by leaves treated to prevent water loss through stomata. We conclude that overall, despite water savings due to closure of mined stomata, natural levels of damage by P. populiella negatively impact water relations due to increased cuticular permeability to water vapor across the mined portions of the epidermis. Leaf mining by P. populiella could exacerbate the negative effects of climate warming and water deficit in interior Alaska.

Osmotic Adjustment of Sorghum and Sunflower Crops in Response to Water Deficits and Its Influence on the Water Potential at Which Stomata Close

1978 ◽  
Vol 5 (5) ◽  
pp. 597 ◽  
Author(s):  
NC Turner ◽  
JE Begg ◽  
ML Tonnet
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Deficits ◽  
Rate Of Increase ◽  
Leaf Osmotic Potential ◽  
Response To Water

The soil and plant water status of irrigated and unirrigated sorghum [Sorghum bicolor (L.) Moench cv. TX610] and sunflower (Helianthus annuus L. cv. Hysun 30) crops were compared on several days from the late vegetative to the early grain-filling stages of development. Additionally, the stems of plants from the irrigated and unirrigated plots of both species were cut near their base; this caused the plants to quickly dry until the stomata closed. The leaf water potential and leaf osmotic potential were measured when the stomatal resistance reached 6 s cm-� to give the water potential for stomatal closure and to provide osmotic potentials at equal turgor. Carbohydrate and potassium levels of leaves were also monitored. The mean daily minimum leaf water potentials in the irrigated sorghum and sunflower did not decrease below - 1 7 MPa and - 2.0 MPa, respectively, but decreased to - 2.1 MPa in the unirrigated sorghum and -2.6 MPa in the unirrigated sunflower. The osmotic potential at stomatal closure in the rapidly dried plants decreased with increasing leaf water deficit in both sunflower and sorghum: in both species the osmotic potential decreased approximately 0.6 MPa for each megapascal decrease in leaf water potential. The results indicate that both sorghum and sunflower adjusted osmotically in response to water deficits and that adjustment occurred at a rate of at least 0.1 MPa per day. The lowering of osmotic potential persisted less than 9 days after the relief of stress in both sunflower and sorghum. The soluble sugar concentration increased linearly in both sunflower and sorghum with osmotic adjustment: the rate of increase of soluble sugars was significantly greater in sunflower than sorghum. No changes in potassium concentration were observed during osmotic adjustment. The water potential at which the stomata closed varied from - 1.5 to -2.6 MPa in sorghum and - 1.7 to -2.7 MPa in sunflower: the water potential that induced stomatal closure decreased as the osmotic potential decreased. Stomatal closure occurred at a mean turgor of -0-5 MPa in both species: systematic error in the measurement of osmotic potential on frozen and thawed leaf tissue is considered the reason for the low turgor potentials at stomatal closure. The adaxial stomatal closed before the abaxial stomata in the sorghum and unirrigated sunflower but, since the leaf water potential initially fell rapidly and then became stable before the adaxial stomata closed, both the adaxial and abaxial stomata closed at the same leaf water potential.

Effects of Low Water Potentials on Transpiration and Photosynthesis in Mitchell Grass (Astrebla lappacea)

1974 ◽  
Vol 1 (4) ◽  
pp. 539 ◽  
Author(s):  
D Doley ◽  
NBA Trivett
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Severe Drought ◽  
Water Potentials ◽  
Linear Relationships ◽  
Diffusive Resistance ◽  
Remarkable Recovery

Gas-exchange studies were carried out on potted Mitchell grass plants raised in the glasshouse and in growth cabinets. Provided that nutrition was adequate, the low irradiance of the growth cabinets did not impair the photosynthetic capacity at levels approaching full sunlight. The optimum temperature for net photosynthesis was in excess of 40�C. Close linear relationships were established between leaf water potential and both transpiration and net photosynthesis. Most of the variation in gas exchange could be attributed to changes in stomatal diffusive resistance. Although there was an increase in mesophyll resistance as leaf water potential decreased, the proportion of the total resistance attributable to the mesophyll became substantially smaller. Gas exchange exhibited a remarkable recovery after brief but severe drought, during which leaf water potentials fell to about -48 bars. There was some inhibition of both transpiration and photosynthesis for about one week following rewatering. It is concluded that A. lappacea demonstrates a high degree of true drought tolerance.

Photosynthesis, transpiration, and leaf diffusive conductance of the cassava leaf in response to water stress

1983 ◽  
Vol 61 (1) ◽  
pp. 373-376 ◽  
Author(s):  
Jairo A. Palta
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Water Shortage ◽  
Leaf Water ◽  
Manihot Esculenta Crantz ◽  
Water Potential Measurements ◽  
Response To Water ◽  
Made In

The effects of short periods of water shortage on the CO2 and water vapour exchange of attached cassava (Manihot esculenta Crantz 'M Col 72') leaves were measured. Gas-exchange and leaf water potential measurements were made in outdoor grown plants previously subjected to varying periods without water. Leaf water potentials fell to between −0.61 and −1.06 MPa and net photosynthesis and transpiration rates declined as leaf water potential decreased. Estimations of the leaf internal CO2 conductance indicated that the linear relationship established between leaf water potential and net photosynthesis is dominated by, but not completely explained by, stomatal closure.

Photosynthesis Response of Sunlit and Shade Pepper (Capsicum annuum) Leaves at Different Positions in the Canopy Under Two Water Regimes

1994 ◽  
Vol 21 (3) ◽  
pp. 377 ◽  
Author(s):  
A Alvino ◽  
M Centritto ◽  
FD Lorenzi
Keyword(s):  
Water Potential ◽  
Capsicum Annuum ◽  
Leaf Water Potential ◽  
Co2 Exchange ◽  
Leaf Water ◽  
Predawn Leaf Water Potential ◽  
Water Regimes ◽  
Water Potentials ◽  
Sun And Shade ◽  
Shade Leaves

Pepper (Capsicum annuum L.) plants were grown in 1 m2 lysimeters under two different water regimes in order to investigate differences in the spatial arrangements of the leaves and to relate this to daily assimilation rates of leaves of the canopy. The control regime (well-watered (W) treatment) was irrigated whenever the accumulated 'A' pan evaporation reached 4 cm, whereas the water-stressed (S) treatment was watered whenever the predawn leaf water potential fell below -1 MPa. During the growing cycle, equal numbers of sun and shade leaves were chosen from the apical, middle and basal parts of the canopy, corresponding to groups of leaves of increasing age. The CO2 exchange rate (CER) was measured at 0830, 1230 and 1530 hours on 8 days along the crop cycle, on leaves in their natural inclination and orientation. Leaf water potentials were measured on apical leaves before dawn and concurrently with gas exchange measurements. Control plants maintained predawn leaf water potential at -0.3 MPa, but S plants reached values lower than -1.2 MPa. Midday leaf water potentials were about twice as low in the S plants as in the controls. Water stress reduced LA1 during the period of crop growth, and dry matter production at harvest. Stressed apical leaves appeared to reduce stress by changing their inclination. They were paraheliotropic around midday and diaheliotropic at 0830 and 1530 hours. The CER values of the S treatment were significantly lower than those of the W treatment in apical and middle leaves, whereas the CER of basal leaves did not differ in either treatments. In the S treatment, reduction in the CER values of sunlit apical leaves was more evident in the afternoon than at midday or early in the morning, whereas basal leaves were less affected by water than basal stress leaves if sunlit, and negligibly in shaded conditions.

scholarly journals Interactions between leaf water potential, stomatal conductance and abscisic acid content of orange trees submitted to drought stress

2004 ◽  
Vol 16 (3) ◽  
pp. 155-161 ◽  
Author(s):  
Mara de Menezes de Assis Gomes ◽  
Ana Maria Magalhães Andrade Lagôa ◽  
Camilo Lázaro Medina ◽  
Eduardo Caruso Machado ◽  
Marcos Antônio Machado
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Acid Content ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Orange Trees ◽  
Abscisic Acid Content

Thirty-month-old 'Pêra' orange trees grafted on 'Rangpur' lemon trees grown in 100 L pots were submitted to water stress by the suspension of irrigation. CO2 assimilation (A), transpiration (E) and stomatal conductance (g s) values declined from the seventh day of stress, although the leaf water potential at 6:00 a.m. (psipd) and at 2:00 p.m. (psi2) began to decline from the fifth day of water deficiency. The CO2 intercellular concentration (Ci) of water-stressed plants increased from the seventh day, reaching a maximum concentration on the day of most severe stress. The carboxylation efficiency, as revealed by the ratio A/Ci was low on this day and did not show the same values of non-stressed plants even after ten days of rewatering. After five days of rewatering only psi pd and psi2 were similar to control plants while A, E and g s were still different. When psi2 decreases, there was a trend for increasing abscisic acid (ABA) concentration in the leaves. Similarly, stomatal conductance was found to decrease as a function of decreasing psi2. ABA accumulation and stomatal closure occurred when psi2 was lower than -1.0 MPa. Water stress in 'Pera´ orange trees increased abscisic acid content with consequent stomatal closure and decreased psi2 values.

A model of stomatal closure driven by nonlinearities in soil-plant hydraulics

2021 ◽  
Author(s):  
Fabian Wankmüller ◽  
Mohsen Zarebanadkouki ◽  
Andrea Carminati
Keyword(s):  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Environmental Conditions ◽  
Plant Traits ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Optimization Models ◽  
Soil Conditions

<p>Predicting plant responses to drought is a long-standing research goal. Since stomata regulate gas-exchange between plants and the atmosphere, understanding their response to drought is fundamental. Current predictions of stomatal behavior during drought mainly rely on empirical models. These models may suit well to a specific set of plant traits and environmental growth conditions, but their predictive value is doubtful when atmospheric and soil conditions change. Stomatal optimization offers an alternative framework to predict stomatal regulation in response to drought for varying environmental conditions and plant traits. Models which apply this optimization principle posit that stomata maximize the carbon gain in relation to a penalty caused by water loss, such as xylem cavitation. Optimization models have the advantage of requiring a limited number of parameters and have been successfully used to predict stomatal response to drought for varying environmental conditions and species. However, a mechanism that enables stomata to optimally close in response to water limitations, and more precisely to a drop in the ability of the soil-plant continuum to sustain the transpiration demand, is not known. Here, we propose a model of stomatal regulation that is linked to abscisic acid (ABA) dynamics (production, degradation and transport) and that allows plants to avoid excessive drops in leaf water potential during soil drying and increasing vapor pressure deficit (VPD). The model assumes that: 1) stomatal conductance (g<sub>s</sub>) decreases when ABA concentration close to the guard cells (C<sub>ABA</sub>) increases; 2) C<sub>ABA</sub> increases with decreasing leaf water potential (due to higher production); and 3) C<sub>ABA</sub> decreases with increasing photosynthesis (e.g. due to faster degradation or transport to the phloem). Our model includes simulations of leaf water potential based on transpiration rate, soil water potential and variable hydraulic conductances of key elements (rhizosphere, root and xylem), and a function linking stomatal conductance to assimilation. It was tested for different soil properties and VPD. The model predicts that stomata close when the relation between assimilation and leaf water potential becomes nonlinear. In wet soil conditions and low VPD, when there is no water limitation, this nonlinearity is controlled by the relation between stomatal conductance and assimilation. In dry soil conditions, when the soil hydraulic conductivity limits the water supply, nonlinearity is controlled by the excessive drop of leaf water potential for increasing transpiration rates. The model predicts different relations between stomatal conductance and leaf water potential for varying soil properties and VPD. For instance, the closure of stomata is more abrupt in sandy soil, reflecting the steep decrease in hydraulic conductivity of sandy soils. In summary, our model results in an optimal behavior, in which stomatal closure avoids excessive (nonlinear) decrease in leaf water potential, similar to other stomatal optimization models. As based on ABA concentration which increases with decreasing leaf water potential but declines with assimilation, this model is a preliminary attempt to link optimization models to a physiological mechanism.</p>

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