Seasonal Variation in Stomatal Responses of Two Cultivars of Lychee (Litchi chinenis Sonn)

1992 ◽  
Vol 19 (3) ◽  
pp. 317 ◽  
Author(s):  
D Batten ◽  
J Lloyd ◽  
C Mcconchie
Keyword(s):  
Stomatal Conductance ◽  
Temperature Sensitivity ◽  
Vapour Pressure Deficit ◽  
Sensitivity Coefficient ◽  
Cultivar Differences ◽  
Water Vapour Pressure ◽  
Data Sets ◽  
Diurnal Changes ◽  
Whole Plant ◽  
Significant Difference

The effect of cultivar and environment on the stomatal conductance and plant water relations of lychee (Litchi chinensis Sonn.) was investigated. Diurnal changes in stomatal conductance (gs) and leaf water potentials (Ψ1) were determined for leaves of irrigated trees of cv. 'Bengal' and cv. 'Kwai May Pink' between July and December 1990. Leaves of Bengal always had much higher gs than Kwai May Pink in winter, but as summer approached, this difference became less. Ψ1 values at midday for Bengal were always much lower than for Kwai May Pink. The linear model, E = G(Ψ1-Ψsoil), where E is transpiration rate and G is whole plant conductance, was found to be valid for nearly all the data sets collected. The values of G for Kwai May Pink were higher than for Bengal, especially in summer, and the average values of G (Bengal 4.1 and Kwai May Pink 6.3 mmol H2O m-2 s-1 Mpa-1) indicate that the lychee has a relatively efficient water transport system compared with other fruit tree species. Laboratory measurements of the responses of these cultivars confirmed observed differences in gs in the field. The responses of each cultivar to irradiance (I), leaf temperature (Tl) and leaf-air water vapour pressure deficit (D) were obtained and used to model the orchard data. The equation (see pdf) where Topt is the temperature for maximum gs, gdark is the basal gs in the dark at given T1 and D, and kI, kT and kD are constants fitted by non-linear least squares, provided an acceptable fit for both cultivars (R2 = 0.68 for Bengal and 0.55 for Kwai May Pink). The fit was not improved by including Ψ1 in the model. There was a significant difference between cultivars in kT, the temperature sensitivity coefficient. Possible implications of inter-cultivar differences in temperature sensitivity are discussed.

Genotypic variation in whole-plant transpiration efficiency in sorghum only partly aligns with variation in stomatal conductance

2019 ◽  
Vol 46 (12) ◽  
pp. 1072 ◽  
Author(s):  
Geetika Geetika ◽  
Erik J. van Oosterom ◽  
Barbara George-Jaeggli ◽  
Miranda Y. Mortlock ◽  
Kurt S. Deifel ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Photosynthetic Capacity ◽  
Genotypic Variation ◽  
Vapour Pressure Deficit ◽  
Genotypic Differences ◽  
Transpiration Efficiency ◽  
Plant Transpiration ◽  
Leaf Chlorophyll ◽  
Residual Variation ◽  
Whole Plant

Water scarcity can limit sorghum (Sorghum bicolor (L.) Moench) production in dryland agriculture, but increased whole-plant transpiration efficiency (TEwp, biomass production per unit of water transpired) can enhance grain yield in such conditions. The objectives of this study were to quantify variation in TEwp for 27 sorghum genotypes and explore the linkages of this variation to responses of the underpinning leaf-level processes to environmental conditions. Individual plants were grown in large lysimeters in two well-watered experiments. Whole-plant transpiration per unit of green leaf area (TGLA) was monitored continuously and stomatal conductance and maximum photosynthetic capacity were measured during sunny conditions on recently expanded leaves. Leaf chlorophyll measurements of the upper five leaves of the main shoot were conducted during early grain filling. TEwp was determined at harvest. The results showed that diurnal patterns in TGLA were determined by vapour pressure deficit (VPD) and by the response of whole-plant conductance to radiation and VPD. Significant genotypic variation in the response of TGLA to VPD occurred and was related to genotypic differences in stomatal conductance. However, variation in TGLA explained only part of the variation in TEwp, with some of the residual variation explained by leaf chlorophyll readings, which were a reflection of photosynthetic capacity. Genotypes with different genetic background often differed in TEwp, TGLA and leaf chlorophyll, indicating potential differences in photosynthetic capacity among these groups. Observed differences in TEwp and its component traits can affect adaptation to drought stress.

Stomatal conductance in a northern temperate deciduous forest: temporal and spatial patterns

1993 ◽  
Vol 23 (2) ◽  
pp. 245-252 ◽  
Author(s):  
Antonio Iacobelli ◽  
J. Harry McCaughey
Keyword(s):  
Stomatal Conductance ◽  
Deciduous Forest ◽  
Vapour Pressure Deficit ◽  
Diurnal Changes ◽  
White Birch ◽  
Temperate Deciduous Forest ◽  
Vertical Variation ◽  
Temperate Deciduous ◽  
Temporal And Spatial ◽  
Rain Events

Stomatal conductance measurements were obtained in the summer of 1989 in a deciduous forest near Chalk River, Ontario. Seasonal changes in stomatal conductance of trembling aspen (Populustremuloides Michx.) and white birch (Betulapapyrifera Marsh.) were related to changes in soil water content. Rehydration of water stores in trees following each of the two major rain events observed over the growing season likely influenced the magnitude of stomatal conductance. Diurnal changes in stomatal conductance were found to be related primarily to changes in solar radiation, vapour-pressure deficit, and air temperature. There was considerable vertical variation in stomatal conductance, such that the canopy could be divided into a total of five layers. There was also considerable variation in stomatal conductance trees.

Conducting sapwood area, foliage area, and permeability in mature trees of Piceasitchensis and Pinuscontorta

1984 ◽  
Vol 14 (6) ◽  
pp. 940-947 ◽  
Author(s):  
D. Whitehead ◽  
W. R. N. Edwards ◽  
P. G. Jarvis
Keyword(s):  
Vapour Pressure Deficit ◽  
Basal Area ◽  
Water Vapour Pressure ◽  
Mature Trees ◽  
Area Index ◽  
Sapwood Area ◽  
Local Climate ◽  
Significant Difference ◽  
Physiological Analysis ◽  
The Relationship

The relationships between foliage area and sapwood area between trees and within the crowns of 20 Piceasitchensis (Bong.) Carr., provenance Queen Charlotte Island, British Columbia (10 in a control plot and 10 in a plot fertilized with potassium and phosphorus 8 years before harvest) and 10 Pinuscontorta Dougl., provenance Ladysmith trees were examined using a physiological analysis based on Darcy's law. Foliage area index on the fertilized P. sitchensis plot was higher than on the control. The variation of foliage area density with depth in the canopies followed a normal distribution. Relationships between foliage area and sapwood basal area were linear but the slopes were different for the two species. There was no significant difference between the control and fertilized P. sitchensis trees. The relationship between foliage area and the product of sapwood area and permeability was linear and data from the three plots fell on the same line. Sapwood area, permeability, and their product decreased with depth through the crowns of the trees. Within the crowns, relationships between cumulative foliage area and sapwood area, and between cumulative foliage area and the product of sapwood area × permeability were different with species and treatment. A single linear relationship resulted when the product of cumulative foliage area above an internode × the internode length was plotted against sapwood area × permeability for the internode. This suggests that it is the drop in potential across a node and internode rather than the gradient of potential across the internode that is related to the flux of water through tree crowns. The data support the hypothesis that the relationship between foliage area and sapwood area depends on permeability of the sapwood and the local climate through its influence on transpiration rate, particularly via average water vapour pressure deficit of the air and stomatal conductance.

Processes controlling understorey evapotranspiration

1989 ◽  
Vol 324 (1223) ◽  
pp. 207-231 ◽  
Keyword(s):  
Stomatal Conductance ◽  
Forest Floor ◽  
Root Zone ◽  
Significant Proportion ◽  
Vapour Pressure Deficit ◽  
Water Vapour Pressure ◽  
Removal Experiments ◽  
Radiation Regime ◽  
Water Vapour Pressure Deficit

The understorey often accounts for a significant proportion of forest evapo- transpiration. In this paper we discuss the role of the understorey radiation regime, and the aerodynamic and stomatal conductance characteristics of the understorey in understorey evapotranspiration. Values of the McNaughton—Jarvis parameter Ω for the understorey in two mid-rotation Douglas-fir stands indicate considerable coupling between the understorey and the atmosphere above the overstorey. However, the stronger coupling between the overstorey and the atmosphere accounts for the observation that the fraction of stand evapotranspiration originating at the understorey increases as the water vapour pressure deficit increases and the soil dries. We also discuss the approaches to describing the process of evaporation from the forest floor and the results of understorey removal experiments. These show small decreases in stand evapotranspiration and root-zone soil water content, but significant increases in the transpiration and growth of the trees.

Stomatal conductance, transpiration, and resistance to water uptake in a Pinussylvestris spacing experiment

1984 ◽  
Vol 14 (5) ◽  
pp. 692-700 ◽  
Author(s):  
D. Whitehead ◽  
P. G. Jarvis ◽  
R. H. Waring
Keyword(s):  
Stomatal Conductance ◽  
Hydraulic Resistance ◽  
Vapour Pressure Deficit ◽  
Water Vapour Pressure ◽  
Canopy Conductance ◽  
Cross Sectional ◽  
Summer Maximum ◽  
The Mean ◽  
Monteith Equation ◽  
Water Vapour Pressure Deficit

Stomatal conductance was measured with porometers in two plots of Pinussylvestris L. with markedly different tree spacings (plot 1, 608 stems ha−1; plot 2, 3281 stems ha−1), and hourly rates of transpiration were calculated using the Penman–Monteith equation at intervals throughout one growing season. Stomatal conductance varied little in relation to height or age of foliage. There was a linear decrease in canopy conductance with increasing water vapour pressure deficit of the air. Transpiration rates on both plots increased during the summer (maximum 0.3 mm h−1); rates on plot 1 were always lower (ca. 0.7 times) than on plot 2. Needle water potentials were similar throughout the season and only slightly lower on plot 1 than on plot 2. The mean hydraulic resistance of the trees on plot 1 was 2.4 times that on plot 2. The results support a hypothesis that considers the changes in transpiration rate, conducting cross-sectional area, canopy leaf area, water potential, and hydraulic resistance following thinning as a set of homeostatic relationships.

scholarly journals Evaluating the models of stomatal conductance response to humidity in a tropical rain forest of Xishuangbanna, southwest China

2011 ◽  
Vol 42 (4) ◽  
pp. 307-317 ◽  
Author(s):  
Zhiheng Li ◽  
Yiping Zhang ◽  
Shusen Wang ◽  
Guofu Yuan ◽  
Yan Yang ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Vapour ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Model Comparison ◽  
Southwest China ◽  
Vapour Pressure Deficit ◽  
Water Vapour Pressure ◽  
Comparison Results ◽  
High Consistency

The ecosystem-level fluxes of water vapour and carbon dioxide were measured from 2003 to 2006 at a tropical rain forest in Xishuangbanna, southwest China, using the eddy covariance (EC) technique. These flux measurements allowed the canopy-level evaluation of stomatal conductance (g) response to humidity models. The results showed that both the BWB model and the Leuning model discussed here underestimated g at high humidity and overestimated g at the mid-to-low range of humidity. In contrast, the Wang models discussed here (model-ha and model-Da) perfectly described the relationship of g response to humidity. The model comparison results also demonstrated high consistency over all the observation years. The good performance of the Wang model-ha and model-Da indicated that stomatal conductance responds more sensitively to humidity deficit or water vapour pressure deficit than to relative humidity itself at canopy level.

scholarly journals The contribution of PIP2-type aquaporins to photosynthetic response to increased vapour pressure deficit

2021 ◽  
Author(s):  
D Israel ◽  
S Khan ◽  
C R Warren ◽  
J J Zwiazek ◽  
T M Robson
Keyword(s):  
Vapour Pressure Deficit ◽  
Air Humidity ◽  
Wild Type ◽  
Knockout Mutant ◽  
Evaporative Demand ◽  
Co2 Transport ◽  
Whole Plant ◽  
Knockout Mutants ◽  
Leaf Level ◽  
Low Humidity

Abstract The roles of different plasma membrane aquaporins (PIPs) in leaf-level gas exchange of Arabidopsis thaliana were examined using knockout mutants. Since multiple Arabidopsis PIPs are implicated in CO2 transport across cell membranes, we focused on identifying the effects of the knockout mutations on photosynthesis, and whether they are mediated through the control of stomatal conductance of water vapour (gs), mesophyll conductance of CO2 (gm) or both. We grew Arabidopsis plants in low and high humidity environments and found that the contribution of PIPs to gs was larger under low air humidity when the evaporative demand was high, whereas any effect of lacking PIP function was minimal under higher humidity. The pip2;4 knockout mutant had 44% higher gs than the wild type plants under low humidity, which in turn resulted in an increased net photosynthetic rate (Anet). We also observed a 23% increase in whole-plant transpiration (E) for this knockout mutant. The lack of functional AtPIP2;5 did not affect gs or E, but resulted in homeostasis of gm despite changes of humidity, indicating a possible role in regulating CO2 membrane permeability. CO2 transport measurements in yeast expressing AtPIP2;5 confirmed that this aquaporin is indeed permeable to CO2.

Prevalence Rates for Medical Problems among Flautists: A Comparison of the UNT-Musician Health Survey and the Flute Health Survey

2001 ◽  
Vol 16 (3) ◽  
pp. 99-101
Author(s):  
Cari Spence
Keyword(s):  
Health Survey ◽  
Sleep Disturbances ◽  
Data Sets ◽  
Prevalence Rates ◽  
Medical Problems ◽  
North Texas ◽  
University Of North Texas ◽  
Left Hand ◽  
Significant Difference ◽  
The University

The purpose of this study was to identify prevalence rates of medical problems among flautists. The Flute Health Survey (FHS), a questionnaire with items regarding musculoskeletal and nonmusculoskeletal problems, was distributed at the 1999 National Flute Association annual meeting (n = 40). This questionnaire was pilot tested at the 1999 Texas Flute Festival, which is hosted by the Texas Flute Society. The University of North Texas has posted on the Internet a similar questionnaire regarding the medical problems of all musicians. Responses from the University of North Texas Musician Health Survey (UNT-MHS) were filtered to include only those respondents who denoted flute as their primary instruments (n = 328). Data sets from both surveys were then processed using comparative statistics. Findings show that there was no significant difference between the demographics of the two populations. Only one musculoskeletal site, the left hand, was found to be statistically significant between the two groups. Four nonmusculoskeletal items, depression, earache, headache, and sleep disturbances, were found to be different between the two groups. The overall findings of this comparison show that there are many medical problems facing the flute playing community. Further investigation and observations of this population are necessary.

Sign in / Sign up

Export Citation Format

Share Document