What determines the complex kinetics of stomatal conductance under blueless PAR in Festuca arundinacea? Subsequent effects on leaf transpiration

Estimating transpiration as an individual component of canopy evapotranspiration using a theoretical approach is extremely useful as it eliminates the complexity involved in partitioning evapotranspiration. A model to predict transpiration based on radiation intercepted at various levels of canopy leaf area index (LAI) was developed in a controlled environment using a pasture species, tall fescue (Festuca arundinacea var. Demeter). The canopy was assumed to be a composite of two indistinct layers defined as sunlit and shaded; the proportion of which was calculated by utilizing a weighted model (W model). The radiation energy utilized by each layer was calculated from the PAR at the top of the canopy and the fraction of absorbed photosynthetically active radiation (fAPAR) corresponding to the LAI of the sunlit and shaded layers. A relationship between LAI and fAPAR was also established for this specific canopy to aid the calculation of energy interception. Canopy conductance was estimated from scaling up of stomatal conductance measured at the individual leaf level. Other environmental factors that drive transpiration were monitored accordingly for each individual layer. The Penman–Monteith and Jarvis evapotranspiration models were used as the basis to construct a modified transpiration model suitable for controlled environment conditions. Specially, constructed self-watering tubs were used to measure actual transpiration to validate the model output. The model provided good agreement of measured transpiration (actual transpiration = 0.96 × calculated transpiration, R2 = 0.98; p < 0.001) with the predicted values. This was particularly so at lower LAIs. Probable reasons for the discrepancy at higher LAI are explained. Both the predicted and experimental transpiration varied from 0.21 to 0.56 mm h−1 for the range of available LAIs. The physical proportion of the shaded layer exceeded that of the sunlit layer near LAI of 3.0, however, the contribution of the sunlit layer to the total transpiration remains higher throughout the entire growing season.

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Different Light Radiation Intensities on Cotton: A Physiological Approach

Journal of Experimental Agriculture International ◽

10.9734/jeai/2019/v35i630220 ◽

2019 ◽

pp. 1-8

Author(s):

Lucas Aparecido Manzani Lisboa ◽

Fernando Takayuki Nakayama ◽

Edivaldo Cia ◽

Paulo Alexandre Monteiro de Figueiredo ◽

Sérgio Bispo Ramos ◽

...

Keyword(s):

Stomatal Conductance ◽

Block Design ◽

Co2 Concentration ◽

Co2 Assimilation ◽

Luminous Intensity ◽

Artificial Light ◽

Light Intensities ◽

Leaf Transpiration ◽

Randomized Complete Block Design ◽

Physiological Approach

The luminosity and the temperature are factors that act directly in the photosynthetic process, where an elevation of the luminous intensity can cause a reduction of the assimilation of carbon, which consequently lowers the development of the cotton. The objective of this work was to assess the response of physiological parameters of cotton when subjected to different artificial light intensities. Two varieties of cotton IMA5801B2RF and IACRDN, were interacting with five artificial light intensities: 0 (control); 500; 1000; 1500 and 2000 μmol m−2 s−1 of photosynthetically active radiation provided by LED bulbs. The experiment was set in a randomized complete block design using a 2x5 factorial scheme. The variables measured were the rate of CO2 assimilation, transpiration, stomatal conductance, inner CO2 concentration in the substomatic chamber, and efficient use of water (for which a portable device of gas exchange was used). The cotton varieties responded positively to different luminous intensities until reaching the point of maximum saturation between 1400 and 1600 µmol m-1 s-1 of light, which provided a better rate of CO2 assimilation, concentration of CO2 in the substomatic chamber, and efficient use of water. Leaf transpiration and stomatal conductance showed a positive linear response with increasing light intensity. The ideal luminous intensity for the use of Infra-Red Gas Analyzer - IRGA was 1500 µmol m-1 s-1 for the tested cotton varieties.

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Growth during recovery evidences the waterlogging tolerance of forage grasses

Crop and Pasture Science ◽

10.1071/cp17137 ◽

2017 ◽

Vol 68 (6) ◽

pp. 574 ◽

Cited By ~ 8

Author(s):

R. A. Ploschuk ◽

A. A. Grimoldi ◽

E. L. Ploschuk ◽

G. G. Striker

Keyword(s):

Stomatal Conductance ◽

Festuca Arundinacea ◽

Global Climate ◽

Leaf Gas Exchange ◽

Recovery Period ◽

Dactylis Glomerata ◽

Net Photosynthesis ◽

Forage Grasses ◽

Waterlogging Tolerance ◽

The Impact

Waterlogging is a stress of increasing importance for pastures as a consequence of global climate change. We evaluated the impact of waterlogging on four forage grasses with alleged differential tolerance, emphasising not only responses during the stress but also their reported ability to recover from it. To do this, 42-day plants of Dactylis glomerata, Bromus catharticus, Festuca arundinacea and Phalaris aquatica were subjected to 15-day waterlogging, followed by a subsequent 15-day recovery period. Shoot and root growth (i.e. RGR) during both periods, in addition to net photosynthesis and stomatal conductance rates during waterlogging were assessed. Sensitivity exhibited by D. glomerata and B. catharticus during waterlogging was related to growth arrest of roots – but not of shoots – along with a progressive fall in stomatal conductance and net photosynthesis. The injury during waterlogging preceded a negligible growth of shoots and roots, only evident during recovery in both species. By contrast, P. aquatica exhibited unaltered root RGR and promoted shoot RGR with no impact on leaf gas exchange during waterlogging; whereas F. arundinacea showed intermediate tolerance as root RGR was reduced during waterlogging, with stomatal conductance, net photosynthesis and shoot RGR remaining unaffected. These latter two species fully regained shoot and root RGR during recovery. So, P. aquatica and F. arundinacea seem more suitable for prone-to-flood lowlands, whereas to be conclusive about waterlogging tolerance, it is necessary to examine plant recovery as shown in D. glomerata and B. catharticus.

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The interplay between irrigation and fruiting on branch growth and mortality, gas exchange and water relations of coffee trees

Tree Physiology ◽

10.1093/treephys/tpaa116 ◽

2020 ◽

Author(s):

Wellington L Almeida ◽

Rodrigo T Ávila ◽

Junior P Pérez-Molina ◽

Marcela L Barbosa ◽

Dinorah M S Marçal ◽

...

Keyword(s):

Stomatal Conductance ◽

Gas Exchange ◽

Stomatal Density ◽

Leaf Gas Exchange ◽

Water Status ◽

Co2 Concentration ◽

Plant Hydraulics ◽

Branch Growth ◽

Source To Sink ◽

Leaf Transpiration

Abstract The overall coordination between gas exchanges and plant hydraulics may be affected by soil water availability and source-to-sink relationships. Here we evaluated how branch growth and mortality, leaf gas exchange and metabolism are affected in coffee (Coffea arabica L.) trees by drought and fruiting. Field-grown plants were irrigated or not, and maintained with full or no fruit load. Under mild water deficit, irrigation per se did not significantly impact growth but markedly reduced branch mortality in fruiting trees, despite similar leaf assimilate pools and water status. Fruiting increased net photosynthetic rate in parallel with an enhanced stomatal conductance, particularly in irrigated plants. Mesophyll conductance and maximum RuBisCO carboxylation rate remained unchanged across treatments. The increased stomatal conductance in fruiting trees over nonfruiting ones was unrelated to internal CO2 concentration, foliar abscisic acid (ABA) levels or differential ABA sensitivity. However, stomatal conductance was associated with higher stomatal density, lower stomatal sensitivity to vapor pressure deficit, and higher leaf hydraulic conductance and capacitance. Increased leaf transpiration rate in fruiting trees was supported by coordinated alterations in plant hydraulics, which explained the maintenance of plant water status. Finally, by preventing branch mortality, irrigation can mitigate biennial production fluctuations and improve the sustainability of coffee plantations.

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Xylem transport and shoot accumulation of lumichrome, a newly recognized rhizobial signal, alters root respiration, stomatal conductance, leaf transpiration and photosynthetic rates in legumes and cereals

New Phytologist ◽

10.1111/j.1469-8137.2004.01254.x ◽

2004 ◽

Vol 165 (3) ◽

pp. 847-855 ◽

Cited By ~ 26

Author(s):

V. N. Matiru ◽

F. D. Dakora

Keyword(s):

Stomatal Conductance ◽

Root Respiration ◽

Photosynthetic Rates ◽

Xylem Transport ◽

Leaf Transpiration

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Determination of damaged leaf area and physiological responses of melon plants submitted to different infestation levels of Liriomyza sativae

Horticultura Brasileira ◽

10.1590/s0102-053620170415 ◽

2017 ◽

Vol 35 (4) ◽

pp. 571-575 ◽

Cited By ~ 1

Author(s):

Ewerton M Costa ◽

Rômulo Magno O Freitas ◽

Paolo Augustus F Silva ◽

Elton Lucio Araujo

Keyword(s):

Stomatal Conductance ◽

Leaf Area ◽

Physiological Responses ◽

Co2 Concentration ◽

Internal Co2 Concentration ◽

Liriomyza Sativae ◽

Leaf Transpiration ◽

Rate Of Photosynthesis ◽

Internal Co2

ABSTRACT The leafminer Liriomyza sativae (Diptera: Agromyzidae) is one of the main pests of melon crop (Cucumis melo) in the Brazilian semiarid. The aims of this study were to determine the damaged leaf area and assess the physiological responses of melon plants submitted to different levels of infestation per larvae of L. sativae. The study was carried out in a greenhouse, using plants of melon of the cultivar Iracema (yellow melon). The design utilized was completely randomized, with five treatments {control (no infestation in the leaves) and four infestation levels (1; 10; 20 and 30 larvae per leaf)} and 10 replications (melon plants). Initially we evaluated the physiological aspects: photosynthetic rate (µmol CO2/m2/s), stomatal conductance (mol H2O/m2/s) internal CO2 concentration (µmol CO2/m2) and leaf transpiration (mmol H2O/m2/s). After the measurements of physiological aspects, the evaluated leaves of each plant were cut close to the petiole and scanned individually with a measuring scale on the side, being the determination of the damaged leaf area performed with the aid of software for processing and analysis of images. The averages of damaged leaf area observed were of 1.2; 6.3; 19.6 and 40.8 cm2 for infestations of 1; 10; 20 and 30 larvae/leaf respectively. In relation to the physiological aspects, the rate of photosynthesis, stomatal conductance and transpiration significantly decreased with the increase of leafminer larvae per leaf. The internal CO2 concentration increased with the increase in the number of larvae per leaf.

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Kaolin Particle Film Applications Can Increase Photosynthesis and Water Use Efficiency of `Ruby Red' Grapefruit Leaves

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.128.1.0107 ◽

2003 ◽

Vol 128 (1) ◽

pp. 107-112 ◽

Cited By ~ 58

Author(s):

John L. Jifon ◽

James P. Syvertsen

Keyword(s):

Stomatal Conductance ◽

Water Use Efficiency ◽

Water Use ◽

Leaf Temperature ◽

Citrus Paradisi ◽

Photoinhibition Of Photosynthesis ◽

High Radiation ◽

Leaf Transpiration ◽

Partial Pressures ◽

Use Efficiency

Effects of foliar sprays of a kaolin clay particle film (Surround WP) on leaf temperature (Tlf), net gas exchange, chlorophyll fluorescence and water relations of sun-exposed leaves on field-grown grapefruit trees (Citrus paradisi L.) were studied during Summer and Fall 2001. Trees were sprayed twice a week for 3 weeks with aqueous suspensions of kaolin (Surround) at 60 g·L-1. Physiological effects of kaolin application were most prominent around midday on warm sunny days than in mornings, evenings or cloudy days. Kaolin sprays increased leaf whiteness (62%), reduced midday leaf temperature (Tlf; ≈3 °C) and leaf to air vapor pressure differences (VPD; ≈20%) compared to water-sprayed control leaves. Midday reductions in Tlf and VPD were accompanied by increased stomatal conductance (gs) and net CO2 assimilation rates (ACO2) of kaolin sprayed leaves, suggesting that gs might have limited ACO2 in water-sprayed control leaves. Midday photoinhibition of photosynthesis was 30% lower in kaolin-sprayed leaves than in control leaves. Midday water use efficiency (WUE) of kaolin-sprayed leaves was 25% higher than that of control leaves. However, leaf transpiration and whole-tree water use were not affected by kaolin film sprays. Increased WUE was therefore, due to higher ACO2. Leaf intercellular CO2 partial pressures (Ci) were similar in control and kaolin-sprayed leaves indicating that stomatal conductance was not the major cause of reduced ACO2. These results demonstrate that kaolin sprays could potentially increase grapefruit leaf carbon uptake efficiency under high radiation and temperature stress.

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Variations in leaf temperature, plant internal resistance, photon requirement and transpiration of pigeonpea under bare and mulched soil conditions

MAUSAM ◽

10.54302/mausam.v47i4.3762 ◽

2021 ◽

Vol 47 (4) ◽

pp. 419-424

Author(s):

A. CHOWDHURY ◽

H. P. DAS ◽

R. P. SAMUI ◽

A. M. SHEIKH

Keyword(s):

Stomatal Conductance ◽

Stomatal Resistance ◽

Internal Resistance ◽

Leaf Temperature ◽

Soil Conditions ◽

Crop Canopy ◽

Leaf Transpiration ◽

Diffusive Resistance

ABSTRACT. The paper presents the results of an experiment conducted during 1992 and 1993 crop seasons at the farm of Gujarat Agricultural University, Anand on pigeonpea to determine variations in agro-meteorological characteristics of leaf transpiration leaf temperature plant diffusive resistance and quanta were considered at three levels within the crop canopy in mulched and unmulched fields. The anlilysis rewaled that leaf temperature is more in unmulched field where transpiration rates are lower than the mulched field. Stomatal resistance and the quantum requirements nearly match in both the treatments. Stomatal conductance attains large values in morning and evening hours.

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