Stomatal compensation points for ammonia under field conditions



Stomatal compensation points for ammonia in oilseed rape plants under field conditions

by Husted S., Schjoerring J. K., Nielsen K. H., Nemitz E., Sutton M. A. (2000)

Søren HustedJan K. SchjoerringKent H. NielsenEiko NemitzMark A. Sutton

Søren Husted, Plant Nutrition Laboratory, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871 Frederiksberg C, Copenhagen, Denmark

Mark A. Sutton, Centre for Ecology and Hydrology, Edinburgh, Bush Estate, Penicuik, Midlothian EH26 OQB, UK


in Agricultural and Forest Meteorology 105(4): 371-383 – ISSN :0168-1923 –


Compensation points for gaseous exchange of ammonia (NH 3 ) between stomata and the atmosphere were determined in an oilseed rape (Brassica napus) canopy by analysing the concentrations of NH 4 + and H + in leaf apoplastic solution.

This bioassay approach was applied for the first time in the field, allowing the first intercomparison with compensation points derived from micrometeorological measurements.

Apoplastic NH 4 + and H + concentrations differed between leaf heights but values were relatively stable over time, both diurnally and during a 2-week period.

Stomatal NH 3 compensation points calculated on the basis of apoplastic NH 4 + and H + concentrations and corrected for ambient leaf temperatures were found to correlate positively with the net NH 3 emission from the canopy estimated by micrometeorological measurements. As there was little diurnal variability in apoplastic concentrations, this correlation was largely due to the effect of temperature on NH 3 solubility and NH 4 + dissociation in the apoplast, together with similar effects of temperature on the net NH 3 flux.

Very high NH 4 + concentrations were also found in extracts of fallen litter and resulted in NH 3 partial pressures significantly exceeding NH 3 levels in the atmosphere close to the ground. By comparison of vertical atmospheric NH 3 concentration profiles in the plant canopy with the stomatal NH 3 compensation points determined here at three different plant heights, as well as NH 3 partial pressures in the litter, it is shown that plant residues on the soil surface would have been the primary NH 3 source while attached leaves acted as an NH 3 sink.

Although it was not possible to measure apoplastic concentrations of siliques (seed cases), bulk tissue NH 4 + /H + concentrations and vertical atmospheric NH 3 concentration profiles indicate that these may have acted as an NH 3 source.


Is stomatal conductance optimized over both time and space in plant crowns?



Is stomatal conductance optimized over both time and space in plant crowns? A field test in grapevine (Vitis vinifera)

by Buckley T. N., Martorell S., Diaz‐Espejo A., Tomàs M., Medrano H. (xxxx)


THOMAS N. BUCKLEY, Faculty of Agriculture and Environment, The University of Sydney

SEBASTIA MARTORELL, Departament de Biologia, Universitat de les Illes Baleares

ANTONIO DIAZ‐ESPEJO, Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC)


 in Plant, Cell & Environment 37(12): 2707 – 2721 – DOI10.1111/pce.12343 –


Crown carbon gain is maximized for a given total water loss if stomatal conductance (gs) varies such that the marginal carbon product of water (∂A/∂E) remains invariant both over time and among leaves in a plant crown, provided the curvature of assimilation rate (A) versus transpiration rate (E) is negative.

We tested this prediction across distinct crown positions in situ for the first time by parameterizing a biophysical model across 14 positions in four grapevine crowns (Vitis vinifera), computing optimal patterns of gs and E over a day and comparing these to the observed patterns.

Observed water use was higher than optimal for leaves in the crown interior, but lower than optimal in most other positions. Crown carbon gain was 18% lower under measured gs than under optimal gs. Positive curvature occurred in 39.6% of cases due to low boundary layer conductance (gbw), and optimal gs was zero in 11% of cases because ∂A/∂E was below the target value at all gs.

Some conclusions changed if we assumed infinite gbw, but optimal and measured E still diverged systematically in time and space.

We conclude that the theory’s spatial dimension and assumption of positive curvature require further experimental testing.


Size and frequency of stomata and the capacity of stomata to react under conditions of dehydration.



Morphological observations on the leaf surface of Phaseolus vulgaris L. and their possible relationship to stomatal response.

by Aguirre J. F., Ruiz L. P., Kohashi-Shibata J., Trejo C. L., Acosta-Gallegos J. (1999)


  1. Colegio de Postgraduados, Instituto de Recursos Naturales, Montecillo Mécico, 56230.
  2. Instituto Nacional de ínspestigaciones Forestales y Agropecuarias (ÎNIFAP), Chapingo, México, 56230


in Annu. Rep. Bean Improvement Cooperative 42: 75-76 –

The main port for communication between plants and the atmosphere is through stomatal pores. The opening and closing of stomatal pores allow the plants to regulate gaseous exchange with the atmosphere controlling the intake of carbon dioxide and the loss of water vapour for transpiration.

The coordination to find the optimum point between the maximum carbon dioxide fixation for photosynthesis and the minimum loss of water has been the main problem faced by land plants since they colonised the earth surface.

The mechanisms behind the regulation of stomatal movements are not yet fully understood. However, they are elicited by a variety of environmental factors (light, atmospheric and soil humidity, wind, etc.) and also for a series of plant internal signals (hormones, ions, tissue water potential, etc).

Water soil availability has historically been recognised as the main environmental factor limiting crop productivity around the world. Therefore, it has been a challenge since to understand how plants regulate their internal water content (Boyer, 1982). Phaseolus vulgaris L. (common bean) has been recognised as very sensitive to drought and its yield may be significantly reduced by mild water stress.

Therefore, in this study the objective was to compare the leaf surface of three cultivars of Phaseolus vulgaris L. (surface topography, trichomes number and size and frequency of stomata) and to see whether these characteristics are related to the capacity of stomata to react under conditions of dehydration.

Chloride‐inducible transient apoplastic alkalinizations induce stomata closure



Chloride‐inducible transient apoplastic alkalinizations induce stomata closure by controlling abscisic acid distribution between leaf apoplast and guard cells in salt‐stressed Vicia faba

by Geilfus C._M., Mithöfer A., Ludwig‐Müller J., Zörb C., Muehling K. H. (xxxx)

Christoph‐Martin GeilfusAxel MithöferJutta Ludwig‐MüllerChristian ZörbKarl H. Muehling

Axel Mithöfer, Department Bioorganic Chemistry, Max Planck Institute for Chemical Ecology

Jutta Ludwig‐Müller, Institut für Botanik, Technische Universität Dresden

Christian Zörb, Quality of Plant Products, University Hohenheim

Karl H. Muehling, Institute of Plant Nutrition and Soil Science, Christian Albrechts University


in New Phytologist 208(3): 803 – 816 – DOI10.1111/nph.13507 –


  • Chloride stress causes the leaf apoplast transiently to alkalize, an event that is presumed to contribute to the ability of plants to adapt to saline conditions. However, the initiation of coordinated processes downstream of the alkalinization is unknown. We hypothesize that chloride‐inducible pH dynamics are a key chemical feature modulating the compartmental distribution of abscisic acid (ABA) and, as a consequence, affecting stomata aperture.
  • Apoplastic pH and stomata aperture dynamics in intact Vicia faba leaves were monitored by microscopy‐based ratio imaging and porometric measurements of stomatal conductance. ABA concentrations in leaf apoplast and guard cells were compared with pH dynamics by gas‐chromatography‐mass‐spectrometry (GC‐MS) and liquid‐chromatography–tandem‐mass spectrometry (LC‐MS/MS).
  • Results demonstrate that, upon chloride addition to roots, an alkalizing factor that initiates the pH dynamic propagates from root to leaf in a way similar to xylem‐distributed water. In leaves, it induces a systemic transient apoplastic alkalinization that causes apoplastic ABA concentration to increase, followed by an elevation of endogenous guard cell ABA.
  • We conclude that the transient alkalinization, which is a remote effect of chloride stress, modulates the compartmental distribution of ABA between the leaf apoplast and the guard cells and, in this way, is instrumental in inducing stomata closure during the beginning of salinity.

Stomatal size and intraspecific variation in the regulation of transpiration upon water deprivation

Photo credit: Google 

Rosa hybrida L 

Smaller stomata require less severe leaf drying to close: A case study in Rosa hydrida

by Giday H. , Kjaer K. H., Fanourakis D., Ottosen C.-O. (2013)

Habtamu GidayKatrine H. KjaerDimitrios FanourakisCarl-Otto Ottosen

Habtamu Giday, Århus University, Department of Food Science, Kirstinebjergvej 10, DK-5792 Årslev, Denmark

Dimitrios Fanourakis, IBG-2: Plant Sciences, Institute for Bio- and Geosciences, Forschungszentrum Jülich, 52425 Jülich, Germany


in Journal of Plant Physiology, 170(15): 1309 – 1316 – DOI10.1016/j.jplph.2013.04.007 –


Stomata formed at high relative air humidity (RH) close less as leaf dries; an effect that varies depending on the genotype.

We here quantified the contribution of each stomatal response characteristic to the higher water loss of high RH-grown plants, and assessed the relationship between response characteristics and intraspecific variation in stomatal size.

Stomatal size (length multiplied by width), density and responsiveness to desiccation, as well as pore dimensions were analyzed in ten rose cultivars grown at moderate (60%) or high (85%) RH. Leaf morphological components and transpiration at growth conditions were also assessed. High growth RH resulted in thinner (11%) leaves with larger area.

A strong positive genetic correlation of daytime and nighttime transpiration at either RH was observed. Stomatal size determined pore area (r=0.7) and varied by a factor of two, as a result of proportional changes in length and width.

Size and density of stomata were not related. Following desiccation, high RH resulted in a significantly lower (6–19%) decline of transpiration in three cultivars, whereas the relative water content (RWC) of high RH-expanded leaflets was lower (29–297%) in seven cultivars. The lower RWC of these leaflets was caused by (a) higher (33–72%) stable transpiration and/or (b) lower (12–143%) RWC at which this stable transpiration occurred, depending on the cultivar.

Stomatal size was significantly correlated with both characteristics (r=0.5 and -0.7, respectively).

These results indicate that stomatal size explains much of the intraspecific variation in the regulation of transpiration upon water deprivation on rose.

Chloroplast number in stomata guard cells as a distinctive character of Galinsoga species

Photo credit: Google

Galinsoga ciliata


Chloroplast number in stomata guard cells as a distinctive character of Galinsoga parviflora Pav. [2n-16] and Galinsoga ciliata [Rafin.] blake [2n-32]

by Budzan J. (1998)

Budzan J., Wroclaw University, Kanonia 6-8, 50-328 Wroclaw, Poland

inPrace Naukowe Uniwersytetu Śląskiego w Katowicach 1998: 1696 – ISSN :0208-6336 –

(No abstract found)

Mapping QTLs for stomatal density and size under drought stress



Mapping QTLs for stomatal density and size under drought stress in wheat (Triticum aestivum L.)

by Wang S.-g., Jia S.-s., Sun D.-z., Fan H., Chang X.-p., Jing R.-l. (2016)

Shu-guang WANG, Shou-shan JIA, Dai-zhen SUN, Hua FAN, Xiao-ping CHANG, Rui-lian JING

Shu-guang WANG, College of Agronomy, Shanxi Agricultural University, Taigu 030801, P.R.China

in Journal of Integrative Agriculture 15(9): 1955-1967 –