[⇓][1] 

SERIES “ATS/ERS TASK FORCE: STANDARDISATION OF LUNG FUNCTION TESTING” 

Edited by V. Brusasco, R. Crapo and G. Viegi 

Number 2 in this Series

 [1]: #F13

/pdf/standardisation-of-spirometry-1dkqxgifvl.pdf

Standardisation of spirometry

RELATIONSHIPS of soil water tension and hydraulic conductivity with soil water content are needed to quantify plant available water and to model the move-ment of water and solutes in and through soils. Field and laboratory measurement of these hydraulic soil proper-ties is very difficult, laborous, and costly. To provide the best estimates possible from previous analyses, a com-prehensive search of the literature and data sources for hydraulic conductivity and related soil-water data was made in 1978. From this search, data for 1,323 soils with about 5,350 horizons from 32 states were assembled. From the data, the Brooks and Corey water retention parameters, soil water retention volumes at 0.33 bar and 15 bar, total porosity, and saturated conductivities for the major USDA soil textures classes were developed. Also, relationships for predicting water retention volumes for particular tensions and saturated hydraulic conductivities based on soil properties are presented.

Estimation of Soil Water Properties

https://nicholas.duke.edu/people/faculty/katul/AFM_LAW_2002.pdf

Environmental controls over carbon dioxide and water vapor exchange of terrestrial vegetation

We review the current understanding of the temperature responses of C(3) and C(4) photosynthesis across thermal ranges that do not harm the photosynthetic apparatus. In C(3) species, photosynthesis is classically considered to be limited by the capacities of ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco), ribulose bisphosphate (RuBP) regeneration or P(i) regeneration. Using both theoretical and empirical evidence, we describe the temperature response of instantaneous net CO(2) assimilation rate (A) in terms of these limitations, and evaluate possible limitations on A at elevated temperatures arising from heat-induced lability of Rubisco activase. In C(3) plants, Rubisco capacity is the predominant limitation on A across a wide range of temperatures at low CO(2) (<300 microbar), while at elevated CO(2), the limitation shifts to P(i) regeneration capacity at suboptimal temperatures, and either electron transport capacity or Rubisco activase capacity at supraoptimal temperatures. In C(4) plants, Rubisco capacity limits A below 20 degrees C in chilling-tolerant species, but the control over A at elevated temperature remains uncertain. Acclimation of C(3) photosynthesis to suboptimal growth temperature is commonly associated with a disproportional enhancement of the P(i) regeneration capacity. Above the thermal optimum, acclimation of A to increasing growth temperature is associated with increased electron transport capacity and/or greater heat stability of Rubisco activase. In many C(4) species from warm habitats, acclimation to cooler growth conditions increases levels of Rubisco and C(4) cycle enzymes which then enhance A below the thermal optimum. By contrast, few C(4) species adapted to cooler habitats increase Rubisco content during acclimation to reduced growth temperature; as a result, A changes little at suboptimal temperatures. Global change is likely to cause a widespread shift in patterns of photosynthetic limitation in higher plants. Limitations in electron transport and Rubisco activase capacity should be more common in the warmer, high CO(2) conditions expected by the end of the century.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3040.2007.01682.x

The temperature response of C(3) and C(4) photosynthesis.

The principles, equipment and procedures for meas uring leaf and canopy gas exchange have been described previously as has chlorophyll fluores cence. Simultaneous measurement of the responses of leaf gas exchange and modulated chlorophyll fluorescence to light and C02 concentration now pro vide a means to determine a wide range of key bio chemical and biophysical limitations on photo synthesis in vivo. Here the mathematical frameworks and practical procedures for determining these par ameters in vivo are consolidated. Leaf C02 uptake (4) versus intercellular C02 concentration (Ci) curves may now be routinely obtained from commercial gas exchange systems. The potential pitfalls, and means to avoid these, are examined. Calculation of in vivo maximum rates of ribulose-1,5-b/sphosphate (RuBP) carboxylase/oxygenase (Rubisco) carboxylation (Vc,max)) electron transport driving regeneration of RuBP (Jmax), and triose-phosphate utilization (l^pu) are explained; these three parameters are now widely assumed to represent the major limitations to light saturated photosynthesis. Precision in determining these in intact leaves is improved by the simultan eous measurement of electron transport via modu lated chlorophyll fluorescence. The A/C, response also provides a simple practical method for quantify ing the limitation that stomata impose on C02 assimi lation. Determining the rate of photorespiratory release of oxygen (Rt) has previously only been pos sible by isotopic methods, now, by combining gas exchange and fluorescence measurements, R\ may be determined simply and routinely in the field. The physical diffusion of C02 from the intercellular air space to the site of Rubisco in 03 leaves has long been suspected of being a limitation on photosyn thesis, but it has commonly been ignored because of the lack of a practical method for its determination. Again combining gas exchange and fluorescence provides a means to determine mesophyll conduc tance. This method is described and provides insights into the magnitude and basis of this limita tion.

Gas exchange measurements, what can they tell us about the underlying limitations to photosynthesis? Procedures

A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

W. Gerrard

Papers

Effect of Temperature