Simultaneous Effects of Foliar Nitrogen, Temperature, and Humidity on Gas Exchange in Pinus radiata

1995 ◽  
Vol 22 (4) ◽  
pp. 615 ◽  
Author(s):  
DW Sheriff ◽  
JP Mattay
Keyword(s):  
Gas Exchange ◽  
Pinus Radiata ◽  
Vapour Pressure ◽  
Measurement Data ◽  
Carbon Assimilation ◽  
Vapour Pressure Deficit ◽  
Leaf Temperature ◽  
Carbon Gain ◽  
Foliar Nitrogen ◽  
Foliar N

Seedlings of Pinus radiata were grown in a glasshouse in large pots with sand as the potting mix. They were kept well-watered and frequently supplied with nutrient solutions which contained different amounts of nitrogen for different treatments. Carbon assimilation and diffusive conductance of the foliage were measured under steady-state conditions at saturating light in all treatments. Experimental variables were leaf-air vapour pressure difference and leaf temperature at time of measurement. Data were fitted to a non-linear regression equation to examine responses of carbon assimilation, diffusive conductance, transpiration, assimilatory nitrogen-use efficiency, and assimilatory transpiration efficiency to foliar nitrogen concentration expressed on a leaf area basis ([N]), to leaf temperature, and to leaf-air vapour pressure (D). Parameters from the regression have been used to plot three-dimensional surfaces, so that simultaneous effects of experimental variables can be easily visualised. Carbon assimilation increased linearly with foliar [N], declined exponentially as D increased, and had a broad temperature optimum between c. 14 and 38�C. Diffusive conductance increased linearly with foliar [N], was related to the reciprocal of D, and declined as temperature increased. Using climatic vapour pressure deficit and air temperature data for Canberra, ACT, and for Mount Gambier, SA, and with the functions that had been fitted to experimental data, it was found that these regional climatic differences have potential for appreciably affecting carbon gain and water loss in the regions, which have P. radiata plantations. Predicted differences in carbon gain are of the order of reported differences in stem growth in the regions. This shows the need to take into account regional variation in climatic variables that strongly affect gas exchange when investigating regional differences in productivity.

Gas Exchange of Field-Grown Pinus radiata - Relationships With Foliar Nutrition and Water Potential, and With Climatic Variables

1995 ◽  
Vol 22 (6) ◽  
pp. 1015 ◽  
Author(s):  
DW Sheriff
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Flux Density ◽  
Pinus Radiata ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux

Gas exchange measurements were conducted on Pinus radiata to investigate relationships between these and leaf-air vapour pressure deficit, photosynthetic photon flux density, and foliar temperature, water potential and nutrition in the field. Multiple non-linear regressions indicated strong relationships between gas exchange and foliar [P] (but of no other nutrient), leaf-air vapour pressure deficit, photosynthetic photon flux density, foliar water potential and temperature. The final regression produced for relationships between gas exchange and these variables explained 81% of the variance in the data. Micro-climate and foliar data from another site were used to predict gas exchange using the regressions and calculated parameters. Good agreement was obtained between the predicted values and carbon assimilation measured at that site. The relationship was poorer for leaf conductance.

scholarly journals Photosynthetic traits of five neotropical rainforest tree species: interactions between light response curves and leaf-to-air vapour pressure deficit

2005 ◽  
Vol 48 (5) ◽  
pp. 815-824 ◽  
Author(s):  
Marcelo Schramm Mielke ◽  
Alex-Alan Furtado de Almeida ◽  
Fábio Pinto Gomes
Keyword(s):  
Gas Exchange ◽  
Mathematical Models ◽  
Tree Species ◽  
Vapour Pressure ◽  
Leaf Gas Exchange ◽  
Vapour Pressure Deficit ◽  
Light Response ◽  
Photon Flux ◽  
Neotropical Rainforest ◽  
Photosynthetic Traits

Measurements of leaf gas exchange at different photosynthetic photon flux density (PPFD) levels were conducted in order to compare the photosynthetic traits of five neotropical rainforest tree species, with a special emphasis on empirical mathematical models to estimate the light response curve parameters incorporating the effects of leaf-to-air vapour pressure deficit (D) on the saturated photosynthetic rate (Amax). All empirical mathematical models seemed to provide a good estimation of the light response parameters. Comparisons of the leaf photosynthetic traits between different species needed to select an appropriate model and indicated the microenvironmental conditions when the data were collected. When the vapour pressure deficit inside the chamber was not controlled, the incorporation of linear or exponencial functions that explained the effects of D on leaf gas exchange, was a very good method to enhance the performance of the models.

Incorporating non-stomatal limitation improves the performance of leaf and canopy models at high vapour pressure deficit

2019 ◽  
Author(s):  
J Yang ◽  
R A Duursma ◽  
M G De Kauwe ◽  
D Kumarathunge ◽  
M Jiang ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Primary Production ◽  
Vapour Pressure ◽  
Leaf Gas Exchange ◽  
Gross Primary Production ◽  
Vapour Pressure Deficit ◽  
Stomatal Limitation ◽  
Flow Measurements ◽  
Hydraulic Limitation ◽  
The Future

Abstract Vapour pressure deficit (D) is projected to increase in the future as temperatures rise. In response to increased D, stomatal conductance (gs) and photosynthesis (A) are reduced, which may result in significant reductions in terrestrial carbon, water, and energy fluxes. It is thus important for gas exchange models to capture the observed responses of gs and A with increasing D. We tested a series of coupled A-gs models against leaf gas exchange measurements from the Cumberland Plain Woodland (Australia), where D regularly exceeds 2 kPa and can reach 8 kPa in summer. Two commonly used A-gs models (Leuning 1995 and Medlyn et al. 2011) were not able to capture the observed decrease in A and gs with increasing D at the leaf scale. To explain this decrease in A and gs, two alternative hypotheses were tested: hydraulic limitation (i.e., plants reduce gs and/or A due to insufficient water supply) and non-stomatal limitation (i.e., downregulation of photosynthetic capacity). We found that the model that incorporated a non-stomatal limitation captured the observations with high fidelity and required the fewest number of parameters. While the model incorporating hydraulic limitation captured the observed A and gs, it did so via a physical mechanism that is incorrect. We then incorporated a non-stomatal limitation into the stand model, MAESPA, to examine its impact on canopy transpiration and gross primary production. Accounting for a non-stomatal limitation reduced the predicted transpiration by ~19%, improving the correspondence with sap flow measurements, and gross primary production by ~14%. Given the projected global increases in D associated with future warming, these findings suggest that models may need to incorporate non-stomatal limitation to accurately simulate A and gs in the future with high D. Further data on non-stomatal limitation at high D should be a priority, in order to determine the generality of our results and develop a widely applicable model.

Genotype-dependent influence of night-time vapour pressure deficit on night-time transpiration and daytime gas exchange in wheat

2014 ◽  
Vol 41 (9) ◽  
pp. 963 ◽  
Author(s):  
Rémy Schoppach ◽  
Elodie Claverie ◽  
Walid Sadok
Keyword(s):  
Gas Exchange ◽  
Drought Tolerance ◽  
Strong Correlation ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Preliminary Evidence ◽  
Night Time ◽  
Drought Tolerant ◽  
Triticum Spp ◽  
Semiarid Areas

In crop plants, accumulating evidence indicates non-marginal night-time transpiration (TRNight) that is responsive to environmental conditions, especially in semiarid areas. However, the agronomical advantages resulting from such phenomenon remain obscure. Recently, drought-tolerance strategies directly stemming from daytime TR (TRDay) responses to daytime vapour pressure deficit VPD (VPDDay) were identified in wheat (Triticum spp.), but the existence of similar strategies resulting from TRNight response to night-time VPD (VPDNight) remains to be investigated, especially that preliminary evidence on this species indicates that TRNight might be responsive to VPDNight. Our study aims at investigating such strategies among a group of diverse lines including drought-tolerant genotypes. The study revealed that: (i) TRNight can be as high as 55% that of the maximal TRDay; (ii) VPDNight is the major driver of TRNight in a genotype-dependent fashion and has an impact on following daytime gas exchange; and (iii) a strong correlation exists between TR sensitivities to VPD under night-time and daytime conditions, revealing that tolerance strategies such as conservative water use do also exist under night-time environments. Overall, this report opens the way to further phenotyping and modelling work aiming at assessing the potential of using TRNight as a trait in breeding new drought-tolerant germplasm.

Does increased air humidity affect stomatal morphology and functioning in hybrid aspen?

Botany ◽  
2015 ◽  
Vol 93 (4) ◽  
pp. 243-250 ◽  
Author(s):  
Aigar Niglas ◽  
Meeli Alber ◽  
Kristi Suur ◽  
Anna K. Jasińska ◽  
Priit Kupper ◽  
...  
Keyword(s):  
Vapour Pressure ◽  
Stomatal Density ◽  
Vapour Pressure Deficit ◽  
Carbon Gain ◽  
Hybrid Aspen ◽  
Air Humidity ◽  
Response Curves ◽  
Opposite Pattern ◽  
Stomatal Morphology ◽  
Stomatal Sensitivity

The study investigated the effects of exposure to increased relative air humidity (RH) on stomatal morphology and sensitivity to stomata closure inducing stimulus (low RH) in hybrid aspen (Populus tremula L. × P. tremuloides Michx.) coppice growing in field conditions. Artificially elevated RH reduced air vapour pressure deficit by 5%–10% and altered stomatal sensitivity; trees grown under high RH exhibited stronger stomatal response to decreasing air humidity. We found no difference in mean stomatal pore length between treatments and a small decline in stomatal density under humidification. The lack of correlation between stomatal sensitivity and morphological traits suggests that stomatal sensitivity was unaffected by stomatal morphology. In light of rising atmospheric humidity predicted for high latitudes, strict stomatal control over water loss might be beneficial for trees if drought events become more frequent in the future. However, our experiment revealed that about two-thirds of the leaf-to-air vapour pressure difference (VPDL) response curves demonstrated the opposite pattern, i.e., stomatal opening in response to increasing VPDL. Strict stomatal regulation is probably not beneficial to fast-growing aspen coppice under low RH, as this trait may restrict their carbon gain and growth rate.

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