scholarly journals Stomatal and non-stomatal limitations to photosynthesis of Populus euphratica Oliv. leaves in an extremely arid area of northwestern China

2019 ◽  
Author(s):  
Guanlong Gao ◽  
Qi Feng ◽  
Xiande Liu

Abstract On the basis of successive measurements of leaf gas exchange during the main growing seasons of Populus euphratica Oliv. in 2013 and 2014, respectively, we analyzed the stomatal and non-stomatal limitations to photosynthesis under natural conditions in an extremely arid region of northwestern China. Our results showed that (1) the distribution patterns of net photosynthesis (Pn) and stomatal conductance (gs) were similar, both of which increased in the morning, peaked at around noon, and then decreased. This contrasted with the observed changes in sub-stomatal CO2 concentrations (Ci). (2) The phenomenon of midday depression of photosynthesis (MDP) was obvious from July to September during the two years. At the beginning of MDP, the stomatal limitation to photosynthesis (Ls) peaked, where its predominance was supported by Ci being at a minimum. Thereafter, Ls decreased and Ci/gs increased sharply, indicating that the non-stomatal limitation to photosynthesis predominated. (3) Both the Ls and relative stomatal limitation to photosynthesis (RLs) increased in the morning, and then decreased, whereas Ci/gs presented contrary changes. (4) The RLs values were greater than the Ls values, which was mainly due to the nonlinearity of the Pn/Ci curve, which often leads to large overestimations. (5) The Ls values in our study were much greater than those from other studies under natural conditions. The most probable reason was that the extremely high temperature and scarce water resource caused the stomata to close to reduce transpiration, resulting in the stomatal limitation to photosynthesis being more intense.

1992 ◽  
Vol 22 (9) ◽  
pp. 1387-1394 ◽  
Author(s):  
C.A. Maier ◽  
R.O. Teskey

Leaf gas exchange and water relations were monitored in the upper canopy of two 25 m tall eastern white pine (Pinusstrobus L.) trees over two consecutive growing seasons (1986 and 1987). Examination of the seasonal and diurnal patterns of net photosynthesis and leaf conductance showed that both internal and external (environmental) factors were controlling net photosynthesis and leaf conductance. Internal control was indicated by a rapid increase and then decrease in the photosynthetic capacity of 1-year-old foliage during the development and maturation of current-year foliage, which was independent of environmental conditions. Large differences in net photosynthesis were observed between growing seasons due to seasonal differences in soil water availability, as indexed by predawn xylem pressure potential. Water stress reduced the maximum rate of net photosynthesis and altered the response of net photosynthesis and leaf conductance to absolute humidity deficit.


2017 ◽  
Author(s):  
Zhiguo XUE ◽  
Zhenxing SHEN ◽  
Wei HAN ◽  
Shanyang XU ◽  
Xiaohua MA ◽  
...  

Floating dust weather is an annual natural phenomenon in early spring in south of Xinjiang UygurAutonomous Region, northwestern China. Floating dust in air can influence human health and plant growth. Populus euphratica is a rare tree species which can grow in hot and dry conditions. Some investigations have evaluated the effect of floating dust on plants by means of artificial dust to which simulates the natural sand and dust, but the mechanism by which plants respond to sand is poorly understood. The investigation presented in this paper focused on a comparison of the variation in net photosynthetic rate (Pn) before and during floating dust weather, to elucidate the mechanisms involved. Stomatal conductance (gs) and Pn appeared to increase during floating dust weather;in contrast, stomatal limitation (Ls) and non-stomatal limitation (Lns) decreased with photosynthetic active radiation in the range 500 to 2000 μmol m−2s−1,which is optimum for plant growth. Aerosol ions, including potassium, dissolved in water collected by foliar structures or tender stems, may come into contact with intercellular stroma and improve chloroplast activity or ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) levels, such as potassium, thereby influencing Ls and Lns. Moreover, potassium, phosphorus, nitrogen and sodium in aerosols appeared to increase Pn, and this may be due to nutrient compounds in aerosols, which may have a similar effect to spraying fertilizer on leaves. In addition, the high relative humidity and carbon dioxide concentration in air during floating dust weather may facilitate an increase in Pn.


2017 ◽  
Author(s):  
Zhiguo XUE ◽  
Zhenxing SHEN ◽  
Wei HAN ◽  
Shanyang XU ◽  
Xiaohua MA ◽  
...  

Floating dust weather is an annual natural phenomenon in early spring in south of Xinjiang UygurAutonomous Region, northwestern China. Floating dust in air can influence human health and plant growth. Populus euphratica is a rare tree species which can grow in hot and dry conditions. Some investigations have evaluated the effect of floating dust on plants by means of artificial dust to which simulates the natural sand and dust, but the mechanism by which plants respond to sand is poorly understood. The investigation presented in this paper focused on a comparison of the variation in net photosynthetic rate (Pn) before and during floating dust weather, to elucidate the mechanisms involved. Stomatal conductance (gs) and Pn appeared to increase during floating dust weather;in contrast, stomatal limitation (Ls) and non-stomatal limitation (Lns) decreased with photosynthetic active radiation in the range 500 to 2000 μmol m−2s−1,which is optimum for plant growth. Aerosol ions, including potassium, dissolved in water collected by foliar structures or tender stems, may come into contact with intercellular stroma and improve chloroplast activity or ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) levels, such as potassium, thereby influencing Ls and Lns. Moreover, potassium, phosphorus, nitrogen and sodium in aerosols appeared to increase Pn, and this may be due to nutrient compounds in aerosols, which may have a similar effect to spraying fertilizer on leaves. In addition, the high relative humidity and carbon dioxide concentration in air during floating dust weather may facilitate an increase in Pn.


1997 ◽  
Vol 29 (1) ◽  
pp. 67-82 ◽  
Author(s):  
L. G. Sancho ◽  
B. Schroeter ◽  
F. Valladares

AbstractNet photosynthesis (NP) and dark respiration (DR) of thalli of the lichen species Umbilicaria grisea and U. freyi growing together in the same habitat the Sierra de Guadarrama, central Spain, were measured under controlled conditions in the laboratory and under natural conditions in the field over a range of photosynthetic photon flux densities (PPFD), thallus temperatures and thallus water contents. Laboratory experiments revealed that the photosynthetic response to PPFD at optimum thallus water content is very similar in both species. The light compensation points of NP increased from PPFD of c. 20 µmol m−2 s−1 at 0°C up to c. 100 µmol m−2 s−1 PPFD at 25°C. In both species light saturation was not reached up to 700 µmol m−2 s−1 PPFD except at 0°C. By contrast, the temperature dependence of CO2 gas exchange differed substantially between U. grisea and U. freyi. Both species gave significant rates at 0°C. Optimal temperatures of NP were always higher in U. grisea at various PPFD levels if the samples were kept at optimal thallus water content. NP showed maximal rates at 95% dw in U. grisea and 110% dw in U. freyi respectively. In U. grisea a much stronger depression of NP was observed with only 5% of maximal NP reached at 180% dw. At all PPFD and temperature combinations U. freyi showed higher rates of NP and more negative rates of DR if calculated on a dry weight basis. This was also true under natural conditions at the same site, when U. freyi was always more productive than U. grisea. The differences in the photosynthetic response to temperature between both species correlated well with the different distribution patterns of both species. The possibility of genetic control of the physiological performance of these species and its influence on their distribution patterns and autecology is discussed.


1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.


2013 ◽  
Vol 51 (3) ◽  
pp. 321-329 ◽  
Author(s):  
J. Y. Li ◽  
C. Y. Zhao ◽  
J. Li ◽  
Y. Y. Yan ◽  
B. Yu ◽  
...  

2020 ◽  
pp. 611-615
Author(s):  
Bo Liu ◽  
Rainer W. Bussmann

Author(s):  
J Yang ◽  
R A Duursma ◽  
M G De Kauwe ◽  
D Kumarathunge ◽  
M Jiang ◽  
...  

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.


2020 ◽  
Vol 40 (11) ◽  
pp. 1561-1571 ◽  
Author(s):  
Martina Pollastrini ◽  
Elisabetta Salvatori ◽  
Lina Fusaro ◽  
Fausto Manes ◽  
Riccardo Marzuoli ◽  
...  

Abstract A chlorophyll fluorescence (ChlF) assessment was carried out on oak seedlings (Quercus ilex L., Quercus pubescens Willd., Quercus frainetto Ten.) of Italian and Greek provenance, during the years 2017 and 2018, in a common garden in central Italy planted in 2017. This trial aimed to test the relative performances of the oak species in the perspective of assisted migration as part of the actions for the adaptation of forests to climate change. The assessment of the photosynthetic performance of the tree species included the analysis of the prompt chlorophyll fluorescence (PF) transient and the modulated reflection (MR) at 820 nm, leaf chlorophyll content, leaf gas exchange (net photosynthesis, stomatal conductance), plant growth (i.e., height) and mortality rate after 2 years from the beginning of the experiment. The assessment of the performance of the three oak species was carried out ‘in vivo’. Plants were generated from seeds and exposed to several environmental factors, including changing seasonal temperature, water availability, and soil biological and physical functionality. The results of PF indicate a stable functionality of the photosynthetic system PSII (expressed as FV/FM) across species and provenances and a decline in photochemistry functionality at the I–P phase (ΔVIP) in Q. frainetto, thus indicating a decline of the content of PSI in this species. This result was confirmed by the findings of MR analysis, with the speed of reduction and subsequent oxidation of PSI (VRED and VOX) strongly correlated to the amplitude of ΔVIP. The photosynthetic rates (net photosynthesis, PN) and growth were correlated with the parameters associated with PSI content and function, rather than those related to PSII. The low performance of Q. frainetto in the common garden seems to be related to early foliar senescence with the depletion of nitrogen, due to suboptimal climatic and edaphic conditions. Chlorophyll fluorescence allowed discrimination of populations of oak species and individuation of the less (or/and best) suitable species for future forest ecology and management purposes.


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