THE INFLUENCE OF VAPOUR PRESSURE DEFICIT ON LEAF WATER RELATIONS OF COCOS NUCIFERA IN NORTHEAST BRAZIL

SUMMARYDaily courses of leaf gas exchange and leaf water potential (Ψleaf) of green dwarf coconut palm (Cocos nucifera) were measured in irrigated plantations on the wet coastal plateau and in a dry semi-arid area of northeast Brazil. At both sites, significant correlations were obtained between stomatal conductance (gs) and vapour pressure deficit (VPDair), Ψleaf and VPDair, leaf transpiration (E) and gs, and E-Ψleaf. Despite these similar relationships between sites, stronger correlations involving gs-VPDair and E-Ψleaf were found at the semi-arid site, where whole-plant hydraulic conductance (gp) was correlated significantly with VPDair. In addition, at the semi-arid site, only, the net photosynthesis (PN) was not correlated with E and Ψleaf, and the intrinsic water use efficiency (WUEi) was disconnected from VPDair and Ψleaf. The different behaviour of leaf gas exchange and Ψleaf between sites was probably caused by low gs in response to high VPDair at the semi-arid site. Our results indicate potential for significant alterations in the pattern of leaf gas exchange during future climatic changes with increasing temperature and concomitant increases in VPDair. The atmospheric water stress will probably reinforce the strength of connection among water relation variables (E, Ψleaf, gs, gp, and VPDair), but it will disrupt the linear relationship between net CO2 assimilation and leaf water relations such as PN-E, PN-Ψleaf, WUEi-VPDair and WUEi-Ψleaf.

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Interstock of ‘Valencia’ Orange Affects the Flooding Tolerance in ‘Verna’ Lemon Trees

HortScience ◽

10.21273/hortsci.47.3.403 ◽

2012 ◽

Vol 47 (3) ◽

pp. 403-409 ◽

Cited By ~ 11

Author(s):

Vicente Gimeno ◽

James P. Syvertsen ◽

Inma Simon ◽

Vicente Martinez ◽

Jose M. Camara-Zapata ◽

...

Keyword(s):

Gas Exchange ◽

Water Relations ◽

Leaf Gas Exchange ◽

Fruit Production ◽

Leaf Water ◽

Citrus Limon ◽

Flooding Tolerance ◽

Leaf Water Relations ◽

Chlorophyll Fluorescence Parameters ◽

Valencia Orange

Previous work on citrus trees has shown that an interstock, grafted between the rootstock and scion combination, not only can improve tree growth, longevity, fruit production, and quality, but also can increase salinity tolerance. This research was designed to evaluate flooding responses of 2-year-old ‘Verna’ lemon trees [Citrus limon (L.) Burm.; VL] either grafted on ‘Sour’ orange (C. aurantium L.; SO) rootstock without an interstock (VL/SO) or interstocked with ‘Valencia’ orange (C. sinensis Osbeck;VL/V/SO) or with ‘Castellano’ orange (C. sinensis Osbeck; VL/C/SO). Well-watered and fertilized trees were grown under greenhouse conditions and half were flooded for 9 days. At the end of the flooded period, leaf water relations, leaf gas exchange, chlorophyll fluorescence parameters, mineral nutrition, organic solutes, and carbohydrate concentrations were measured. Leaf water potential (Ψw), relative water content (RWC), net CO2 assimilation rate (ACO2), and stomatal conductance (gS) were decreased by flooding in all the trees but the greatest decreases occurred in VL/V/SO. The Ci/Ca (leaf internal CO2 to ambient CO2 ratio), Fv/Fo (potential activity of PSII) and Fv/Fm (maximum quantum efficiency) ratios were similar in flooded and non-flooded VL/SO and VL/C/SO trees but were decreased in VL/V/SO trees by flooding. Regardless of interstock, flooding increased root calcium (Ca), iron (Fe), copper (Cu), and manganese (Mn) concentration but decreased nitrogen (N) and potassium (K) concentration. Based on the leaf water relations, gas exchange, and chlorophyll parameters, ‘Verna’ lemon trees interstocked with ‘Valencia’ orange had the least flooding tolerance. Regardless of interstock, the detrimental effect of flooding in ‘Verna’ lemon trees was the leaf dehydration which decreased ACO2 as a result of non-stomatal factors. Lowered ACO2 did not decrease the leaf carbohydrate concentration. Flooding decreased root starch in all trees but more so in VL/V/SO trees. Sugars were decreased by flooding in roots of interstocked trees but were increased by flooding in VL/SO roots suggesting that the translocation of carbohydrates from shoots to roots under flooded condition was impaired in interstocked trees.

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Leaf Water Relations and Gas Exchange in Relation to Forage Production in Four Asiatic Bluestems 1

Crop Science ◽

10.2135/cropsci1982.0011183x002200050034x ◽

1982 ◽

Vol 22 (5) ◽

pp. 1036-1040 ◽

Cited By ~ 17

Author(s):

P. I. Coyne ◽

J. A. Bradford ◽

C. L. Dewald

Keyword(s):

Gas Exchange ◽

Water Relations ◽

Leaf Water ◽

Forage Production ◽

Leaf Water Relations

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LEAF GAS EXCHANGE IN TWO DWARF COCONUT GENOTYPES IN THE SOUTHEAST OF BAHIA STATE, BRAZIL.

CORD ◽

10.37833/cord.v18i02.362 ◽

2002 ◽

Vol 18 (02) ◽

pp. 34

Author(s):

Gomes, F.P. ◽

Mielke, M.S. ◽

Almeida, A. F. ◽

Muniz, W. S.

Keyword(s):

Gas Exchange ◽

Water Vapour ◽

Leaf Gas Exchange ◽

Cocos Nucifera ◽

Vapour Pressure Deficit ◽

Light Response ◽

Negative Influence ◽

Water Vapour Pressure ◽

Response Curves ◽

Palm Trees

Net photosynthetic (A) and leaf transpiration (E) rates and stomatal conductance to water vapour (gs) of Malayan Yellow Dwarf (MYD) and Brazilian Green Dwarf (BGD) coconut accessions (Cocos nucifera var. ‘nana’ L.) were studied and discussed in terms of the technical aspects related to light-response curves in field conditions. Measurements of gas exchange were performed during four days, in April and may 2000, at the Cocoa Research Center Experimental Station (Una - BA, Brazil). The A, gs and E parameters were significantly (P < 0.05) different between the two genotypes. The mean maximum values of A, gs and E were 10.4 and 12.0 µmol CO2 m-2 s-1, 0.21 and 0.35 mol H2O m-2 s-1 and 3.07 and 3.69 mmol m-2 s-1 for MYD and BGD, respectively. For both genotypes a good fitting of the light-response curve models were obtained, indicating that A and gs were dependent of the photosynthetically active radiation incident on leaf surface (Qi), in spite of high genotipic variation. Interesting results were achieved when an empirical multiplicative model was used. The model relating A or gs with Qi and with leaf-to-air water vapour pressure deficit inside the chamber (VPDL) was tested for both genotypes and showed a negative influence of the latter on the stomatal behavior and consequently on A. Such effect was more pronounced in BGD than in MYD. These and others relationships involving leaf gas exchange and microclimatic variables in coconut palm trees are discussed

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

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132005000600018 ◽

2005 ◽

Vol 48 (5) ◽

pp. 815-824 ◽

Cited By ~ 13

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.

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

Tree Physiology ◽

10.1093/treephys/tpz103 ◽

2019 ◽

Cited By ~ 1

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.

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