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Asargew MF, Masutomi Y, Kobayashi K, Aono M. Water stress changes the relationship between photosynthesis and stomatal conductance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167886. [PMID: 37858817 DOI: 10.1016/j.scitotenv.2023.167886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/07/2023] [Accepted: 10/15/2023] [Indexed: 10/21/2023]
Abstract
Understanding the relationship between stomatal conductance (gs) and photosynthesis (An) under water stress conditions can improve the accuracy of land surface models for estimating the gas exchange of crop canopies with the atmosphere. However, little is known about the effect of water stress on this relationship in crops. A glasshouse experiment was, therefore, conducted to investigate changes in the linear relationship between gs and An owing to water stress in rice and the association with soil moisture content. Severe (SWS), mild (MWS), and no water stress (NWS) conditions were applied from flowering onwards and the gas exchange in fully developed flag leaves was assessed weekly. The Ball-Woodrow-Berry linear model was used to assess the relationship between gs and An under different treatments. SWS had a significant effect and reduced the slope of the linear relationship between gs and An by 30 % compared with NWS. Only in SWS were An and gs strongly correlated with soil water content. Our study revealed that changes in the linear relationship through a reduction in the slope imply a conservative water-use strategy for rice under intense water stress. We propose that crop models that use the linear relationship should consider the impact of water stress conditions when simulating yields and estimating CO2 and H2O fluxes from crop canopies.
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Affiliation(s)
- Mihretie Fekremariam Asargew
- Center for Climate Change Adaptation, National Institute for Environmental Studies, Tsukuba, Japan; Agriculture and Food, CSIRO, Black Mountain, 2-40 Clunies Ross Street, Acton, ACT 2601, Australia.
| | - Yuji Masutomi
- Center for Climate Change Adaptation, National Institute for Environmental Studies, Tsukuba, Japan.
| | - Kazuhiko Kobayashi
- Center for Climate Change Adaptation, National Institute for Environmental Studies, Tsukuba, Japan
| | - Mitsuko Aono
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Japan
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Gutiérrez-Gordillo S, García-Tejero IF, Durán Zuazo VH, Diaz-Espejo A, Hernandez-Santana V. The effect of nut growth limitation on triose phosphate utilization and downregulation of photosynthesis in almond. TREE PHYSIOLOGY 2023; 43:288-300. [PMID: 36250574 DOI: 10.1093/treephys/tpac122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023]
Abstract
There is a controversy regarding when it is appropriate to apply the irrigation restriction in almond trees (Prunus dulcis Mill.) to save water without penalizing yield. We hypothesized that knowing when plants demand fewer photoassimilates would be a good indicator of less sensitivity of the crop to water deficit. One parameter that defines the photosynthetic capacity is the triose phosphate utilization (TPU). Due to its connection to the export of sugars from the leaves to other sink organs, it is a good candidate for being such an indicator. The objective was to analyze the seasonal evolution of the photosynthetic capacity of three almond cultivars (cvs Guara, Marta and Lauranne) subjected to water stress during vegetative, kernel-filling and postharvest stages. Two sustained deficit irrigation (SDI) treatments (SDI75 and SDI65 with water reductions of 25 and 35%, respectively) and a control treatment (FI) consisting of fully irrigated trees were applied. The response of curves AN-Ci was analyzed to assess the maximum carboxylation rate (Vcmax), maximum rate of electron transport (Jmax), TPU and mesophyll conductance to CO2. In addition, leaf water potential and yield were measured. Our experimental findings showed any significant differences in the variables analyzed among cultivars and irrigation treatments. However, consistent differences arose when the results were compared among the phenological stages. During the kernel-filling and the postharvest stages, a progressive limitation by TPU was measured, suggesting that the demand for photoassimilates by the plant was reduced. This result was supported by the correlation found between TPU and fruit growth rate. As a consequence, a downregulation in Jmax and Vcmax was also measured. This study confirms that the kernel-filling stage might be a good time to apply a reduction in the irrigation and suggests a method to detect the best moments to apply a regulated deficit irrigation in almond trees.
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Affiliation(s)
- S Gutiérrez-Gordillo
- IFAPA Centro "Las Torres", Carretera Sevilla-Cazalla Km 12.2, 41200 Sevilla, Alcalá del Río, Spain
| | - I F García-Tejero
- IFAPA Centro "Las Torres", Carretera Sevilla-Cazalla Km 12.2, 41200 Sevilla, Alcalá del Río, Spain
| | - V H Durán Zuazo
- IFAPA Centro "Camino de Purchil", Camino de Purchil s/n, 18004 Granada, Spain
| | - A Diaz-Espejo
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avda Reina Mercedes 10, 41012 Sevilla, Spain
| | - V Hernandez-Santana
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avda Reina Mercedes 10, 41012 Sevilla, Spain
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Bermudez R, Stefanski A, Montgomery RA, Reich PB. Short- and long-term responses of photosynthetic capacity to temperature in four boreal tree species in a free-air warming and rainfall manipulation experiment. TREE PHYSIOLOGY 2021; 41:89-102. [PMID: 32864704 DOI: 10.1093/treephys/tpaa115] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
High latitude forests cope with considerable variation in moisture and temperature at multiple temporal scales. To assess how their photosynthetic physiology responds to short- and long-term temperature variation, we measured photosynthetic capacity for four tree species growing in an open-air experiment in the boreal-temperate ecotone `Boreal Forest Warming at an Ecotone in Danger' (B4WarmED). The experiment factorially manipulated temperature above- and below-ground (ambient, +3.2 °C) and summer rainfall (ambient, 40% removal). We measured A/Ci curves at 18, 25 and 32 °C for individuals of two boreal (Pinus banksiana Lamb., Betula papyrifera Marsh.) and two temperate species (Pinus strobus L., Acer rubrum L.) experiencing the long-term warming and/or reduced-rainfall conditions induced by our experimental treatments. We calculated the apparent photosynthetic capacity descriptors VCmax,Ci and Jmax,Ci and their ratio for each measurement temperate. We hypothesized that (i) VCmax,Ci and Jmax,Ci would be down-regulated in plants experiencing longer term (e.g., weeks to months) warming and reduced rainfall (i.e., have lower values at a given measurement temperature), as is sometimes found in the literature, and that (ii) plants growing at warmer temperatures or from warmer ranges would show greater sensitivity (steeper slope) to short-term (minutes to hours) temperature variation. Neither hypothesis was supported as a general trend across the four species, as there was not a significant main effect (across species) of either warming or rainfall reduction on VCmax,Ci and Jmax,Ci. All species markedly increased VCmax,Ci and Jmax,Ci (and decreased their ratio) with short-term increases in temperature (i.e., contrasting values at 18, 25 and 32 °C), and those responses were independent of long-term treatments and did not differ among species. The Jmax,Ci:VCmax,Ci ratio was, however, significantly lower across species in warmed and reduced rainfall treatments. Collectively, these results suggest that boreal trees possess considerable short-term plasticity that may allow homeostasis of VCmax,Ci and Jmax,Ci to a longer term temperature treatment. Our results also caution against extrapolating results obtained under controlled and markedly contrasting temperature treatments to responses of photosynthetic parameters to more modest temperature changes expected in the near-term with climate warming in field conditions.
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Affiliation(s)
- Raimundo Bermudez
- Department of Forest Resources, University of Minnesota, St Paul, MN 55108, USA
| | - Artur Stefanski
- Department of Forest Resources, University of Minnesota, St Paul, MN 55108, USA
| | | | - Peter B Reich
- Department of Forest Resources, University of Minnesota, St Paul, MN 55108, USA
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, Locked Bag 1797, Penrith, NSW 2753, Australia
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Lipan L, García-Tejero IF, Gutiérrez-Gordillo S, Demirbaş N, Sendra E, Hernández F, Durán-Zuazo VH, Carbonell-Barrachina AA. Enhancing Nut Quality Parameters and Sensory Profiles in Three Almond Cultivars by Different Irrigation Regimes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:2316-2328. [PMID: 31995376 DOI: 10.1021/acs.jafc.9b06854] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The climate change is already affecting many agricultural systems and human environments, and the implementation of adaptation strategies, especially those related to irrigated agriculture in semiarid regions, is urgent. In this regard, deep knowledge about the effects that irrigation has on the food quality parameters will allow us to estimate the potential benefits of deficit irrigation (DI) strategies. This work presents the effects on the quality parameters of three almond cultivars (Marta, Guara, and Lauranne) subjected to three irrigation doses: (i) full-irrigated treatment (FI) at 100% crop evapotranspiration (ETC), (ii) an overirrigated treatment at 150% ETC (150% ETC), and (iii) regulated deficit irrigation (RDI65) treatment, in which irrigation was done as in FI, expect during the kernel-filling period when this treatment received 65% ETC. According to experimental findings, the cultivar most sensitive to water stress was Marta, having the most significant improvements for RDI65. In general, the effects of the irrigation dose on the morphological and physicochemical parameters were not huge but some improvements were observed in key parameters such as the color and contents of specific sugars, organic acids, and unsaturated fatty acids. Thus, it can be concluded that the irrigation dose did not drastically affect the fruit almond quality, although it is possible to improve several key parameters when a moderate RDI strategy is applied.
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Affiliation(s)
- L Lipan
- Department of Agro-Food Technology, Escuela Politécnica Superior de Orihuela , Universidad Miguel Hernández de Elche , Carretera de Beniel, km 3.2 , 03312 Orihuela , Alicante , Spain
| | - I F García-Tejero
- Centro IFAPA "Las Torres" , Instituto Andaluz de Investigación y Formación Agraria , Ctra. Sevilla-Cazalla, km 12.2, 41200 Alcalá del Río , Sevilla , Spain
| | - S Gutiérrez-Gordillo
- Centro IFAPA "Las Torres" , Instituto Andaluz de Investigación y Formación Agraria , Ctra. Sevilla-Cazalla, km 12.2, 41200 Alcalá del Río , Sevilla , Spain
| | - N Demirbaş
- Department of Agro-Food Technology, Escuela Politécnica Superior de Orihuela , Universidad Miguel Hernández de Elche , Carretera de Beniel, km 3.2 , 03312 Orihuela , Alicante , Spain
- Department of Food Engineering, Faculty of Agriculture , Çukurova University , 01330 Adana , Turkey
| | - E Sendra
- Department of Agro-Food Technology, Escuela Politécnica Superior de Orihuela , Universidad Miguel Hernández de Elche , Carretera de Beniel, km 3.2 , 03312 Orihuela , Alicante , Spain
| | - F Hernández
- Department of Plant Science and Microbiology, Research Group "Plant Production and Technology", Escuela Politécnica Superior de Orihuela , Universidad Miguel Hernández de Elche , Carretera de Beniel, km 3.2 , 03312 Orihuela , Alicante , Spain
| | - V H Durán-Zuazo
- Centro IFAPA "Camino de Purchil" , Instituto Andaluz de Investigación y Formación Agraria , Camino de Purchil s/n , 18004 Granada , Spain
| | - A A Carbonell-Barrachina
- Department of Agro-Food Technology, Escuela Politécnica Superior de Orihuela , Universidad Miguel Hernández de Elche , Carretera de Beniel, km 3.2 , 03312 Orihuela , Alicante , Spain
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Zait Y, Shtein I, Schwartz A. Long-term acclimation to drought, salinity and temperature in the thermophilic tree Ziziphus spina-christi: revealing different tradeoffs between mesophyll and stomatal conductance. TREE PHYSIOLOGY 2019; 39:701-716. [PMID: 30597082 DOI: 10.1093/treephys/tpy133] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/10/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
Photosynthesis is limited by three main factors: stomatal conductance (gs), mesophyll conductance (gm) and maximum capacity for Rubisco carboxylation (Vcmax). It is unclear how limiting factors vary under stress, particularly during long-term stress acclimation. In this work, we compared for the first time photosynthesis limitation resulting from long-term acclimation to three major abiotic stresses: drought, salinity and temperature. We used saplings of Ziziphus spina-christi, a thermophilic and drought-tolerant tree, which recently became more abundant in the Mediterranean, presumably due to increased winter temperatures. Stress acclimation was investigated by measuring growth, gas exchange, chlorophyll fluorescence and leaf structure. For each stress, photosynthesis-limiting factors were compared. We developed an integrative stress index that allowed us to precisely define stress level, enabling a comparison between stress types. Photosynthesis under all stresses was limited mostly by gs and gm (80-90%); whereas biochemistry (Vcmax) made a minor contribution (10-20%). The relative contribution of gs and gm on photosynthetic limitation was influenced by stress type. During acclimation to drought or salinity, photosynthesis was limited by a decline in gs, while intolerance to low temperatures was driven by decline in gm. In all the stresses, gm decreased only under progressive reduction in leaf physiological functionality and was associated with low turgor under drought, an increase in leaf Na+ under salinity and low leaf hydraulic conductance (Kleaf) at low temperatures. Mesophyll structure (mesophyll surface area exposed to the intercellular air spaces, leaf thickness, % intercellular air spaces) did not explain gm acclimation to stress. Current work gives methodology for stress studies, and defines the main factors underlying the plant response to climate change. The ability to minimize mesophyll-imposed limitations on photosynthesis was found as a strong indicator of progressive stress tolerance. Moreover, the results demonstrate how warming climate benefits the photosynthetic function in thermophilic species, such as Ziziphus spina-christi.
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Affiliation(s)
- Yotam Zait
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Ilana Shtein
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Amnon Schwartz
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Knauer J, Zaehle S, De Kauwe MG, Bahar NHA, Evans JR, Medlyn BE, Reichstein M, Werner C. Effects of mesophyll conductance on vegetation responses to elevated CO 2 concentrations in a land surface model. GLOBAL CHANGE BIOLOGY 2019; 25:1820-1838. [PMID: 30809890 PMCID: PMC6487956 DOI: 10.1111/gcb.14604] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/26/2019] [Indexed: 05/13/2023]
Abstract
Mesophyll conductance (gm ) is known to affect plant photosynthesis. However, gm is rarely explicitly considered in land surface models (LSMs), with the consequence that its role in ecosystem and large-scale carbon and water fluxes is poorly understood. In particular, the different magnitudes of gm across plant functional types (PFTs) are expected to cause spatially divergent vegetation responses to elevated CO2 concentrations. Here, an extensive literature compilation of gm across major vegetation types is used to parameterize an empirical model of gm in the LSM JSBACH and to adjust photosynthetic parameters based on simulated An - Ci curves. We demonstrate that an explicit representation of gm changes the response of photosynthesis to environmental factors, which cannot be entirely compensated by adjusting photosynthetic parameters. These altered responses lead to changes in the photosynthetic sensitivity to atmospheric CO2 concentrations which depend both on the magnitude of gm and the climatic conditions, particularly temperature. We then conducted simulations under ambient and elevated (ambient + 200 μmol/mol) CO2 concentrations for contrasting ecosystems and for historical and anticipated future climate conditions (representative concentration pathways; RCPs) globally. The gm -explicit simulations using the RCP8.5 scenario resulted in significantly higher increases in gross primary productivity (GPP) in high latitudes (+10% to + 25%), intermediate increases in temperate regions (+5% to + 15%), and slightly lower to moderately higher responses in tropical regions (-2% to +5%), which summed up to moderate GPP increases globally. Similar patterns were found for transpiration, but with a lower magnitude. Our results suggest that the effect of an explicit representation of gm is most important for simulated carbon and water fluxes in the boreal zone, where a cold climate coincides with evergreen vegetation.
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Affiliation(s)
- Jürgen Knauer
- Department of Biogeochemical IntegrationMax Planck Institute for BiogeochemistryJenaGermany
- International Max Planck Research School for Global Biogeochemical Cycles (IMPRS gBGC)JenaGermany
| | - Sönke Zaehle
- Department of Biogeochemical IntegrationMax Planck Institute for BiogeochemistryJenaGermany
- Michael‐Stifel Center Jena for Data‐Driven and Simulation ScienceJenaGermany
| | - Martin G. De Kauwe
- ARC Centre of Excellence for Climate Extremes and the Climate Change Research CentreUniversity of New South WalesSydneyNSWAustralia
| | - Nur H. A. Bahar
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant SciencesResearch School of Biology, Australian National UniversityCanberraACTAustralia
| | - John R. Evans
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant SciencesResearch School of Biology, Australian National UniversityCanberraACTAustralia
| | - Belinda E. Medlyn
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityRichmondNSWAustralia
| | - Markus Reichstein
- Department of Biogeochemical IntegrationMax Planck Institute for BiogeochemistryJenaGermany
- Michael‐Stifel Center Jena for Data‐Driven and Simulation ScienceJenaGermany
| | - Christiane Werner
- Department of Ecosystem PhysiologyUniversity of FreiburgFreiburgGermany
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Chen TW, Stützel H, Kahlen K. High light aggravates functional limitations of cucumber canopy photosynthesis under salinity. ANNALS OF BOTANY 2018; 121:797-807. [PMID: 29028871 PMCID: PMC5906908 DOI: 10.1093/aob/mcx100] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 07/24/2017] [Indexed: 05/07/2023]
Abstract
Background and Aims Most crop species are glycophytes, and salinity stress is one of the most severe abiotic stresses reducing crop yields worldwide. Salinity affects plant architecture and physiological functions by different mechanisms, which vary largely between crop species and determine the susceptibility or tolerance of a crop species to salinity. Methods Experimental data from greenhouse cucumber (Cucumis sativus), a salt-sensitive species, grown under three salinity levels were interpreted by combining a functional-structural plant model and quantitative limitation analysis of photosynthesis. This approach allowed the quantitative dissection of canopy photosynthetic limitations into architectural and functional limitations. Functional limitations were further dissected into stomatal (Ls), mesophyll (Lm) and biochemical (Lb). Key Results Architectural limitations increased rapidly after the start of the salinity treatment and became stronger than the sum of functional limitations (Ls + Lm + Lb) under high salinity. Stomatal limitations resulted from ionic effects and were much stronger than biochemical limitations, indicating that canopy photosynthesis was more limited by the effects of leaf sodium on stomatal regulation than on photosynthetic enzymes. Sensitivity analyses suggested that the relative importance of salinity effects on architectural and functional limitations depends on light conditions, with high light aggravating functional limitations through salinity effects on stomatal limitations. Conclusions Salinity tolerance of cucumber is more likely to be improved by traits related to leaf growth and stomatal regulation than by traits related to tissue tolerance to ion toxicity, especially under high light conditions.
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Affiliation(s)
- Tsu-Wei Chen
- Institute of Horticultural Production Systems, Leibniz Universität Hannover, Hannover, Germany
| | - Hartmut Stützel
- Institute of Horticultural Production Systems, Leibniz Universität Hannover, Hannover, Germany
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Zhang YJ, Sack L, Cao KF, Wei XM, Li N. Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines. Sci Rep 2017; 7:42085. [PMID: 28186201 PMCID: PMC5301202 DOI: 10.1038/srep42085] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 01/04/2017] [Indexed: 11/29/2022] Open
Abstract
We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate.
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Affiliation(s)
- Yong-Jiang Zhang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, 621 Charles E. Young Drive South, Los Angeles, CA 90095 1606, USA
| | - Kun-Fang Cao
- Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi 530004, China
| | - Xue-Mei Wei
- National Cycad Germplasm Conservation Center, Fairylake Botanical Garden, Shenzhen and Chinese Academy of Sciences, 160 Xianhu Rd., Liantang, Shenzhen 518004, China
| | - Nan Li
- National Cycad Germplasm Conservation Center, Fairylake Botanical Garden, Shenzhen and Chinese Academy of Sciences, 160 Xianhu Rd., Liantang, Shenzhen 518004, China
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Rodriguez-Dominguez CM, Buckley TN, Egea G, de Cires A, Hernandez-Santana V, Martorell S, Diaz-Espejo A. Most stomatal closure in woody species under moderate drought can be explained by stomatal responses to leaf turgor. PLANT, CELL & ENVIRONMENT 2016; 39:2014-26. [PMID: 27255698 DOI: 10.1111/pce.12774] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/17/2016] [Accepted: 05/17/2016] [Indexed: 05/21/2023]
Abstract
Reduced stomatal conductance (gs ) during soil drought in angiosperms may result from effects of leaf turgor on stomata and/or factors that do not directly depend on leaf turgor, including root-derived abscisic acid (ABA) signals. To quantify the roles of leaf turgor-mediated and leaf turgor-independent mechanisms in gs decline during drought, we measured drought responses of gs and water relations in three woody species (almond, grapevine and olive) under a range of conditions designed to generate independent variation in leaf and root turgor, including diurnal variation in evaporative demand and changes in plant hydraulic conductance and leaf osmotic pressure. We then applied these data to a process-based gs model and used a novel method to partition observed declines in gs during drought into contributions from each parameter in the model. Soil drought reduced gs by 63-84% across species, and the model reproduced these changes well (r(2) = 0.91, P < 0.0001, n = 44) despite having only a single fitted parameter. Our analysis concluded that responses mediated by leaf turgor could explain over 87% of the observed decline in gs across species, adding to a growing body of evidence that challenges the root ABA-centric model of stomatal responses to drought.
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Affiliation(s)
- Celia M Rodriguez-Dominguez
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain
| | - Thomas N Buckley
- IA Watson Grains Research Centre, Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri, NSW, 2390, Australia
| | - Gregorio Egea
- Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad de Sevilla, Ctra Utrera, km 1, 41013, Seville, Spain
| | - Alfonso de Cires
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain
| | - Virginia Hernandez-Santana
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain
| | - Sebastia Martorell
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122, Palma, Illes Balears, Spain
| | - Antonio Diaz-Espejo
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain
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Chen TW, Nguyen TMN, Kahlen K, Stützel H. High temperature and vapor pressure deficit aggravate architectural effects but ameliorate non-architectural effects of salinity on dry mass production of tomato. FRONTIERS IN PLANT SCIENCE 2015; 6:887. [PMID: 26539203 PMCID: PMC4612157 DOI: 10.3389/fpls.2015.00887] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 10/06/2015] [Indexed: 05/23/2023]
Abstract
Tomato (Solanum lycopersicum L.) is an important vegetable crop and often cultivated in regions exposed to salinity and high temperatures (HT) which change plant architecture, decrease canopy light interception and disturb physiological functions. However, the long-term effects of salinity and HT combination (S+HT) on plant growth are still unclear. A dynamic functional-structural plant model (FSPM) of tomato was parameterized and evaluated for different levels of S+HT combinations. The evaluated model was used to quantify the contributions of morphological changes (architectural effects) and physiological disturbances (non-architectural effects) on the reduction of shoot dry mass under S+HT. The model predicted architectural variables with high accuracy (>85%), which ensured the reliability of the model analyses. HT enhanced architectural effects but reduced non-architectural effects of salinity on dry mass production. The stronger architectural effects of salinity under HT could not be counterbalanced by the smaller non-architectural effects. Therefore, long-term influences of HT on shoot dry mass under salinity were negative at the whole plant level. Our model analysis highlights the importance of plant architecture at canopy level in studying the plant responses to the environments and shows the merits of dynamic FSPMs as heuristic tools.
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Affiliation(s)
- Tsu-Wei Chen
- Department of Vegetable Systems Modelling, Institute of Horticultural Production Systems, Leibniz Universität HannoverHannover, Germany
| | - Thi M. N. Nguyen
- Department of Vegetable Systems Modelling, Institute of Horticultural Production Systems, Leibniz Universität HannoverHannover, Germany
| | - Katrin Kahlen
- Department of Vegetable Crops, Hochschule Geisenheim UniversityGeisenheimw, Germany
| | - Hartmut Stützel
- Department of Vegetable Systems Modelling, Institute of Horticultural Production Systems, Leibniz Universität HannoverHannover, Germany
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Chen TW, Kahlen K, Stützel H. Disentangling the contributions of osmotic and ionic effects of salinity on stomatal, mesophyll, biochemical and light limitations to photosynthesis. PLANT, CELL & ENVIRONMENT 2015; 38:1528-1542. [PMID: 25544985 DOI: 10.1111/pce.12504] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/16/2014] [Accepted: 12/16/2014] [Indexed: 06/04/2023]
Abstract
There are conflicting opinions on the relative importance of photosynthetic limitations under salinity. Quantitative limitation analysis of photosynthesis provides insight into the contributions of different photosynthetic limitations, but it has only been applied under saturating light conditions. Using experimental data and modelling approaches, we examined the influence of light intensity on photosynthetic limitations and quantified the osmotic and ionic effects of salinity on stomatal (LS ), mesophyll (LM ), biochemical (LB ) and light (LL ) limitations in cucumber (Cucumis sativus L.) under different light intensities. Non-linear dependencies of LS , LM and LL to light intensity were found. Osmotic effects on LS and LM increased with the salt concentration in the nutrient solution (Ss ) and the magnitude of LM depended on light intensity. LS increased with the Na(+) concentration in the leaf water (Sl ) and its magnitude depended on Ss . Biochemical capacity declined linearly with Sl but, surprisingly, the relationship between LB and Sl was influenced by Ss . Our results suggest that (1) improvement of stomatal regulation under ionic stress would be the most effective way to alleviate salinity stress in cucumber and (2) osmotic stress may alleviate the ionic effects on LB but aggravate the ionic effects on LS .
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Affiliation(s)
- Tsu-Wei Chen
- Institute of Horticultural Production Systems, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Katrin Kahlen
- Department of Vegetable Crops, Geisenheim University, Geisenheim, 65366, Germany
| | - Hartmut Stützel
- Institute of Horticultural Production Systems, Leibniz Universität Hannover, Hannover, 30419, Germany
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Morales LV, Coopman RE, Rojas R, Escandón AB, Flexas J, Galmés J, García-Plazaola JI, Gago J, Cabrera HM, Corcuera LJ. Acclimation of leaf cohorts expanded under light and water stresses: an adaptive mechanism of Eucryphia cordifolia to face changes in climatic conditions? TREE PHYSIOLOGY 2014; 34:1305-1320. [PMID: 25398632 DOI: 10.1093/treephys/tpu085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Eucryphia cordifolia Cav. is a long-lived evergreen tree species, commonly found as a canopy emergent tree in the Chilean temperate rain forest. This species displays successive leaf cohorts throughout the entire growing season. Thus, full leaf expansion occurs under different environmental conditions during growing such as air temperature, vapor pressure deficit and the progress of moderate water stress (WS). These climate variations can be reflected as differences in anatomical and physiological characteristics among leaf cohorts. Thus, we investigated the potential adaptive role of different co-existing leaf cohorts in seedlings grown under shade, drought stress or a combination of the two. Photosynthetic and anatomical traits were measured in the first displayed leaf cohort and in a subsequent leaf cohort generated during the mid-season. Although most anatomical and photosynthetic pigments did not vary between cohorts, photosynthetic acclimation did occur in the leaf cohort and was mainly driven by biochemical processes such as leaf nitrogen content, Rubisco carboxylation capacity and maximal Photosystem II electron transport rather than CO2 diffusion conductance. Cohort acclimation could be relevant in the context of climate change, as this temperate rainforest will likely face some degree of summer WS even under low light conditions. We suggest that the acclimation of the photosynthetic capacity among current leaf cohorts represents a well-tuned mechanism helping E. cordifolia seedlings to face a single stress like shade or drought stress, but is insufficient to cope with simultaneous stresses.
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Affiliation(s)
- Loreto V Morales
- Laboratorio de Ecofisiología para la Conservación de Bosques, Instituto de Conservación, Biodiversidad y Territorio, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Rafael E Coopman
- Laboratorio de Ecofisiología para la Conservación de Bosques, Instituto de Conservación, Biodiversidad y Territorio, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Roke Rojas
- Laboratorio de Ecofisiología para la Conservación de Bosques, Instituto de Conservación, Biodiversidad y Territorio, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Antonio B Escandón
- Laboratorio de Fisiología Vegetal, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Jaume Flexas
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Departament de Biologia, Universitat de les Illes Balears, Ctra de Valldemossa km 7.5, 07122 Palma, Spain
| | - Jeroni Galmés
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Departament de Biologia, Universitat de les Illes Balears, Ctra de Valldemossa km 7.5, 07122 Palma, Spain
| | - José I García-Plazaola
- Departamento de Biología Vegetal y Ecología, Universidad del País Vasco UPV/EHU, Apdo 644, E-48080 Bilbao, Spain
| | - Jorge Gago
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Departament de Biologia, Universitat de les Illes Balears, Ctra de Valldemossa km 7.5, 07122 Palma, Spain
| | - Hernán M Cabrera
- Centro de Ecología Aplicada Ltda Av. Príncipe de Gales 6465, Santiago, Chile
| | - Luis J Corcuera
- Laboratorio de Fisiología Vegetal, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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Chen TW, Henke M, de Visser PHB, Buck-Sorlin G, Wiechers D, Kahlen K, Stützel H. What is the most prominent factor limiting photosynthesis in different layers of a greenhouse cucumber canopy? ANNALS OF BOTANY 2014; 114:677-88. [PMID: 24907313 PMCID: PMC4217677 DOI: 10.1093/aob/mcu100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 04/10/2014] [Indexed: 05/06/2023]
Abstract
BACKGROUND AND AIMS Maximizing photosynthesis at the canopy level is important for enhancing crop yield, and this requires insights into the limiting factors of photosynthesis. Using greenhouse cucumber (Cucumis sativus) as an example, this study provides a novel approach to quantify different components of photosynthetic limitations at the leaf level and to upscale these limitations to different canopy layers and the whole plant. METHODS A static virtual three-dimensional canopy structure was constructed using digitized plant data in GroIMP. Light interception of the leaves was simulated by a ray-tracer and used to compute leaf photosynthesis. Different components of photosynthetic limitations, namely stomatal (S(L)), mesophyll (M(L)), biochemical (B(L)) and light (L(L)) limitations, were calculated by a quantitative limitation analysis of photosynthesis under different light regimes. KEY RESULTS In the virtual cucumber canopy, B(L) and L(L) were the most prominent factors limiting whole-plant photosynthesis. Diffusional limitations (S(L) + M(L)) contributed <15% to total limitation. Photosynthesis in the lower canopy was more limited by the biochemical capacity, and the upper canopy was more sensitive to light than other canopy parts. Although leaves in the upper canopy received more light, their photosynthesis was more light restricted than in the leaves of the lower canopy, especially when the light condition above the canopy was poor. An increase in whole-plant photosynthesis under diffuse light did not result from an improvement of light use efficiency but from an increase in light interception. Diffuse light increased the photosynthesis of leaves that were directly shaded by other leaves in the canopy by up to 55%. CONCLUSIONS Based on the results, maintaining biochemical capacity of the middle-lower canopy and increasing the leaf area of the upper canopy would be promising strategies to improve canopy photosynthesis in a high-wire cucumber cropping system. Further analyses using the approach described in this study can be expected to provide insights into the influences of horticultural practices on canopy photosynthesis and the design of optimal crop canopies.
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Affiliation(s)
- Tsu-Wei Chen
- Institute of Horticultural Production Systems, Leibniz Universität Hannover, Herrenhäuser Straße 2, D-30419 Hannover, Germany
| | - Michael Henke
- Department of Ecoinformatics, Biometrics and Forest Growth, Georg-August University of Gö ttingen, Gö ttingen, Germany
| | - Pieter H. B. de Visser
- Greenhouse Horticulture, Wageningen UR, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Gerhard Buck-Sorlin
- UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), AGROCAMPUS OUEST, Centre d'Angers, 2 rue André le Nôtre 2, 49045 Angers Cedex 01, France
| | | | - Katrin Kahlen
- Geisenheim University, Von-Lade-Straße 1, D-65366 Geisenheim, Germany
| | - Hartmut Stützel
- Institute of Horticultural Production Systems, Leibniz Universität Hannover, Herrenhäuser Straße 2, D-30419 Hannover, Germany
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Saa S, Brown PH. Fruit presence negatively affects photosynthesis by reducing leaf nitrogen in almond. FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:884-891. [PMID: 32481042 DOI: 10.1071/fp13343] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/19/2014] [Indexed: 06/11/2023]
Abstract
Fruit presence often positively and seldom negatively affects leaf carbon assimilation rate in fruit-trees. In almond (Prunus dulcis (Mill.) DA Webb) the presence of fruit often results in the death of the fruit bearing spurs. The mechanism of this effect is unclear, but may be a consequence of diminished carbon assimilation rate in leaves adjacent to fruit and the subsequent depletion of nutrient and carbohydrates reserves. This study evaluated the influence of fruit on leaf carbon assimilation rate and leaf nitrogen throughout the season. Carbon assimilation rate (Aa), rubisco carboxylation capacity at leaf temperature (Vcmax@Tleaf), maximum rate of RubP regeneration at leaf temperature (Jmax@Tleaf), leaf nitrogen on a mass basis (N%) and area basis (Na), and specific leaf weight data were recorded. Fruit presence negatively affected leaf nitrogen concentration by a reduction in specific leaf weight and leaf nitrogen content. The impact of fruit presence on carbon assimilation rate was predominantly associated with the negative effect of fruit on Na and resulted in a significant reduction in Jmax@Tleaf and therefore in Aa, especially after full leaf and fruit expansion. The reduction in leaf area, leaf nitrogen, reduced Jmax@Tleaf and decreased carbon assimilation rate in the presence of fruit explains the negative effects of fruit presence on spur vitality.
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Affiliation(s)
- Sebastian Saa
- Facultad de Agronomía, Pontificia Universidad Católica de Valparaíso, Casilla 4D, Quillota, Chile
| | - Patrick H Brown
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
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Broeckx LS, Fichot R, Verlinden MS, Ceulemans R. Seasonal variations in photosynthesis, intrinsic water-use efficiency and stable isotope composition of poplar leaves in a short-rotation plantation. TREE PHYSIOLOGY 2014; 34:701-15. [PMID: 25074859 PMCID: PMC4131770 DOI: 10.1093/treephys/tpu057] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/03/2014] [Indexed: 05/10/2023]
Abstract
Photosynthetic carbon assimilation and transpirational water loss play an important role in the yield and the carbon sequestration potential of bioenergy-devoted cultures of fast-growing trees. For six poplar (Populus) genotypes in a short-rotation plantation, we observed significant seasonal and genotypic variation in photosynthetic parameters, intrinsic water-use efficiency (WUEi) and leaf stable isotope composition (δ13C and δ18O). The poplars maintained high photosynthetic rates (between 17.8 and 26.9 μmol m(-2) s(-1) depending on genotypes) until late in the season, in line with their fast-growth habit. Seasonal fluctuations were mainly explained by variations in soil water availability and by stomatal limitation upon photosynthesis. Stomatal rather than biochemical limitation was confirmed by the constant intrinsic photosynthetic capacity (Vcmax) during the growing season, closely related to leaf nitrogen (N) content. Intrinsic water-use efficiency scaled negatively with carbon isotope discrimination (Δ13Cbl) and positively with the ratio between mesophyll diffusion conductance (gm) and stomatal conductance. The WUEi-Δ13Cbl relationship was partly influenced by gm. There was a trade-off between WUEi and photosynthetic N-use efficiency, but only when soil water availability was limiting. Our results suggest that seasonal fluctuations in relation to soil water availability should be accounted for in future modelling studies assessing the carbon sequestration potential and the water-use efficiency of woody energy crops.
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Affiliation(s)
- L S Broeckx
- Department of Biology, Research Group of Plant and Vegetation Ecology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - R Fichot
- University of Orléans, INRA, LBLGC, F-45067 Orléans, France
| | - M S Verlinden
- Department of Biology, Research Group of Plant and Vegetation Ecology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - R Ceulemans
- Department of Biology, Research Group of Plant and Vegetation Ecology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
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Egea G, González-Real MM, Martin-Gorriz B, Baille A. Leaf-to-branch scaling of C-gain in field-grown almond trees under different soil moisture regimes. TREE PHYSIOLOGY 2014; 34:619-629. [PMID: 24970267 DOI: 10.1093/treephys/tpu045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Branch/tree-level measurements of carbon (C)-acquisition provide an integration of the physical and biological processes driving the C gain of all individual leaves. Most research dealing with the interacting effects of high-irradiance environments and soil-induced water stress on the C-gain of fruit tree species has focused on leaf-level measurements. The C-gain of both sun-exposed leaves and branches of adult almond trees growing in a semi-arid climate was investigated to determine the respective costs of structural and biochemical/physiological protective mechanisms involved in the behaviour at branch scale. Measurements were performed on well-watered (fully irrigated, FI) and drought-stressed (deficit irrigated, DI) trees. Leaf-to-branch scaling for net CO2 assimilation was quantified by a global scaling factor (fg), defined as the product of two specific scaling factors: (i) a structural scaling factor (fs), determined under well-watered conditions, mainly involving leaf mutual shading; and (ii) a water stress scaling factor (fws,b) involving the limitations in C-acquisition due to soil water deficit. The contribution of structural mechanisms to limiting branch net C-gain was high (mean fs ∼0.33) and close to the projected-to-total leaf area ratio of almond branches (ε = 0.31), while the contribution of water stress mechanisms was moderate (mean fws,b ∼0.85), thus supplying an fg ranging between 0.25 and 0.33 with slightly higher values for FI trees with respect to DI trees. These results suggest that the almond tree (a drought-tolerant species) has acquired mechanisms of defensive strategy (survival) mainly based on a specific branch architectural design. This strategy allows the potential for C-gain to be preserved at branch scale under a large range of soil water deficits. In other words, almond tree branches exhibit an architecture that is suboptimal for C-acquisition under well-watered conditions, but remarkably efficient to counteract the impact of DI and drought events.
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Affiliation(s)
- Gregorio Egea
- Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad de Sevilla, Ctra Utrera km 1, 41013 Sevilla, Spain
| | - María M González-Real
- Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Paseo Alfonso XIII, 48, 30203 Cartagena, Spain
| | - Bernardo Martin-Gorriz
- Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Paseo Alfonso XIII, 48, 30203 Cartagena, Spain
| | - Alain Baille
- Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Paseo Alfonso XIII, 48, 30203 Cartagena, Spain
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Diaz-Espejo A. New challenges in modelling photosynthesis: temperature dependencies of Rubisco kinetics. PLANT, CELL & ENVIRONMENT 2013; 36:2104-7. [PMID: 23998434 DOI: 10.1111/pce.12192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
This article comments on: Temperature response of in vivo Rubisco kinetics and mesophyll conductance in Arabidopsis thaliana: comparisons to Nicotiana tabacum
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Affiliation(s)
- A Diaz-Espejo
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, Sevilla, 41012, Spain
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Egea G, González-Real MM, Baille A, Nortes PA, Conesa MR, Ruiz-Salleres I. Effects of water stress on irradiance acclimation of leaf traits in almond trees. TREE PHYSIOLOGY 2012; 32:450-63. [PMID: 22440881 DOI: 10.1093/treephys/tps016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Photosynthetic acclimation to highly variable local irradiance within the tree crown plays a primary role in determining tree carbon uptake. This study explores the plasticity of leaf structural and physiological traits in response to the interactive effects of ontogeny, water stress and irradiance in adult almond trees that have been subjected to three water regimes (full irrigation, deficit irrigation and rain-fed) for a 3-year period (2006-08) in a semiarid climate. Leaf structural (dry mass per unit area, N and chlorophyll content) and photosynthetic (maximum net CO(2) assimilation, A(max), maximum stomatal conductance, g(s,max), and mesophyll conductance, g(m)) traits and stem-to-leaf hydraulic conductance (K(s-l)) were determined throughout the 2008 growing season in leaves of outer south-facing (S-leaves) and inner northwest-facing (NW-leaves) shoots. Leaf plasticity was quantified by means of an exposure adjustment coefficient (ε=1-X(NW)/X(S)) for each trait (X) of S- and NW-leaves. Photosynthetic traits and K(s-l) exhibited higher irradiance-elicited plasticity (higher ε) than structural traits in all treatments, with the highest and lowest plasticity being observed in the fully irrigated and rain-fed trees, respectively. Our results suggest that water stress modulates the irradiance-elicited plasticity of almond leaves through changes in crown architecture. Such changes lead to a more even distribution of within-crown irradiance, and hence of the photosynthetic capacity, as water stress intensifies. Ontogeny drove seasonal changes only in the ε of area- and mass-based N content and mass-based chlorophyll content, while no leaf age-dependent effect was observed on ε as regards the physiological traits. Our results also indicate that the irradiance-elicited plasticity of A(max) is mainly driven by changes in leaf dry mass per unit area, in g(m) and, most likely, in the partitioning of the leaf N content.
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Affiliation(s)
- Gregorio Egea
- Área de Ingeniería Agroforestal, Universidad Politécnica de Cartagena, Paseo Alfonso XIII, 48, 30203 Cartagena, Spain
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Pérez-López U, Robredo A, Lacuesta M, Mena-Petite A, Muñoz-Rueda A. Elevated CO2 reduces stomatal and metabolic limitations on photosynthesis caused by salinity in Hordeum vulgare. PHOTOSYNTHESIS RESEARCH 2012; 111:269-83. [PMID: 22286185 DOI: 10.1007/s11120-012-9721-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 01/17/2012] [Indexed: 05/05/2023]
Abstract
The future environment may be altered by high concentrations of salt in the soil and elevated [CO(2)] in the atmosphere. These have opposite effects on photosynthesis. Generally, salt stress inhibits photosynthesis by stomatal and non-stomatal mechanisms; in contrast, elevated [CO(2)] stimulates photosynthesis by increasing CO(2) availability in the Rubisco carboxylating site and by reducing photorespiration. However, few studies have focused on the interactive effects of these factors on photosynthesis. To elucidate this knowledge gap, we grew the barley plant, Hordeum vulgare (cv. Iranis), with and without salt stress at either ambient or elevated atmospheric [CO(2)] (350 or 700 μmol mol(-1) CO(2), respectively). We measured growth, several photosynthetic and fluorescence parameters, and carbohydrate content. Under saline conditions, the photosynthetic rate decreased, mostly because of stomatal limitations. Increasing salinity progressively increased metabolic (photochemical and biochemical) limitation; this included an increase in non-photochemical quenching and a reduction in the PSII quantum yield. When salinity was combined with elevated CO(2), the rate of CO(2) diffusion to the carboxylating site increased, despite lower stomatal and internal conductance. The greater CO(2) availability increased the electron sink capacity, which alleviated the salt-induced metabolic limitations on the photosynthetic rate. Consequently, elevated CO(2) partially mitigated the saline effects on photosynthesis by maintaining favorable biochemistry and photochemistry in barley leaves.
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Affiliation(s)
- Usue Pérez-López
- Departamento de Biología Vegetal y Ecología, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, Apdo. 644, 48080 Bilbao, Spain.
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