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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 Physiol 2014; 34:619-629. [PMID: 24970267 DOI: 10.1093/treephys/tpu045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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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 Physiol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Egea G, González-Real MM, Baille A, Nortes PA, Diaz-Espejo A. Disentangling the contributions of ontogeny and water stress to photosynthetic limitations in almond trees. Plant Cell Environ 2011; 34:962-979. [PMID: 21388414 DOI: 10.1111/j.1365-3040.2011.02297.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Very few studies have attempted to disentangle the respective role of ontogeny and water stress on leaf photosynthetic attributes. The relative significance of both effects on photosynthetic attributes has been investigated in leaves of field-grown almond trees [Prunus dulcis (Mill.) D. A. Webb] during four growth cycles. Leaf ontogeny resulted in enhanced leaf dry weight per unit area (W(a)), greater leaf dry-to-fresh weight ratio and lower N content per unit of leaf dry weight (N(w)). Concomitantly, area-based maximum carboxylation rate (V(cmax)), maximum electron transport rate (J(max)), mesophyll conductance to CO₂ diffusion (gm)' and light-saturated net photosynthesis (A(max)) declined in both well-watered and water-stressed almond leaves. Although g(m) and stomatal conductance (g(s)) seemed to be co-ordinated, a much stronger coordination in response to ontogeny and prolonged water stress was observed between g(m) and the leaf photosynthetic capacity. Under unrestricted water supply, the leaf age-related decline of A(max) was equally driven by diffusional and biochemical limitations. Under restricted soil water availability, A(max) was mainly limited by g(s) and, to a lesser extent, by photosynthetic capacity and g(m). When both ontogeny and water stress effects were combined, diffusional limitations was the main determinant of photosynthesis limitation, while stomatal and biochemical limitations contributed similarly.
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Affiliation(s)
- Gregorio Egea
- Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain
| | - María M González-Real
- Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain
| | - Alain Baille
- Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain
| | - Pedro A Nortes
- Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain
| | - Antonio Diaz-Espejo
- Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain
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