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Within-stand and seasonal variations of specific leaf area in a clonal Eucalyptus plantation in the Republic of Congo

NOUVELLON, Yann; LACLAU, Jean-Paul; EPRON, Daniel; KINANA, Antoine; MABIALA, Andre; ROUPSARD, Olivier; BONNEFOND, Jean-Marc; MAIRE, Guerric le; MARSDEN, Claire; BONTEMPS, Jean-Daniel; SAINT-ANDRE, Laurent
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.22%
Specific leaf area (SLA; m(leaf)(2) kg(leaf)(-1)) is a key ecophysiological parameter influencing leaf physiology, photosynthesis, and whole plant carbon gain. Both individual tree-based models and other forest process-based models are generally highly sensitive to this parameter, but information on its temporal or within-stand variability is still scarce. In a 2-4-year-old Eucalyptus plantation in Congo, prone to seasonal drought, the within-stand and seasonal variability in SLA were investigated by means of destructive sampling carried out at 2-month intervals, over a 2-year period. Within-crown vertical gradients of SLA were small. Highly significant relationships were found between tree-average SLA (SLA(t)) and tree size (tree height, H(t), or diameter at breast height, DBH): SLA(t) ranged from about 9 m(2) kg(-1) for dominant trees to about 14-15 m(2) kg(-1) for the smallest trees. The decrease in SLA(t) with increasing tree size was accurately predicted from DBH using power functions. Stand-average SLA varied by about 20% during the year, with lowest values at the end of the 5-month dry season, and highest values about 2-3 months after the onset of the wet season. Variability in leaf water status according to tree size and season is discussed as a possible determinant of both the within-stand and seasonal variations in SM. (C) 2009 Elsevier B.V. All rights reserved.; Observatoire de Recherche en Environnement F-ORE-T; European Integrated Project Ultra Low CO2 Steelmaking[515960]; EU

Efeito de práticas silviculturais sobre a produtividade primária líquida de madeira, o índice de área foliar e a eficiência do uso da luz em plantios de restauração da Mata Atlântica; Effects of silvicultural practices on wood net primary production, leaf area index and light use efficiency of Atlantic Forest restorations

Campoe, Otávio Camargo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/06/2008 PT
Relevância na Pesquisa
66.15%
Os objetivos do estudo foram identificar o melhor modelo de restauração pela manipulação da composição florística e práticas silviculturais, e compreender como este melhor desenvolvimento é explicado pelos fatores que controlam o uso e a eficiência do uso da luz pelo dossel florestal. Com esta fundamentação foi instalado em 2004, na Estação Experimental de Anhembi/ESALQ/USP, o ensaio "Modelos de restauração de áreas degradadas da Mata Atlântica visando o seqüestro de carbono", com 20 espécies nativas e oito sistemas de restauração florestal, baseados em um delineamento fatorial 23, com três fatores, e dois níveis por fator: i) Composição florística, com maior (67%) ou menor (50%) percentagem de pioneiras; ii) Espaçamento de plantio (3x1m e 3x2m); e iii) Manejo silvicultural, com manejo usual (maior estresse ambiental) e manejo máximo (minimização do estresse ambiental), referentes ao controle da matocompetição e fertilização. Em todos os tratamentos, até os 42 meses, foram determinados: produtividade primária líquida de madeira (PPLM), com base em inventários semestrais, determinação da densidade básica da madeira e fator de forma de todas as espécies, índice de área foliar (IAF, com calibração de fotos hemisféricas)...

Influence of potassium and sodium nutrition on leaf area components in Eucalyptus grandis trees

Battie-Laclau, Patricia; Laclau, Jean-Paul; Piccolo, Marisa de Cassia; Arenque, Bruna Cersózimo; Beri, Constance; Mietton, Lauriane; Muniz, Marta R. Almeida; Jordan-Meille, Lionel; Buckeridge, Marcos Silveira; Nouvellon, Yann; Ranger, Jacques; Bouillet,
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 19-35
ENG
Relevância na Pesquisa
66.27%
Background and Aims: Recent studies showed a positive tree response to Na addition in K-depleted tropical soils. Our study aimed to gain insight into the effects of K and Na fertilizations on leaf area components for a widely planted tree species. Methods: Leaf expansion rates, as well as nutrient, polyol and soluble sugar concentrations, were measured from emergence to abscission of tagged leaves in 1-year-old Eucalyptus grandis plantations. Leaf cell size and water status parameters were compared 1 and 2 months after leaf emergence in plots with KCl application (+K), NaCl application (+Na) and control plots (C). Results: K and Na applications enhanced tree leaf area by increasing both leaf longevity and the mean area of individual leaves. Higher cell turgor in treatments +K and +Na than in the C treatment resulting from higher concentrations of osmotica contributed to increasing both palisade cell diameters and the size of fully expanded leaves. Conclusions: Intermediate total tree leaf area in treatment +Na compared to treatments C and +K might result from the capacity of Na to substitute K in osmoregulatory functions, whereas it seemed unable to accomplish other important K functions that contribute to delaying leaf senescence. © 2013 Springer Science+Business Media Dordrecht.

Leaf area expansion and dry matter accumulation during establishment of broad bean and sorghum at different temperatures and soil water contents in two types of soil in mediterranean Portugal

Andrade, José; Abreu, Francisco
Fonte: Deutscher Wetterdienst, 2005 Publicador: Deutscher Wetterdienst, 2005
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.23%
Crop establishment is a major factor determining crop productivity in the field and is strongly controlled by soil temperature and soil moisture. Fast leaf expansion and dry matter accumulation during crop establishment are required for an adequate establishment. Leaf area expansion and accumulation of dry matter during the establishment of broad bean (Vicia faba L.) and sorghum (Sorghum vulgare L.) were studied at different soil temperatures and soil moisture contents in a Vertisol (Lisboa) and a Luvisol (Évora) from November 1993 to November 1996. Soil temperature was measured at 2 and 4 cm depth with thermocouples, air temperature was measured with a ventilated psychrometer and soil moisture was measured using the gravimetric method. Leaf area was estimated non-destructively. Above ground seedling dry matter was weighed after oven drying at 65ºC. Data analysis was based on the thermal time concept. For each crop no significant differences were found on leaf area at establishment in both soils under favourable water conditions, but significant differences were found on seedling dry matter. In moist soils, leaf area of both species increased linearly with accumulated temperature and dry matter increased exponentially with accumulated temperature. Low soil water during establishment reduced leaf expansion and dry matter accumulation of both crops...

Leaf area expansion and dry matter accumulation during establishment of broad bean and sorghum at different temperatures and soil water contents in two types of soil in mediterranean Portugal

Andrade, José; Abreu, Francisco
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Aula
POR
Relevância na Pesquisa
66.23%
Crop establishment is a major factor determining crop productivity in the field and is strongly controlled by soil temperature and soil moisture. Fast leaf expansion and dry matter accumulation during crop establishment are required for an adequate establishment. Leaf area expansion and accumulation of dry matter during the establishment of broad bean (Vicia faba L.) and sorghum (Sorghum vulgare L.) were studied at different soil temperatures and soil moisture contents in a Vertisol (Lisboa) and a Luvisol (Évora) from November 1993 to November 1996. Soil temperature was measured at 2 and 4 cm depth with thermocouples, air temperature was measured with a ventilated psychrometer and soil moisture was measured using the gravimetric method. Leaf area was estimated non-destructively. Above ground seedling dry matter was weighed after oven drying at 65ºC. Data analysis was based on the thermal time concept. For each crop no significant differences were found on leaf area at establishment in both soils under favourable water conditions, but significant differences were found on seedling dry matter. In moist soils, leaf area of both species increased linearly with accumulated temperature and dry matter increased exponentially with accumulated temperature. Low soil water during establishment reduced leaf expansion and dry matter accumulation of both crops...

Salinity-induced effects on transpiration rate, stomatal conductance and leaf area of three olive (Olea europaea L.) varieties

Coelho, Renato; Moitas, Mário; Rato, Ana; Vaz, Margarida
Fonte: Actas XII Congresso Luso-Espanhol de Fisiologia Vegetal, Lisboa Publicador: Actas XII Congresso Luso-Espanhol de Fisiologia Vegetal, Lisboa
Tipo: Aula
ENG
Relevância na Pesquisa
66.32%
Transpiration of two year-old olive trees of three different varieties, Arbequina, Cobrançosa and Galega (18 trees per variety), irrigated with three levels of salt (0, 80 or 200 mM NaCl) for about 90 days, was measured by a gravimetric method. To determine leaf area, each tree was photographed from the side against a white background and the total area of each projected image was determined with ImageJ software. To calibrate these area determinations, one tree of each variety was subsequently stripped of all its leaves and its total leaf area was accurately measured. A correlation was then obtained between the area on the photograph of this particular tree and the total area of the detached leaves of the same tree. Using the leaf area determined by this procedure, transpiration rates of the trees could be calculated. Knowing leaf and air temperatures and RH, it was possible to determine the difference in molar fraction of water between the leaf and the air. Using this and the values of the transpiration rate, stomatal conductance could be calculated (gs calc) and compared with the conductance measured on the same trees with a porometer (gs). Actual leaf area of a plant was 1,40 (Arbequina), 1,42 (Cobrançosa) or 1,24 (Galega) times the area measured with ImageJ on the photograph of the same plant. Leaf area of the trees...

A simplified methodology for the correction of Leaf Area Index (LAI) measurements obtained by ceptometer with reference to Pinus Portuguese forests

Lopes, D.; Nunes, L; Walford, N; Aranha, J.; Sette, CJ; Viana, H.; Hernandez, C
Fonte: Instituto Politécnico de Viseu Publicador: Instituto Politécnico de Viseu
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
66.19%
Forest leaf area index (LAI) is an important structural parameter controlling many biological and physiological processes associated with vegetation. A wide array of methods for its estimation has been proposed, including those based on the sunfleck ceptometer, a ground-based easy-to-use device taking non-deForest leaf area index (LAI) is an important structural parameter controlling many biological and physiological processes associated with vegetation. A wide array of methods for its estimation has been proposed, including those based on the sunfleck ceptometer, a ground-based easy-to-use device taking non-deForest leaf area index (LAI) is an important structural parameter controlling many biological and physiological processes associated with vegetation. A wide array of methods for its estimation has been proposed, including those based on the sunfleck ceptometer, a ground-based easy-to-use device taking non-destructive LAI measures. However, use of ceptometer in pine stands leads to the underestimation of LAI due to foliage clumping of this species. Previous studies have proposed a correction of biased LAI estimates based on the multiplication by a constant factor. In this study, a new method for obtaining a correction factor is proposed by considering the bias (the difference between the ceptometer measure and the reference LAI) as a function of the stand structural variables...

Leaf area estimation from tree allometrics in Eucalyptus globulus plantations

Fabião, António; Pereira, J.M.C.; Tomé, Margarida; Carreiras, J.M.B.; Tomé, José; Pereira, J.S.; David, J.S.
Fonte: Universidade Técnica de Lisboa Publicador: Universidade Técnica de Lisboa
Tipo: Artigo de Revista Científica
Publicado em //1997 ENG
Relevância na Pesquisa
66.16%
Data from five studies on the relationships between dendrometric measurements and leaf area of Eucalyptus globulus Labill. plantations were pooled and analyzed to develop regression models for the estimation of leaf area of individual trees. The data, collected at two sites in west-central and southwestern Portugal, varied in age from 2 to 19 years and in plant density from 481 to 1560 trees/ha and included both first and second rotation coppice stands. A total of 29 nonlinear regression models were tested and ranked with a multicriteria evaluation (MCE) procedure, based on goodness-of-fit statistics, predictive ability statistics, and collinearity diagnostics. The best models were validated using an independent data set. The final model selection was based on comparisons of prediction residuals data, statistical tests, and silvicultural and physiological considerations. One model is proposed as adequate for leaf area estimation of E. globulus plantation trees. This model contains four parameters and independent variables that quantify stem diameter, crown size, and stand density.

A new method for estimating the leaf area index of cucumber and tomato plants

Blanco,Flávio Favaro; Folegatti,Marcos Vinícius
Fonte: Associação Brasileira de Horticultura Publicador: Associação Brasileira de Horticultura
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 EN
Relevância na Pesquisa
66.26%
Non-destructive methods of leaf area measurement are useful for small plant populations, such as experiments with potted plants, and allow the measurement of the same plant several times during the growing period. A methodology was developed to estimate the leaf area index (LAI) of cucumber and tomato plants through the evaluation of the leaf area distribution pattern (LADP) of the plants and the relative height of the leaves in the plants. Plant and leaf height, as well as the length and width of all leaves were measured and the area of some leaves was determined by a digital area meter. The obtained regression equations were used to estimate the leaf area for all relative heights along the plant. The LADP adjusted to a quadratic model for both crops and LAI were estimated by measuring the length and width of the leaves located at the relative heights representing the mean leaf area of the plants. The LAI estimations presented high precision and accuracy when the proposed methodology was used resulting in time and effort savings and being useful for both crops.

Influence of leaf area reduction on clonal production of eucalyptus seedlings

Santana,Reynaldo Campos; Dutra,Tiago Reis; Carvalho Neto,José Pereira; Nogueira,Gilciano Saraiva; Grazziotti,Paulo Henrique; Barros Filho,Nairam Félix de
Fonte: UFLA - Universidade Federal de Lavras Publicador: UFLA - Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2010 EN
Relevância na Pesquisa
66.16%
Clonal production of eucalyptus seedlings has made considerable progress in recent years. Significant developments have taken place in irrigation and fertilization systems as well as in management of clonal miniorchards. However, the proportion of leaf area in stem minicuttings remains almost the same as that used in macrocutting systems. This work aimed to evaluate the effect of leaf area reduction on seedling production of eight eucalyptus clones. The experiment was conducted over a period of 105 days using a randomized block design and three replicates in an 8 x 4 factorial arrangement, with eight clones and four leaf reduction levels (0%, 25%, 50% and 75%). Variables evaluated included height, root collar diameter, shoot and root dry matter and relationships between these variables. Experimental results demonstrated that clones behaved differently as to leaf reduction and that the 0% reduction level can be adopted in most clones being evaluated.

Evaluation efficiency of severity of angular leaf spot in common bean based on diseased and healthy leaf area

Parrella,Rafael Augusto da Costa; Santos,João Bosco dos; Parrella,Nádia Nardely Lacerda Durães; Silva,Diego Velásquez Faleiro e
Fonte: Crop Breeding and Applied Biotechnology Publicador: Crop Breeding and Applied Biotechnology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2013 EN
Relevância na Pesquisa
66.23%
This study compared severity of angular leaf spot in common bean lines, based on the healthy and diseased leaf area, and the graded scale. We used 12 common bean lines in the dry and rainy seasons. Two contiguous experiments were conducted in each season, with and without chemical control of the pathogen. We evaluated the percentage of the healthy and diseased leaf area; severity based on a graded scale and the area under the disease progress curve; and yield. The diseased or healthy leaf area is efficient to evaluate the severity of angular leaf spot with a sample of 20 to 30 leaflets per plot. For all traits, the results of central and border areas did not differ, indicating that the evaluation of border rows is unnecessary and, finally, the severity assessment of the upper plant half can discriminate the lines more efficiently.

Leaf area index and above-ground biomass of terra firme rain forest and adjacent clearings in Amazonia.

MCWILLIAM, A. L. C.; ROBERTS, J. M.; CABRAL, O. M. R.; LEITAO, M. V. B. R.; COSTA, A. C. L. de; MAITELLI, G. T.; ZAMPARONI, C. A. G. P.
Fonte: Functional Ecology, v. 7, p. 310-317, 1993. Publicador: Functional Ecology, v. 7, p. 310-317, 1993.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
66.26%
Leaf area index (L*) and above-ground biomass were determined by destructive sampling for a 400m2 area of terra firme Amazonian rain forest and for an adjacent clearing. While L* in the forest varied considerably with height though the canopy for four separately sampled 100m2 subplots, the cumulative L* was similar with a mean value of 5.7 + ou - 0.5. The total above-ground dry biomass of the forest was 265 + ou - 95t ha-1, while the leaf dry biomass was 6.3 + ou - 0.5t ha-1. The specific leaf area (SLA, cm2g-1) was determined, and found to vary linearlywith canopy depth rising from 65cm2g-1 at the canopy top, to 114cm2g-1at 5m above the forest floor. The average for the four subplots was 90cm2g-1. The leaf area index of grass in the clearing (blade only) averaged 0.8 + ou - 0.4, and total green area index (blade + stem) averaged 1.2 + ou - 0.6. Total above-ground dry biomass (blade, stem) was 2.3 + ou - 0.6t ha-1, while including dead plant material gave a total dry biomass of 5.6 + ou - 2.1t ha-1. Specific leaf area of the grass was 79cm2g-1. The results clearly demonstrate the profound change in leaf area and biomass which accompany Amazonian deforestation.; 1993

Influence of leaf area reduction on clonal production of eucalyptus seedlings; Influência da redução da área foliar na produção de mudas clonais de eucalipto

Fonte: UFLA - Universidade Federal de Lavras Publicador: UFLA - Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
EN
Relevância na Pesquisa
66.2%
Clonal production of eucalyptus seedlings has made considerable progress in recent years. Significant developments have taken place in irrigation and fertilization systems as well as in management of clonal miniorchards. However, the proportion of leaf area in stem minicuttings remains almost the same as that used in macrocutting systems. This work aimed to evaluate the effect of leaf area reduction on seedling production of eight eucalyptus clones. The experiment was conducted over a period of 105 days using a randomized block design and three replicates in an 8 x 4 factorial arrangement, with eight clones and four leaf reduction levels (0%, 25%, 50% and 75%). Variables evaluated included height, root collar diameter, shoot and root dry matter and relationships between these variables. Experimental results demonstrated that clones behaved differently as to leaf reduction and that the 0% reduction level can be adopted in most clones being evaluated.

Testing four methods to assess leaf area in young olive trees

Coelho, Renato; Dambiro, José; Carlos, Rui; Pirata, Madalena; Campos, Tiago; Queirós, Rui; Carrilho, João; Barreto, Sérgio; Tufik, Camila; Mestre, Teresa
Fonte: Book of Proceedings of the XII Portuguese-Spanish Symposium on Plant Water Relations (2014) ISBN 978-989-8096-52-4 Publicador: Book of Proceedings of the XII Portuguese-Spanish Symposium on Plant Water Relations (2014) ISBN 978-989-8096-52-4
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.34%
Assessment of leaf area is of fundamental importance to calculate diverse physiological parameters such as the total rate of transpiration or photosynthesis of a plant or its leaf area index (LAI). This paper reports the determination of total leaf area in 3 year-old olive trees of two varieties using four different methods and leaf counting as the control method. Leaf area was determined on 7 plants of each variety, Arbequina and Cobrançosa, by thoroughly counting the total number of leaves on each plant and then multiplying by the average leaf area for each variety Leaf area of the same plants was then estimated by (1) the analysis, with software ImageJ, of a photo of each plant from a side or from the top, (2) the crown light scattering measured with a ceptometer (AccuPAR Model LP-80) in the ground at 10 and 20 cm from the trunk, (3) the analysis with software Hemisfer of a photo of the plant from the top, and finally (4) by the determination of the transpiration (mmol s-1) of each plant over a 2 hour period by a weighing method and dividing this value by the mean transpiration rate (E) of each plant, calculated from the measurement of stomatal conductance (gs) on 10 leaves with a porometer and mean air RH and leaf and air temperature over the same period. Both the ceptometer and the Hemisfer software give a value of leaf area index (LAI). In order to obtain the leaf area...

Photosynthetic acclimation of plants to growth irradiance: The relative importance of specific leaf area and nitrogen partitioning in maximizing carbon gain

Evans, John; Poorter, H
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.25%
Changes in specific leaf area (SLA, projected leaf area per unit leaf dry mass) and nitrogen partitioning between proteins within leaves occur during the acclimation of plants to their growth irradiance. In this paper, the relative importance of both of these changes in maximizing carbon gain is quantified. Photosynthesis, SLA and nitrogen partitioning within leaves was determined from 10 dicotyledonous C3 species grown in photon irradiances of 200 and 1000 μmol m-2 s-1. Photosynthetic rate per unit leaf area measured under the growth irradiance was, on average, three times higher for high-light-grown plants than for those grown under low light, and two times higher when measured near light saturation. However, light-saturated photosynthetic rate per unit leaf dry mass was unaltered by growth irradiance because low-light plants had double the SLA. Nitrogen concentrations per unit leaf mass were constant between the two light treatments, but plants grown in low light partitioned a larger fraction of leaf nitrogen into light harvesting. Leaf absorptance was curvilinearly related to chlorophyll content and independent of SLA. Daily photosynthesis per unit leaf dry mass under low-light conditions was much more responsive to changes in SLA than to nitrogen partitioning. Under high light...

Estimating Leaf Area Index From Satellite Imagery Using Bayesian Networks

Kalacska, Margaret; Sanchez-Azofeifa, G Arturo; Caelli, Terry; Rivard, Benoit; Boerlage, Brent
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.17%
In this study, we investigated the use of Bayesian networks for inferring tropical dry forest leaf area index (LAI) from satellite imagery in dry and wet seasons. LAI was chosen as the variable of interest because leaf area is the exchange surface between the photosynthetically active component of the canopy and the atmosphere. Initial network estimates were obtained from ground truth plot data with known forest structure, LAI, and satellite reflectance in the red and near-infrared bands (as observed by the Landsat 7 Enhanced Thematic Mapper Plus sensor). We tested the performance of the Bayesian networks with scoring rules and also with confidence and surprise scores. We evaluated the networks on a per-pixel basis and created both LAI maps of the study area as well predicted the probability maps for the highest LAI states. Results not only demonstrate the predictive power of a Bayesian network but also its explanatory power which is far beyond what is typically available with current pixel classifier approaches such as spectral vegetation indices or other approaches such as neural networks.

How should leaf area, sapwood area and stomatal conductance vary with tree height to maximize growth?

Buckley, Thomas; Roberts, David W
Fonte: Heron Publishing Publicador: Heron Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.13%
Conventional wisdom holds that the ratio of leaf area to sapwood area (L/S) should decline during height (H) growth to maintain hydraulic homeostasis and prevent stomatal conductance (gs) from declining. We contend that L/S should increase with H based on a numerical simulation, a mathematical analysis and a conceptual argument: (1) numerical simulation - a tree growth model, DESPOT (Deducing Emergent Structure and Physiology Of Trees), in which carbon (C) allocation is regulated to maximize C gain, predicts L/S should increase during most of H growth; (2) mathematical analysis - the formal criterion for optimal C allocation, applied to a simplified analytical model of whole tree carbon-water balance, predicts L/S should increase with H if leaf-level gas exchange parameters including gs are conserved; and (3) conceptual argument - photosynthesis is limited by several substitutable resources (chiefly nitrogen (N), water and light) and H growth increases the C cost of water transport but not necessarily of N and light capture, so if the goal is to maximize C gain or growth, allocation should shift in favor of increasing photosynthetic capacity and irradiance, rather than sustaining gs. Although many data are consistent with the prediction that L/S should decline with H...

Optimal stomatal control in relation to leaf area and nitrogen content

Farquhar, Graham; Buckley, Thomas; Miller, Jeffrey
Fonte: Suomen Geologinen Seura Publicador: Suomen Geologinen Seura
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.32%
We introduce the simultaneous optimisation of water-use efficiency and nitrogen-use efficiency of canopy photosynthesis. As a vehicle for this idea we consider the optimal leaf area for a plant in which there is no self-shading among leaves. An emergent result is that canopy assimilation over a day is a scaled sum of daily water use and of photosynthetic nitrogen display. The respective scaling factors are the marginal carbon benefits of extra transpiration and extra such nitrogen, respectively. The simple approach successfully predicts that as available water increases, or evaporative demand decreases, the leaf area should increase, with a concomitant reduction in nitrogen per unit leaf area. The changes in stomatal conductance are therefore less than would occur if leaf area were not to change. As irradiance increases, the modelled leaf area decreases, and nitrogen/leaf area increases. As total available nitrogen increases, leaf area also increases. In all the examples examined, the sharing by leaf area and properties per unit leaf area means that predicted changes in either are less than if predicted in isolation. We suggest that were plant density to be included, it too would further share the response, further diminishing the changes required per unit leaf area.

Relationships between growth, specific leaf area and water use in six populations of Eucalyptus microtheca seedlings from two climates grown in controlled conditions

Tuomela, K; Koskela, J; Gibson, Ann
Fonte: Institute of Foresters of Australia Publicador: Institute of Foresters of Australia
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.27%
To gain a better understanding of those parameters that control growth and productivity of Eucalyptus microtheca populations from seasonally dry to semi-arid sites in Australia we measured their total plant biomass, allocation of dry matter to roots and shoots, specific leaf area (SLA) and water use. For this purpose the seedlings were raised up to five months under three different pot moisture conditions applied by cyclical watering regimes. Young seedlings of six provenances of Eucalyptus microtheca fell generally into two groups, the Rockhampton, Walgett and Maree provenances which evolved in evenly distributed, though erratic, rainfall conditions at semi-arid sites, and the Pilbara, West Kimberleys and Camooweal provenances which evolved in seasonally dry sites with a reliable monsoon. The former group had the greater leaf area and total plant biomass. Specific leaf area correlated positively with leaf area and total plant biomass at various times across the experimental period. However, as only mino r differences in the average plant water use and carbon discrimination were detected among the populations, greater biomass production in semi-arid populations appears to stem from their capacity to produce a large total leaf area with thin leaves...

Caracterização de nove genótipos de milho (Zea mays L.) en relação à área foliar e coeficiente de extinção de luz; Caracterizacion de nueve genotipos de maiz (Zea mays L.) en relacion a area foliar y coeficiente de extincion de luz; Evaluation of nine corn (Zea mays L.) genotypes in relation to leaf area and light extinction coefficient

Camacho, R.G.; Garrido, O.; Lima, M.G.
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/08/1995 SPA
Relevância na Pesquisa
66.29%
Foram caracterizados nove materiais genéticos de milho (Arichuna, Baraure, Braquítico, Experimental-2, Foremaíz PB, FM-6, Obregón, Proseca-71 y Tocorón) com relação a área foliar média de folhas por planta(AF), área foliar total por planta (AFT), índice de área foliar (IAF) e coeficiente de extinção de luz (K) a 0,50m, 1,00m, 1,50m, 2,00m e 2,50m de altura (a partir do solo). Foram encontrados os seguintes intervalos de variação para as diversas variáveis: área média de folhas por planta (471 cm² para Foremaíz PB e 606 cm² Baraure); área foliar total por planta: 5 327 cm² (Foremaiz PB) e 8 411 cm² (Braquítico), índice de área foliar: 4,26 (Foremaiz PB) e 6,67 (Braquítico); coeficiente de extinção de luz: 0,23 (Braquítico) e 0,42 (Arichuna); rendimento: 2 877 kg.ha-1 (Braquítico) e 4 784 kg.ha-1 (Tocorón). Não foi encontrada relação entre o rendimento e o IAF (r = 0,07), e a associação do IAF e K foi muito bem explicada pela lei de Beer.; Se caracterizaron nueve materiales genéticos de maíz (Arichuna, Baraure, Braquítico, Experimental-2, Foremaíz PB, FM-6, Obregón, Proscca-71 y Tocorón), en relación con área promedio de hoja por planta, área foliar total por planta (AFT), índice de área foliar (IAF)...