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Eucalypts are the most planted hardwood in the world, with 30 million ha. under cultivation. There are approximately 700 species of eucalypts, but more than 90 % of the plantations are concentrated in nine species of the Subgenus Symphyomyrtus in the Sections Exsertaria, Latoangulatae and Maidenaria. Since 2000, with the advancement of biotechnology, many species have been reclassified and regrouped according to their morphological and physiological characteristics, DNA structure and geographic distribution. This work had as its objective the formulation of a critical analysis which presents the main characteristics that will identify the species of Eucalyptus of these new sections. The species are classified mainly according to geographic distribution, where crosses occur; as evolution in the subgenus Symphyomyrtus is preferably reticulated (with backcrosses), which makes it difficult to identify the rate by molecular and morphological markers. Environmental ecological similarity will define whether the hybrid will become a new species or regress to one parent and become an ecotype. The hybrid will become a new species when it has ecological characteristics different from its parents.

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Eucalypts are the most planted hardwood in the world, with 30 million ha. under cultivation. There are approximately 700 species of eucalypts, but more than 90 % of the plantations are concentrated in nine species of the Subgenus Symphyomyrtus in the Sections Exsertaria, Latoangulatae and Maidenaria. Since 2000, with the advancement of biotechnology, many species have been reclassified and regrouped according to their morphological and physiological characteristics, DNA structure and geographic distribution. This work had as its objective the formulation of a critical analysis which presents the main characteristics that will identify the species of Eucalyptus of these new sections. The species are classified mainly according to geographic distribution, where crosses occur; as evolution in the subgenus Symphyomyrtus is preferably reticulated (with backcrosses), which makes it difficult to identify the rate by molecular and morphological markers. Environmental ecological similarity will define whether the hybrid will become a new species or regress to one parent and become an ecotype. The hybrid will become a new species when it has ecological characteristics different from its parents.(AU)

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Genomic Best Linear Unbiased Prediction (GBLUP) in tree breeding typically only uses information from genotyped trees. However, information from phenotyped but non-genotyped trees can also be highly valuable. The single-step GBLUP approach (ssGBLUP) allows genomic prediction to take into account both genotyped and non-genotyped trees simultaneously in a single evaluation. In this study, we investigated the advantage, in terms of breeding value accuracy and bias, of including phenotypic observation from non-genotyped trees in a standard tree GBLUP evaluation. We compared the efficiency of the conventional pedigree-based (ABLUP), GBLUP and ssGBLUP approaches to evaluate eight growth and wood quality traits in a Eucalyptus hybrid population, genotyped with 33,398 single nucleotide polymorphisms (SNPs) using the EucHIP60k. Theoretical accuracies, predictive ability and bias were calculated by ten-fold cross validation on all traits. The use of additional phenotypic information from non-genotyped trees by means of ssGBLUP provided higher predictive ability (from 37% to 75%) and lower prediction bias (from 21% to 73%) for the genetic component of non-phenotyped but genotyped trees when compared to GBLUP. The increase (decrease) in the prediction accuracy (bias) became stronger as trait heritability decreased. We concluded that ssGBLUP is a promising breeding tool to improve accuracies and bias over classical GBLUP for genomic evaluation in Eucalyptus breeding practice.

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This study focuses on the effects of different thinning regimes on clonal Eucalyptus plantations growth. Four different trials, planted in 1999 and located in Bahia and Espírito Santo States, were used. Aside from thinning, initial planting density, and post thinning fertilization application were also evaluated. Before canopy closure, and therefore before excessive competition between trees took place, it was found that stands planted under low densities (667 trees per hectare) presented a lower mortality proportion when compared to stand planted under higher densities (1111 trees per hectare). However, diameter growth prior to thinning operations was not statistically different between these two densities, presenting an overall mean of 4.9 cm/year. After canopy closure and the application of the thinning treatments, it was found that thinning regimes beginning early in the life of the stand and leaving a low number of residual trees presented the highest diameter and height growth. Unthinned treatments and thinning regimes late in the life of the stand (after 5.5 years), leaving a large number of residual trees presented the highest values of basal area production. The choice of the best thinning regime for Eucalyptus clonal material will vary according to the plantation objective.

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This study evaluated the quality of heartwood and sapwood from mature trees of three species of Eucalyptus, by means of the qualification of their proportion, determination of basic and apparent density using non-destructive attenuation of gamma radiation technique and calculation of the density uniformity index. Six trees of each species (Eucalyptus grandis - 18 years old, Eucalyptus tereticornis - 35 years old and Corymbia citriodora - 28 years old) were used in the experimental program. The heartwood and sapwood were delimited by macroscopic analysis and the calculation of areas and percentage of heartwood and sapwood were performed using digital image. The uniformity index was calculated following methodology which numerically quantifies the dispersion of punctual density values of the wood around the mean density along the radius. The percentage of the heartwood was higher than the sapwood in all species studied. The density results showed no statistical difference between heartwood and sapwood. Differently from the density results, in all species studied there was statistical differences between uniformity indexes for heartwood and sapwood regions, making justifiable the inclusion of the density uniformity index as a quality parameter for Eucalyptus wood.

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ABSTRACT This study focuses on the effects of different thinning regimes on clonal Eucalyptus plantations growth. Four different trials, planted in 1999 and located in Bahia and Espírito Santo States, were used. Aside from thinning, initial planting density, and post thinning fertilization application were also evaluated. Before canopy closure, and therefore before excessive competition between trees took place, it was found that stands planted under low densities (667 trees per hectare) presented a lower mortality proportion when compared to stand planted under higher densities (1111 trees per hectare). However, diameter growth prior to thinning operations was not statistically different between these two densities, presenting an overall mean of 4.9 cm/year. After canopy closure and the application of the thinning treatments, it was found that thinning regimes beginning early in the life of the stand and leaving a low number of residual trees presented the highest diameter and height growth. Unthinned treatments and thinning regimes late in the life of the stand (after 5.5 years), leaving a large number of residual trees presented the highest values of basal area production. The choice of the best thinning regime for Eucalyptus clonal material will vary according to the plantation objective.

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ABSTRACT This study evaluated the quality of heartwood and sapwood from mature trees of three species of Eucalyptus, by means of the qualification of their proportion, determination of basic and apparent density using non-destructive attenuation of gamma radiation technique and calculation of the density uniformity index. Six trees of each species (Eucalyptus grandis - 18 years old, Eucalyptus tereticornis - 35 years old and Corymbia citriodora - 28 years old) were used in the experimental program. The heartwood and sapwood were delimited by macroscopic analysis and the calculation of areas and percentage of heartwood and sapwood were performed using digital image. The uniformity index was calculated following methodology which numerically quantifies the dispersion of punctual density values of the wood around the mean density along the radius. The percentage of the heartwood was higher than the sapwood in all species studied. The density results showed no statistical difference between heartwood and sapwood. Differently from the density results, in all species studied there was statistical differences between uniformity indexes for heartwood and sapwood regions, making justifiable the inclusion of the density uniformity index as a quality parameter for Eucalyptus wood.

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This study focuses on the effects of different thinning regimes on clonal Eucalyptus plantations growth. Four different trials, planted in 1999 and located in Bahia and Espírito Santo States, were used. Aside from thinning, initial planting density, and post thinning fertilization application were also evaluated. Before canopy closure, and therefore before excessive competition between trees took place, it was found that stands planted under low densities (667 trees per hectare) presented a lower mortality proportion when compared to stand planted under higher densities (1111 trees per hectare). However, diameter growth prior to thinning operations was not statistically different between these two densities, presenting an overall mean of 4.9 cm/year. After canopy closure and the application of the thinning treatments, it was found that thinning regimes beginning early in the life of the stand and leaving a low number of residual trees presented the highest diameter and height growth. Unthinned treatments and thinning regimes late in the life of the stand (after 5.5 years), leaving a large number of residual trees presented the highest values of basal area production. The choice of the best thinning regime for Eucalyptus clonal material will vary according to the plantation objective.

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Wood density can be considered as a measure of the internal wood structure, and it is usually used as a proxy measure of other mechanical and functional traits. Eucalyptus is one of the most important commercial forestry genera worldwide, but the relationship between wood density and vulnerability to cavitation in this genus has been little studied. The analysis is hampered by, among other things, its anatomical complexity, so it becomes necessary to address more complex techniques and analyses to elucidate the way in which the different anatomical elements are functionally integrated. In this study, vulnerability to cavitation in two races of Eucalyptus globulus Labill. with different wood density was evaluated through Path analysis, a multivariate method that allows evaluation of descriptive models of causal relationship between variables. A model relating anatomical variables with wood properties and functional parameters was proposed and tested. We found significant differences in wood basic density and vulnerability to cavitation between races. The main exogenous variables predicting vulnerability to cavitation were vessel hydraulic diameter and fibre wall fraction. Fibre wall fraction showed a direct impact on wood basic density and the slope of vulnerability curve, and an indirect and negative effect over the pressure imposing 50% of conductivity loss (P50) through them. Hydraulic diameter showed a direct negative effect on P50, but an indirect and positive influence over this variable through wood density on one hand, and through maximum hydraulic conductivity (ks max) and slope on the other. Our results highlight the complexity of the relationship between xylem efficiency and safety in species with solitary vessels such as Eucalyptus spp., with no evident compromise at the intraspecific level.

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The yield of lumber is one of the main parameters of evaluation of log sawing. Using this information, you can judge the quality of the conversion of logs into sawed parts. This variable indicates the percentage of the original volume of the log that has been transformed into lumber. Therefore, this study aimed to expand knowledge of the mechanical processing of Eucalyptus wood. For this, we employed 72 logs of three species: Eucalyptus dunnii, Eucalyptus grandis and Eucalyptus saligna. We compared the income of lumber of the three species, as well as three diameter classes per species. Additionally we evaluated some characteristics of the shape of the stem and phenomena that occurred during the sawing. The results showed that the larger diameter logs from E. saligna and E.grandis obtained the best performances in income, then the logs of the two intermediate species. The logs from E. dunnii had the worst performance among the three diameter classes, due to the shape of the logs and the manifestation of growth stresses during sawing.

O rendimento é uma informação relevante, pois indica a porcentagem do volume original da tora que foi efetivamente transformada em madeira serrada e, portanto, reflete a qualidade da operação de conversão de toras. O presente estudo teve por objetivo ampliar os conhecimentos sobre o processamento mecânico da madeira do gênero Eucalyptus. Foi conduzido o desdobro de 72 toras de três espécies: Eucalyptus dunnii, Eucalyptus grandis e Eucalyptus saligna, as quais foram comparadas quanto ao rendimento do processo em função da espécie e em função da separação das toras em três classes de diâmetro. Adicionalmente avaliaram-se algumas características relacionadas à qualidade do fuste e aquelas atribuídas a manifestação das tensões de crescimento para verificar sua influência sobre o rendimento. Os resultados apontaram que as toras de maior diâmetro das espécies E. saligna e E. grandis foram as que forneceram os maiores rendimentos, seguidas das toras de classe de diâmetro intermediário. Já as toras de E. dunnii apresentaram os piores desempenhos para as três classes diamétricas avaliadas, o que pode ser atribuído a forma das toras e também por conta da manifestação de tensões de crescimento durante o processo de desdobro.

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The yield of lumber is one of the main parameters of evaluation of log sawing. Using this information, you can judge the quality of the conversion of logs into sawed parts. This variable indicates the percentage of the original volume of the log that has been transformed into lumber. Therefore, this study aimed to expand knowledge of the mechanical processing of Eucalyptus wood. For this, we employed 72 logs of three species: Eucalyptus dunnii, Eucalyptus grandis and Eucalyptus saligna. We compared the income of lumber of the three species, as well as three diameter classes per species. Additionally we evaluated some characteristics of the shape of the stem and phenomena that occurred during the sawing. The results showed that the larger diameter logs from E. saligna and E.grandis obtained the best performances in income, then the logs of the two intermediate species. The logs from E. dunnii had the worst performance among the three diameter classes, due to the shape of the logs and the manifestation of growth stresses during sawing.(AU)

O rendimento é uma informação relevante, pois indica a porcentagem do volume original da tora que foi efetivamente transformada em madeira serrada e, portanto, reflete a qualidade da operação de conversão de toras. O presente estudo teve por objetivo ampliar os conhecimentos sobre o processamento mecânico da madeira do gênero Eucalyptus. Foi conduzido o desdobro de 72 toras de três espécies: Eucalyptus dunnii, Eucalyptus grandis e Eucalyptus saligna, as quais foram comparadas quanto ao rendimento do processo em função da espécie e em função da separação das toras em três classes de diâmetro. Adicionalmente avaliaram-se algumas características relacionadas à qualidade do fuste e aquelas atribuídas a manifestação das tensões de crescimento para verificar sua influência sobre o rendimento. Os resultados apontaram que as toras de maior diâmetro das espécies E. saligna e E. grandis foram as que forneceram os maiores rendimentos, seguidas das toras de classe de diâmetro intermediário. Já as toras de E. dunnii apresentaram os piores desempenhos para as três classes diamétricas avaliadas, o que pode ser atribuído a forma das toras e também por conta da manifestação de tensões de crescimento durante o processo de desdobro.(AU)

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This study aimed to estimate photosynthetic pigments contents from leaves of Eucalyptus dunni Maiden based on values of reflectance spectra of red, green and blue colors obtained with a digital color analyzer. We collected fifty leaves from the lower third of the crown of twenty trees including young as well as mature leaves. From each leaf an area of 14 cm2 of the leaf blade was cut in which we measured reflectance values on the red, green and blue spectra with a portable digital colorimeter, obtained relative index of chlorophyll with a SPAD 502 and determined the content of the chlorophyll a, b, and a + b by classic method of solvent extraction. We submitted the data to multiple linear regression and nonlinear analysis at 5% of error probability. It was evaluated the occurrence of multicollinearity. The negative exponential model resulted in good fit when data from red spectrum was used for chlorophyll a, green spectrum for chlorophyll b and a + b, making possible correlation coefficients between the estimated values and the extracted above 0.85. Except for the chlorophyll a content, the accuracy in estimates of photosynthetic pigments were higher than estimated by the chlorophyll meter, even with linearity between methods. Therefore, it is possible to estimate photosynthetic pigments on E. dunni leaves through values of red and green wavelengths from a digital color...

O presente trabalho objetivou estimar a concentração de pigmentos clorofilianos em folhas de Eucalyptus dunni Maiden com base nos valores de refletância de cores no espectro eletromagnético no vermelho, verde e azul obtidos por um analisador de cores. Cinquenta folhas coletadas do terço inferior da copa de vinte árvores foram utilizadas abrangendo folhas jovens até folhas em processo de abscisão. De cada folha foi retirada uma área de 14 cm2 de limbo foliar, e nesta mensurados os valores da refletância no espectro na faixa do vermelho, verde e azul com um colorímetro portátil, obtido o índice relativo de clorofila com um SPAD 502 e determinada a concentração de clorofila a, b e a + b pelo método clássico de extração por solvente. Os resultados foram submetidos a análise de regressão linear múltipla e não linear a 5% de probabilidade de erro. Avaliou-se a ocorrência de multicolinearidade. Dos modelos ajustados foi realizada uma análise dos resíduos e correlacionados com a concentração extraída. Houve multicolinearidade entre os valores do espectro de cores, inviabilizando a estimativa das clorofilas por um modelo linear múltiplo. O modelo exponencial negativo possuiu maior aderência, quando utilizados os valores do espectro vermelho para a concentração de clorofila a, e do verde para a concentração de clorofila b e a + b, possibilitando coeficientes de correlação entre os...

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This study aimed to estimate photosynthetic pigments contents from leaves of Eucalyptus dunni Maiden based on values of reflectance spectra of red, green and blue colors obtained with a digital color analyzer. We collected fifty leaves from the lower third of the crown of twenty trees including young as well as mature leaves. From each leaf an area of 14 cm2 of the leaf blade was cut in which we measured reflectance values on the red, green and blue spectra with a portable digital colorimeter, obtained relative index of chlorophyll with a SPAD 502 and determined the content of the chlorophyll a, b, and a + b by classic method of solvent extraction. We submitted the data to multiple linear regression and nonlinear analysis at 5% of error probability. It was evaluated the occurrence of multicollinearity. The negative exponential model resulted in good fit when data from red spectrum was used for chlorophyll a, green spectrum for chlorophyll b and a + b, making possible correlation coefficients between the estimated values and the extracted above 0.85. Except for the chlorophyll a content, the accuracy in estimates of photosynthetic pigments were higher than estimated by the chlorophyll meter, even with linearity between methods. Therefore, it is possible to estimate photosynthetic pigments on E. dunni leaves through values of red and green wavelengths from a digital color...(AU)

O presente trabalho objetivou estimar a concentração de pigmentos clorofilianos em folhas de Eucalyptus dunni Maiden com base nos valores de refletância de cores no espectro eletromagnético no vermelho, verde e azul obtidos por um analisador de cores. Cinquenta folhas coletadas do terço inferior da copa de vinte árvores foram utilizadas abrangendo folhas jovens até folhas em processo de abscisão. De cada folha foi retirada uma área de 14 cm2 de limbo foliar, e nesta mensurados os valores da refletância no espectro na faixa do vermelho, verde e azul com um colorímetro portátil, obtido o índice relativo de clorofila com um SPAD 502 e determinada a concentração de clorofila a, b e a + b pelo método clássico de extração por solvente. Os resultados foram submetidos a análise de regressão linear múltipla e não linear a 5% de probabilidade de erro. Avaliou-se a ocorrência de multicolinearidade. Dos modelos ajustados foi realizada uma análise dos resíduos e correlacionados com a concentração extraída. Houve multicolinearidade entre os valores do espectro de cores, inviabilizando a estimativa das clorofilas por um modelo linear múltiplo. O modelo exponencial negativo possuiu maior aderência, quando utilizados os valores do espectro vermelho para a concentração de clorofila a, e do verde para a concentração de clorofila b e a + b, possibilitando coeficientes de correlação entre os...(AU)

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Water stress modifies plant above- vs belowground biomass allocation, i.e., morphological plasticity. It is known that all species and genotypes reduce their growth rate in response to stress, but in the case of water stress it is unclear whether the magnitude of such reduction is linked to the genotype's growth potential, and whether the reduction can be largely attributed to morphological adjustments such as plant allocation and leaf and root anatomy. We subjected seedlings of six seed sources, three from each of Eucalyptus camaldulensis (potentially fast growing) and E. globulus (inherently slow growing), to three experimental water regimes. Biomass, leaf area and root length were measured in a 6-month glasshouse experiment. We then performed functional growth analysis of relative growth rate (RGR), and aboveground (leaf area ratio (LAR), specific leaf area (SLA) and leaf mass ratio (LMR)) and belowground (root length ratio (RLR), specific root length (SRL) and root mass ratio (RMR)) morphological components. Total biomass, root biomass and leaf area were reduced for all Eucalyptus provenances according to drought intensity. All populations exhibited drought plasticity, while those of greater growth potential (RGRmax) had a larger reduction in growth (discounting the effect of size). A positive correlation was observed between drought sensitivity and RGRmax. Aboveground, drought reduced LAR and LMR; under severe drought a negative correlation was found between LMR and RGRmax. Belowground, drought reduced SRL but increased RMR, resulting in no change in RLR. Under severe drought, a negative correlation was found between RLR, SRL and RGRmax. Our evidence strongly supports the classic ecophysiological trade-off between growth potential and drought tolerance for woody seedlings. It also suggests that slow growers would have a low capacity to adjust their morphology. For shoots, this constraint on plasticity was best observed in partition (i.e., LMR) whereas for roots it was clearest in morphology/anatomy (i.e., SRL). Thus, a low RGRmax would limit plastic response to drought not only at the whole plant level but also at the organ and even the tissue level.

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O presente trabalho objetivou estimar parâmetros, correlações e ganhos genéticos para caracteres de crescimento e forma, em um teste de progênies deEucalyptus camaldulensis na região centro-oeste do Brasil. Aos três anos de idade, as progênies foram avaliadas quanto aos caracteres: altura total (ALTT), altura comercial (ALTC), diâmetro à altura do peito (DAP) e forma de fuste (FF). A análise de deviance detectou diferenças significativas para os caracteres ALTC, DAP e FF. As estimativas das herdabilidades individuais foram de baixa magnitude para ALTT (0,10) e DAP (0,16), porém, ALTC (0,18) e FF (0,25) apresentaram valores de média a alta magnitude. Os coeficientes de variação genética individual (CVgi%) variaram de 8,59% para FF a 15,91% para ALTC. As correlações fenotípicas e genéticas preditas foram positivas e de alta magnitude entre ALTT e ALTC (0,80 e 0,82, respectivamente) e ALTT e DAP (0,85 e 0,86, respectivamente), indicando que a seleção indireta pode ser utilizada para essas associações. A seleção individual se mostrou superior, quando comparada à seleção entre e dentro. Os valores encontrados indicaram perspectivas de progressos genéticos com seleção baseada nos caracteres avaliados.(AU)

This study aimed to estimate parameters, correlations and genetic gain for growth and shape traits in a progeny trial using Eucalyptus camaldulensisin Central Brazil. When it was three years old, progenies were evaluated for the following traits: total height (ALTT), commercial height (ALTC), diameter at breast height (DAP) and stem form (FF). Deviance analysis detected significant differences for ALTC, DAP and FF. Estimates of individual heritability showed low magnitude for ALTT (0.10) and DAP (0.16). However, ALTC (0.18) and FF (0.25), showed median to high magnitude values. Individual genetic variation coefficients (CVgi%), ranged from 8.59% (FF) to 15.91% (ALTC). Predicted phenotypic and genetic correlations were positive and of high magnitude between ALTT and ALTC (0.80 and 0.82) as well as between ALTT and DAP (0.85 and 0.86), indicating that indirect selection can be used for these associations. Individual selection showed to be superior when compared to selection between and within. Found values indicated perspectives of genetic progress with selection based on the evaluated characters.(AU)

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O conhecimento das relações existentes entre a estrutura anatômica da madeira com suas propriedades físicas ou mecânicas é importante para seu uso adequado. Este trabalho teve como objetivo caracterizar a anatomia microscópica e propriedades físicas da madeira de quatro diferentes espécies florestais. A madeira estudada foi proveniente das seguintes espécies: Cedrela fissilis (Cedro), Híbrido clonal Eucalyptus urophylla × Eucalyptus grandis (Eucalipto urograndis), Hovenia dulcis (Uva do Japão) e Gallesia integrifolia (Pau d'alho). Para a determinação da retratibilidade, utilizou-se a norma MB26/40 da ABNT (1940); as dimensões lineares foram obtidas com palmer, precisão de 0,001mm. O estudo da anatomia da madeira seguiu as recomendações da norma de procedimento em estudos de anatomia de madeira, da COPANT (1974) e também da IAWA (1989). Os caracteres anatômicos avaliados foram: diâmetro tangencial (µm) e frequência de vasos (nomm-2); comprimento de fibra (µm), diâmetro de lume (µm) e espessura de parede de fibra (µm); altura (µm), largura (µm) e frequência de raios (nomm-1). Os valores do coeficiente anisotrópico foram de 1,16; 1,77; 1,81 e 1,84 para a madeira de C. fissilis, H. dulcis, Híbrido clonal e G. integrifolia, respectivamente, demonstrando que a madeira de C. fissilis possui elevada estabilidade dimensional e as demais madeiras, valores aceitáveis para esse coeficiente.

This study aimed to characterize the microscopic anatomy and physical properties of wood from four different forest species. The wood has been studied from the following species: Cedrela fissilis, Crossbreed clone Eucalyptus urophylla × Eucalyptus grandis, Hovenia dulcis and Gallesia integrifolia. To determine the shrinkage it was used the standard of MB26/40 of ABNT (1940), the linear dimensions were obtained with palmer, accuracy of 0.001mm. The study of wood anatomy followed the recommendations of standard procedure in studies of anatomy of wood, COPANT (1974) and also the IAWA (1989). The anatomical characters evaluated were: tangential diameter (µm) and frequency of vessels (nomm-2), fiber length (µm), diameter of lumen (µm) and wall thickness of fiber (µm), height (µm), width (µm) and frequency of rays (nomm-1). The anisotropic factor values were of 1.17, 1.83, 1.89 and 1.90 for C. fissilis, H. dulcis, Crossbreed clone and G. integrifolia, respectively, showing that the C. fissilis wood has high stability dimensional and wood other acceptable values for this coefficient.

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O conhecimento das relações existentes entre a estrutura anatômica da madeira com suas propriedades físicas ou mecânicas é importante para seu uso adequado. Este trabalho teve como objetivo caracterizar a anatomia microscópica e propriedades físicas da madeira de quatro diferentes espécies florestais. A madeira estudada foi proveniente das seguintes espécies: Cedrela fissilis (Cedro), Híbrido clonal Eucalyptus urophylla × Eucalyptus grandis (Eucalipto urograndis), Hovenia dulcis (Uva do Japão) e Gallesia integrifolia (Pau d'alho). Para a determinação da retratibilidade, utilizou-se a norma MB26/40 da ABNT (1940); as dimensões lineares foram obtidas com palmer, precisão de 0,001mm. O estudo da anatomia da madeira seguiu as recomendações da norma de procedimento em estudos de anatomia de madeira, da COPANT (1974) e também da IAWA (1989). Os caracteres anatômicos avaliados foram: diâmetro tangencial (µm) e frequência de vasos (nomm-2); comprimento de fibra (µm), diâmetro de lume (µm) e espessura de parede de fibra (µm); altura (µm), largura (µm) e frequência de raios (nomm-1). Os valores do coeficiente anisotrópico foram de 1,16; 1,77; 1,81 e 1,84 para a madeira de C. fissilis, H. dulcis, Híbrido clonal e G. integrifolia, respectivamente, demonstrando que a madeira de C. fissilis possui elevada estabilidade dimensional e as demais madeiras, valores aceitáveis para esse coeficiente.(AU)

This study aimed to characterize the microscopic anatomy and physical properties of wood from four different forest species. The wood has been studied from the following species: Cedrela fissilis, Crossbreed clone Eucalyptus urophylla × Eucalyptus grandis, Hovenia dulcis and Gallesia integrifolia. To determine the shrinkage it was used the standard of MB26/40 of ABNT (1940), the linear dimensions were obtained with palmer, accuracy of 0.001mm. The study of wood anatomy followed the recommendations of standard procedure in studies of anatomy of wood, COPANT (1974) and also the IAWA (1989). The anatomical characters evaluated were: tangential diameter (µm) and frequency of vessels (nomm-2), fiber length (µm), diameter of lumen (µm) and wall thickness of fiber (µm), height (µm), width (µm) and frequency of rays (nomm-1). The anisotropic factor values were of 1.17, 1.83, 1.89 and 1.90 for C. fissilis, H. dulcis, Crossbreed clone and G. integrifolia, respectively, showing that the C. fissilis wood has high stability dimensional and wood other acceptable values for this coefficient.(AU)

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Although vast areas in tropical regions have weathered soils with low potassium (K) levels, little is known about the effects of K supply on the photosynthetic physiology of trees. This study assessed the effects of K and sodium (Na) supply on the diffusional and biochemical limitations to photosynthesis in Eucalyptus grandis leaves. A field experiment comparing treatments receiving K (+K) or Na (+Na) with a control treatment (C) was set up in a K-deficient soil. The net CO2 assimilation rates were twice as high in +K and 1.6 times higher in +Na than in the C as a result of lower stomatal and mesophyll resistance to CO2 diffusion and higher photosynthetic capacity. The starch content was higher and soluble sugar was lower in +K than in C and +Na, suggesting that K starvation disturbed carbon storage and transport. The specific leaf area, leaf thickness, parenchyma thickness, stomatal size and intercellular air spaces increased in +K and +Na compared to C. Nitrogen and chlorophyll concentrations were also higher in +K and +Na than in C. These results suggest a strong relationship between the K and Na supply to E. grandis trees and the functional and structural limitations to CO2 assimilation rates.

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PREMISE OF THE STUDY: Herein, we name, describe, and illustrate new macrofossil material representing Eucalyptus (Myrtaceae: Myrtoideae, Eucalypteae) from the diverse early Eocene Laguna del Hunco (LH) flora of Chubut Province, Patagonia, Argentina. We explore the significance of these fossils in light of understanding the fossil record of eucalypts and the biogeography of the Eucalypteae. METHODS: Fossils representing vegetative and reproductive organs were collected from multiple LH localities over several field seasons. These specimens were prepared, photographed, and compared to extant Eucalyptus. Additional historical collections of Patagonian fossil Eucalyptus were also examined. KEY RESULTS: Vegetative and reproductive organs representing five different Eucalyptus taxa were identified in the LH paleoflora. One new taxon each representing leaves, flower buds, and infructescences with co-occurring, isolated capsules are described and named as new Eucalyptus species. Additionally, two flower types cf. Eucalyptus, represented by one specimen each, are illustrated and briefly described. The fossil species have unique characteristics that independently suggest each belongs within the Eucalypteae. The reproductive material is most similar morphologically to extant Eucalyptus, although it also shares many similarities to the closely related genus Corymbia. CONCLUSIONS: The LH fossil Eucalyptus material is among the few eucalypt macrofossils that have recently been named and described and are the oldest macrofossils that can presently be definitively ascribed to the Eucalypteae. They also represent the only credible description of Eucalyptus fossils occurring outside of Australasia and suggest a once broader geographic distribution for this group.

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BACKGROUND: Eucalyptus globulus and its hybrids are very important for the cellulose and paper industry mainly due to their low lignin content and frost resistance. However, rooting of cuttings of this species is recalcitrant and exogenous auxin application is often necessary for good root development. To date one of the most accurate methods available for gene expression analysis is quantitative reverse transcription-polymerase chain reaction (qPCR); however, reliable use of this technique requires reference genes for normalization. There is no single reference gene that can be regarded as universal for all experiments and biological materials. Thus, the identification of reliable reference genes must be done for every species and experimental approach. The present study aimed at identifying suitable control genes for normalization of gene expression associated with adventitious rooting in E. globulus microcuttings. RESULTS: By the use of two distinct algorithms, geNorm and NormFinder, we have assessed gene expression stability of eleven candidate reference genes in E. globulus: 18S, ACT2, EF2, EUC12, H2B, IDH, SAND, TIP41, TUA, UBI and 33380. The candidate reference genes were evaluated in microccuttings rooted in vitro, in presence or absence of auxin, along six time-points spanning the process of adventitious rooting. Overall, the stability profiles of these genes determined with each one of the algorithms were very similar. Slight differences were observed in the most stable pair of genes indicated by each program: IDH and SAND for geNorm, and H2B and TUA for NormFinder. Both programs identified UBI and 18S as the most variable genes. To validate these results and select the most suitable reference genes, the expression profile of the ARGONAUTE1 gene was evaluated in relation to the most stable candidate genes indicated by each algorithm. CONCLUSION: Our study showed that expression stability varied between putative reference genes tested in E. globulus. Based on the AGO1 relative expression profile obtained using the genes suggested by the algorithms, H2B and TUA were considered as the most suitable reference genes for expression studies in E. globulus adventitious rooting. UBI and 18S were unsuitable for use as controls in qPCR related to this process. These findings will enable more accurate and reliable normalization of qPCR results for gene expression studies in this economically important woody plant, particularly related to rooting and clonal propagation.

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