Caribaea Var Research Articles

Genetic parameters in subtropical pine F1 hybrids: heritabilities, between-trait correlations and genotype-by-environment interactions

Growth and stem straightness traits of 29 Pinus caribaea var. hondurensis × Pinus tecunumanii (PCH × PTEC) and 26 P. caribaea var. hondurensis × Pinus oocarpa (PCH × POOC) hybrid pair-crosses plus a total of 16 intraspecific families were assessed at ages 5, 8 and 15 years from planting at two sites. The PCH × PTEC hybrid was the most productive, yielding 37 % more than a Pinus elliottii local control and was 21 % superior to either parental species in DBH growth. PCH × POOC hybrid was, on average, 16 % superior to either parental species for DBH. Narrow-sense heritability estimates were low to moderate for growth traits (average of 0.27) and stem straightness (0.16). The estimated additive genetic correlations between growth traits and ages within traits were high (>0.8) and positive, providing confidence in early selection based on diameter at breast height. The high proportion of estimated additive genetic variance compared to dominance variance in the F1 pine hybrids suggests that breeding strategies that maximize the use of additive genetic variance may be effective. The ranking of the 11 PCH parents based on general hybridizing ability predictions (estimated breeding values as hybrids) was somewhat inconsistent between PTEC and POOC hybrid crosses for all traits (r 9 d.f. = 0.38–0.45; p ∼0.15–0.25). There was no evidence of practically important G × E interaction for the hybrids except for PCH × PTEC height growth. This study suggests that a single, multi-hybrid breeding population seems appropriate in Zimbabwe if the trial sites are representative of the planting target zone.

Xylem hydraulic properties in subtropical coniferous trees influence radial patterns of sap flow: implications for whole tree transpiration estimates using sap flow sensors

A high spatial resolution dataset of sap flux density in subtropical conifers is used to assess the minimum number and location of sap flow sensors required to monitor tree transpiration accurately. Tree transpiration is commonly estimated by methods based on in situ sap flux density (SFD) measurements, where the upscaling of SFD from point measurements to the individual tree has been identified as the main source of error. The literature indicates that the variation in SFD with radial position across a tree stem section can exhibit a wide range of patterns. Adequate capture of the SFD profile may require a large number of point measurements, which is likely to be prohibited. Thus, it is of value to develop protocols, which rationalize the number of point measurements, while retaining a satisfactory precision in the tree SFD estimates. This study investigates cross-sectional SFD variability within a tree and successively for six individual trees within a stand of Pinus elliottii var. elliottii × caribaea var. hondurensis (PEE × PCH). The stand is part of a plantation in subtropical coastal Australia. SFD is estimated using the Heat Field Deformation method simultaneously for four cardinal directions with measurements at six depths from the cambium. This yields a reference value of single tree SFD based on the twenty-four point measurements. Large variability of SFD is observed with measurement depth, cardinal direction and selected tree. We suggest that this is linked to the occurrence of successive narrow early and latewood rings with contrasting-specific hydraulic conductivities and wood water contents. Thus, an accurate placement of sensors within each ring is difficult to achieve in the field with the sensor footprint covering several rings of both early and latewood. Based on the reference dataset, we identified both an “ideal” setup and an “optimal” setup in terms of cost effectiveness and accuracy. Our study shows the need of using a systematic protocol to optimize the number of sensors to be used as a trade-off between precision and cost. It includes a preliminary assessment of the SFD variability at a high spatial resolution, and only then based on this, an appropriate placement of sensors for the long-term monitoring.

First Record of the Wood-BorerHylettus seniculus(Coleoptera: Cerambycidae) inPinus caribaeavar.HondrurensisPlantations in Brazil

Summary Here we report for the first time the occurrence of Hylettus seniculus Germar 1824 (Coleoptera: Cerambycidae) boring Pinus caribaea var. hondurensis Morelet (Pinaceae) trunks. Damage by this insect were evaluated from August to Dec 2008 and 2009 by cutting a tree per month from 5 groups of trap trees (5 plants per group) stressed with systemic herbicide. The damage by H. seniculus on trap trees P. caribaea var. hondurensis indicates that prolonged storage of pine logs in the field should be avoided.

Net and gross N transformation rates in subtropical forest soils under aerobic and anaerobic conditions

This study investigated the differences between net and gross rates of N transformation in subtropical forest soils under aerobic and anaerobic conditions. We aim to explore the factors responsible for the differences observed and to evaluate the ability of net and gross N transformation measurements to reflect the occurrence and stimulation of N transformation in subtropical forest soils. Subtropical soil samples from adjacent native forest (NF) and two plantation forest sites (Pinus caribaea var. hondurensis (PCH) and Hoop pine (HP), Araucaria cunninghammii), with different initial pool sizes of NH4 + and NO3 −, were collected from South East Queensland, Australia. Soil samples were incubated at 25 °C to determine net and gross N transformation rates (15N pool dilution method) under aerobic and anaerobic conditions. Under aerobic and anaerobic conditions, gross N transformation rates differed significantly from net N transformation rates. NH4 + immobilization occurred under aerobic and anaerobic conditions for all soils. NO3 − immobilization occurred under aerobic conditions in the NF soils but was negligible in both the PCH and HP soils. Gross ammonification rates were significantly correlated with the C/N ratios (R 2 = 0.714, p < 0.001). Gross nitrification rates were significantly correlated with soil carbon composition (13C, R 2 = 0.569, p < 0.01). The ratios of the gross rates of NH4 + immobilization to the gross ammonification rates (R_i a/g a) were significantly correlated with δ13C (R 2 = 0.829, p < 0.001). The results indicated that in the subtropical forest soils, both the variability of gross N production and immobilization mainly influenced the net N transformation rates. Forest type affected the gross production or immobilization of NH4 + and NO3 − via C turnover, which was indicated by the relationship between the N transformation rates and soil C/N ratio or soil 13C. Although subtropical forest soils are generally an N-unlimited system, the immobilization of NH4 + and NO3 − under aerobic or anaerobic conditions played an important role in the N transformations. Net rates of NH4 +/NO3 − accumulation are not suitable to describe the occurrence and stimulation of N transformations in subtropical soils when immobilization (or other consumption processes) of NH4 + and NO3 − is occurring, especially under anaerobic conditions.

Relação entre perfil de densidade e ligação interna de painéis OSB de Pinus spp

O presente trabalho teve por objetivos determinar a densidade aparente de painéis OSB de Pinus taeda e Pinus elliottii var. elliottii × Pinus caribaea var. hondurensis pelo método gravimétrico e pela densitometria de raios X, obter os perfis densitométricos e verificar sua correlação com a propriedade mecânica de ligação interna. A densidade aparente dos painéis foi determinada pela densitometria de raios X e pelo método gravimétrico, utilizando três corpos de prova (50 × 50 mm) por tratamento. Após as determinações de densidade aparente, os 24 corpos de prova foram submetidos ao ensaio de ligação interna. O método gravimétrico aplicado na determinação da densidade aparente apresentou resultados significativamente maiores do que o método densitométrico. Verificou-se que a densidade mínima do painel, obtida pela densitometria de raios X, teve forte influência na densidade média do painel. Houve correlação entre os valores de densidade aparente dos painéis obtidos por atenuação de raios X e os resultados de ligação interna.

Avaliação de adesivos à base de taninos de &lt;i&gt;Pinus caribaea&lt;/i&gt; var. bahamensis e de &lt;i&gt;Acacia mearnsii&lt;/i&gt; na fabricação de painéis aglomerados

http://dx.doi.org/10.5902/1980509814588Este trabalho teve por objetivo avaliar os métodos para a extração dos taninos da casca do Pinus caribaea var. bahamensis, assim como verificar a viabilidade técnica de utilização dos taninos da casca de Pinus caribaea var. bahamensis, de Acacia mearnsii, de misturas de taninos de acácia negra e pinus e de misturas do adesivo ureia-formaldeído (UF) com taninos de acácia e pinus na produção de adesivos para aglomerados. As cascas de Pinus caribaea var. bahamensis foram fragmentadas em moinho de martelo, peneiradas, extraídas sob refluxo, por 2 horas, utilizada uma relação casca:licor de 1:15 p:v, em nove tratamentos. A melhor forma de extração foi utilizada para obtenção de grandes quantidades de extratos, que foram utilizados na confecção de adesivos tânicos e nas misturas com adesivo UF e com taninos comerciais de acácia negra na fabricação de painéis aglomerados. A adição de sulfito de sódio proporcionou maior extração de taninos, sendo recomendável a extração com adição de 5% de sulfito de sódio. Os resultados mostraram que tanto os taninos de acácia, quanto os de Pinus caribaea var. bahamensis, apresentam boas propriedades de colagem. É possível a adição de solução tânica de pinus à solução tânica de acácia e também substituir parte do adesivo UF pelos taninos de acácia em até 25% sem comprometer a qualidade da colagem. A substituição de 10% de UF por extrato tânico, tanto de pinus quanto de acácia, não alterou os valores de inchamento em espessura (IE) dos painéis. É possível obter boas propriedades mecânicas com adesivos UF modificados com extratos tânicos na proporção de 10%. Os altos valores encontrados para ligação interna (LI) dos painéis fabricados com extratos tânicos evidenciaram o potencial desses taninos para colagem de painéis de madeira.

How weed control and fertilisation influence tree physiological processes and growth at early establishment in an exotic F1 hybrid pine plantation of subtropical Australia

This study investigated how nitrogen (N) nutrition and key physiological processes varied under changed water and nitrogen competition resulting from different weed control and fertilisation treatments in a 2-year-old F1 hybrid (Pinus elliottii Engelm var. elliottii × P. caribaea var. hondurensis Barr. ex Golf.) plantation on a grey podzolic soil type, in Southeast Queensland. The study integrated a range of measures including growth variables (diameter at ground level (DGL), diameter at breast height (DBH) and height (H)), foliar variables (including foliar N concentration, foliar δ13C and δ15N) and physiological variables (including photosynthesis (An), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUEi) (A/gs) and xylem pressure potential (ΨXPP)) to better understand the mechanisms influencing growth under different weed control and fertilisation treatments. Five levels of weed control were applied: standard (routine), luxury, intermediate, mechanical and nil weed control, all with routine fertilisation plus an additional treatment, routine weed control and luxury fertilisation. Relative weed cover was assessed at 0.8, 1.1 and 1.6 years after plantation establishment to monitor the effectiveness of weed control treatments. Soil investigation included soil ammonium (NH4 +-N), nitrate (NO3 −-N), potentially mineralizable N (PMN), gravimetric soil moisture content (MC), hot water extractable organic carbon (HWETC), hot water extractable total N (HWETN), total C, total N, stable C isotope composition (δ13C), stable N isotope composition (δ15N), total P and extractable K. There were significant relationships between foliar N concentrations and relative weed cover and between tree growth and foliar N concentration or foliar δ15N, but initial site preparation practices also increased soil N transformations in the planting rows reducing the observable effects of weed control on foliar δ15N. A positive relationship between foliar N concentration and foliar δ13C or photosynthesis indicated that increased N availability to trees positively influenced non-stomatal limitations to photosynthesis. However, trees with increased foliar N concentrations and photosynthesis were negatively related to xylem pressure potential in the afternoons which enhanced stomatal limitations to photosynthesis and WUEi. Luxury and intermediate weed control and luxury fertilisation positively influenced growth at early establishment by reducing the competition for water and N resources. This influenced fundamental key physiological processes such as the relationships between foliar N concentration, A n, E, gs and ΨXPP. Results also confirmed that time from cultivation is an important factor influencing the effectiveness of using foliar δ15N as an indicator of soil N transformations.

Spatial structure and genetic diversity of natural populations of the Caribbean pine,Pinus caribaeavar. bahamensis(Pinaceae), in the Bahaman archipelago

For the first time a comprehensive population genetics study of the endemic Caribbean pine, Pinus caribaea var. bahamensis, in the Bahamas and the Turks and Caicos Islands (TCI) is undertaken. Information on inbreeding levels, genetic diversity and spatial structure in the focus taxon are important tools for its future conservation and can help guide local forest management. Plastid (pDNA) and nuclear microsatellite (nDNA) loci were used to reveal past and contemporary patterns of genetic differentiation and levels of genetic diversity and to test the hypothesis of isolation by distance of populations in the Bahamas and TCI regions. Due to its non-recombinant nature, low mutation rates and uniparental inheritance, pDNA can give an insight into an earlier state of the populations than that revealed by nDNA. Data from pDNA showed only 12 haplotypes, with one of them present in c. 81% of individuals, low unbiased genetic diversity (uh < 0.107) and lack of significant variation between regions (FCT = 0.011, P = 0.20); whereas nDNA showed higher unbiased genetic diversity (uHS > 0.487) and significant variation between regions (FCT = 0.156, P < 0.01). Isolation by distance was only significant for nDNA (r2 = 0.56, P < 0.01). Only two of the populations had significant levels of inbreeding (FIS = 0.090, FIS = 0.113). High levels of gene flow and lack of isolation in the past were revealed by pDNA, whereas nDNA showed a more recent spatial isolation and genetic differentiation between the Bahamas and TCI populations. Conservation measures are discussed in view of the genetic diversity, inbreeding and spatial structure found in the taxon.

Identifying Hybridisation in Pinus Species Using near Infrared Spectroscopy of Foliage

Near infrared (NIR) spectra from foliage of the tropical pine species Pinus caribaea var. hondurensis, P. elliottii var. elliottii and their hybrids have been used to classify the extent of hybridisation for the F1 and backcross progeny. Comparison of results for F1 hybrids with simulated hybrids, made from admixtures of pure parent foliage samples, showed increased variation in the NIR spectra of the F1 hybrids as evidenced by greater scatter in the principal component analysis scores plot. Both partial least-squares–discriminant analysis and soft independent modelling of class analogy using the foliage spectra provide identification of the hybrid individuals from the parent taxa. In addition, it is possible to visualise the extent of genetic additive effect in hybrid-parent backcrosses. NIR spectra from foliage samples of P. radiata, a temperate pine species, were clearly discriminated from P. elliottii and P. caribaea. Near infrared spectroscopy has the potential to confirm and assess the extent of hybridisation in softwood species. In extreme situations whereby trial records are lost or trial plot labelling is missing, it might be possible to use NIR spectra from foliage to recover taxon information of seedlings.

Produção e Avaliação da Qualidade de Lâminas de Madeira de um Híbrido de Pinus elliottii var. elliottii × Pinus caribaea var. hondurensis

This work aimed to evaluate the utilization potential of wood from Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis hybrid, seven years and 10 months of age, for veneer production. Wood density, peeling yield and the quality of the veneers produced from logs taken from two positions on the tree trunk were assessed: from the base (A logs) and subsequent (B logs). The wood presented low basic density (0.320 g/cm3) and proved to be easily processed in the rotary cutting lathe. The peeling yield (average based on logs without bark) was approximately 53%. The veneers graded in the C and C+ classes accounted for approximately 61% of the total obtained. The A logs yielded more veneers, but the veneers produced presented lower quality compared with those produced from the B logs. We concluded that the hybrid wood herein studied shows good potential for veneer production.

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The objective of this work was to select volumetric models and evaluate the efficiency of three methods to estimate the wood volume of Pinus caribaea var. hondurensis in an even-aged stand in Vitoria da Conquista, State of Bahia, Brazil. After the trees were selected, they were cut down and their volume were rigorously measured to calculate total and commercial individual volume, with and without bark. Eight volumetric models were adjusted. Higher performance models were selected based on the weighted value of the statistical parameters scores. The volumes obtained by measurement were compared to those obtained by form factor, form quotient and adjusted models. The Stoate model was the most efficient in estimating total and commercial volumes with bark. The Stoate model and the modified Naslund model had better performance in estimating the total and commercial volumes, respectively, without bark. The form factor and the volumetric models are recommended for accurately predicting wood volume for this species.

Evaluación de las clases de calidad de sitio de Pinus caribaea var. caribaea en la Empresa Forestal Integral Macurije (Pinar del Río, Cuba).

Gonzalez Izquierdo, E., Barredo Medel, H., Carrasco Rodriguez Y. 2013. Evaluation of site index classes for Pinus caribaea var. caribaea in the Integral Forest Company Macurije (Pinar del Rio, Cuba). Ecosistemas 22(3):46-51. Doi.: 10.7818/ECOS.2013.22-3.07. Evaluation of site index classes for Pinus caribaea var. caribaea in the Integral Forest Company Macurije (Pinar del Rio, Cuba).The research was carried out in stands of Pinus caribaea var. caribaea in plantations of the Integral Forest Company (IFC) Macurije (22o 06´ y 22o 42´ North latitude and 83o 48´ y 84o 23´ longitude West) belonging to the province of Pinar del Rio (western Cuba). The objective of this work was to evaluate the classes of site index of Pinus caribaea var. caribaea in the Integral Forest Company Macurije to correlate them with the proprieties of soil, allowing then to estimate growth of pine stands based on soil features. To do so, we took a random sample of 50 stands among the 677 existent stands in this company, having as variable of interest the site index and as prediction variables: soil type, texture, saturation, humifycation, depth of the soil, pedological depth and topographical slope. These variables were chosen to the strong influence on the site quality. We chose as restrictions for the selection that there should be 10 stands for each site index (SI), and that they are in the age classes superior to 10 years. A model of regression lineal multiple step by step was developed, which explained the existent relationship between the edaphic variables and the topographical slope with the site index. The best model explained 30 % of the variation in site quality. The soil subtype and the topographical slope were the most explanatory variables in the site index. Therefore, they should be taken as reference when planning the forest administration of the plantations of Pinus caribaea var. caribaea .

Effects of weed control and fertilization at early establishment on tree nitrogen and water use in an exotic F1 hybrid pine of subtropical Australia

Purpose We investigated the effects of weed control and fertilization at early establishment on foliar stable carbon (δ13C) and nitrogen (N) isotope (δ15N) compositions, foliar N concentration, tree growth and biomass, relative weed cover and other physiological traits in a 2-year old F1 hybrid (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Barr. ex Golf.)) plantation grown on a yellow earth in southeast Queensland of subtropical Australia. Materials and methods Treatments included routine weed control, luxury weed control, intermediate weed control, mechanical weed control, nil weed control, and routine and luxury fertilization in a randomised complete block design. Initial soil nutrition and soil fertility parameters included (hot water extractable organic carbon (C) and total nitrogen (N), total C and N, C/N ratio, labile N pools (nitrate (NO3 −) and ammonium (NH4 +)), extractable potassium (K+)), soil δ15N and δ13C. Relative weed cover, foliar N concentrations, tree growth rate and physiological parameters including photosynthesis, stomatal conductance, photosynthetic nitrogen use efficiency, foliar δ15N and foliar δ13C were also measured at early establishment. Results and discussion Foliar N concentration at 1.25 years was significantly different amongst the weed control treatments and was negatively correlated to the relative weed cover at 1.1 years. Foliar N concentration was also positively correlated to foliar δ15N and foliar δ13C, tree height, height growth rates and tree biomass. Foliar δ15N was negatively correlated to the relative weed cover at 0.8 and 1.1 years. The physiological measurements indicated that luxury fertilization and increasing weed competition on these soils decreased leaf xylem pressure potential (Ψxpp) when compared to the other treatments. Conclusions These results indicate how increasing N resources and weed competition have implications for tree N and water use at establishment in F1 hybrid plantations of southeast Queensland, Australia. These results suggest the desirability of weed control, in the inter-planting row, in the first year to maximise site N and water resources available for seedling growth. It also showed the need to avoid over-fertilisation, which interfered with the balance between available N and water on these soils.

QTL detection for growth traits in Pinus elliottii var. elliottii and P. caribaea var. hondurensis

Quantitative trait locus (QTL) detection was carried out for growth traits in 122 F1 progenies of Pinus elliottii var. elliottii (PEE) × P. caribaea var. hondurensis (PCH) hybrid. The PCH male parent linkage map contained 108 markers in 16 linkage groups, while the PEE female parent contained 93 markers in 19 linkage groups. Sequence-related amplified polymorphism (SRAP), microsatellite (SSR), expressed sequence tag polymorphism (ESTP) and inter-simple sequence repeat (ISSR) were selected from an existing linkage map. Growth traits investigated were height at age five (HT05) and six years (HT06), diameter at breast height at age five (DBH05) and six years (DBH06) and annual growth from age five to six years of height (AGHT) and diameter at breast height (AGDBH). Kruskal-Wallis and interval mapping approaches were used to estimate levels of significance, the number of QTLs, the percentage of the phenotypic variation explained by each of QTLs and their positions on the genetic linkage maps. Twenty six QTLs with significance levels p < 0.05 were detected on the parental maps for the six growth traits, which explained more than 15% of the phenotypic variation, suggesting an existence of major-effect genes. Several QTLs had the pleiotropy controlling more than one single growth trait. Overall, the proportion of phenotypic variation explained by QTLs ranged from 5.9% to 40.6% for HT05 and HT06, from 6.6% to 42.0% for DBH05 and DBH06 and from 5.8% to 22.3% for AGHT and AGDBH. The results from this study provide a basis for marker-aided selection (MAS) in PEE × PCH hybrids.

Constructing genetic linkage maps for Pinus elliottii var. elliottii and Pinus caribaea var. hondurensis using SRAP, SSR, EST and ISSR markers

A total of 122 F1 individuals from a single full-sib interspecific hybrid family crossed between Pinus elliottii var. elliottii (PEE) and P. caribaea var. hondurensis (PCH) were used to construct a detailed genetic linkage maps using four types of molecular markers: sequence-related amplified polymorphism (SRAP), microsatellite (SSR), expressed sequence tag polymorphism (ESTP) and inter-simple sequence repeat (ISSR). There were 381 SRAP, 108 SSR, 25 ESTP and 32 ISSR loci, segregating in the interspecific F1 hybrid individuals. Framework maps were constructed at a LOD score threshold of 4.0 using the JoinMap® 3.0. The map for the male parent (PCH) had 108 markers in 16 linkage groups (LGs), with a total length of 1,065.9 cM (Kosambi) and an average marker interval of 9.87 cM. The map for the female parent (PEE) contained 93 markers in 19 LGs, with a total length of 1,006.7 cM (Kosambi) and an average marker interval of 10.82 cM. The maps for PCH and PEE covered 56.5 and 70.3 % of their respective genomes. Based on the position of 36 loci segregating in both parents, 8 homologous LGs between PEE and PCH were identified.

Influência do vento no volume de toras e no fator de forma de Pinus caribaea var. hondurensis

Neste trabalho, objetivou-se quantificar a velocidade do vento e observar sua influência no fator de forma e no volume de toras ao longo do fuste, na margem e dentro de uma plantação de Pinus caribaea var. hondurensis no município de Jaborandi (BA). A velocidade do vento foi medida por meio de anemômetros, o volume das toras por um xilômetro, e o fator de forma foi obtido pela divisão do volume da tora mensurado pelo xilômetro e pelo seu volume ajustado em um cilindro. Diferenças significativas (p&lt;0,001) foram encontradas entre as amostras à margem e dentro do talhão, das variáveis estudadas, no teste estatístico não paramétrico. Houve uma relação sigmoidal inversamente proporcional entre a velocidade do vento e o fator de forma e o volume das toras de P. caribaea var. hondurensis, ou seja, quanto maior o valor da velocidade do vento, menores os valores do fator de forma e do volume das toras.

Discrimination of Pinus TaedaxP. Caribaea var. hondurensis between its Allele-Species and Hybrids using near Infrared Spectroscopy

It is not easy to distinguish hybrid pines using their morphological characteristics. Traditional methods of identification, such as chemical analysis or molecular marker technology, are complicated, time-consuming and costly and are not very accurate. They are not, therefore, an ideal means of identification and the use of near-infrared technology, which is comparatively inexpensive and simple to use, is preferable. For the future development of Pinus taedax P. caribaea var. hondurensis (PTC) hybrid trials and breeding programmes, and to provide a more comprehensive understanding of their physiological and biochemical characteristics, it is necessary to identify PTC among the parents ( P. elliottii, P. taeda and P. caribaea var. hondurensis) and other possible hybrids ( P. elliottiix P. caribaea var. hondurensis) in order to be able to distinguish them from each other. In this study, partial least-squares discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) regression modelling are used, The results are as follows: PLS-DA has a low accuracy rate, at 89.09%, but using the PLS-DA scores as the input data into the LDA resulted in LDA distinction models, with accuracy rates reaching 99%, allowing a reliable identification of pure species and hybrids. It is clear from the results that near infrared technology can be used to identify hybrid and purebreds in pine and that the accuracy rate is higher than that derived when using standard molecular techniques.

Avaliação da estabilidade dimensional de espécies de Pinus tropicais

The objective of this research was to evaluate the dimensional stability of tropical pine species and establish correlations between shrinkage, anisotropy, and density. Seven species of tropical pines were utilized: Pinus caribaea var. bahamensis, Pinus caribaea var. caribaea, Pinus caribaea var. hondurensis, Pinus chiapensis, Pinus maximinoi, Pinus oocarpa, and Pinus tecunumanii; Pinus taeda was also used as reference. The samples were from 17 and 18-year-old experimental plantings located in the municipalities of Ventania, State of Parana and Itarare, State of Sao Paulo. Dimensional stability was evaluated according to the COPANT 462 (1972c) norm. The results indicated that Pinus chiapensis is an unstable species (Ac > 2.6), and that other tropical pine species and Pinus taeda presented low average stability (2.1 to 2.5). There were no strong correlations between the properties proposed probably due to the presence of resin and extractives, which can alter density and inhibit contraction.

Produção de painéis compensados estruturais com diferentes composições de lâminas de Eucalyptus saligna e Pinus caribaea

Este trabalho teve como objetivo avaliar a qualidade de painéis compensados estruturais produzidos com lâminas de Eucalyptus saligna e Pinus caribaea var. caribaea, var. hondurensis e var. bahamensis com diferentes composições de lâminas. Foram produzidos painéis experimentais com dimensões de 50 x 50 cm, utilizando-se cinco lâminas de 2,2 mm, com as seguintes composições: (1) painéis com todas as lâminas de mesma espécie/variedades (T1, T2, T3 e T4); e (2) painéis com lâminas de Eucalyptus saligna de forma intercalada com as lâminas de três variedades de Pinus caribaea (T5 a T10). Os painéis produzidos exclusivamente com lâminas de Eucalyptus saligna apresentaram valores superiores de resistência da linha de cola aos esforços de cisalhamento, MOE e MOR paralelo e perpendicular. A composição dos painéis com lâminas das duas espécies/variedades de forma intercalada não influenciou, de forma significativa, a resistência da linha de cola e MOE e MOR perpendicular. A disposição das lâminas de Eucalyptus saligna na capa dos compensados resultou em maiores valores de MOE e MOR paralelo. Os resultados das propriedades mecânicas avaliadas foram satisfatórios, em comparação com os valores de referência apresentados na literatura e com aqueles requisitos mínimos requeridos pela norma técnica, indicando a viabilidade de produção de painéis compensados do tipo "combi" com combinação de espécies de folhosas e coníferas.

Divergência genética entre progênies de Pinus caribaea var. caribaea com base em caracteres quantitativos

The objective of this research was to quantify the genetic dissimilarity among P.caribaea var. caribaea progenies to identify divergent parents aiming to generate highly productive genotypes and to evaluate the total variability by phenotypic characters of commercial importance. The progeny trial of P. caribaea var. caribaea was set up through 10 x 10 triple lattice design, with 99 progenies and a commercial control in Selviria, MS, Brazil. We have evaluated quantitative characters before and after thinning procedures such as: total plant height (m), diameter at breast height (dbh) (cm); wood volume (m 3 tree -1 ), stem form, wood density at dbh and wood density at the middle of the total height of tree stem (g cm -3 ), and survival of progenies (%). There was low genetic divergence among P. caribaea var. caribaea progenies. The diameter at breast height was the character that most contributes to genetic diversity among progenies, for both before and after thinning. The information of Mahalanobis distance and the clustering of progenies by Tocher's method will be important to define the future strategies for breeding programs and genetic conservation of the species. doi: 10.4336/2012.pfb.32.69.69