José Louzada

Radial variation of wood density components and ring width in cork oak trees

The radial variation of ring width and wood density was studied in cork oaks (Quercus suber) using microdensitometry. The observations were made in young never debarked cork oaks (30–40 years of age) and in mature trees under cork production (37–60 years of age). The cork oak wood is very dense (mean ring density 0.86 g.cm−3, between 0.79 g.cm−3 and 0.97 g.cm−3) with a small intra-ring variability (mean earlywood density 0.80 g.cm−3 and latewood density 0.90 g.cm−3). The density components decreased from pith to bark more rapidly until the 15th ring, and then only slightly. There were no significant differences in the mean density components between never debarked trees and trees under cork production but their outwards decrease was accentuated in the never debarked trees. The annual growth was high, with a ring width mean of 3.9 mm (4.2 mm in the first 30 years) and the latewood represented 57% of the annual growth.RésuméLa variation radiale de la largeur des cernes et de la densité du bois a été étudiée dans le chêne-liège (Quercus suber) par microdensitométrie. Les observations ont été réalisées dans des arbres jeunes jamais écorcés (âge 30–40 ans) et des arbres en phase de production de liège (37–60 ans). Le bois de chêne-liège est très dense (densité moyenne 0,86 g.cm−3, variant entre 0,79 g.cm−3 et 0,97 g.cm−3) avec une variabilité dans le cerne faible (densité moyenne du bois initial 0,80 g.cm−3 et du bois final 0,97 g.cm−3). Les composantes de la densité diminuent du cœur à la périphérie rapidement jusqu’au 15e cerne, puis plus lentement. Les différences entre valeurs moyennes des composantes de la densité du bois des arbres non écorcés et écorcés ne sont pas statistiquement significatives, quoique la diminution radiale soit plus accentuée dans les arbres non écorcés. La croissance annuelle était élevée avec une largeur moyenne de cerne de 3,9 mm (4,2 mm dans les premiers 30 ans) avec le bois final correspondant à 57 % de la croissance annuelle.

Use of molecular markers for estimating breeding parameters: a case study in a Pinus pinaster Ait. progeny trial

The management of a genetic improvement program is based on the knowledge of the genetic parameters and their relationships to determine the genetic gains. Knowledge of the coefficient of coancestry (θ) is a requirement for efficient progeny testing scheme and for estimating additive variance components for any quantitative trait. When using open-pollinated families, most authors assume that the seedlings are related as half-sibs, but this is not always true. Our aim was to estimate a mean value of the coancestry coefficient of the families present in a maritime pine Pinus pinaster Ait. (maritime or cluster pine) progeny trial originating from seed collected in a clonal seed orchard and to study how deviations from the standard assumption of θ = 0.125 affect heritability estimations. Five highly polymorphic microsatellite markers were scored in 125 offspring from a subsample of five families from the progeny trial. The mean value of the coancestry coefficient of the families present in this progeny trial was 0.130. Differences between the unadjusted and adjusted heritability estimates were more pronounced in wood density (0.609 and 0.586, respectively) than in diameter (0.166 and 0.154, respectively). We conclude that in the trial, the associated error in heritability estimates due to the inclusion of full-sibs, when assuming a standard coefficient of relationship among open-pollinated sibs of 0.250, was low and that this result is robust with respect to the number of families sampled, given unbiased estimates of average relationship among offspring within sib families.

Genetic correlations between wood quality traits of Pinus pinaster Ait

Abstract• It is essential to understand how characteristics are related to each other in breeding programmes to select wood properties, in order to avoid that, in selecting for one trait, we are negatively affecting another. Moreover, measuring wood properties is time consuming and expensive.• This study assesses genetic and phenotypic correlations between wood density components and spiral grain of 46 half-sib families of Pinus pinaster in seventeen-year-old trees.• Results showed that genetic correlations for all wood density components were higher than corresponding phenotypic correlations. Furthermore, all wood density components were highly genetically correlated with ring density, and also closely associated among themselves. Results showed a higher genetic correlation of ring density with earlywood density (rg = 0.96) than with latewood density rg = 0.79). A moderate to high positive genetic correlation was found between spiral grain and wood density characteristics (0.29–0.61).• We conclude that ring density (overall wood density) can be improved by increasing either earlywood density, latewood percent, or both of these traits, and spiral grain can be modify in future plantations.Résumé• En amélioration génétique, il est essentiel de connaître le degré de liaison entre caractères de manière à éviter lors de la sélection pour un caractère une contre-sélection pour un autre. De plus, la mesure des propriétés du bois est lourde et coûteuse.• Dans cette étude, nous étudions les corrélations génétiques et phénotypiques entre les composantes de la densité du bois et l’angle du fil chez 46 familles de demi-frères de Pinus pinaster âgées de 17 ans.• Les résultats montrent que les corrélations génétiques pour toutes les composantes de la densité du bois sont plus élevées que les corrélations phénotypiques. De plus, toutes les composantes de la densité sont fortement corrélées génétiquement avec la densité du cerne et étroitement liées entre elles. Les résultats indiquent une liaison génétique plus forte entre la densité du cerne et la densité du bois initial (rg = 0.96) qu’avec le bois final (rg = 0.79). Une corrélation génétique modérée à forte est mise en évidence entre l’angle du fil du bois et les caractéristiques de densité (0.29–0.61).• Nous concluons que la densité du cerne peut être améliorée soit en augmentant la densité du bois initial, soit la proportion de bois final, soit les deux et que l’angle du fil peut être modifié pour les plantations futures.

Assessment and Description of Magnesium Deficiencies in Chestnut Groves

Abstract In order to diagnose the symptoms of conspicuous magnesium (Mg) deficiency in sweet chestnuts (Castanea sativa Mill.) and to determine its effect on yield, two types of studies were carried out. In study 1, twenty six chestnut groves were selected to assess both foliar and soil nutrient status. In study 2, a twenty year‐old chestnut grove with a conspicuous Mg deficiency was selected and trees were classified according to foliar chlorosis, into three categories, in order to determine the effect of Mg deficiency on several tree growth parameters and yield. Study 1, showed an average foliar Mg concentration of 0.5 g kg−1 in trees with evident leaf chlorosis. When Mg concentration was 0.3 g kg−1 or less premature leaf fall was observed. The symptom free trees had an average Mg concentration of 1.6 g kg−1 or higher. The foliar K/Mg ≥ 9 ratio seemed to be the threshold value above which leaf chlorosis was observed. The ratio N/Mg ≥ 23 also indicated the boundary above which visible Mg deficiencies might be observed. Most soil fertility parameters were more favorable in the vigorous groves and no significant differences were detected in the soil within the chlorotic groves regardless of some Mg deficiency. Calcium (Ca) and Mg are well correlated both in the leaves and in the soil. Very low values of exchangeable Mg and Ca and a high percentage of exchangeable acidity in Mg deficient chestnut stands were observed. Multiregression analysis reveals that the Mg/NH4, Mg/Al + H and Mg/K ratios in the soil explain 53% of the foliar Mg variation. Study 2, showed a negative correlation between severity of chlorosis and foliar Mg concentration, tree growth parameters and nut yield. Tree height, leaf area index and nut production were reduced to half in trees with acute leaf chlorosis. Nut calibre (fruits/kg) increased 50%. The threshold value below which the foliar Mg deficiency could be detected was 1.2 g kg−1. Soil exchangeable Mg was, in general, very low and few differences in soil fertility parameters were observed beneath the three categories of leaf chlorosis, excepting the high levels of inorganic N underneath the chlorotic trees.

Evaluation of genetic diversity of Portuguese Pinus sylvestris L. populations based on molecular data and inferences about the future use of this germplasm.

1Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology (IBB/CGB), 3Department of Forestry Sciences and Landscape (CIFAP), and 4Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Tras-os-Montes and Alto Douro (UTAD), P.O. Box 1013, 5001-801 Vila Real, Portugal 2Centre of Forestry Studies (CEF), ISA, UTL Tapada da Ajuda, 1349-017 Lisbon, Portugal

The Transcriptomics of Secondary Growth and Wood Formation in Conifers

In the last years, forestry scientists have adapted genomics and next-generation sequencing (NGS) technologies to the search for candidate genes related to the transcriptomics of secondary growth and wood formation in several tree species. Gymnosperms, in particular, the conifers, are ecologically and economically important, namely, for the production of wood and other forestry end products. Until very recently, no whole genome sequencing of a conifer genome was available. Due to the gradual improvement of the NGS technologies and inherent bioinformatics tools, two draft assemblies of the whole genomes sequence of Picea abies and Picea glauca arose in the current year. These draft genome assemblies will bring new insights about the structure, content, and evolution of the conifer genomes. Furthermore, new directions in the forestry, breeding and research of conifers will be discussed in the following. The identification of genes associated with the xylem transcriptome and the knowledge of their regulatory mechanisms will provide less time-consuming breeding cycles and a high accuracy for the selection of traits related to wood production and quality.

Genetic variation of chemical and mechanical traits of maritime pine (Pinus pinaster Aiton). Correlations with wood density components

Abstract• BackgroundGenetic selection for one trait can have an impact on other important traits for final use; thus, it is important to assess the correlation between traits.• MethodsGenetic control and relationships among lignin content predicted by near infrared spectroscopy, radial modulus of elasticity (MOERad) and the radial modulus of rupture (MORRad), as well as its correlations with wood density components and spiral grain were assessed by estimating heritability, phenotypic and genetic correlations using 552 Pinus pinaster trees from 46 half-sib families.• ResultsThe results of this study showed that lignin amount is under a moderate genetic control (h2 = 0.34) but due to the low coefficient of variation observed, selection for lignin content through breeding could yield modest gains. Selection based on density will result in a decrease of the lignin content, and that the lignin content was more dependent on the proportion of latewood.• ConclusionsThe results show that MOERad and MORRad are under moderate genetic control (h2 = 0.34 and h2 = 0.30 respectively), suggesting possible genetic gains by selection for higher resistance and elasticity. MOERad had higher correlations with latewood than earlywood components. Negative correlations were observed between mechanical traits and lignin content, while the correlations with spiral grain were positive.

EARLY DIAGNOSIS OF BORON DEFICIENCY IN CHESTNUT

This study aims to identify an alternative plant tissue to be used in the early diagnosis of boron (B) deficiency in chestnut (Castanea sativa Mill.). A B-deficient orchard was selected, and 16 trees were submitted to two levels of B fertilization. When flowers were in bloom, the following tissues were sampled: leaves, androgynous catkins and flowers. There was a significant increase in B content in plant tissues due to B application. In July, the highest B content was observed in flowers in B0, but leaves had the greatest content in B1. Boron content in the tissues collected in July was positively correlated with B contents in leaves sampled in September. Foliar B concentrations, irrespective of the sampling period, were correlated with chestnut productivity, while the other tissues did not. These results suggest that the leaves, sampled in bloom, were the most efficient tissue for the early diagnosis of B deficiency.

BORON APPLICATION ON A CHESTNUT ORCHARD: EFFECT ON YIELD AND QUALITY OF NUTS

Although boron (B) deficiency in chestnuts (Castanea sativa Mill.) has been identified in Portugal and B fertilization was carried out in some orchards, the post-treatment evaluations have not been made to date. So the objective of this trial was to confirm the B deficiency and to quantify the effect of B applications to the soil on nut yield and quality. In October 2006, a fertilizer trial was established in a 15 year-old orchard in a very acid soil derived from siliceous schists. Soil liming and a basal fertilization were carried out in 16 trees and two levels of sodium tetraborate (Granubor, 14.6% B) were applied to eight trees: control (B0) and 100 g of Granubor per tree (B1). In the beginning of September chestnut leaves were collected from five trees and analyzed for macro- and micronutrients. Nut productivity was measured per tree and some nut quality parameters were evaluated, including the chemical composition of the kernel (soluble sugars, starch, total fiber, crude protein, and crude fat) in 2007, and dry matter, nut caliber, and fruit damage in 2007 and 2008. Boron fertilization of chestnuts significantly increased nut production: 75% in the first year (8 kg and 14 kg per tree, respectively, in the B0 and B1) and, in the second year, was over four times higher (4 kg and 17 kg per tree, respectively, in the B0 and B1). No significant differences were found in dry matter, nut caliber, nut damage and chemical composition of the kernel in the first year, but in the second year lower fruit damage by chestnut tortrix (P<0.0089) was observed. Foliar analyses exhibit relatively low B concentrations in the control trees (average value of 8 mg kg−1) in both years, while in the fertilized trees the foliar B concentration were in average 61 mg kg−1 in the first year, and 34 mg kg−1 in the second year. The large drop in the foliar B concentration in the second year suggests the need to monitoring the nutrient status of chestnut orchards or more frequent of B application than usual practice.

Assessment of Boron Application in Chestnuts: Nut Yield and Quality

A field trial was conducted between 2006 and 2009 in order to quantify the effect of boron (B) application on the yield and quality of chestnuts. The trial was established in an acid soil derived from siliceous schist and two levels of B were applied. Fruit abortion and nut yield per tree were measured, and nut quality parameters and chemical composition of the kernel were determined. Foliar B concentration was 8.6 mg kg−1 in the control trees and 48.4 mg kg−1 in fertilized chestnuts. Boron improved fruit setting and promoted nut production by 77%. In 2008, the occurrence of cold temperatures enhanced the effect of B on fruit setting, which was four-fold, whereas with the normal temperatures of 2009 the increase was lower. The drought of 2009 was responsible for the ruinous chestnut caliber and shell cracking. Boron induced a significant increase in the crude fat of chestnut kernel.