To cite this version:Róger Moya, Alexander Berrocal. Wood colour variation in sapwood and heartwood of young trees of Tectona grandis and its relationship with plantation characteristics, site, and decay resistance. Annals of Forest Science, Springer Verlag/EDP Sciences, 2010, 67 (1), <10.1051/forest/2009088>. Ann. For. Sci. 67 (2010) • With the purpose of understanding the colour variation, different fast-growth plantations were sampled with different growth rates, tree ages, and sites.• Wood colour was measured with a CIELab system, where three variables are estimated: coordinate L * for lightness, coordinate a * defines redness and coordinate b * defines yellowness.• Results showed only a negative correlation between L * and a * . L * and a * were negatively and positively respectively correlated with pith distance in heartwood, but not for b * . No correlations were found between L * and b * in sapwood and plantation characteristics, while a * was positively correlated with age and height of tree and growth rate. In heartwood, tree age and diameter at breast height were correlated with all colour parameters, but tree height and plantation density were correlated with a * and b * . Cluster site had correlation with L * . Multiple correlation analysis showed that the heartwood is increasing darker (L * ) and redder (a * ) when the trees are older and bigger. Correlation coefficient shown that sapwood and heartwood with lighter colour (L * ) is less resistance to fungal attack, but redness colour (a * ) increasing decay resistance. Mots-clés :CIELab / bois tropicaux / Tectona grandis / aubier / bois de coeur / plantations Résumé -Les variations de couleur dans l'aubier et le duramen de jeunes arbres de Tectona grandis, en relation avec les caractéristiques des plantations, du site et de la durabilité.• Il y a une grande variabilité de la couleur du bois de Tectona grandis produit à partir de plantations à croissance rapide et les causes de ces variations sont relativement inconnues.• Pour comprendre l'origine des variations de couleur nous avons échantillonné dans des plantations à croissance rapide qui diffèrent entre elles en termes de vitesse de croissance, d'âge et de site.• La couleur du bois a été mesurée avec le système CIELab qui permet la mesure de trois variables colorimétriques : la luminance L * allant du noir au blanc, a * et b * allant respectivement du vert au rouge et du bleu au jaune.• Les résultats montrent une corrélation négative entre L * et a * . Dans le bois le coeur il y a une corrélation négative entre L * et la distance à la moelle et une corrélation positive entre a * et la distance à la moelle : aucune corrélation n'apparaît pour b * .

SUMMARYThis study details information about physical, chemical and mechanical properties, drying, preservation and workability of wood from Cordia alliodora, Dipteryx panamensis, Enterolobium cyclocarpum, Hieronyma alchorneoides, Samanea saman and Vochysia ferruginea trees, growing in forest plantations in Costa Rica. Variation of the general properties in relation to height showed that heartwood percentage decreases, bark percentage increases and pith percentage is not affected. Dipteryx panamensis showed both the highest values for specific gravity and the highest mechanic resistance. Both chemical properties and extractives presence were different among species. Heartwood was not possible to preserve in any of the species, though sapwood was. Penetration varied from partial irregular or vascular in the species. The highest durability was for Hieronyma alchorneoides and Vochysia ferruginea, species classified as of high durability. Finally, all species had good performance in the workability tests. The previous results indicate that these species, used for trading reforestation in Costa Rica, have acceptable characteristics to be commercialized and used in wooden products.Key words: tropical species, Central America, wood variation, commercial wood. RESUMENEl presente estudio detalla información de las propiedades físicas, químicas, mecánicas, de secado, preservación y trabajabilidad de la madera de Cordia alliodora, Dipteryx panamensis, Enterolobium cyclocarpum, Hieronyma alchorneoides, Samanea saman y Vochysia ferruginea proveniente de plantaciones forestales en Costa Rica. La variación de las propiedades con respecto a la altura mostró que el porcentaje de duramen disminuyó, el porcentaje de corteza aumentó y el porcentaje de médula no se vio afectado por la altura del árbol. Dipteryx panamensis presentó los valores de peso específico más altos, por lo tanto, también presentó los valores de resistencia mecánica más altos. No fue posible preservar el duramen en ninguna especie, pero la albura sí y su penetración varió de parcial irregular o vascular en las especies. La mayor durabilidad se presentó en Hieronyma alchorneoides y Vochysia ferruginea, especies clasificadas como de alta durabilidad. Finalmente, todas las especies presentaron buen comportamiento en las pruebas de trabajabilidad. Los resultados anteriores indican que estas especies, utilizadas en la reforestación comercial de Costa Rica, poseen características aceptables para ser utilizadas en la comercialización y uso en productos de madera.

The objective of this study was to show the radial variation of some anatomic characteristics, wood density and natural durability of teak (Tectona grandis L.F.) growing in Costa Rica. Samples of trees 13 years old were obtained from two growing sites (high and low growing) of plantations established in a humid tropical climate (CHT) and dry tropical climate (CST). The variables measured of the fibers as well as for the rays were not affected by the climate or the type of growing site, except for the length of the fibers. The fibers of teak wood from the best growing site were significantly larger. Vessels were found with a greater frequency for the CST but mostly solitary in comparison with the CHAverage density, maximum density and the variation within the ring presented a light higher magnitude for the CSThe quality of the growing site did not affect these variables. The resistance of fungus attack was similar in the area of heartwood near the pith compared to the heartwood near the sapwood for all the conditions evaluated. Nevertheless, it was observed in some trees a similar resistance of fungus attack for areas of sapwood compared to similar areas of heartwood.

Trametes versicolor and Pleurotus ostreatus were used for the biopulping from pineapple leaf fiber (PALF). PALF substrate was subjected to T. versicolor for 2 to 6 weeks and to P. ostreatus for 4 to 8 weeks. The yields, holocellulose and lignin contents, and extractives in ethanol-toluene mixture and in sodium hydroxide (NaOH) solution were evaluated. Fourier transform infrared spectroscopy (FTIR) spectra, thermogravimetric analysis (TGA), and color studies by L*a*b* systems were used for sample analysis. The results showed that the pulp yield was 55% to 70% with P. ostreatus and 35% to 50% with T. versicolor. Longer colonization periods increased the amount of holocellulose and decreased the amount of lignin and extractives in ethanol-toluene and NaOH solution. TGA showed an increase in intensity associated with cellulose, and the observed inflexion was attributed to lignin, which showed a tendency to fade. The FTIR spectrum showed high intensity between 3100 cm -1 and 3600 cm -1(cellulose) and decreased intensity at 1730 cm -1 (lignin). For both fungi, the pulp color produced an increase in L* color parameter and decreased in yellowness, while little variation was observed in redness. The most appropriate colonization period was 5 weeks for P. ostreatus and 4 weeks for T. versicolor.

Aims:  For Ophiostoma (Ceratocystis) ulmi, the ability to undergo morphological change is a crucial factor for its virulence. To gain an understanding of quorum‐sensing activity in O. ulmi as it relates to yeast‐mycelium dimorphism control, this study examines the effects of branched‐chain amino acids as well as their fusel alcohols and fusel acids as quorum sensing molecules. Methods and Results:  In a defined medium containing glucose, proline and salts, O. ulmi grew as yeasts when the culture was inoculated with a high density of spores (2 × 107 CFU ml−1) and as mycelia when inoculated with a low spore density (4 × 105 CFU ml−1). The cultures displaying yeast morphology secreted a quorum‐sensing factor that shifted the morphology from mycelia to yeast. This quorum‐sensing molecule was lipophilic and extractable by organic solvents from the spent medium. Using GC/MS analysis, it was determined that the major compound in the extract was 2‐methyl‐1‐butanol. A similar effect was observed when the branched‐chain amino acids (fusel alcohol precursors) were used as the nitrogen source. E, E‐farnesol had no effect on the morphology of O. ulmi. Conclusions:  Addition of the branched‐chain amino acids or one of the compounds detected in the spent medium, 2‐methyl‐1‐butanol or 4‐hydroxyphenylacetic acid, or methylvaleric acid, decreased germ tube formation by more than 50%, thus demonstrating a quorum sensing molecule behaviour in O. ulmi cultures. Significance and impact of the study:  This study presents advances in the investigation of dimorphism in O. ulmi, complementing the existing scientific basis, for studying, understanding and controlling this phenomenon.