The Dipteryx genus has a natural distribution throughout several tropical countries in Latin America. This taxon has several tree species, all recognized for their high-density wood. The objective of ...this research was to study the variation and genetic control of several wood properties, including bark, sapwood, heartwood, green density (GD), specific gravity (SG), moisture content in green condition (MC-G), and mechanical properties, in a Dipteryx panamensis provenance/progeny test at 8 years old. The results showed that bark varied little among families and provenances, but heartwood (diameter and percentage) showed high genetic variation. SG and MC-G showed significant variation between provenances and families, while GD showed little variation. Among the mechanical properties evaluated, the greatest genetic variation was observed in the MOR in bending and shear stress. Families from the Coope San Juan provenance registered the highest values in all wood properties investigated, and families from Puerto Viejo obtained the lowest. Family heritability and the coefficient of genetic variation exhibited high values in heartwood/sapwood and the MOR in bending (h2 > 0.9 and CV > 20%) and lower values in SG, MC-G, compression stress, and shear stress. D. panamensis wood properties have a high potential to be improved through breeding programs.
Dipteryx panamensis is used in reflorestation in Costa Rica and a genetic improvement program has been recently started in the country. The objective of the present study was to study the effect of ...tree trunk height on the variation of bark, sapwood, heartwood, green density (GD), specific gravity (SG) and green moisture content in green condition (MC-G), in a collection of 8-year-old provenances/progenies planted in the town of Florencia in San Carlos in the northern region of Costa Rica The wood of each of 17 families were studied based on 3 of their progenies, evaluating the properties relative to 0, 25%, 50%, 75% and 100% of the commercial height. According to the results, tree diameter and bark thickness showed no statistical differences in their values across trunk. Significant differences were found in diameter and percentage of heartwood and sapwood between provenances and families. The thickness and percentage of sapwood, thickness and percentage of bark, diameter, pith percentage and percentage of pith eccentricity, showed no significant differences between families. SG and the MC-G presented significant variation between provenances, while GD registered differences at above 25 % commercial height. The variation of physical properties, especially SG, between families within each provenance, shows selection potential for genetic improvement, focusing particularly on the bottom section of the tree. Keywords: Almendro; Camurú; Genetic improvement; Tropical forestry A madeira de Dipteryx panamensis é usada no reflorestamento na Costa Rica, tendo um programa de melhoramento genético iniciado recentemente no país. O objetivo do presente estudo foi estudar o efeito da altura do tronco das árvores na variação de casca, alburno, cerne, densidade verde (GD), densidade básica (SG) e teor de umidade na condição verde (MC-G) em uma coleção de procedências/progênies aos 8 anos de idade, plantados na vila de Florencia no município de San Carlos na região nordeste da Costa Rica. De cada uma das 17 famílias, a madeira foi investigada em três progênies e as propriedades foram avaliadas em 0, 25, 50, 75 e 100 % da altura comercial. Os resultados mostraram que o diâmetro das árvores e a espessura da casca não apresentaram valores com differenças estatísticas nas diferentes alturas da árvore. Houve diferenças significativas em diâmetro e porcentagem de cerne e alburno entre procedências e famílias. A espessura e porcentagem de alburno, espessura e porcentagem de casca, diâmetro, porcentagem e porcentagem de excentricidade da medula não registraram diferenças significativas entre as famílias. Nas propriedades físicas da madeira, determinou-se que o SG e o MC-G apresentaram uma variação significativa entre procedências em todas as alturas das árvores. Enquanto o GD registrou diferenças ao 25 %. A variação nas propriedades físicas, especialmente a SG, entre famílias dentro de cada proveniência, mostra o potencial de seleção para melhoramento genético, com ênfase na seleção com base na parte mais basal do tronco das árvores. Palavras chaves: Almendro; Cumaru; Melhoramento genético; Silvicultura tropical
Dipteryx panamensis is used in reforestation in Costa Rica and a genetic improvement program has been recently started in the country. The objective of the present study was to study the effect of ...tree trunk height on the variation of bark, sapwood, heartwood, green density (GD), specific gravity (SG) and green moisture content in green condition (MC-G), in a collection of 8-year-old provenances/progenies planted in the town of Florencia in San Carlos in the northern region of Costa Rica The wood of each of 17 families were studied based on 3 of their progenies, evaluating the properties relative to 0, 25%, 50%, 75% and 100% of the commercial height. According to the results, tree diameter and bark thickness showed no statistical differences in their values across trunk. Significant differences were found in diameter and percentage of heartwood and sapwood between provenances and families. The thickness and percentage of sapwood, thickness and percentage of bark, diameter, pith percentage and percentage of pith eccentricity, showed no significant differences between families. SG and the MC-G presented significant variation between provenances, while GD registered differences at above 25 % commercial height. The variation of physical properties, especially SG, between families within each provenance, shows selection potential for genetic improvement, focusing particularly on the bottom section of the tree.
Un Premio Nobel para la medicina cubana Pérez Ramírez, Luis Alberto; Rodríguez Rodríguez, Dalina Laritza; Ramírez Pacheco, Élida Yadira
Revista médica electrónica,
04/2019
Journal Article
Recenzirano
Odprti dostop
RESUMEN Se realizó una revisión bibliográfica con el objetivo general de identificar los cubanos que por su excepcional obra merecieron la nominación al Premio Nobel, así como también de describir ...las semblanzas de su vida y obra, para lo cual se trabajó con un total de 24 bibliografías. Muchos han desfilado por el podio de premiación para recibir tan alto reconocimiento a su esfuerzo, orientados al descubrimiento de los secretos de la naturaleza para proteger la salud. Aunque sin lograr dicho premio, los cubanos también han aportado relevantes hallazgos, destacándose aquellos estrechamente relacionados con la medicina, que marcaron una pauta a nivel mundial y merecieron nominaciones junto a personalidades de renombre universal.
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