Résumé
Resumen Varias especies de los géneros Eucalyptus y Acacia son adecuadas para la producción de biomasa útil en la generación de energía. El objetivo del presente estudio fue evaluar la supervivencia y características del rebrote en tocones de cuatro especies dendroenergéticas en tres diferentes densidades poblacionales. Se utilizó un diseño de bloques completos al azar con tres repeticiones, en tres sitios (Parcelas Collipulli, La Aguada y Pilpilco Abajo) con características edafoclimáticas contrastantes. Se estudió Eucalyptus globulus, Eucalyptus denticulata, Eucalyptus nitens y Acacia dealbata en tres densidades de plantación (5 000 árboles/ ha; 10 000 árboles/ha y 15 000 árboles/ha). Se evaluó el porcentaje de supervivencia y las características del rebrote por tocón. Las variables especie, densidad de plantación y sitio de siembra afectaron los parámetros analizados. La densidad de plantación afectó el diámetro y altura de los rebrotes dominantes de tipo proventicio en las cuatro especies estudiadas. La mayor tasa de supervivencia de tocones (97 %), la presentó Eucalyptus nitens en Pipilco Abajo, con 79 % de supervivencia de rebrotes a una densidad de 5 000 árboles/ha. Sin embargo, en densidades de 15 000 árboles/ha, la supervivencia de rebrote fue de 29 %. Acacia dealbata es una especie reconocida por su capacidad de colonización, sin embargo, en La Aguada, con densidades de siembra de 5 000 árboles/ha y 10 000 árboles/ha, mostró baja tasa de supervivencia de tocones (19 % y 18 %, respectivamente) y de rebrotes (57 % y 63 %, respectivamente). La especie Eucalyptus globulus mostró altas tasas de supervivencia de tocones y rebrotes en todos los sitios evaluados, por lo que puede ser considerada como una buena opción para optimizar el sistema de monte bajo.
Abstract Several species of the genera Eucalyptus and Acacia are suitable for biomass production useful in energy generation. The objective of this research was to evaluate the survival and chaof four dendroenergetic species in three population densities. A randomized block design with three replications was used in three sites (Collipulli, La Aguada and Pilpilco Abajo plots) with contrasting edaphoclimatic characteristics. Eucalyptus globulus, Eucalyptus denticulata, Eucalyptus nitens and Acacia dealbata were studied in three plantation densities (5 000 trees/ha, 10 000 trees/ha and 15 000 trees/ha). The survival percentage and characteristics of stump regrowth characteristics of each stump were evaluated. The variables specie, plantation density and planting site affected the analyzed parameters. Plantation density affected the diameter and height of prevalent sprouts of proventic proventitious shoots in all species. Hihest stump survival rate (97 %) was presented by Eucalyptus nitens in Pipilco Abajo, with 79 % shoots survival of sprouts at a density of 5 000 trees/ha. However, at densities of 15 000 trees/ ha, regrowth survival was 29%. The Acacia dealbata is a species characterized by its colonization capacity. However, at La Aguada, which had population densities of 5 000 trees/ha and 10 000 trees/ha, it showed a low stump (19% and 18 % respectively) and shoots (57 % and 63 % respectively) survival rate. The species Eucalyptus globulus showed high stump and shoot survival rates in all sites evaluated, therefore it can be considered a good option to optimize the scrub system.
Résumé
A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5 percent polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation.