Resumen Prosopis alba (algarrobo blanco) es una especie forestal nativa utilizada principalmente para aserrío en Argentina. La Ley 27.487/19 de fomento forestal considera las densidades y prácticas adecuadas para el logro de madera de calidad. Además del buen manejo, la correcta selección del origen del material genético es una estrategia importante para la obtención de buenos rendimientos de madera. Con el objeto de evaluar el comportamiento de plantas de P. alba de tres procedencias se establecieron ensayos en las localidades de Corrientes y Chaco (Argentina). Se trabajó con plantines logrados a partir de semillas de las procedencias Santiagueña, Chaqueña y Salta Norte. Una vez establecidos en campo se evaluó el índice de respuesta neta y cuatro variables dasométricas (altura total, diámetro a la altura del cuello, volumen de árbol en pie e incremento corriente anual). No se detectó efecto del origen geográfico de las plantas sobre la sobrevivencia. Considerando los parámetros dasométricos estudiados, la procedencia Salta Norte resultó superior respecto a las procedencias Chaqueña y Santiagueña. En Sáenz Peña (Chaco) todas las variables dasométricas evaluadas resultaron estadísticamente superiores, mientras que en Corrientes solamente el diámetro a la altura del cuello y altura total fueron superiores. Se observó que la procedencia Salta Norte se destaca como la de mejor comportamiento en ambas localidades. Por tanto, se concluye que la procedencia del germoplasma de P. alba influye en su comportamiento productivo.

Abstract Prosopis alba is one of the most widely used native forest species for sawmilling in Argentina. The forestry development law N° 27.487/19 considers the plantation of this specie taking into account densities and suitable practices for quality wood achievement. Coupled with good management right selection of the origin of the genetic material is a strategy that contributes to obtain good yields. In order to evaluate the behavior of P. alba three provenances plants were established in Corrientes and Chaco to assess their performance in these environments. It was worked with seedlings compound by seeds from the provenance of Santiago, Chaco and North Salta. As established on field, net response rate and four dasometric variables (total height, diameter at neck height, standing tree volume and annual current increase) were evaluated. Effect of plants’ geographical origin over survival was not detected. In consideration of dasometric studied parameters, North Salta provenance was higher than the ones from Chaco and Santiago. In Sáenz Peña (Chaco) for this provenance all the evaluated dasometric variables were statistically greater, whereas in Corrientes they only were the diameter at neck height and total height. It has been proved that North Salta provenance stands out as the one with the best behavior in both tested locations. Therefore, it is concluded that the geographic origin of P. alba germplasm influences its productive behavior.

Abstract Prosopis is a primitive genus in the Mimosoid’s clade characterized by disjunctions in its distribution areas and the difficulty in establishing its phylogeny. This paper presents an updated literature review on the evolutionary, cytogenetic, genetic and hybridization characteristics of the genus. The available data suggest that it diverged early in several major lineages, although in some of them recent episodes of partial speciation have occurred. Genetic diversity within and between populations depends on the reproductive system and adaptative strategies, among other factors. Populations’ structure also sets restrictions to evolutive processes leading to the increasing adaptation to the environment and/or specific differentiation. It is an essentially diploid genus (2n = 28) never the less polyploidy and frequent processes of interspecific hybridization and introgression have been informed. High genetic and chromosomal similarity between species of the genus allows the generation of viable hybrids, reinforcing the idea that some species are evolutionarily active and highlights the difficulties this causes in the taxonomic treatment and the phylogeny of the group.

Resumen Prosopis es un género dentro del clado Mimosoid caracterizado por las disyunciones que presentan sus actuales áreas de distribución y las dificultades para esclarecer su filogenia. Este trabajo presenta un análisis bibliográfico actualizado sobre las características evolutivas, citogenéticas, genéticas e hibridaciones del género. Los datos disponibles sugieren que divergió tempranamente en varios linajes principales, aunque dentro de algunos de ellos han ocurrido episodios recientes de especiación parcial. La forma en que se distribuye la variabilidad genética dentro y entre poblaciones depende, entre otros factores, del sistema reproductivo y la estrategia adaptativa. La estructura de las poblaciones, a su vez, establece restricciones a los procesos evolutivos tendientes a la adaptación creciente al ambiente y/o la diferenciación específica. . Es un género esencialmente diploide (2n = 28) pero se ha informado poliploidía y frecuentes procesos de hibridación e introgresión interespecífica. La alta similitud genética y cromosómica entre las distintas especies del género permite la obtención de híbridos viables, reforzando la idea de que algunas especies del género están evolutivamente activas, y pone de manifiesto las dificultades que esto ocasiona en el tratamiento taxonómico y la filogenia del grupo.

With the aim of developing an efficient plant regeneration protocol, leaflet explants of three accessions of Arachis villosa Benth. (S2866, S2867 and L97) were cultured on basic Murashige and Skoog medium supplemented with different combinations of plant growth regulators: α-naphthalenacetic acid, indole-3-butyric acid, 6-benzylaminopurine, kinetin and thidiazuron. The accession L97 was the only one able to differentiate buds through indirect organogenesis. The most suitable combination for bud regeneration was the basic medium added with 13.62 μM thidiazuron and 4.44 μM 6-benzylaminopurine. These results show the important role of the genotype in morphogenetic responses and the organogenetic effect of thidiazuron in Arachis villosa accession L97. A thidiazuron lacking media (only 0.54 μM α-naphthalenacetic acid, 13.95 μM kinetin and 13.32 μM 6-benzylaminopurine were added) promoted the elongation of the regenerated buds. Adventitious rooting was achieved 90 days after the isolated shoots were transferred to a rooting medium containing 0.54 μM α-naphthalenacetic acid.