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Germination rate and seedling establishment control post-fire regeneration of trees and may foster invasion of exotic species particularly of fire-adapted species as the serotinous Pinus radiata. We analyzed the influence of heat shock and the presence of ash as substrate on seed germination and early vigor of seedlings of distinct cohorts of P. radiata that developed under the influence of fire or in the absence of it, i.e. post-fire invasion and unburned plantation, respectively. Seeds were collected from the Reserva Forestal Lago Epuyén in Northern Patagonia, Argentina. The natural history of this region is characterized by the occurrence of extensive fires. Ten randomly selected trees from unburned plantations and post-fire invasion that occurred in 1987 of similar age were cut down and 10 serotinous cones by plant were collected without color or size bias. Seeds from both stand types were subjected to four treatments: ash solution (5 g/L) and two thermal shocks (90 and 120 °C for 5 min), and a control without thermal shock or ash presence. The number of germinated seeds was counted every 5 days during 30 days. Germination percentages observed were high (between 80 and 100%) for both seed sources and under all the fire-associated treatments. Post-fire invasion had longer radicles with ash and under the thermal shock at 90 °C, as well as a higher percentage of seedlings that developed cotyledons and with the highest survival. Recurrent fires exert a significant effect on germination and early growth of the exotic P. radiata which may foster invasion. [ABSTRACT FROM AUTHOR]

Eucalyptus dunnii Maiden (Dunn's white gum) is a fast-growing tall tree with a restricted natural distribution in south-east Australia and favorable wood properties for pulp production. In this study, selected and native forest family seedlots of E. dunnii were evaluated in 17 open-pollinated progeny trials located in Australia, Uruguay, China, Argentina, and Spain for diameter at breast height and total height between the ages of 1 and 7 years. The generality of the factor analytic approach was extended to accommodate unbalance in treatment effects and traits, by modelling each dimension of the genotype covariance matrix as a unique combination of location, age, and trait. Genetic correlations between the two growth traits, between trials and between ages were generally high with only five trials exhibiting average trial-trial correlations below 0.7, indicating genotype by environment interactions were low. Estimated individual seedlot repeatability varied from 0.04 to 0.18 for both traits. The results of this study show that selection and deployment across multiple trials within Australia, Uruguay, China, and Argentina is possible from a single breeding program of E. dunnii, however some environments will require further investigation to determine the drivers of the observed GxE. [ABSTRACT FROM AUTHOR]

Non-spatial and spatial analyses were carried out to estimate genetic parameters for growth and stem straightness traits between ages 4 and 7 in two series of eight progeny trials of Pinus elliottii Engelm. var. elliottii (PEE) established in 2004 and 2008, comprising 429 open-pollinated families from Instituto Nacional de Tecnología Agropecuaria (INTA) tree breeding population in Argentina. A first-order autoregressive spatial mixed model was found to significantly improve the fit of the model, compared with the standard non-spatial mixed model approach, due to substantial spatial heterogeneity within sites. The average individual-tree narrow-sense heritability estimates based on this spatial analysis were 0.49 for diameter at breast height, 0.36 for total height, and 0.48 for volume, with stem straightness being low to moderate (average = 0.11). The additive genetic correlation estimates between growth traits were positive (0.51 ≤ r ^ a ≤ 0.99) and statistically significant from zero. In contrast, the genetic correlations between growth traits and stem straightness although in general also positive were not significantly different from zero (− 0.22 ≤ r ^ a ≤ 0.59). Age-to-age genetic correlations were consistently higher for growth traits ( r ^ a ≥ 0.81) than for stem straightness ( r ^ a ≥ 0.33). The average additive genetic correlation estimated between sites within test series was high for all traits evaluated (average > 0.72). In contrast, average additive genetic correlation estimated between sites across series was slightly lower (average < 0.63). Implications of all these parameter estimates for genetic improvement of PEE in Argentina are discussed. [ABSTRACT FROM AUTHOR]

Most Argentinean forests have been lost by over exploitation and expansion of agricultural areas. The National breeding program for the native species Prosopis alba is still in its initial phase with only a few progeny trials installed from material collected in the wild and the first genetic studies are underway. Breeding value (BV) estimates based on pedigree data from a progeny trial were first compared to those derived by using microsatellite based kinship estimates to confirm the potential accuracy of g-best linear unbiased predictions (G-BLUP) when pedigree information is lacking. Afterwards, the possible genetic effects of alternative selection strategies to collect improved seeds from a wild population were evaluated. To achieve this goal the relationship among average genetic gain (predicted by G-BLUP), inbreeding and sampling size of the collected materials were weighed in a wild population consisting of trees of similar ages. The results obtained suggest that kinship estimates based on molecular data and breeding value predictions BV used for the selection of elite trees in wild populations may contribute to improve the genetic properties of the founder population. Controlling kinship allows reducing sampling size from 20 to 10 individuals per origin with no significant increase of inbreeding or loss of genetic gain. For a selected group of only ten top individuals per origin, the replacement of two strongly reduces the average group coancestry with minimal gain loss. Simultaneous selection for two traits by selection index might produce a gain of near 6 % in height and 2 % in diameter. The use of molecular marker information may contribute to reduce the time needed in a P. alba improvement program. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal (EM) fungi incorporation in nursery production is necessary for afforestation with exotic tree species and native forests restoration programs. The fact that spore use as EM inocula is inexpensive and effective, makes it an option more realistic than vegetative inoculum production for many regions around the world. To determine spore activity from EM species selected as inoculants for Nothofagus pumilio and exotic conifers planted in Patagonia, two conservation methods were applied (i.e., dried fruit bodies and spore slurries), and their change over time was assessed (over 8-9 months). Spore activity decreased significantly with time for both native and exotic EM species. Conservation methods showed no significant differences for N. pumilio EM species considered together or for exotic conifer EM species. However, spore activity of different EM species behaved differently with conservation method and over time when considered separately. Taxa which better kept spore activity over time were Austropaxillus statuum and Setchelliogaster fragilis for N. pumilio, and Inocybe kauffmanii for exotic conifers. However, considering together fruit body spore density and spore activity, the species Hallingea purpurea and Cortinarius sp. also appeared as suitable for N. pumilio and Rhizopogon roseolus, R. villosulus, Suillus luteus and S. lakei for exotic conifers. Spore density found in EM fungal fructifications were also established in order to estimate fructification weights necessary to apply a reference dose of active spores in inoculation programs. [ABSTRACT FROM AUTHOR]

Performances of Pinus taxa were studied to 10 years of age in two trials in each of Misiones and Entre Ríos provinces across the Mesopotamia region of Argentina. Taxa comprised 22 populations from sources in Argentina, Australia, Brazil and Zimbabwe including Pinus elliottii var. elliottii (P ee), Pinus caribaea var. hondurensis (P ch), their four, inter-specific hybrids (F, F and backcrosses from F to P ch and to P ee-all as broadly based bulks); other P ee and Pinus taeda (P t) comprised narrower or unspecified bulks. Variable numbers of taxa were missing at each site. Mean survival across sites at age 10 years ranged 53.2-91.3% averaging 74.2%. Analysis of variance of plot means indicated population effect was statistically significant ( p < 0.05) for all or most growth and quality traits at all sites. However, significant differences from the nominated check seedlot at the Entre Ríos sites (P ee, Australia) were extremely rare, while quite common at the northern, Misiones sites (check seedlot a P t population). In the Misiones trials, F, F and both backcross hybrids showed better stem straightness than P ee and P t from Argentina, generally with statistically significant differences ( p < 0.05). P t showed lowest forking scores (desirable). Taxon × environment interaction was statistically significant ( p < 0.01) for growth traits only ( p > 0.05). However, this interaction contributed an average of only 34.1% of the taxon variance suggesting a lack of practical importance. Taxa most suitable for deployment in the Mesopotamia region, Argentina are suggested. [ABSTRACT FROM AUTHOR]

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Studies the early growth differentiation among Prosopis flexuosa D.C. provenances from the Monte phytogeographic province in Argentina. Key issues of interest; Analysis of pertinent topics and related issues; Implications on forest conservation.