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There is an increasing interest in using plant growth-promoting rhizobacteria (PGPR) to improve hybrid poplar performance under water stress conditions. We assessed the growth and leaf-level physiological responses of different hybrid poplar clones to the inoculation of a microbial consortium and subjected to moderate water shortage. In a nursery experiment, growth, leaf gas exchange, and biomass partitioning traits were assessed during one growing season on twenty hybrid clones from interspecific crosses of Populus trichocarpa × P.deltoides and (P. trichocarpa × P. deltoides) × P. deltoides, which were submitted to two treatments of PGPM inoculation (Inoculated, Inoc_1 vs. non-inoculated, Inoc_0) and two irrigation treatments (full water vs. water restriction). The water restriction decreased shoot growth, photosynthetic rate (Asat), and stomatal conductance (gs); increased intrinsic water use efficiency (WUEint) of the hybrid clones but it did not change the root-to-shoot ratio. Unlike our expectations, by the end of the study, treatment Inoc_1 slightly decreased basal diameter (D) and height (H) relative to Inoc_0 (5.8% and 5.2 %, respectively). Moreover, seven clones significantly decreased the root biomass by 37% to 62% in the Inoc_1 relative to Inoc_0 treatment, while the other clones showed no response to the inoculation. Oppositely, while most of the clones showed no response to the Inoc_1 treatment on leaf-physiological traits compared to Inoc_0, some of them exhibited an increase of Asat of 15% to 39%. Overall, the consortium applied did not improve the responses to the water restriction, and responses to the inoculation were more associated with a deleterious than a growth-promoting effect, which is discussed in the context of nutrient immobilization, application method, and timing.

The Maulino forest is a temperate ecosystem of the Mediterranean zone of Chile classified as one of the 34 biodiversity hot-spots of the world; however, there is still limited information about the ecological factors that make this native forest prone to be invaded. We assess to what extent forest attributes such as light availability and native species diversity control the invasion process of Teline monspessulana (L.) K. Koch, an aggressive weed, into the Maulino forest, an endemic forest ecosystem of Central Chile. We examined whether the seedling density of this exotic plant is related to forest attributes such as cover, incoming photosynthetically active radiation, litter depth, and native species density and richness. We found that a decrease of light availability reduces T. monspessulana invasion. No relationships were observed between native species diversity and the abundance of T. monspessulana plants. Increasing the forest cover will recover forest structure but at the same time, it will prevent the invasion of T. monspessulana and other exotic plants with similar regeneration niche requirements.

Adesmia bijuga Phil. is an endemic and endangered shrub species of central Chile. Its potential shade intolerance is one of the leading hypotheses for its vigor loss when the species grows beneath closed canopies. The objective of this study was to assess the growth and physiological acclimation to the shade of young plants of A. bijuga. A nursery experiment was established with three light levels based on the interception of photosynthetic active radiation (PAR) (TRT0: control at full sun; TRT60: 60% shaded; TRT90: 90% shaded), and maintained for 71 days during the summer season. Growth and leaf morpho-physiological responses were evaluated at the beginning, at the middle, and at the end of the experiment. The shading treatment increased plant height (H), live crown percentage (Lcrown), and specific leaf area (SLA) compared to the control treatment at full sun. However, light-saturated photosynthetic rate (Amax), dark respiration rate (Rd), and light compensation point (Γi) were higher in TRT60 than in the other treatments, while no differences were found among treatments for the apparent quantum yield (α). At this stage of plant development, our results suggest high acclimation plasticity of A. bijuga to light levels; however, a semi-shade environment (i.e., TRT60) favored a better performance of the species.

Nothofagus alessandrii (ruil) is a threatened, endemic tree of the Mediterranean zone of Chile. As a result of past anthropogenic activities, its current cover has been reduced to only 314 hectares across several fragmented and degraded areas. Although activities to conserve and recover such forests have been developed, little is known about their propagation and nursery cultivation, since the plant’s quality is one of the most important factors for restoration and reforestation plans, re-vegetation, or forest enrichment. The success of restoration programs in these areas will require improvements in plant production, being important to test the shade effects on seedling survival and growth. This paper reports the results of testing for survival, morphological and chlorophyll fluorescence differences in N. alessandrii seedlings grown for approximately 32 weeks in unshaded conditions and under three different levels of shading (18%, 50%, and 80% shade). Morphological traits (stem height, root collar diameter, specific leaf area, shoot and root biomass, and quality indexes) and survival were measured. Chlorophyll fluorescence was also measured to analyze the shade tolerance of the species. Analysis showed significant differences for most traits as a consequence of the shade level. Seedlings exposed to 18% shade showed the highest total dry biomass, while those exposed to 80% shade showed the highest survival rate (92%). Chlorophyll fluorescence was high in the unshaded conditions and medium in the 18-50% shade. Morphological and chlorophyll fluorescence responses differed greatly among shade levels and corresponded with the degree of shade tolerance of the species.

Se realiza un acercamiento histórico y epidemiológico de la presencia de la fiebre amarilla en Sudamérica y en particular en Perú, remarcando la diferencia entre fiebre amarilla urbana (FAU) y fiebre amarilla selvática (FAS). La FAU asoló toda la costa peruana afectando mayormente los principales puertos costeros, dejando a su paso miles de muertos en los grandes asentamientos urbanos. Actualmente el Perú es el país que en América del Sur notifica la mayor cantidad de casos de FAS. Desde el punto de vista epidemiológico existen áreas enzoóticas plenamente identificadas, especialmente del nicho ecológico denominado selva alta (rupa-rupa). La población afectada por FAS mayoritariamente corresponde a varones jóvenes (agricultores-migrantes), con antecedente negativo de inmunización antiamarílica. El análisis de dos periodos de vigilancia de FAS en el Perú, 1994 - 1999 y 2000 - 2004, no revela mayores cambios epidemiológicos a excepción de la letalidad que de 38% se incrementó a 56%, recordando los niveles de letalidad de periodos anteriores, 1991 - 1994 (54%). Desde hace cinco años se inició en el Perú la estrategia de vacunar al 100% de los niños que cumplen su primer año de edad y desde hace dos años se ha comenzado a vacunar masivamente en regiones expulsoras de emigrantes, además de los pobladores de regiones endémicas, con el objetivo de eliminar la FAS del ámbito nacional.