From dark to darkness, negative phototropism influences the support-tree location of the massive woody climber Hydrangea serratifolia (Hydrangeaceae) in a Chilean temperate rainforest.

Climbing plants rely on suitable support to provide the light conditions they require in the canopy. Negative phototropism is a directional search behavior proposed to detect a support-tree, which indicates growth or movement away from light, based on light attenuation. In a Chilean temperate rainforest, we addressed whether the massive woody climber Hydrangea serratifolia (H. et A.) F. Phil (Hydrangeaceae) presents a support-tree location pattern influenced by light availability. We analyzed direction and light received in two groups of juvenile shoots: searching shoots (SS), with plagiotropic (creeping) growth vs. ascending shoots (AS), with orthotropic growth. We found that, in accordance with light attenuation, SS and AS used directional orientation to search and then ascend host trees. The light available to H. serratifolia searching shoots was less than that of the general forest understory; the directional orientation in both groups showed a significant deviation from a random distribution, with no circular statistical difference between them. Circular-linear regression indicated a relationship between directional orientations and light availability. Negative phototropism encodes the light environment's heterogeneous spatial and temporal information, guiding the shoot apex to the most shaded part of the support-tree base, the climbing start point.

Consequences of swamp forest fragmentation on assemblages of vascular epiphytes and climbing plants: Evaluation of the metacommunity structure.

AIM: Habitat reduction in fragmented landscapes provides an opportunity to study the biogeographic patterns that drive changes in diversity in poorly studied metacommunities. In this study, colonization-extinction dynamics were indirectly evaluated through the analysis of the species-area relationship and the nestedness of vascular epiphytes and climbing plants in 30 swamp forest fragments. LOCATION: Coast of the Araucanía Region in Chile. TAXON: Vascular epiphytes (16 species, mainly Pteridophytes) and climbing plants (15 species). METHODS: We used the database in Pincheira-Ulbrich et al. (New Zealand Journal of Botany, 54, 2016, 458), where 904 trees were sampled and a total abundance of 41,097 fern fronds and 3,098 climbing stems were reported. For the species-area relationship, a simple linear regression model (SLR) and two models that consider the spatial autocorrelation of species richness among fragments, generalized least squares (GLS) and simultaneous autoregressive model (SAR), were compared. For the species nestedness, the nestedness measure based on overlap and decreasing fills (NODF) and weighted nestedness metric based on overlap and decreasing fill (WNODF) indexes were used on presence-absence and abundance matrices, respectively. These matrices were sorted by area size and distance from the largest fragment and then contrasted with the probability distribution of a randomized null model based on 10,000 simulations. RESULTS: The results showed that the area size had a significantly positive effect on epiphyte species richness, while spatial autocorrelation played a fundamental role in explaining the richness of climbing plants. Both metacommunities had a general nestedness structure in terms of species incidence, which was determined first by area size and secondly by isolation. MAIN CONCLUSIONS: Our results indicate that local colonization processes determined by species' dispersal capacities could be the predominant mechanism for the spatial configuration of climbing plant species composition. On the other hand, selective extinction determined by patch size could characterize the spatial structure of epiphyte species' composition.

Woody climbers show greater population genetic differentiation than trees: Insights into the link between ecological traits and diversification.

The climbing habit is a key innovation in plants: climbing taxa have higher species richness than nonclimbing sister groups. We evaluated the hypothesis that climbing plant species show greater among-population genetic differentiation than nonclimber species. We compared the among-population genetic distance in woody climbers (eight species, 30 populations) and trees (seven species, 29 populations) coexisting in nine communities in a temperate rainforest. We also compared within-population genetic diversity in co-occurring woody climbers and trees in two communities. Mean genetic distance between populations of climbers was twice that of trees. Isolation by distance (increase in genetic distance with geographic distance) was greater for climbers. Climbers and trees showed similar within-population genetic diversity. Our longevity estimate suggested that climbers had shorter generation times, while other biological features often associated with diversification (dispersal and pollination syndromes, mating system, size, and metabolic rate) did not show significant differences between groups. We hypothesize that the greater population differentiation in climbers could result from greater evolutionary responses to local selection acting on initially higher within-population genetic diversity, which could be driven by neutral processes associated with shorter generation times. Increased population genetic differentiation could be incorporated as another line of evidence when testing for key innovations.

Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.

Some epiphytic Hymenophyllaceae are restricted to lower parts of the host (< 60 cm; 10-100 µmol photons m(-2) s(-1)) in a secondary forest of Southern Chile; other species occupy the whole host height (≥ 10 m; max PPFD > 1000 µmol photons m(-2) s(-1)). Our aim was to study the photosynthetic light responses of two Hymenophyllaceae species in relation to their contrasting distribution. We determined light tolerance of Hymenoglossum cruentum and Hymenophyllum dentatum by measuring gas exchange, PSI and PSII light energy partitioning, NPQ components, and pigment contents. H. dentatum showed lower maximum photosynthesis rates (A max) than H. cruentum, but the former species kept its net rates (An) near Amax across a wide light range. In contrast, in the latter one, An declined at PPFDs > 60 µmol photons m(-2) s(-1). H. cruentum, the shadiest plant, showed higher chlorophyll contents than H. dentatum. Differences in energy partitioning at PSI and PSII were consistent with gas exchange results. H. dentatum exhibited a higher light compensation point of the partitioning of absorbed energy between photochemical Y(PSII) and non-photochemical Y(NPQ) processes. Hence, both species allocated energy mainly toward photochemistry instead of heat dissipation at their light saturation points. Above saturation, H. cruentum had higher heat dissipation than H. dentatum. PSI yield (YPSI) remained higher in H. dentatum than H. cruentum in a wider light range. In both species, the main cause of heat dissipation at PSI was a donor side limitation. An early dynamic photo-inhibition of PSII may have caused an over reduction of the Qa+ pool decreasing the efficiency of electron donation to PSI. In H. dentatum, a slight increase in heat dissipation due to acceptor side limitation of PSI was observed above 300 µmol photons m(-2)s(-1). Differences in photosynthetic responses to light suggest that light tolerance and species plasticity could explain their contrasting vertical distribution.

Phenotypic selection on leaf functional traits of two congeneric species in a temperate rainforest is consistent with their shade tolerance.

Several studies across species have linked leaf functional traits with shade tolerance. Because evolution by natural selection occurs within populations, in order to explain those interspecific patterns it is crucial to examine variation of traits associated with shade tolerance and plant fitness at an intraspecific scale. In a southern temperate rainforest, two climbing plant species coexist but differ in shade tolerance. Whereas Luzuriaga radicans is most abundant in the shaded understory, L. polyphylla typically occurs in intermediate light environments. We carried out an intraspecific approach to test the hypothesis of differential selection patterns in relation to shade tolerance in these congeneric species. The probability of showing reproductive structures increased with specific leaf area (SLA) in L. polyphylla, and decreased with dark respiration in L. radicans. When reproductive output of fertile individuals was the fitness variable, we detected positive directional selection on SLA in L. polyphylla, and negative directional selection on dark respiration and positive directional selection on leaf size in L. radicans. Total light radiation differed between the microsites where the Luzuriaga species were sampled in the old-growth forest understory. Accordingly, L. radicans had a lower minimum light requirement and showed fertile individuals in darker microsites. L. radicans showed lower dark respiration, higher chlorophyll content, and greater leaf size and SLA than L. polyphylla. Results suggest that in more shade-tolerant species, established in the darker microsites, selection would favor functional traits minimizing carbon losses, while in less shade-tolerant species, plants displaying leaf traits enhancing light capture would be selected.

Ecophysiological traits may explain the abundance of climbing plant species across the light gradient in a temperate rainforest.

Climbing plants are a key component of rainforests, but mechanistic approaches to their distribution and abundance are scarce. In a southern temperate rainforest, we addressed whether the dominance of climbing plants across light environments is associated with the expression of ecophysiological traits. In mature forest and canopy gaps, we measured leaf size, specific leaf area, photosynthetic rate, and dark respiration in six of the most abundant woody vines. Mean values of traits and their phenotypic change (%) between mature forest and canopy gaps were predictor variables. Leaf size and specific leaf area were not significantly associated with climbing plant dominance. Variation in gas-exchange traits between mature forest and canopy gaps explained, at least partly, the dominance of climbers in this forest. A greater increase in photosynthetic rate and a lower increase in dark respiration rate when canopy openings occur were related to the success of climbing plant species. Dominant climbers showed a strategy of maximizing exploitation of resource availability but minimizing metabolic costs. Results may reflect phenotypic plasticity or genetic differentiation in ecophysiological traits between light environments. It is suggested that the dominant climbers in this temperate rainforest would be able to cope with forest clearings due to human activities.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display.

BACKGROUND AND AIMS: The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. METHODS: This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LAR(d)) was used to indicate plant light interception potential: LAR(d) is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. RESULTS: Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LAR(d) was about twice that of conifers. Although specific leaf area was the most pervasive influence on LAR(d), differences in self-shading also significantly influenced LAR(d) of large seedlings. CONCLUSIONS: The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

Ontogeny, understorey light interception and simulated carbon gain of juvenile rainforest evergreens differing in shade tolerance.

BACKGROUND AND AIMS: A long-running debate centres on whether shade tolerance of tree seedlings is mainly a function of traits maximizing net carbon gain in low light, or of traits minimizing carbon loss. To test these alternatives, leaf display, light-interception efficiency, and simulated net daily carbon gain of juvenile temperate evergreens of differing shade tolerance were measured, and how these variables are influenced by ontogeny was queried. METHODS: The biomass distribution of juveniles (17-740 mm tall) of seven temperate rainforest evergreens growing in low (approx. 4 %) light in the understorey of a second-growth stand was quantified. Daytime and night-time gas exchange rates of leaves were also determined, and crown architecture was recorded digitally. YPLANT was used to model light interception and carbon gain. RESULTS: An index of species shade tolerance correlated closely with photosynthetic capacities and respiration rates per unit mass of leaves, but only weakly with respiration per unit area. Accumulation of many leaf cohorts by shade-tolerant species meant that their ratios of foliage area to biomass (LAR) decreased more gradually with ontogeny than those of light-demanders, but also increased self-shading; this depressed the foliage silhouette-to-area ratio (STAR), which was used as an index of light-interception efficiency. As a result, displayed leaf area ratio (LAR(d) = LAR × STAR) of large seedlings was not related to species shade tolerance. Self-shading also caused simulated net daily carbon assimilation rates of shade-tolerant species to decrease with ontogeny, leading to a negative correlation of shade tolerance with net daily carbon gain of large (500 mm tall) seedlings in the understorey. CONCLUSIONS: The results suggest that efficiency of energy capture is not an important correlate of shade tolerance in temperate rainforest evergreens. Ontogenetic increases in self-shading largely nullify the potential carbon gain advantages expected to result from low respiration rates and long leaf lifespans in shade-tolerant evergreens. The main advantage of their long-lived leaves is probably in reducing the costs of crown maintenance.

Climbing plants in a temperate rainforest understorey: searching for high light or coping with deep shade?

BACKGROUND AND AIMS: While the climbing habit allows vines to reach well-lit canopy areas with a minimum investment in support biomass, many of them have to survive under the dim understorey light during certain stages of their life cycle. But, if the growth/survival trade-off widely reported for trees hold for climbing plants, they cannot maximize both light-interception efficiency and shade avoidance (i.e. escaping from the understorey). The seven most important woody climbers occurring in a Chilean temperate evergreen rainforest were studied with the hypothesis that light-capture efficiency of climbers would be positively associated with their abundance in the understorey. METHODS: Species abundance in the understorey was quantified from their relative frequency and density in field plots, the light environment was quantified by hemispherical photography, the photosynthetic response to light was measured with portable gas-exchange analyser, and the whole shoot light-interception efficiency and carbon gain was estimated with the 3-D computer model Y-plant. KEY RESULTS: Species differed in specific leaf area, leaf mass fraction, above ground leaf area ratio, light-interception efficiency and potential carbon gain. Abundance of species in the understorey was related to whole shoot features but not to leaf level features such as specific leaf area. Potential carbon gain was inversely related to light-interception efficiency. Mutual shading among leaves within a shoot was very low (<20 %). CONCLUSIONS: The abundance of climbing plants in this southern rainforest understorey was directly related to their capacity to intercept light efficiently but not to their potential carbon gain. The most abundant climbers in this ecosystem match well with a shade-tolerance syndrome in contrast to the pioneer-like nature of climbers observed in tropical studies. The climbers studied seem to sacrifice high-light searching for coping with the dim understorey light.

Variables predictivas del aprovechamiento formativo en la policía local / Predictive variables of training proficiency in the local police

La selección policial incluye un periodo de entrenamiento en el que los aspirantes adquieren conocimientos y destrezas relevantes para el trabajo. Este trabajo, realizado en la Policía Local de la ciudad de Zaragoza, examina la validez de la habilidad mental general, las dimensiones de personalidad y los conocimientos teóricos aplicados al trabajo, para predecir el aprovechamiento de la formación. Se realizaron análisis correlacionales, de regresión múltiple y path analysis con los datos correspondientes a 240 aspirantes a policía. Los resultados muestran que el aprovechamiento formativo se puede predecir a partir de la habilidad mental general, los conocimientos teóricos aplicados al puesto y tres dimensiones de personalidad, conciencia, apertura a la experiencia y amigabilidad. Se presenta un modelo causal que incluye los efectos directos e indirectos de las variables sobre el aprovechamiento de la formación en el caso de los policías locales(AU)

Police selection includes a period of training in which candidates acquire the relevant skills and knowledge for work. This study was carried out with the Local Police of Zaragoza. It examines the validity of general mental ability, the personality dimensions and theoretical knowledge applied to work, in order to predict training proficiency. A multiple regression correlational analysis and path analysis were carried out using the data of 240 candidates to be police officers. The results show that training proficiency can be predicted by general mental ability, theoretical knowledge applied to the job and three personality dimensions: conscientiousness, openness to experience and agreeableness. A causal model is presented, including the direct and indirect effects the variables have on training proficiency in the case of local police officers(AU)

Iron and zinc fortification of corn tortilla made either at the household or at industrial scale.

Fe and Zn deficiencies among the Mexican population are widespread, and one-third of children and women of childbearing age are anemic. Since diets that are Fe-deficient are most probably also Zn-deficient, a proprietary process was developed to fortify corn tortilla with these trace elements at the first stage of treatment with lime. Phytic acid (PA), Ca, Fe, and Zn content were determined, as well as the molar ratios of phytate/Fe, phytate/Zn, and Ca x phytate to Zn in traditional and fortified tortillas; the Student's t-test was used to detect differences between the treatments (p < 0.001). Contents of Fe and Zn in the fortified tortilla relative to the traditional tortilla were 1.9 and 3.4 times greater than the latter, whereas PA contents showed the opposite result, i.e. traditional tortillas had 1.65 times more PA than the fortified tortilla. Consequently the calculated molar ratios were statistically more favorable for fortified than for traditional tortillas (p < 0.001). The process developed allows making iron- and zinc-fortified tortillas by lime-treating or nixtamalizing corn either at the household, at small-scale tortilla shops, or at industrial scale by using lime fortified with both trace elements. The cost of this fortification is negligible.

Obtención de una harina de pulido de arroz desengrasado con bajo contenido de fibra neutro detergente / Obtaining a flour with low content of neutral detergent fibre from defatted rice bran

Por su contenido de proteínas y minerales, el pulido de arroz (PA) podría ser empleado en alimentación humana o animal si son eliminados el aceite y las fracciones con alto contenido de fibra. Para ello se realizó la extracción sólido-líquido al PA, con una eficiencia en la extracción del extracto etéreo del 95,6 por ciento, a fin de obtener el pulido de arroz desengranado (PAD). Se efectuó la clasificación granulométrica del PA y PAD, y de cada fracción se determinó su composición química proximal: proteína, extracto etéreo, cenizas, fibra neutro detergente (FND) y extracto libre de nitrógeno (ELN). El PA tiene un alto contenido de fracciones gruesas (>70 por ciento corresponden a partículas con tamaño de malla > 120), mientras que el PAD posee una distribución de partícula más uniforme y un contenido de grasas < 10g-kg -¹. Los perfiles del análisis químico para PA y PAD, muestran diferencias en FND y ELN, e indican que las partículas finas están constituidas principalmente por ELN (600g-kg-¹), y las partículas gruesas tienen alto contenido de FND (420g-kg-¹). El tamaño de partícula con alto y bajo contenido de fibra es el punto de inflexión de los perfiles de FND y ELN del PAD, que corresponde a la malla 180 (0,092 mm). Del PAD se puede obtener un 36 por ciento de harina (fracción 2) con 126,6g-kg-¹ de proteína y 180g-kg-1 de FND, y un 64 por ciento de harina (fracción 1) con 130.3g-kg-¹ de proteína y alto contenido de FND (420g-kg-¹). Esta harina ameritaría estudios posteriores respecto de su potencial en alimentación humana o en aplicaciones para alimentación animal

Elaboración de una harina integral de yuca (N.esculenta Crantz) para alimentación de pollitos de engorde: I caracterización químico-nutrimental de hojas, raíces y harina integral de yuca / Producción of cassava whole meal (N. esculenta Crantz) to elaborate a feed growing chicks: I chemical and nutritive characterization of leaves, roots and cassava whole meal

Las raíces de yuca son usadas frecuentemente como una fuente de energía en raciones para animales. Las hojas debido a su alto contenido de fibra no son usadas en alimentos para animales no obstante que ellas tienen un buen contenido de proteínas y un nivel balanceado de aminoácidos esenciales. El objetivo de esta investigación fue producir una harina integral de yuca (HIY) con bajo contenido de fibra para usarse en alimentación de pollitos. Hojas y raíces por separado. Fueron deshidratadas a 60ºC por 20 h, molidas en molino de martillos y cernidas en un tamiz de malla 60. Por este procedimiento fueron obtenidas una harina de raíz (HTY) y una harina de hojas (HHY). El contenido de fibra in HHY fue reducido 25.8 por ciento y el contenido de proteína fue incrementado 8.2 por ciento. La HIY fue elaborada con 61.2 por ciento de HRY y 38.8 por ciento de HHY, teniendo un contenido de proteína, y fibra de 9.15 por ciento, y 9.73 por ciento, respectivamente. La Energia Metabolizable Verdadera (EMV) de HIY fue 2,454 kcal/kg con una biodigestabilidad promedio de los aminoácidos de 68.8 por ciento

Elaboración de una harina integral de yuca (N. esculenta Crantz) para alimentación de pollitos de engorde II: evaluación de una harina integral de yuca en pollitos de engorde / Production of cassava whole meal (N. esculenta Crantz) to elaborate a feed growing chicks II: evaluation of cassava whole meal in growing chicks

Aproximadamente, 50 por ciento de las materias primas usadas para alimento de pollos está constituido de sorgo como fuente de energía. El objetivo de esta investigación fue evaluar la calidad nutrimental de una harina integral de yuca (HIY: 61.2 por ciento y 38.8 por ciento de harinas de raíz y hoja, respectivamente) para pollitos en crecimiento. El sorgo fue sustituido parcialmente de una dieta base por 15,30 y 45 por ciento de HIY. Cuatro dietas a base de sorgo, harina de soya y HIY fueron formuladas. Niveles de 0.0, 8.6, 16,4 y 23.7 por ciento de HIY fueron incluidos en las dietas. Pollitos Vantress blancos (96) fueron usados en el experimento durante 28 días. Cada tratamiento fue probado con 24 pollitos. La dieta con 23.7 por ciento de HIY mostró menor ganancia de peso y eficiencia alimentaria (p<0.05) al compararla con las otras dietas, y la relación peso hígado: peso ave aumentó en forma directa con el incremento de HIY en las raciones

Reducción del contenido de fibra cruda en pasta de cártamo (Carthamus tinctorius L) y su posible utilización en la alimentación humana / Reduction of crude fibre content in sofflower meal (Carthamus tinctorius L) and the feasibility of using in human food

El objetivo del trabajo fue reducir el contenido de fibra cruda (FC) y cuantificar el contenido de compuestos fenólicos (CF) e inhibidores de tripsina (IT) en pasta de cártamo (PC) para plantear su posible utilización en la alimentación humana. A la PC se le efectuó una molienda en licuadora y en molino de martillos, posteriormente se clasificó por tamaño de partícula y se comparó con la PC(23,3 por ciento de PC, 22,4 por ciento de proteína y 1,75 por ciento de CF) y sus respectivas fracciones. La molienda en molino de martillos resultó más efectiva ya que en la fracción de finos (60,5 por ciento) el contenido de PC se redujo en un 36,3 por ciento, la proteína y los CF se concentraron en 39,3 y 50,3 por ciento, respectivamente. La prueba de IR resultó negativa. La molienda y tamizado resultó ser un método sencillo y económico de separación de fibra en la PC, que permite concentrar proteína y obtener un adecuado rendimiento de material, características por las cuales es posible plantear su utilización en la alimentación humana, en niveles de incorporación no elevados