Potencial dendrocronológico de tres especies de Podocarpáceas de la Cordillera de los Andes / Dendrochronological potential of three Podocarpaceae species from the Andean Cordillera

Resumen Introducción: Poco se conoce del potencial dendrocronológico de las Podocarpáceas en el trópico. Objetivo: Explorar el potencial dendrocronológico de tres especies de podocarpáceas: Retrophyllum rospigliosii, Podocarpus oleifolius y Prumnopitys harmsiana. Métodos: De plantaciones no manejadas localizadas en los Andes colombianos, se muestrearon y analizaron 88 árboles: 30 muestras de R. rospigliosii provenientes de secciones transversales, 30 y 28 muestras de P. oleifolius y P. harmsiana, respectivamente, provenientes de núcleos de madera extraídos con barreno de incrementos. Las muestras se procesaron siguiendo las técnicas dendrocronológicas estándar. Resultados: En general, las características anatómicas de los anillos de crecimiento son similares para las tres especies, con una anatomía simple de traqueidas alineadas radialmente por tratarse de coníferas. Dado que la edad conocida de la plantación coincide con el número de anillos se considera una fuerte evidencia de la frecuencia anual de su formación en R. rospigliosii y P. oleifolius, las cuales presentaron buena sincronización (cofechado) con una inter-correlación promedio de 0.55 (r-Pearson). Para P. harmsiana no fue posible concretar series de ancho de anillos de las muestras recolectadas. Las series estandarizadas de R. rospigliosii y P. oleifolius mostraron una relación con los registros instrumentales de precipitación y temperatura, indicando que estas especies pueden ser promisorias para estudios adicionales. Conclusión: La investigación dendrocronología con especies de Podocarpáceas podría realizarse exitosamente con R. rospigliosii y P. oleifolius, pero no con P. harmsiana.

Abstract Introduction: Little is known about the dendrochronological potential of Podocarpaceaes in the tropics. Objective: To explore the dendrochronological potential of three Podocarpaceae species: Retrophyllum rospigliosii, Podocarpus oleifolius, and Prumnopitys harmsiana. Methods: From a non-managed plantation in the Andean cordillera in Colombia, a total of 88 trees were analyzed: 30 samples of cross-sections of R. rospigliosii, and 30 and 28 samples of P. oleifolius and P. harmsiana, respectively, obtained with an increment borer. Samples were processed according to standard dendrochronological methods. Results: The anatomical characteristics of the growth rings of the three species are similar, with a simple conifer anatomy with radially oriented tracheids. Since the known age of the plantation coincides with the number of tree rings this is strong evidence of annual tree-ring frequency of R. rospigliosii and P. oleifolius which also showed a satisfactory cross-dating with an average inter-correlation of 0.55 (r-Pearson). For P. harmsiana, it was not possible to build a tree-ring series from the collected samples. R. rospigliosii and P. oleifolius standardized ring-width chronologies showed a relationship with the instrumental records of rainfall and temperature, indicating these species may be promising further studies. Conclusions: Dendrochronological research with Podocarpaceae species could be carried out successfully with R. rospigliosii and P. oleifolius but not with P. harmsiana.

Shoot and root interference of morning glory on the initial growth of sugarcane

ABSTRACT Among weeds, morning glories comprise a very important group of climbing plants that infest sugarcane crops. The objective of this study was to evaluate the shoot and root interference of Merremia cissoides on the initial growth of sugarcane cultivar RB 966928. The experiment consisted of five treatment groups: (i) sugarcane monocropping, (ii) morning glory monocropping, (iii) sugarcane intertwined with morning glory but inseparate boxes, (iv) sugarcane intertwined with morning glory in attached boxes and (v) sugarcane with morning glory in attached boxes with morning glory prevented from intertwining with the sugarcane. The experimental design consisted of randomized blocks with four replicates. Merremia cissoides adversely affected the initial growth of the RB 966928 sugarcane starting at 90 days after transplanting (DAT). This effect increased with the time of intercropping, reaching at 180 DAT with a reduction of 57.3% in height,15.5% in stalk diameter, 90.4% in leaf areas, 86.6 and 75.2% in stalk and leaf dry mass, respectively. These reductions primarily due to the weed intertwining with the sugarcane plants because the weed had a physical choking and shading effect. This negative effect of morning glory on the sugarcane plants increased when they shared the substrate (i.e., when they competed for space and water), which also adversely affected weed growth, reducing 50.2% leaf areas and 42.1% shoot dry mass. The leaf area and the stalk and leaf dry mass of sugarcane are the characteristics more sensitive to the weed interference. Thus, both the shoot and root of M. cissoides interferes negatively in the growth of sugarcane, with the effect proportional to the period of coexistence, highlighting the detrimental effect on the stem (greater economic interest), and may also compromise the mechanical harvesting of the crop.

Efeito da Aloe arborescens Miller e da Aloe barbadensis Miller sobre o desenvolvimento vegetativo em Aspergillus nidulans / Effects of the Aloe arborescens Millerand Aloe barbadensis Milleron over vegetative growth in the Aspergillus nidulans

RESUMOA pesquisa de produtos naturais benéficos à saúde humana vem crescendo nos últimos 20 anos. Considerando que as plantas de Aloe são amplamente utilizadas pela população humana, em geral de maneira terapêutica, o objetivo deste estudo foi avaliar os efeitos de Aloearborescens Miller e Aloe barbadensis Miller, sobre o desenvolvimento vegetativo de linhagens normais e mutantes de Aspergillus nidulans. Conídios da linhagem biA1methG1, MSE e CLB3 de A. nidulans, foram inoculados em meio completo sem (Controle) e com extratos das duas espécies incubados por 2, 4, 6 e 8 horas a 37ºC, no escuro. Foi analisado em microscópio óptico, 200 conídios de cada tratamento. Para o desenvolvimento das colônias, as linhagens foram inoculadas no centro das placas juntamente com o meio de cultura sólido e sobre a membrana de diálise, visando a medição do diâmetro e do peso. A análise estatística foi baseada no teste de Tukey e todos os procedimentos experimentais foram conduzidos em triplicata. Todas as linhagens apresentaram interferências positivas quando expostas às plantas de Aloe, porém, de maneira variada. Ambas as espécies aceleraram a germinação em todas as linhagens testadas e atuaram na redução significativa de conídios mortos e/ou malformados. Em relação ao desenvolvimento vegetativo, todos os dados referentes ao peso úmido e diâmetro corrigido dos tratamentos demonstraram progressos, contudo, a razão diâmetro/peso apresentou somente na linhagem MSE, ação favorável dos tratamentos naturais. As informações deste estudo sugerem benefícios de A. arborescens e A. barbadensis, justificando a importância e continuidade da investigação, para melhor elucidar os mecanismos de ação dessas plantas.

ABSTRACTThe researches about natural products that arebeneficial to human health have been growing over the past 20 years. Since Aloe plants are broadly used by the general population, frequently due to therapeutic reasons, the objective of this study was to evaluate the effects of Aloe arborescens Millerand Aloe barbadensis Miller on the vegetative growth of normal and mutant strains of Aspergillus nidulans. The conidia of thebiA1methG1, MSE and CLB3 strains of A. nidulans were inoculated in complete environment without (control) and with extracts of two species of Aloeincubated for 2, 4, 6 and 8 hours at 37˚C. 200 conidia were analyzed by optical microscopy. For the development of the colonies, the strains were inoculated in the center of the plates together with the solid environment of the cultivation and over the dialysis membrane for measuring the diameter and weighing. The statistical analysis was based on the Tukey test and all experimental procedures were performed in triplicate. All strains showed positive interference when exposed to Aloe plants, however, through different manners. Both species have accelerated the germination in all tested strains and acted in the significant reduction of dead and / or malformed conidia. Regarding the vegetative growth, all data related to wet weight and corrected diameter of the treatments revealed progress, however, the ratio diameter/weightpresented improvement only in the MSE lineage, favorable action of natural treatments. The information from this study suggest that A. arborescens and A. barbadensis are beneficial, thus justifying the importance of research maintenance in order to better elucidate the action mechanisms of these plants.

Seed bank and established vegetation in the last remnants of the Mexican Central Plateau wetlands: the Lerma marshes

Banco de semillas y vegetación establecida en los últimos remanentes de los humedales de la Meseta Central Mexicana: las ciénagas de Lerma. Seed banks play a central role in vegetation dynamics of many wetlands. Therefore, knowledge of seed reservoirs in the soils of aquatic communities should provide useful tools for conservation and restoration efforts. This study was conducted in the Lerma marshes, one of the last remnants of the vast wetlands that were once in the Mexican Central Plateau. The main objective was to determine the composition and abundance of seed bank and its relationship with established vegetation of the three Lerma marshes. In each marsh, we systematically selected 18 to 40 sampling sites. In each site, the composition of vascular plant vegetation was evaluated in two 10m lines perpendicular to the shore. Every 0.5m, we determined the coverage of species by measuring the intercepted length for each plant or group of plants. At each sampling site where we had evaluated the established vegetation, we collected a sample of the top 10cm of sediment; the soil cores were divided into an upper layer (0-5cm) and a lower layer (5-10cm). These samples were used to evaluate the seed bank by the seedling emergence method. All samples were placed in a greenhouse at 20-25ºC and remained flooded for 15 weeks. Fortynine species were recorded in the vegetation. Chiconahuapan had the richest and most diverse flora and the greatest number of perennial species. A life-forms analysis showed that perennial herbs, especially rooted-emergent hydrophytes, dominated in the three wetlands. Sixty-one species were identified in the total seed bank; Chimaliapan had the most diverse total seed bank, whereas the mean seedling density was higher in Chignahuapan. Only two species of the total seed bank of each marsh had a density greater than 10% of the total, and more than half were uncommon. The upper layer of sediment (0-5cm) contained two times more seeds/m² and species per sample than the lower layer (5-10cm), and there was a significant decrease of seed density with depth. The detrended correspondence analysis produced a clear separation between the composition of the seed banks and established vegetation. In general, in each marsh there was less species diversity in the established vegetation than in the seed bank. Dominance by a few species in the seed bank, the presence of opportunistic species, and the low representation of established species in the seed bank suggest wetland degradation and a low probability of regenerating the natural communities from the seed bank. To ensure the permanence of these marshes, their biodiversity, and therefore the environmental services they provide, up to date planning is a must, and efforts to control and monitor hydrology, water quality, and the influence of human activities are suggested.

Los bancos de semillas desempeñan un papel central en la dinámica de la vegetación de muchos humedales. Por lo tanto, el conocimiento de los depósitos de semillas en los suelos de las comunidades acuáticas debe proporcionar herramientas útiles para los esfuerzos de conservación y restauración. Este estudio se llevó a cabo en las ciénegas de Lerma, uno de los últimos vestigios de las grandes zonas inundadas que antes cubrían la Meseta Central Mexicana. El objetivo principal fue determinar la composición y abundancia de los bancos de semillas y su relación con la vegetación establecida en las tres ciénegas de Lerma. En cada humedal se seleccionaron sistemáticamente de 18 a 40 sitios de muestreo. En cada sitio se colocaron dos líneas de 10m perpendiculares a la orilla sobre las que se evaluó la composición y cobertura de plantas vasculares a intervalos de 0.5m. En los sitios de muestreo donde se evaluó la vegetación establecida, se recolectó una muestra de los 10cm superiores de sedimento y se separó en una capa superior (0 a 5cm) y otra inferior (5-10cm). Estas muestras se utilizaron para evaluar el banco de semillas por el método de emergencia de plántulas. Todas las muestras se colocaron en un invernadero a 20-25ºC y se mantuvieron inundadas durante 15 semanas. Cuarenta y nueve especies se registraron en la vegetación. Chiconahuapan presentó la flora más rica y diversas, así como el mayor número de especies perennes. El análisis de las formas de vida mostró que las hierbas perennes y especialmente las hidrófitas arraigada emergente dominaron en los tres humedales. Sesenta y un especies se identificaron en el banco de semillas total, Chimaliapan presentó el banco de semillas total más diverso, mientras que la densidad promedio de plántulas fue mayor en Chignahuapan. Sólo dos especies de todo el banco de semillas de cada ciénega presentaron una densidad mayor del 10% del total y más de la mitad de las especies fueron poco frecuentes. La capa superior de sedimentos (0-5cm) exhibió dos veces más semillas/m² y especies por muestra que la capa inferior (5-10cm), se observó una disminución significativa de la densidad de semillas con la profundidad. El análisis de correspondencia sin tendencia produjo una separación clara entre la composición de los bancos de semillas y la de la vegetación establecida. En general, en cada ciénega hay menos diversidad de especies en la vegetación establecida que en el banco de semillas. El dominio de pocas especies en el banco de semillas, la presencia de especies oportunistas y la escasa representación de las plantas establecidas en el banco de semillas sugiere degradación de los humedales y una baja probabilidad de regeneración de las comunidades naturales desde el banco de semillas. Para garantizar la permanencia de estos sistemas, su biodiversidad y por tanto los servicios ambientales que ofrecen, se requiere de esfuerzos para controlar y supervisar la hidrología y la influencia de las actividades humanas.

Does plant architectural complexity increase with increasing habitat complexity? A test with a pioneer shrub in the Brazilian Cerrado / A complexidade arquitetural de plantas aumenta com a complexidade do habitat? Um teste com um arbusto pioneiro de Cerrado

Understanding variation in plant traits in heterogeneous habitats is important to predict responses to changing environments, but trait-environment associations are poorly known along ecological gradients. We tested the hypothesis that plant architectural complexity increases with habitat complexity along a soil fertility gradient in a Cerrado (Neotropical savanna) area in southeastern Brazil. Plant architecture and productivity (estimated as the total number of healthy infructescences) of Miconia albicans (SW.) Triana were examined in three types of vegetation which together form a natural gradient of increasing soil fertility, tree density and canopy cover: grasslands (campo sujo, CS), shrublands (cerrado sensu strico, CE) and woodlands (cerradão, CD). As expected, plants growing at the CS were shorter and had a lower branching pattern, whereas plants at the CD were the tallest. Unexpectedly, however, CD plants did not show higher architectural complexity compared to CE plants. Higher architectural similarity between CE and CD plants compared to similarity between CS and CE plants suggests reduced expression of functional architectural traits under shade. Plants growing at the CE produced more quaternary shoots, leading to a larger number of infructescences. This higher plant productivity in CE indicates that trait variation in ecological gradients is more complex than previously thought. Nematode-induced galls accounted for fruit destruction in 76.5% infructescences across physiognomies, but percentage of attack was poorly related to architectural variables. Our data suggest shade-induced limitation in M. albicans architecture, and point to complex phenotypic variation in heterogeneous habitats in Neotropical savannas.

O entendimento da variação dos atributos de plantas em ambientes heterogêneos é importante para prever respostas às mudanças climáticas; entretanto, a resposta de atributos das plantas às mudanças ambientais é pouco conhecida ao longo de gradientes ecológicos. Testou-se a hipótese de que a complexidade arquitetural de Miconia albicans (SW.) Triana aumenta com a complexidade ambiental, ao longo de um gradiente de fertilidade de solo em um Cerrado no sudeste brasileiro. A arquitetura e a produtividade (estimada por meio do número total de infrutescências sadias) foram examinadas em três tipos de vegetação, que formam um gradiente de fertilidade de solo, de densidade de árvores e de cobertura vegetal: campo sujo (CS), cerrado sensu stricto (CE) e cerradão (CD). Plantas crescendo no CS foram menores e apresentaram menor complexidade arquitetural, enquanto plantas no CD foram maiores. No entanto, de forma inesperada, plantas no CD não demonstraram maior complexidade arquitetural quando comparadas às plantas de CE, e a maior similaridade arquitetural entre plantas de CE e CD, quando comparadas com plantas de CE e CS, sugere que a expressão de atributos funcionais da arquitetura é limitada sob condições de sombra. Plantas de CE produziram mais ramos quaternários e maior número de infrutescências, sendo que a maior produtividade destas plantas indica que a variação de atributos em gradientes ecológicos é mais complexa do que se pensava anteriormente. Galhas de nematóides destruíram 76,5% das infrutescências nas vegetações, mas a porcentagem de ataque não esteve fortemente correlacionada com as variáveis arquiteturais. Os resultados do presente trabalho sugerem limitação na expressão da arquitetura da planta induzida pela sombra e apontam para uma complexa variação fenotípica na colonização de ambientes heterogêneos de savanas neotropicais.