Plant growth-promoting traits of yeasts isolated from the tank bromeliad Vriesea minarum L.B. Smith and the effectiveness of Carlosrosaea vrieseae for promoting bromeliad growth.

Yeasts can play important roles in promoting plant growth; however, little information is available in this regard for yeasts in water of bromeliad tanks. Here, we characterize the ability of 79 yeast isolates from tank bromeliad Vriesea minarum, an endangered species, to solubilize phosphate, secrete siderophores, and synthesize indole-3-acetic acid (IAA). The results showed that 67.8% of all assayed yeast isolates mobilized inorganic phosphate; 40.0% secreted siderophores; and 89.9% synthetized IAA and IAA-like compounds. Among the species studied, Carlosrosaea vrieseae UFMG-CM-Y6724 is highlighted for producing IAA (76.1 µg mL-1) and siderophores, and solubilizing phosphate. In addition, evaluation of the effects of filtrate containing IAA-like compounds produced by the C. vrieseae on the development and photosynthetic performance of V. minarum seedlings found it to improve seedling growth equal to that of commercial IAA. These results demonstrate that C. vrieseae can produce compounds with great potential for future use as biofertilizer agents.

Micropropagation and in vitroconservation of Alcantarea nahoumii (Bromeliaceae), an endemic and endangered species of the Brazilian Atlantic Forest

Alcantarea nahoumii(Leme) J. R. Grant is a species native to theAtlantic Forest that stands out for ornamental purposes. The objective of this work was to evaluate the in vitrogerminationof A. nahoumiiseeds and establish a micropropagation protocol for production of seedlings so as to minimize the effects of predatory extractivism and develop an in vitroconservation system. Mature seeds were disinfested, established in three culture media (MS, MS½ and MS⅓) and incubated at four temperatures (20, 25, 30 and 35ºC)in a germination chamber. In the micropropagation experiment, stem segments were introduced in MS medium supplemented with 0.5 μM of 1-naphthaleneacetic acid (NAA) and 0.0, 2.2, 4.4 and 6.6 μM of 6-benzylaminopurine (BAP). For the in vitroconservation, plantlets were established in MS or MS½ medium supplemented with 15 g L-1or 30 g L-1of sucrose. The plants were acclimated with commercial substrate. The highest seed germination percentages were promoted by temperature conditions of 20 and 25ºC, with MS culture medium. The highest multiplication rate of shoots was obtained from the treatment without addition of the growth regulator or when combined with 2.2 μM of BAP + 0.5 μM of NAA. The acclimation of the plants occurred with high survival rate. The species can be conserved in vitrounder slow growth condition for 24 months when incubated in MS medium supplemented with 30 g L-1of sucrose.

Does oxidative stress determine the thermal limits of the regeneration niche of Vriesea friburgensis and Alcantarea imperialis (Bromeliaceae) seedlings?

The predicted environmental changes may be detrimental to initial seedling growth, particularly the expected increase in air temperature. We therefore investigated the thermal limits for growth and development of Vriesea friburgensis and Alcantarea imperialis seedlings in the context of oxidative stress. The optimal temperatures for the growth of V. friburgensis and A. imperialis were 25 and 25-30 °C, respectively. Extreme temperatures (15, 30, or 35 °C) induced oxidative stress in both species with significant accumulation of hydrogen peroxide (H2O2) and nitric oxide (NO). Under oxidative stress, the amount of chlorophyll decreased in both species, more prominently in V. friburgensis, while carotenoid levels dramatically increased in A. imperialis. Notably, the activities of superoxide dismutase, catalase (CAT), and ascorbate peroxidase increased in A. imperialis at extreme temperatures. Similar results were observed for V. friburgensis; however, the activity of CAT remained unaffected regardless of temperature. Seedlings of A. imperialis survived at a wider range of temperatures than V. friburgensis, which had greater than 40% mortality when growing at 30 °C. Overall, precise control of cellular H2O2 and NO levels takes place during the establishment of A. imperialis seedlings, allowing the species to cope with relatively high temperatures. The thermal limits of the fundamental niches of the species investigated, determined based on the ability of seedlings to cope with oxidative stress, were distinct from the realized niches of these species. The results suggest that recruitment success is dependent on the ability of seedlings to handle extreme temperature-triggered oxidative stress, which limits the regeneration niche.

Morpho-physiological changes in Billbergia zebrina due to the use of silicates in vitro.

The use of silicon in Billbergia zebrina cultivation in vitro is an alternative for optimizing micropropagation of this important ornamental plant species. The objective of the present study was to evaluate the growth and anatomical and physiological alterations in Billbergia zebrina (Herbert) Lindley plants as a function of different sources and concentrations of silicon during in vitro cultivation and acclimatization. The experimental design was completely randomized, with a double factorial arrangement and an additional control treatment (2 x 3 + 1). The first factor was relative to calcium silicate and sodium silicate added to the Murashige & Skoog culture medium; the second factor was related to its concentrations, 0.5, 1.0, and 2.0 mg L-1. After 100 days, their growth, anatomical characteristics, level of silicon and chlorophyll content were evaluated. Growth characteristics were assessed after 60 days of acclimatization period. Plants absorbed more sodium silicate than calcium silicate. This source also stressed the plants impairing their growth, but the highest silicon absorption at 1 mg L-1 attenuated the stressful conditions. The supplementation of the culture medium with calcium silicate led to improved growth, anatomical, and physiological characteristics, which benefited the development of more resistant seedlings with better performance during acclimatization.

Epiphytic bromeliads in a changing world: the effect of elevated CO2 and varying water supply on growth and nutrient relations.

Global climate change is likely to impact all plant life. Vascular epiphytes represent a life form that may be affected more than any other by possible changes in precipitation leading to water shortage, but negative effects of drought may be mitigated through increasing levels of atmospheric CO2 . We studied the response of three epiphytic Aechmea species to different CO2 and watering levels in a full-factorial climate chamber study over 100 days. All species use crassulacean acid metabolism (CAM). Response variables were relative growth rate (RGR), nocturnal acidification and foliar nutrient levels (N, P, K, Mg). Both elevated CO2 and increased water supply stimulated RGR, but the interaction of the two factors was not significant. Nocturnal acidification was not affected by these factors, indicating that the increase in growth in these CAM species was due to higher assimilation in the light. Mass-based foliar nutrient contents were consistently lower under elevated CO2 , but most differences disappeared when expressed on an area basis. Compared to previous studies with epiphytes, in which doubling of CO2 increased RGR, on average, by only 14%, these Aechmea species showed a relatively strong growth stimulation of up to +61%. Consistent with earlier findings with other bromeliads, elevated CO2 did not mitigate the effect of water shortage.

Growth responses to elevated temperatures and the importance of ontogenetic niche shifts in Bromeliaceae.

Epiphytic bromeliads represent a major component of Neotropical forests, but the potential effect of climate change on these plants is unclear. We investigated whether and how bromeliads are affected by the predicted 3°C temperature rise by the end of the century. We conducted growth experiments with 17 epiphytic bromeliad species at different temperatures to determine their fundamental thermal niches. By comparing those with niches for germination, we tested whether ontogenetic niche shift or niche contraction occurs in Bromeliaceae. Applying a classical growth analysis, we assessed the relative importance of the underlying growth components on interspecific variations in growth. Members of two bromeliad subfamilies differed in their response to elevated temperatures: Tillandsioideae may be negatively affected, whereas Bromelioideae moved closer to their thermal optimum. Across different ontogenetic stages, thermal niche characteristics revealed both niche shift and niche contraction. Interspecific variation in growth was driven almost exclusively by net assimilation rate at all temperatures. We conclude that the vulnerability of tropical plants to a future increase in temperature may be more variable than suggested by previous studies. We emphasize the importance of assessing niche breadth over multiple life stages and the need for better microclimatic data to link laboratory data with field conditions.

Heteroblasty in epiphytic bromeliads: functional implications for species in understorey and exposed growing sites.

Background and Aims: The functional relevance of heteroblasty, an abrupt morphological change in the ontogeny of a considerable number of angiosperm species, is still largely unresolved. During the ontogeny of many epiphytic Tillandsioids (Bromeliaceae), such a change occurs when small individuals transform into larger, tank-forming individuals that are capable of external water storage. Apart from its fundamental effect on plant water relations, the associated transition from narrow to broader leaves also affects plant architecture. The morphological changes and their effect on light interception may be especially relevant for heteroblastic species in the moist understorey, which are expected to be limited primarily by light. Methods: A functional structural plant model (Yplant) was used to construct digital replicas of atmospheric and tank-forming individuals of four species, two of them naturally growing in exposed conditions and two occurring in understorey sites. This allowed the determination of leaf display efficiencies as well as a systematic analysis of leaf architectural traits and their effect on light interception. Key Results: Modifying existing plant morphologies showed that broader leaves cause more self-shading within the plant. This supports the hypothesis that species from the light-limited understorey benefit from the early atmospheric life form through increased light capture. Modelling plant morphology that continuously followed the ontogenetic trajectories of the leaf architectural traits revealed that the rising total leaf number in atmospheric individuals constantly increased self-shading. Therefore, at a certain ontogenetic stage, a tipping point was reached when the tank form was even favourable in terms of light capture as it was associated with fewer leaves. Conclusions: The effects of changes in leaf morphology and leaf architecture on plant light capture may explain the common occurrence of heteroblastic species in the understorey of Neotropical forests, which does not negate a simultaneous positive effect of heteroblasty on plant water relations.

Trade-off between soluble protein production and nutritional storage in Bromeliaceae.

BACKGROUND AND AIMS: Bromeliads are able to occupy some of the most nutrient-poor environments especially because they possess absorptive leaf trichomes, leaves organized in rosettes, distinct photosynthetic pathways [C3, Crassulacean acid metabolism (CAM) or facultative C3-CAM], and may present an epiphytic habit. The more derived features related to these traits are described for the Tillandsioideae subfamily. In this context, the aims of this study were to evaluate how terrestrial predators contribute to the nutrition and performance of bromeliad species, subfamilies and ecophysiological types, whether these species differ in their ecophysiological traits and whether the physiological outcomes are consistent among subfamilies and types (e.g. presence/absence of tank, soil/tank/atmosphere source of nutrients, trichomes/roots access to nutrients). METHODS: Isotopic (15N-enriched predator faeces) and physiological methods (analyses of plant protein, amino acids, growth, leaf mass per area and total N incorporated) in greenhouse experiments were used to investigate the ecophysiological contrasts between Tillandsioideae and Bromelioideae, and among ecophysiological types when a predatory anuran contributes to their nutrition. KEY RESULTS: It was observed that Bromelioideae had higher concentrations of soluble protein and only one species grew more (Ananas bracteatus), while Tillandsioideae showed higher concentrations of total amino acids, asparagine and did not grow. The ecophysiological types that showed similar protein contents also had similar growth. Additionally, an ordination analysis showed that the subfamilies and ecophysiological types were discrepant considering the results of the total nitrogen incorporated from predators, soluble protein and asparagine concentrations, relative growth rate and leaf mass per area. CONCLUSIONS: Bromeliad subfamilies showed a trade-off between two strategies: Tillandsioideae stored nitrogen into amino acids possibly for transamination reactions during nutritional stress and did not grow, whereas Bromelioideae used nitrogen for soluble protein production for immediate utilization, possibly for fast growth. These results highlight that Bromeliaceae evolution may be directly associated with the ability to stock nutrients.

The effects of food web structure on ecosystem function exceeds those of precipitation.

Ecosystems are being stressed by climate change, but few studies have tested food web responses to changes in precipitation patterns and the consequences to ecosystem function. Fewer still have considered whether results from one geographic region can be applied to other regions, given the degree of community change over large biogeographic gradients. We assembled, in one field site, three types of macroinvertebrate communities within water-filled bromeliads. Two represented food webs containing both a fast filter feeder-microbial and slow detritivore energy channels found in Costa Rica and Puerto Rico, and one represented the structurally simpler food webs in French Guiana, which only contained the fast filter feeder-microbial channel. We manipulated the amount and distribution of rain entering bromeliads and examined how food web structure mediated ecosystem responses to changes in the quantity and temporal distribution of precipitation. Food web structure affected the survival of functional groups in general and ecosystem functions such as decomposition and the production of fine particulate organic matter. Ecosystem processes were more affected by decreased precipitation than were the abundance of micro-organisms and metazoans. In our experiments, the sensitivity of the ecosystem to precipitation change was primarily revealed in the food web dominated by the single filter feeder-microbial channel because other top-down and bottom-up processes were weak or absent. Our results show stronger effects of food web structure than precipitation change per se on the functioning of bromeliad ecosystems. Consequently, we predict that ecosystem function in bromeliads throughout the Americas will be more sensitive to changes in the distribution of species, rather than to the direct effects caused by changes in precipitation.

AfAP2-1, An Age-Dependent Gene of Aechmea fasciata, Responds to Exogenous Ethylene Treatment.

The Bromeliaceae family is one of the most morphologically diverse families with a pantropical distribution. To schedule an appropriate flowering time for bromeliads, ethylene is commonly used to initiate flower development in adult plants. However, the mechanism by which ethylene induces flowering in adult bromeliads remains unknown. Here, we identified an APETALA2 (AP2)-like gene, AfAP2-1, in Aechmea fasciata. AfAP2-1 contains two AP2 domains and is a nuclear-localized protein. It functions as a transcriptional activator, and the activation domain is located in the C-terminal region. The expression level of AfAP2-1 is higher in juvenile plants than in adult plants, and the AfAP2-1 transcript level was rapidly and transiently reduced in plants treated with exogenous ethylene. Overexpression of AfAP2-1 in Arabidopsis thaliana results in an extremely delayed flowering phenotype. These results suggested that AfAP2-1 responds to ethylene and is a putative age-dependent flowering regulator in A. fasciata.

Proline levels, oxidative metabolism and photosynthetic pigments during in vitro growth and acclimatization of Pitcairnia encholirioides L.B. Sm. (Bromeliaceae).

This study aimed to evaluate the variation in the levels of proline, oxidative metabolism and photosynthetic pigments in plants of Pitcairnia encholirioides grown in vitro under different conditions and after acclimatization. The analyses were performed after 150 days of in vitro cultivation in MS media supplemented with 10 µM GA3 or 0.2 µM NAA, sucrose at 15 or 30 g L-1, in test tubes which allowed gas exchange or in a hermetically sealed system, and 180 days after acclimatization. The in vitro maintenance in hermetically sealed flasks, with GA3 and 15 g L-1 sucrose had adverse metabolic effects, which was demonstrated by the lower proline and photosynthetic pigments accumulation and by the increase in antioxidant enzymes activities. After acclimatization, differences for proline and photosynthetic pigments were no longer found and the enzymatic activities ranged unevenly. The results suggest that the in vitro cultivation in media with 0.2 µM NAA and 30 g L-1 sucrose, in test tubes capped with closures which allowed gas exchange, is more suitable for micropropagation of P. encholirioides, providing a prolonged maintenance of in vitro cultures and plantlets with superior quality for ex vitro development.

Proline levels, oxidative metabolism and photosynthetic pigments during in vitro growth and acclimatization of Pitcairnia encholirioides L.B. Sm. (Bromeliaceae) / Niveis de prolina, do metabolismo oxidativo e dos pigmentos fotossintéticos durante o crescimento in vitro e aclimatização de Pitcairnia encholirioides L.B. Sm. (Bromeliaceae)

Abstract This study aimed to evaluate the variation in the levels of proline, oxidative metabolism and photosynthetic pigments in plants of Pitcairnia encholirioides grown in vitro under different conditions and after acclimatization. The analyses were performed after 150 days of in vitro cultivation in MS media supplemented with 10 µM GA3 or 0.2 µM NAA, sucrose at 15 or 30 g L–1, in test tubes which allowed gas exchange or in a hermetically sealed system, and 180 days after acclimatization. The in vitro maintenance in hermetically sealed flasks, with GA3 and 15 g L–1 sucrose had adverse metabolic effects, which was demonstrated by the lower proline and photosynthetic pigments accumulation and by the increase in antioxidant enzymes activities. After acclimatization, differences for proline and photosynthetic pigments were no longer found and the enzymatic activities ranged unevenly. The results suggest that the in vitro cultivation in media with 0.2 µM NAA and 30 g L–1 sucrose, in test tubes capped with closures which allowed gas exchange, is more suitable for micropropagation of P. encholirioides, providing a prolonged maintenance of in vitro cultures and plantlets with superior quality for ex vitro development.

Resumo Este trabalho objetivou avaliar a contribuição da prolina, do metabolismo oxidativo e dos pigmentos fotossintéticos na propagação in vitro e aclimatização de Pitcairnia encholirioides, uma bromélia criticamente ameaçada de extinção. As análises foram realizadas após 150 dias de cultivo in vitro em meio MS suplementado com 10 µM de GA3 ou 0,2 µM de ANA, 15 ou 30 g L–1 de sacarose, em tubos de ensaio que permitiam trocas gasosas ou em sistema hermeticamente vedado, e também 180 dias após aclimatização. A manutenção in vitro em frascos hermeticamente fechados, com GA3 e 15 g L–1 de sacarose apresentou efeito metabólico adverso, demonstrado pelo menor acúmulo de prolina e pigmentos fotossintéticos e também pelo aumento das atividades de enzimas antioxidantes. Após aclimatização, as diferenças para prolina e pigmentos fotossintéticos não foram mais encontradas e as atividades enzimáticas variaram de maneira desuniforme. Os resultados sugerem que o cultivo in vitro em meio com 0,2 µM de ANA e 30 g L–1 de sacarose, em tubos fechados com tampas que permitem trocas gasosas, é mais adequado para a micropropagação de P. encholirioides, proporcionando uma manutenção prolongada das culturas in vitro e plântulas com qualidade superior para o desenvolvimento ex vitro.

Effects of Seasonality and Dispersal on the Ciliate Community Inhabiting Bromeliad Phytotelmata in Riparian Vegetation of a Large Tropical River.

This study evaluated the influence of rainfall amount on the abundance, species richness, and species occurrence and abundance distribution of the ciliate community associated with the bromeliad Aechmea distichantha. The plants were collected from a rock wall of about 10-km long at the left bank of Paraná River. We assessed the effects of both spatial and temporal variables on the community attributes, as well as whether plants geographically closer have a similar abundance distribution and species composition. The ciliate community was substantially distinct between both hydrological periods, with greater values of species richness and abundance in the rainy period. No spatial structuring (differences in the species occurrence and abundance distribution among strata) or geographical similarity (similarity in ciliate species composition among the plants) was found. Multiple regression analysis showed a positive relationship only between the ciliate abundances and water volumes for both periods. Although few of the formulated predictions were confirmed, our study provides valuable information on the ecological aspects of the ciliate community inhabiting bromeliad phytotelmata.

Diurnal versus nocturnal pollination success in Billbergia horrida Regel (Bromeliaceae) and the first record of chiropterophily for the genus.

Billbergia horrida is endemic of the Atlantic Forest fragments in southeastern Brazil and characterized by flowers with typical traits for pollination by nocturnal animals. Although the majority of Billbergia species rely on diurnal pollination by hummingbirds, B. horrida is also visited by bats and this study evidences for the first time the occurrence of chiropterophily within the genus. The role of different groups of pollinators on the reproductive success of B. horrida was evaluated, as well as the correlation of nectar features in sustaining these animals during different periods of the day. Bats contributed to 82.1% of fruit set of B. horrida. Hummingbirds, in turn, contributed to only 10% of fruit set, and were poorly related to the reproductive success of this species. Amounts of nectar production and sugar concentration were similar to those of other chiropterophilous bromeliads and only the nectar volume changed significantly throughout the period of flower availability. Recurring visits by hummingbirds were probably because the flowers of B. horrida were open for 24h, offering energetic rewards for daytime visitors and due to the presence of other attractive bromeliad species growing at the same phorophyte and flowering at the same time.

Patterns of gene flow in Encholirium horridum L.B.Sm., a monocarpic species of Bromeliaceae from Brazil.

Encholirium horridum is a bromeliad that occurs exclusively on inselbergs in the Atlantic Forest biome of Brazil. These rock outcrops form natural islands that isolate populations from each other. We investigated gene flow by pollen through paternity analyses of a bromeliad population in an area of approximately 2 ha in Espírito Santo State, Brazil. To that end, seed rosettes and seedlings were genotyped using nuclear microsatellite loci. A plot was also established from the same population and specimens were genotyped to evaluate their fine-scale spatial genetic structure (SGS) through analyses of spatial autocorrelation and clonal growth. Paternity analysis indicated that 80% of the attributed progenitors of the genotyped seedlings were from inside the study area. The pollen dispersal distances within the area were restricted (mean distance of 45.5 m, varying from 3 to 156 m) and fine-scale SGS was weak (F(ij) = 0.0122, P < 0.001; Sp = 0.009). Clonal growth was found to be a rare event, supporting the monocarpy of this species.

A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest.

Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between 'Aechmea-areas' and 'control-areas' of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests.

Natural history and morphology of the hoverfly Pseudomicrodon biluminiferus and its parasitic relationship with ants nesting in bromeliads.

The syrphid subfamily Microdontinae is characterized by myrmecophily of their immature stages, i.e., they develop in ant nests. Data on natural history of microdontines are scarce, especially in the Neotropics. Based on fieldwork in southern Brazil, this study provided new data on development and ecology of the hoverfly Pseudomicrodon biluminiferus (Hull) (Diptera: Syrphidae) as well as the first morphological descriptions of male genitalia, larvae, and pupa. Immature specimens were specifically found in colonies of the ant species Crematogaster limata Smith (Hymenoptera: Formicidae) found in rosettes of the bromeliad species Aechmea lindenii (E. Morren) Baker (Poales: Bromeliaceae) and A. nudicaulis (L.) Grisebach. Third instar larvae were observed preying on ant larvae, revealing the parasitic nature of P. biluminiferus. In this and several other aspects, the natural history of P. biluminiferus is similar to that of Holarctic microdontine species. Exceptions include: (i) indications that adults of P. biluminiferus outlast the winter months (in contrast to 3(rd)instar larvae in Holarctic species) and (ii) P. biluminiferus' relationship with bromeliads. The importance of bromeliads for this host-parasite system is evaluated in this paper. The single occurrence of another, unidentified microdontine species' pupae in a nest of the ant species Camponotus melanoticus Emery (Hymenoptera: Formicidae) is reported.

Foraging behaviour of the Scale-throated Hermit Phaethornis eurynome Lesson, 1832 (Aves, Trochilidae) in Vriesea incurvata Gaudich (Bromeliaceae).

In this study we tested for density-dependent relationships between visitation rates of the Scale-throated Hermit (Phaethornis eurynome) and the plant density and flower number of the bromeliad Vriesea incurvata, by comparing plots with varying densities of this bromeliad. Eight 100 m2 plots were established at least 200 m from each other; four plots contained 10-15 individuals of V. incurvata each, whereas the other four contained 4-5 individuals each. The visitors, number of visits, behaviour (nectar thief or potential pollinator) and the height of foraging were recorded during focal observations on the plants. The number of visits of P. eurynome varied according to the local density of V. incurvata, showing that the heterogeneous distribution of this bromeliad species may promote adjustments in the pollinator populations, through resource variation at a local scale.

In vitro growth of the bromeliad Alcantarea imperialis (Carrière) Harms with different concentrations of nitrogen / Crescimento in vitro da bromélia Alcantarea imperialis (Carrière) Harms com diferentes concentrações de nitrogênio

In various ecosystems, many plants have been reduced in number or even eliminated from natural habitats, including the endangered ornamental bromeliad Alcantarea imperialis (Carrière) Harms. The in vitro culture is a tool that has been used for conservation of endangered species and widely used for the production of ornamental plants. This study aimed at investigating the influence of different nitrogen concentrations on the growth of plantlets of the bromeliad A. imperialis grown in vitro. Seedlings of A. imperialis were cultured on Murashige and Skoog medium, supplemented with different concentrations of nitrogen (0.00, 3.75, 7.50, 15.00, 30.00, 60.00, 90.00, 120.00, and 175.00 mM) at 30 mmol m- 2 s-1, at 12 hour photoperiod and 26±2°C for six months. The results showed that plants grown with 15.00 and 60.00 mM N showed the best growth.

Em vários ecossistemas, o número de plantas está se reduzindo ou até mesmo erradicadas de seus hábitats naturais, e uma dessas espécies que está em perigo é a bromélia ornamental Alcantarea imperialis (Carrière) Harms. O cultivo in vitro é uma ferramenta que tem sido utilizada na conservação de espécies em extinção e tem sido amplamente utilizado para a produção de plantas ornamentais. Este trabalho teve como objetivo investigar a influência de diferentes concentrações de nitrogênio sobre o crescimento da bromélia A. imperialis cultivadas in vitro. Plântulas de A. imperialis foram cultivadas em meio de Murashige e Skoog, suplementado com diferentes concentrações de nitrogênio (0,00; 3,75; 7,50; 15,00; 30,00; 60,00; 90,00; 120,00 e 175,00 mM) em 30 mmol m-2 s-1, em 12h fotoperíodo, a 26±2°C durante seis meses. Os resultados mostraram que as plantas crescidas com 15,00 e 60,00 mM de N proporcionam o melhor crescimento.

Foraging behaviour of the Scale-throated Hermit Phaethornis eurynome Lesson, 1832 (Aves, Trochilidae) in Vriesea incurvata Gaudich (Bromeliaceae) / Comportamento alimentar de Phaethornis eurynome Lesson, 1832 (Aves, Trochilidae) em Vriesea incurvata Gaudich (Bromeliaceae)

In this study we tested for density-dependent relationships between visitation rates of the Scale-throated Hermit (Phaethornis eurynome) and the plant density and flower number of the bromeliad Vriesea incurvata, by comparing plots with varying densities of this bromeliad. Eight 100 m2 plots were established at least 200 m from each other; four plots contained 10-15 individuals of V. incurvata each, whereas the other four contained 4-5 individuals each. The visitors, number of visits, behaviour (nectar thief or potential pollinator) and the height of foraging were recorded during focal observations on the plants. The number of visits of P. eurynome varied according to the local density of V. incurvata, showing that the heterogeneous distribution of this bromeliad species may promote adjustments in the pollinator populations, through resource variation at a local scale.

Neste estudo foram testadas as relações entre taxas de visitação de Phaethornis eurynome e a densidade e o número de flores de Vriesea incurvata, comparando-se parcelas com diferentes densidades desta bromélia. Oito parcelas de 100 m2 foram estabelecidas a pelo menos 200 m uma da outra; quatro parcelas continham de 10 a 15 indivíduos de V. incurvata cada, enquanto as outras quatro continham de 4 a 5 indivíduos cada. Os visitantes, o número de visitas, o comportamento (pilhador ou potencial polinizador) e altura de forrageamento foram registrados em observações focais das plantas. O número de visitas por P. eurynome variou conforme a densidade de V. incurvata na área, demonstrando que a distribuição heterogênea desta bromélia pode promover ajustes populacionais por parte dos polinizadores, através da variação da oferta de recursos em uma escala local.