ECOLOGIA ISOTÓPICA (δ13C E δ15N) DE ESPÉCIES DE PISCICULTURA: POSSÍVEIS CONSEQUÊNCIAS DA MUDANÇA DE DIETA E VARIAÇÃO DE HABITAT

This study aims to assess changes of the isotopic signal - δ13C and δ15N - of muscle tissue among fish species of natural and breeding environments as a way to understand the relationship between habitat, diet and trophic composition of these watersports animals. Thus, we used four different species of fishes, being the peacock bass and tuna from different natural environments and the salmon and tilapia of breeding environments or fattening farms. From this, excepting the species of tuna the values of δ13C of Tilapia was significantly larger than others - peacock bass, salmon and tambaqui - while for the values of δ15N the species of Tilapia were significantly the lowest of all. Furthermore, the hatchery species of Tilapia and Salmon considerably had the lower variability. These results together suggest a significant difference in isotopic signal between species of hatchery and natural environments, reflecting different diets and composition of food chains according to the source environment of species. Este estudo tem como objetivo avaliar as mudanças do sinal isotópico - δ13C e δ15N - do tecido muscular entre espécies de peixes de ambientes naturais e de criação como uma forma de entender a relação entre habitat, dieta e composição trófica destes animais aquáticos. Assim, foram utilizadas quatro espécies diferentes de peixes, sendo o tucunaré e o atum de diferentes ambientes naturais e o salmão e a tilápia de ambientes de criação ou engorda. A partir disso, excetuando as espécies de atum os valores de δ13C de tilápia foram significativamente maiores do que os outros, enquanto que para os valores de δ15N as espécies de tilápia foram significativamente menores. Além disso, as espécies de piscicultura de tilápia e salmão tiveram consideravelmente a menor variabilidade. Estes resultados em conjunto sugerem uma diferença significativa no sinal isotópico entre as espécies de piscicultura e ambientes naturais, refletindo as dietas diferentes e a composição das cadeias alimentares de acordo com o ambiente de origem das espécies

Índices de eficiência do nitrogênio para avaliação da absorção e da utilização de nitrogênio no sistema radicular e no tanque de bromélias ornamentais

The objective of this work was to evaluate if nitrogen use efficiency (NUE) indexes can elucidate functional differences in nutrient uptake between the root system and tank of epiphytic bromeliads. The bromeliads Guzmania lingulata and Vriesea 'Harmony' received fertilizers in their tanks or through their roots using modified Hoagland & Arnon solution, with 0.00, 2.62, or 5.34 mmol L-1 nitrogen, as urea. After 90 days, nitrogen contents in leaves and plant biomass were evaluated, and NUE indexes were calculated. Guzmania lingulata and V. 'Harmony' fertilized in their tanks with 5.34 mmol L-1 had the highest averages of nitrogen uptake efficiency and recovery efficiency; those fertilized with 2.62 mmol L-1 through their roots showed the highest averages of NUE, nitrogen utilization efficiency, nitrogen physiological efficiency, and biomass conversion efficiency. The NUE indexes, besides being an effective tool to assess the nutritional status of ornamental bromeliads, reveal that the root system of epiphytic bromeliads is functional for nitrogen uptake and use.O objetivo deste trabalho foi avaliar se os índices de eficiência de uso do nitrogênio (EUN) podem elucidar diferenças funcionais na absorção de nutrientes entre o sistema radicular e o tanque de bromélias epifíticas. As bromélias Guzmania lingulata e Vriesea 'Harmony' receberam fertilizantes nos seus tanques ou pelas raízes com solução de Hoagland & Arnon modificada, com 0,00, 2,62 ou 5,34 mmol L-1 de nitrogênio na forma de ureia. Após 90 dias, o conteúdo de nitrogênio nas folhas e a biomassa das plantas foram avaliados, e os índices de EUN calculados. Guzmania lingulata e V. 'Harmony' adubadas no tanque com 5,34 mmol L-1 apresentaram maiores médias de eficiência de absorção de nitrogênio e de eficiência de recuperação; as adubadas nas raízes, com 2,62 mmol L-1, apresentaram as maiores médias de EUN, eficiência de utilização de nitrogênio, eficiência fisiológica de nitrogênio e índice de eficiência de conversão de biomassa. Os índices de EUN, além de serem importantes ferramentas para avaliação do status nutricional das bromélias, revelam que o sistema radicular das bromélias epífitas é funcional para absorção e utilização de nitrogênio

Leaf development and demography explain photosynthetic seasonality in Amazon evergreen forests

In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality in these forests. Specifically, synchronization of new leaf growth with dry season litterfall shifts canopy composition toward younger, more light-use efficient leaves, explaining large seasonal increases (~27%) in ecosystem photosynthesis. Coordinated leaf development and demography thus reconcile seemingly disparate observations at different scales and indicate that accounting for leaf-level phenology is critical for accurately simulating ecosystem-scale responses to climate change. © 2016 by the American Association for the Advancement of Science; all rights reserved

Prática de cultivo e uso de plantas domésticas em diferentes cidades brasileiras

O cultivo de plantas tem uma relação com o homem desde as primeiras organizações humanas. O uso de plantas em quintais é uma tradição que tem passado de geração a geração em determinadas localidades. O objetivo deste trabalho foi levantar a ocorrência de quintais domésticos em diferentes cidades de três estados brasileiros, além de conhecer uso das plantas cultivadas para fins alimentícios, medicinais e ornamentais. Este estudo foi realizado nas cidades de três estados brasileiros: Mato Grosso (Cuiabá e Cáceres); Sergipe (Aracajú e Lagarto) e Paraná (Curitiba e Campo Mourão), localizados em diferentes regiões do país (Centro Oeste, Nordeste e Sul; respectivamente). Foram realizadas entrevistas semi-estruturadas com moradores das capitais e cidades interioranas. Os dados foram avaliados quanto ao conhecimento popular em relação ao uso das plantas pelas populações, bem como as estruturas vegetais utilizadas. A maior parte dos entrevistados possuía quintais com plantas cultivadas. Foi observado um maior cultivo e uso de plantas alimentícias pelos entrevistados. As pessoas das cidades interioranas apresentaram maior hábito de cultivar plantas quando comparadas às pessoas residentes nas capitais dos estados. Dentre os órgãos da planta mais citados, a folha se destacou na maioria dos entrevistados. Assim, conclui-se que há prática de cultivo de plantas nos municípios estudados, entretanto, o uso varia de uma região para outr

Nitrogen use efficiency as a tool to evaluate the development of ornamental cacti species

Nitrogen efficiency, along with associated indexes, is a widely used tool for assessing nutritional status in agricultural species. However, this parameter is not used in studies with ornamental plants, especially epiphytic cacti species. In particular, we know very little about the potential response of ornamental cacti to N absorption and use. Therefore, this study aimed to evaluate N use efficiency (NUE), along with its associated parameters, in three species of ornamental cacti under nitrogen nutrition. To accomplish this, Rhipsalis baccifera, Rhipsalis paradoxa and Hatiora salicornioides were fertilized by Hogland and Arnon nutrition solution modified and enriched with urea in the concentrations of 0, 33.3 or 66.6 mM N during 180 days. At the end of the experiment, efficiency indexes were calculated. Efficiency parameters varied according to species. R. baccifera presented the greatest dissimilarity among the species, with highest uptake efficiency (NUpE), but lowest use efficiency (NUtE) and biomass conversion (BCE). R. paradoxa presented high values for NUE, NUtE, BCE and physiological efficiency (NPE) at concentrations of 33.3 mM N, suggesting greater investment in biological processes with lower supply of N. H. salicornioides had the highest averages in most parameters measured. Our results show that these indexes provided important comparative baseline information on nutritional status and investment strategy, thus serving as a suitable analytical tool to increase knowledge about this group of ornamental plants

Gas exchange and chlorophyll a fluorescence parameters of ornamental bromeliads

Gas exchange and chlorophyll a fluorescence are widely used in physiological and ecological studies; however, few studies have used these techniques with ornamental plants. This study tested the potential contribution of gas exchange and chlorophyll a fluorescence to evaluate the water and nutrients uptake by the tank and root system of epiphyte bromeliad Guzmania lingulata. For this purpose, we conducted an experiment with different water regime and another with different concentrations of nitrogen. The experiments were: 1 - Watering: Control (application of water into Tank and Root), Tank (watering into Tank), Root (watering Root) and Drought (water suspension during the 90 days of experimentation) and 2 - Nitrogen: Plants fertilized with Hoagland and Arnon nutrient solution exclusively into Tank or Root with nitrogen concentrations of control and 2.62 or 5.34 mM N applied as urea. The Fv /Fm ratio allowed comparing the treatments between experiments, demonstrating that Root and Tank both have the capacity to maintain G. lingulata photosynthetic activity and growth, while Drought treatment (water suspension) was the limiting factor for energy conversion efficiency of PSII. However, gas exchange was more permissive as a parameter for comparing treatments in the nitrogen experiment, providing important information about the general aspects of the photosynthetic process in the watering experiment. Both gas exchange and chlorophyll a fluorescence can support the evaluation of G. lingulata physiological status and can be useful tools in ornamental horticultural studies