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Archaeological cobs from Paredones and Huaca Prieta (Peru) represent some of the oldest maize known to date, yet they present relevant phenotypic traits corresponding to domesticated maize. This contrasts with the earliest Mexican macro-specimens from Guila Naquitz and San Marcos, which are phenotypically intermediate for these traits, even though they date more recently in time. To gain insights into the origins of ancient Peruvian maize, we sequenced DNA from three Paredones specimens dating ~6700-5000 calibrated years before present (BP), conducting comparative analyses with two teosinte subspecies (Zea mays ssp. mexicana and parviglumis) and extant maize, that include highland and lowland landraces from Mesoamerica and South America. We show that Paredones maize originated from the same domestication event as Mexican maize and was domesticated by ~6700 BP, implying rapid dispersal followed by improvement. Paredones maize shows no relevant gene flow from mexicana, smaller than that observed in teosinte parviglumis. Thus, Paredones samples represent the only maize without confounding mexicana variation found to date. It also harbors significantly fewer alleles previously found to be adaptive to highlands, but not of alleles adaptive to lowlands, supporting a lowland migration route. Our overall results imply that Paredones maize originated in Mesoamerica, arrived in Peru without mexicana introgression through a rapid lowland migration route, and underwent improvements in both Mesoamerica and South America.

The plant we know today as maize or corn began its story 9,000 years ago in modern-day Mexico, when farmers of the Balsas River basin started to carefully breed its ancestor, the wild grass teosinte parviglumis. Recent discoveries suggest the crop may have started to travel to South America before its domestication was fully complete, leading to a complex history of semi-tamed lineages evolving in parallel in different regions. For example, 5,300-year-old corn specimens found in Tehuacán, in central Mexico, still genetically and morphologically resemble teosinte. Meanwhile, cobs harvested about 6,700 to 5,000 years ago on the northern coast of Peru ­ 3800km away from where maize was first domesticated ­ look like the ones we know today. Vallebueno-Estrada et al. aimed to explore the evolutionary history of this Peruvian maize, which was discovered at the archaeological coastal site of Paredones. To do so, they extracted and sequenced its genetic information, and compared these sequences with those from modern varieties of lowland and highland maize, as well as from teosinte parviglumis and teosinte mexicana. The analyses showed that the ancestor of the Paredones maize emerged from teosinte parviglumis like any other lineage, but that it was already domesticated when it started to spread South; by the time it was present in Peru 6,700 years ago, it was genetically closer to modern-day crops. This early departure is consistent with the fact that the Paredones specimens lacked teosinte mexicana genetic variants; this highland relative of lowland parviglumis is believed to have interbred with maize lineages from Central America more recently, when these were brought to higher altitudes. The presence of genetic marks tailored to low-elevation regions suggested that the Paredones maize lineage migrated through a coastal corridor connecting Central and South America, arriving in northern Peru about 2,500 years after first arising from teosinte parviglumis in Central America around 9,000 years ago. Under the care of rapidly developing Central Andean societies, the crop then evolved to adapt to its local conditions. Maize today has spread to all continents besides Antarctica; we produce more of it than wheat, rice or any other grain. How our modern varieties will adapt to the environmental constraints brought by climate change remains unclear. By peering into the history of maize, Vallebueno-Estrada et al. hope to find genetic variations which could inform new breeding strategies that improve the future of this crop.

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Objective: To relate the socio-demographic profile with access to health services of the population living in environmentally degraded areas in an estuary region.Study design: A sectional field study of 8819 people, evaluating three contaminated areas of São Vicente.Methods: Households were divided by studied area. A structured and pre-tested questionnaire was applied to obtain the data. A probabilistic sample was used. The prevalence of each of the outcomes of interest by area was calculated. To verify the existence of an association between the outcomes of interest and other variables (qualitative), by area, a descriptive analysis and to compare percentages and a comparison test was used between two proportions, a Chi-square test and/or a Fisher's exact test and a Kruska-wallis and Dunn multiple comparison were used as well. The significance level was 5%.Results: Most residents (94%) reported the use of public health services at least once a year (p < 0.001), mainly through the Basic Health Units (BHU) (p < 0.001). Most of the studied population (65%) did not have private health insurance and their schooling was basically restricted to primary education (p < 0.001). The predominant family income (70%) in the three areas was between one and five minimum wages (p < 0.001), with a higher incidence of people receiving one to three minimum wages at the time. The demand for health services was not associated with education or income.Conclusion: The population of the regions analysed heavily rely on the Unified Health System - SUS, but there was no association between income and frequency of health services and there was also no association between education and use of health services.

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Grasslands in southern South America are extensive ecosystems which harbor a unique biodiversity; however, studies on the evolution of their taxa are scarce. Here we studied the phylogeography and population history of the Correndera Pipit (Anthus correndera), a grassland specialist bird with a large breeding distribution in southern South America, with the goals of investigating its phylogeographic history and relate it to the historical development of South American grasslands. The mitochondrial NADH dehydrogenase subunit II gene (ND2) was sequenced in 66 individuals from 19 localities and the intron 9 of the sex-linked gene for aconitase (ACOI9) was sequenced from a subset of those individuals, including all five subspecies of A. correndera, as well as the closely related A. antarcticus. Phylogenetic analysis revealed two distinct lineages within the complex: the first (A) corresponding to Andean subspecies A. c. calcaratus and A. c. catamarcae and the second (B) including birds traditionally assigned to A. c. correndera, A. c. chilensis, A. c. grayi and some individuals of A. c. catamarcae. A. antarcticus is nested within this second lineage. These results were also supported by evidence of niche divergence for variables associated with precipitation. The oldest split between clade A and B was estimated at c. 0.37 Mya, during the middle Pleistocene. Species distribution models for the present and the Last Glacial Maximum (LGM) suggest that grassland areas in southern South America remained relatively stable, in contrast to the general view of a reduction in grassland cover in South America since the LGM. Recent divergences and low phylogeographic structure (for lowland vs. highland geographic groups, intra-population genetic variance was greater than inter-groups; e.g., for ACOI9: 95.47% and ND2: 51.51% respectively), suggest widespread gene flow between lowland populations.

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The southern Brazilian lowlands have been historically used for flooded rice cultivation. Over time, heavy machinery and intensive tillage practices have resulted in soil structure disruption, soil compaction, higher production costs and lower agricultural profitability. This study aimed to evaluate the effect of different deployment times of no-tillage (NT). Soil properties including bulk density (BD), compression index (CI), preconsolidation pressure (σp), bulk density at preconsolidation pressure (BDσp), degree of compactness (DC), soil water retention curve (SWRC), plant available water (PAW) and total organic carbon (TOC) content were evaluated using a 30-yr non-cultivated field (NC), adjacent to the experimental plots as a control. The BD, σp, BDσp and DC decreased in response to NT adoption time while the soil water holding capacity increased, allowing for higher PAW. Results from this study demonstrated the positive effects of NT on the overall quality of soils.(AU)

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The southern Brazilian lowlands have been historically used for flooded rice cultivation. Over time, heavy machinery and intensive tillage practices have resulted in soil structure disruption, soil compaction, higher production costs and lower agricultural profitability. This study aimed to evaluate the effect of different deployment times of no-tillage (NT). Soil properties including bulk density (BD), compression index (CI), preconsolidation pressure (σp), bulk density at preconsolidation pressure (BDσp), degree of compactness (DC), soil water retention curve (SWRC), plant available water (PAW) and total organic carbon (TOC) content were evaluated using a 30-yr non-cultivated field (NC), adjacent to the experimental plots as a control. The BD, σp, BDσp and DC decreased in response to NT adoption time while the soil water holding capacity increased, allowing for higher PAW. Results from this study demonstrated the positive effects of NT on the overall quality of soils.

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It has been suggested that traditional ecological knowledge (TEK) may play a key role in forest conservation. However, empirical studies assessing to what extent TEK is associated with forest conservation compared with other variables are rare. Furthermore, to our knowledge, the spatial overlap of TEK and forest conservation has not been evaluated at fine scales. In this paper, we address both issues through a case study with Tsimane' Amerindians in the Bolivian Amazon. We sampled 624 households across 59 villages to estimate TEK and used remote sensing data to assess forest conservation. We ran statistical and spatial analyses to evaluate whether TEK was associated and spatially overlapped with forest conservation at the village level. We find that Tsimane' TEK is significantly and positively associated with forest conservation although acculturation variables bear stronger and negative associations with forest conservation. We also find a very significant spatial overlap between levels of Tsimane' TEK and forest conservation. We discuss the potential reasons underpinning our results, which provide insights that may be useful for informing policies in the realms of development, conservation, and climate. We posit that the protection of indigenous cultural systems is vital and urgent to create more effective policies in such realms.

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We present a molecular phylogeny of snake genus Atractus, with an improved taxon sampling that includes 30 of the 140 species currently recognized. The phylogenetic tree supports the existence of at least three new species in the Pacific lowlands and adjacent Andean slopes of the Ecuadorian Andes, which we describe here. A unique combination of molecular, meristic and color pattern characters support the validity of the new species. With the newly acquired data, we propose and define the Atractus iridescens species group, as well as redefine the Atractus roulei species group. The species Atractus iridescens is reported for the first time in Ecuador, whereas Atractus bocourti and Atractus medusa are removed from the herpetofauna of this country. We provide the first photographic vouchers of live specimens for Atractus multicinctus, Atractus paucidens and Atractus touzeti, along with photographs of 19 other Ecuadorian Atractus species. The current status of Atractus occidentalis and Atractus paucidens is maintained based on the discovery of new material referable to these species. With these changes, the species number reported in Ecuador increases to 27, a number that is likely to increase as material not examined in this work becomes available and included in systematic studies.

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We describe a new species of the genus Ninia from the Chocó-Magdalena biogeographic province, which was previously reported as a distinct population of N. maculata or as N. atrata from the western slopes of the Cordillera Occidental of Colombia. The new species is similar to N. atrata, N. celata, N. espinali, N. franciscoi, and N. maculata. It shares the following characteristics with the species mentioned above: 19 dorsal scale rows without reductions; dorsal ground color black or dark brown; white or cream occipital nuchal collar. However, it is easily distinguished from all other congeners because it has a non-regular color pattern in the ventral surfaces of the head and body, subcaudal surface homogeneously black or dark brown, two nasal scales, and one lateral projection ornamented with a large basal hook-shaped spine that is larger than any other spine on the hemipenial body. The presence of a lateral projection on the hemipenial body makes the new species the only member of the genus from South America that shares this feature with its Central American congeners. This feature suggests a closer relationship with this linage. Finally, our results indicate that proper and careful revision of the Ninia atrata species complex will help to understand and clarify the taxonomic composition of the genus.

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We report on the morphological variation (meristic, morphometric, pholidosis, and color pattern characters) and sexual dimorphism of Trilepida macrolepis. We also took the opportunity to redescribe the holotype of Rena affinis in an effort to evaluate its taxonomic status. Based on the congruence of characters from external morphology, we transfer Stenostoma affine to the genus Trilepida. We also discuss the Andean specimens previously refereed to Trilepida affinis and Trilepida macrolepis and provide an identification key for the genus Trilepida.

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O município de Iguaçu ocupava o que atualmente é denominado de Baixada Fluminense, englobando o que hoje são os municípios de Belford Roxo, Duque de Caxias, Japeri, Mesquita, Nilópolis, Nova Iguaçu, Queimados e São João de Meriti, com um território que representava 35% da atual região metropolitana do Rio de Janeiro. A noção de Baixada Fluminense unifica o que as emancipações fragmentaram, já que a região no final do século XIX era um município com atividades rurais e, ao longo do século XX, transformou-se em periferia urbana. Chama a atenção a afirmação recorrente dos pesquisadores que estudam a região acerca da existência de um vazio demográfico que teria ocorrido no final do século XIX (1890/1910). O objetivo deste texto é apresentar os principais argumentos utilizados na construção da imagem de vazio demográfico e, com base nos dados obtidos nos censos, oferecer alguns elementos que questionam essa leitura na forma como é enunciada, pois a principal tese é a de que a região da Baixada (como um todo) ficou despovoada e, com as terras vazias, foi ocupada desordenadamente por uma população urbana fugindo dos altos preços da capital federal. Esta leitura recorrente obscurece outras dinâmicas existentes no território, além da própria história da região.

The municipality of Iguaçu occupied what is currently known as the Baixada Fluminense, i.e., it was part of the large municipality which are now Belford Roxo, Duque de Caxias, Japeri, Mesquita, Nilópolis, Nova Iguaçu, Queimados and São João de Meriti, covering a territory representing 35% of the current metropolitan area of Rio de Janeiro city. The term Baixada Fluminense unifies what emancipations divided, since, at the end of the XIXth Century, the region was a municipality with rural activities and throughout the 20th century, it became an urban periphery. The recurring claim from researchers studying the region, regarding the existence of a demographic void which would have occurred in the late nineteenth century (1890-1910) drew our attention. The aim of this paper is to present the main arguments used in the construction of said image of demographic void and, based on the data obtained in the censuses, to offer some elements which challenge this reading in the manner in which it is stated, since the main thesis is that the region of Baixada (asa whole) became uninhabited, its empty lands becoming disorderly occupied by an urban population fleeing the federal capital and its high prices. This recurrent reading obscures other existing dynamics in the territory beyond the region's own history.

El municipio de Iguaçu ocupaba la que ahora se llama Baixada Fluminense, es decir que Belford Roxo, Duque de Caxias, Japeri, Mesquita, Nilópolis, Nova Iguaçu, Queimados y São João de Meriti eran parte del grande municipio y abarcaban un territorio que representaba 35% de la actual región metropolitana de la ciudad de Río de Janeiro. La noción de Baixada Fluminense unifica lo que las emancipaciones fragmentaron, ya que a finales del siglo XIX la región era un municipio con actividades rurales y a lo largo del siglo XX se convirtió en la periferia urbana. Llamó nuestra atención la recurrente declaración de los investigadores que estudian la región sobre la existencia de un vacío demográfico que se habría producido a finales del siglo XIX (1890-1910). El propósito de este trabajo es presentar los principales argumentos utilizados en la construcción de la imagen de vacío demográfico y, con base en los datos obtenidos a partir de los censos de, proporcionar algunos elementos que cuestionan esta lectura que lleva a la afirmación mencionada y cuya tesis principal es que el conjunto de la región de la Baixada se despobló y que las tierras fueron ocupadas por una población urbana desordenada que huía de los altos precios de la capital federal. Esta lectura recurrente opaca la existencia de otras dinámicas en el territorio y la propia historia de la región.

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HIGHLIGHTS R49 genotype displayed best performance on selected physiological parameters and highest tolerance to drought.R49 drought over-represented transcripts has exhibited 19% of genes (306 contigs) that presented no homology to published databases.Expression pattern for canonical responses to drought such as ABA biosynthesis and other genes induced in response to drought were assessed by qPCR. Global freshwater shortage is one of the biggest challenges of our time, often associated to misuse, increased consumption demands and the effects of climate change, paralleled with the desertification of vast areas. Chenopodium quinoa (Willd.) represents a very promising species, due to both nutritional content and cultivation under water constraint. We characterized drought tolerance of three Chilean genotypes and selected Genotype R49 (Salares ecotype) based upon Relative Water Content (RWC), Electrolyte Leakage (EL) and maximum efficiency of photosystem II (Fv/Fm) after drought treatment, when compared to another two genotypes. Exploratory RNA-Seq of R49 was generated by Illumina paired-ends method comparing drought and control irrigation conditions. We obtained 104.8 million reads, with 54 million reads for control condition and 51 million reads for drought condition. Reads were assembled in 150,952 contigs, were 31,523 contigs have a reading frame of at least 300 nucleotides (100 aminoacids). BLAST2GO annotation showed a 15% of genes without homology to NCBI proteins, but increased to 19% (306 contigs) when focused into drought-induced genes. Expression pattern for canonical drought responses such as ABA biosynthesis and other genes induced were assessed by qPCR, suggesting novelty of R49 drought responses.

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ABSTRACT The objective of this study was to verify the richness and density of aquatic benthic macroinvertebrates after exposure to fungicides and insecticides of the rice paddy fields. In the crop seasons of 2012/13 and 2013/14, field experiments were performed, which consisted of single-dose applications of the fungicides trifloxystrobin + tebuconazole and tricyclazole, and the insecticides lambda-cyhalothrin + thiamethoxam and diflubenzuron, in 10 m2 experimental plots, over rice plants in the R3 stage. Control plots with and without rice plants were maintained in order to simulate a natural environment. Soil samples were collected during rice cultivation for assessment of the macroinvertebrate fauna. Chemical-physical parameters assessed in the experiments included temperature, pH and oxygen dissolved in the water and pesticide persistence in the water and in the soil. The application of a single dose of the pesticides and fungicides in the recommended period does not cause significant negative effects over the richness and density of the macroinvertebrates. Tebuconazole, tricyclazole and thiamethoxam showed high persistence in the irrigation water of rice paddy fields. Thus, the doses and number of applications of these products in crops should be carefully handled in order to avoid contamination of the environment.

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The intensive use of plant protection products in rice paddy fields (Oryza sativa L.) has caused concern about the environmental impact on communities of non-target organisms that are natural inhabitants in these agroecosystems. The purpose of this review is to analyze the data currently available in the literature about some important fungicides and insecticides (such as trifloxystrobin, tebuconazole, tricyclazole, lambda-cyhalothrin, and thiamethoxam), which are currently used to control pests and diseases in rice paddy fields, as well as their effects on the community of non-target aquatic organisms.(AU)

O uso intensivo de produtos fitossanitários na lavoura de arroz irrigado (Oryza sativa L.) tem causado preocupação quanto ao impacto ambiental sobre comunidades de organismos aquáticos não alvos que são habitantes naturais nesses agroecossistemas. O objetivo da presente revisão é analisar os dados atualmente existentes na literatura sobre alguns importantes fungicidas e inseticidas (tais como trifloxistrobina, tebuconazol, triciclazol, lambda-cialotrina e tiametoxam), os quais são usados para controlar pragas e doenças na lavoura de arroz irrigado, bem como seus efeitos sobre a comunidade de organismos aquáticos não alvos.(AU)

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The intensive use of plant protection products in rice paddy fields (Oryza sativa L.) has caused concern about the environmental impact on communities of non-target organisms that are natural inhabitants in these agroecosystems. The purpose of this review is to analyze the data currently available in the literature about some important fungicides and insecticides (such as trifloxystrobin, tebuconazole, tricyclazole, lambda-cyhalothrin, and thiamethoxam), which are currently used to control pests and diseases in rice paddy fields, as well as their effects on the community of non-target aquatic organisms.

O uso intensivo de produtos fitossanitários na lavoura de arroz irrigado (Oryza sativa L.) tem causado preocupação quanto ao impacto ambiental sobre comunidades de organismos aquáticos não alvos que são habitantes naturais nesses agroecossistemas. O objetivo da presente revisão é analisar os dados atualmente existentes na literatura sobre alguns importantes fungicidas e inseticidas (tais como trifloxistrobina, tebuconazol, triciclazol, lambda-cialotrina e tiametoxam), os quais são usados para controlar pragas e doenças na lavoura de arroz irrigado, bem como seus efeitos sobre a comunidade de organismos aquáticos não alvos.

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A revision of the avian Neotropical genus Automolus and the Furnariidae family points to the paraphyly of A. infuscatus and reveals a species complex comprising A. infuscatus, A. ochrolaemus, A. paraensis, A. leucophthalmus, A. lammi and A. subulatus, the latter historically classified in the genus Hyloctistes. Detailed knowledge of the taxonomy, geographic distribution, phylogenetic relationship and divergence times of a taxon allows exploration of its evolutionary history and the testing of different scenarios of diversification. In this context, we studied the A. infuscatus complex using molecular data in order to unveil its cryptic diversity and reveal its evolutionary history. For that we sequenced two mitochondrial (ND2 and cytb) and three nuclear markers (G3PDH, ACO, Fib7) for 302 individuals belonging to all species in the complex and most described subspecies. Our analysis supports the paraphyly of A. infuscatus, indicating the existence of at least two distinct clades not closely related. The remaining species were all recovered as monophyletic. Notwithstanding, a well-structured intraspecific diversity was found with 19 lineages suggesting substantial cryptic diversity within the described species. A. subulatus was recovered within the complex, corroborating its position inside the genus. In spite of the high congruence between distributions of different lineages, with several sister lineages currently separated by the same barriers, the temporal incongruence between divergences over the same barriers reveals a complex evolutionary history. While older events might be related to the emergence of barriers such as the Andes and major Amazonian rivers, younger events suggest dispersal after the consolidation of those barriers. Our analysis suggests that the complex had its origin around 6million years (Ma) and inhabited Western Amazonia in Late Miocene-Early Pliocene. Considering the riparian habit of species in its sister clade, the rise and early diversifications of the complex may be related to the establishment of terra firme forests as it changed from a floodplain to a fluvial system. The late Amazonian colonization by A. subulatus and A. ochrolaemus lineages may have been hampered by the previous existence of well established A. infuscatus lineages in the region.

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The pollen spectrum of honey of the Melipona fasciculata was analyzed aiming to elucidate the nectariferous resources used by this species. The identification of the visited plants was based upon the analysis of the pollen spectrum of 12 honey samples collected in one meliponarium located in Palmeirândia county, lowland area of Maranhão State, Brazil (02º40'47,6S, 44º52'39,8"W). The quantitative and qualitative analysis of honey samples was conducted in order to determine the pollen type percentages and frequency classes. Forty-five pollen types were found, being Pontederia parviflora Alexander (Pontederiaceae) the most frequent species during period of sampling (38.6%) and considered dominant pollen in October (86%), June (85%), July (76%), August (49%) and September (51%) and accessory pollen in December, January and March. Mimosa caesalpiniifolia Benth (Mimosaceae) was the second most frequent species (22.8%) and was a dominant pollen in November (46%), April (74%) and May (72%). Myrcia eximia DC. (Myrtaceae) was considered important isolated pollen. The most representative families found in the pollen spectrum of the honey samples were Pontederiaceae and Mimosaceae. 50% of honey samples was bifloral, but there were also monofloral (41.7%) and heterofloral (8.3%) honeys.

O espectro polínico do mel de Melipona fasciculata Smith foi analisado com o objetivo de identificar os recursos nectaríferos utilizados por essa espécie. A identificação das plantas visitadas foi realizada com base na análise dos tipos polínicos encontrados em 12 amostras de mel coletadas, mensalmente, em uma colônia localizada no município de Palmeirândia, na área da Baixada Ocidental Maranhense (02º40'47,6S, 44º52'39,8"W), Brasil. As análises quantitativas e qualitativas foram realizadas com o objetivo de determinar as porcentagens e classes de frequência dos tipos polínicos presentes nas amostras de mel. Foram encontrados 45 tipos polínicos, sendo Pontederia parviflora Alexander (Pontederiaceae), espécie mais frequente em todo o período de amostragem (38,6%), pólen dominante em Outubro (86%), Junho (85%), Julho (76%), Agosto (49%) e Setembro (51%) e pólen acessório em Dezembro, Janeiro e Março. Mimosa caesalpiniifolia Benth (Mimosaceae) foi a segunda espécie mais frequente (22,8%) sendo pólen dominante em Novembro (46%), Abril (74%) e Maio (72%). Myrcia eximia DC (Myrtaceae) foi considerada pólen isolado importante. As famílias mais representativas no espectro polínico das amostras de mel foram Pontederiaceae e Mimosaceae. 50% dos méis foram biflorais, havendo também méis monoflorais (41,7%) e heteroflorais (8,3%).

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O espectro polínico do mel de Melipona fasciculata Smith foi analisado com o objetivo de identificar os recursos nectaríferos utilizados por essa espécie. A identificação das plantas visitadas foi realizada com base na análise dos tipos polínicos encontrados em 12 amostras de mel coletadas, mensalmente, em uma colônia localizada no município de Palmeirândia, na área da Baixada Ocidental Maranhense (02º40'47,6S, 44º52'39,8"W), Brasil. As análises quantitativas e qualitativas foram realizadas com o objetivo de determinar as porcentagens e classes de frequência dos tipos polínicos presentes nas amostras de mel. Foram encontrados 45 tipos polínicos, sendo Pontederia parviflora Alexander (Pontederiaceae), espécie mais frequente em todo o período de amostragem (38,6 por cento), pólen dominante em Outubro (86 por cento), Junho (85 por cento), Julho (76 por cento), Agosto (49 por cento) e Setembro (51 por cento) e pólen acessório em Dezembro, Janeiro e Março. Mimosa caesalpiniifolia Benth (Mimosaceae) foi a segunda espécie mais frequente (22,8 por cento) sendo pólen dominante em Novembro (46 por cento), Abril (74 por cento) e Maio (72 por cento). Myrcia eximia DC (Myrtaceae) foi considerada pólen isolado importante. As famílias mais representativas no espectro polínico das amostras de mel foram Pontederiaceae e Mimosaceae. 50 por cento dos méis foram biflorais, havendo também méis monoflorais (41,7 por cento) e heteroflorais (8,3 por cento).

The pollen spectrum of honey of the Melipona fasciculata was analyzed aiming to elucidate the nectariferous resources used by this species. The identification of the visited plants was based upon the analysis of the pollen spectrum of 12 honey samples collected in one meliponarium located in Palmeirândia county, lowland area of Maranhão State, Brazil (02º40'47,6S, 44º52'39,8"W). The quantitative and qualitative analysis of honey samples was conducted in order to determine the pollen type percentages and frequency classes. Forty-five pollen types were found, being Pontederia parviflora Alexander (Pontederiaceae) the most frequent species during period of sampling (38.6 percent) and considered dominant pollen in October (86 percent), June (85 percent), July (76 percent), August (49 percent) and September (51 percent) and accessory pollen in December, January and March. Mimosa caesalpiniifolia Benth (Mimosaceae) was the second most frequent species (22.8 percent) and was a dominant pollen in November (46 percent), April (74 percent) and May (72 percent). Myrcia eximia DC. (Myrtaceae) was considered important isolated pollen. The most representative families found in the pollen spectrum of the honey samples were Pontederiaceae and Mimosaceae. 50 percent of honey samples was bifloral, but there were also monofloral (41.7 percent) and heterofloral (8.3 percent) honeys.

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RESUMO

A deficiente drenagem natural dos solos de várzea proporciona um ambiente anaeróbico, favorecendo a formação de substâncias tóxicas, como o ácido acético, que afeta o desempenho de espécies de sequeiro nesses ecossistemas. O presente estudo foi conduzido com os objetivos de avaliar os efeitos e estabelecer os níveis críticos de toxidez do ácido acético para culturas de sequeiro alternativas para solos de várzea, como o milho, a soja e o sorgo. Os tratamentos constaram de seis doses de ácido acético, entre zero e 8mM, para milho (Embrapa BRS 1001) e sorgo (BRS 307), e quatro doses entre zero e 4mM, para soja (Embrapa BRS 133), com seis repetições, em delineamento completamente casualizado. Os indicadores avaliados foram os parâmetros morfológicos do sistema radicular (comprimento, raio, área e massa seca relativas) e concentração de N, P, K, Ca e Mg e massa seca relativa da parte aérea das plantas. O ácido acético foi tóxico para as culturas do milho, da soja e do sorgo, causando reduções no comprimento, na área e na massa seca radicular e na massa seca e na concentração de N, P, K, Ca e Mg da parte aérea. As concentrações de ácido acético responsáveis pela inibição de 50 por cento do comprimento radicular relativo foram de 2mM para a soja e 2,7mM para o milho e o sorgo.

The poor drainage of wetland soils originates an anaerobic environment favoring the appearance of toxic substances, like acetic acid, which affects negatively the growth of dryland crops. The present work was carried out with the objective of evaluating the effects of acetic acid and establishing its threshold for alternative crops cultivated in wetland soils, such as maize, soybean and sorghum. Plants of maize (Embrapa BRS 1001) and sorghum (BRS 307) were exposed to six acetic acid levels, from zero to 8mM; whereas plants of soybean (Embrapa BRS 133) were exposed to four levels, from zero to 4mM. The experimental design used was completely randomized with six replications. Morphological parameters of plant root system (length, root radium, area and relative dry mass), relative shoot dry mass and N, P, K, Ca and Mg concentration in plant shoot were assessed. The acetic acid was toxic to maize, soybean and sorghum, being evidenced by decreases in the root length and dry mass, in the total plant dry mass and in the N, P, K, Ca and Mg contents in the plant shoot. The acetic acid concentrations responsible for decreasing 50 percent of the relative root length were 2mM for soybean and 2.7mM for maize and sorghum.

RESUMO

The poor drainage of wetland soils originates an anaerobic environment favoring the appearance of toxic substances, like acetic acid, which affects negatively the growth of dryland crops. The present work was carried out with the objective of evaluating the effects of acetic acid and establishing its threshold for alternative crops cultivated in wetland soils, such as maize, soybean and sorghum. Plants of maize (Embrapa BRS 1001) and sorghum (BRS 307) were exposed to six acetic acid levels, from zero to 8mM; whereas plants of soybean (Embrapa BRS 133) were exposed to four levels, from zero to 4mM. The experimental design used was completely randomized with six replications. Morphological parameters of plant root system (length, root radium, area and relative dry mass), relative shoot dry mass and N, P, K, Ca and Mg concentration in plant shoot were assessed. The acetic acid was toxic to maize, soybean and sorghum, being evidenced by decreases in the root length and dry mass, in the total plant dry mass and in the N, P, K, Ca and Mg contents in the plant shoot. The acetic acid concentrations responsible for decreasing 50% of the relative root length were 2mM for soybean and 2.7mM for maize and sorghum.

A deficiente drenagem natural dos solos de várzea proporciona um ambiente anaeróbico, favorecendo a formação de substâncias tóxicas, como o ácido acético, que afeta o desempenho de espécies de sequeiro nesses ecossistemas. O presente estudo foi conduzido com os objetivos de avaliar os efeitos e estabelecer os níveis críticos de toxidez do ácido acético para culturas de sequeiro alternativas para solos de várzea, como o milho, a soja e o sorgo. Os tratamentos constaram de seis doses de ácido acético, entre zero e 8mM, para milho (Embrapa BRS 1001) e sorgo (BRS 307), e quatro doses entre zero e 4mM, para soja (Embrapa BRS 133), com seis repetições, em delineamento completamente casualizado. Os indicadores avaliados foram os parâmetros morfológicos do sistema radicular (comprimento, raio, área e massa seca relativas) e concentração de N, P, K, Ca e Mg e massa seca relativa da parte aérea das plantas. O ácido acético foi tóxico para as culturas do milho, da soja e do sorgo, causando reduções no comprimento, na área e na massa seca radicular e na massa seca e na concentração de N, P, K, Ca e Mg da parte aérea. As concentrações de ácido acético responsáveis pela inibição de 50% do comprimento radicular relativo foram de 2mM para a soja e 2,7mM para o milho e o sorgo.

RESUMO

The poor drainage of wetland soils originates an anaerobic environment favoring the appearance of toxic substances, like acetic acid, which affects negatively the growth of dryland crops. The present work was carried out with the objective of evaluating the effects of acetic acid and establishing its threshold for alternative crops cultivated in wetland soils, such as maize, soybean and sorghum. Plants of maize (Embrapa BRS 1001) and sorghum (BRS 307) were exposed to six acetic acid levels, from zero to 8mM; whereas plants of soybean (Embrapa BRS 133) were exposed to four levels, from zero to 4mM. The experimental design used was completely randomized with six replications. Morphological parameters of plant root system (length, root radium, area and relative dry mass), relative shoot dry mass and N, P, K, Ca and Mg concentration in plant shoot were assessed. The acetic acid was toxic to maize, soybean and sorghum, being evidenced by decreases in the root length and dry mass, in the total plant dry mass and in the N, P, K, Ca and Mg contents in the plant shoot. The acetic acid concentrations responsible for decreasing 50% of the relative root length were 2mM for soybean and 2.7mM for maize and sorghum.

A deficiente drenagem natural dos solos de várzea proporciona um ambiente anaeróbico, favorecendo a formação de substâncias tóxicas, como o ácido acético, que afeta o desempenho de espécies de sequeiro nesses ecossistemas. O presente estudo foi conduzido com os objetivos de avaliar os efeitos e estabelecer os níveis críticos de toxidez do ácido acético para culturas de sequeiro alternativas para solos de várzea, como o milho, a soja e o sorgo. Os tratamentos constaram de seis doses de ácido acético, entre zero e 8mM, para milho (Embrapa BRS 1001) e sorgo (BRS 307), e quatro doses entre zero e 4mM, para soja (Embrapa BRS 133), com seis repetições, em delineamento completamente casualizado. Os indicadores avaliados foram os parâmetros morfológicos do sistema radicular (comprimento, raio, área e massa seca relativas) e concentração de N, P, K, Ca e Mg e massa seca relativa da parte aérea das plantas. O ácido acético foi tóxico para as culturas do milho, da soja e do sorgo, causando reduções no comprimento, na área e na massa seca radicular e na massa seca e na concentração de N, P, K, Ca e Mg da parte aérea. As concentrações de ácido acético responsáveis pela inibição de 50% do comprimento radicular relativo foram de 2mM para a soja e 2,7mM para o milho e o sorgo.