Semi-arid Northeast Research Articles

Dracontium nivosum (Lem.) G.H.Zhu (Araceae): range extension from Amazonia to a brejo forest refugium in Northeast Brazil confirmed

The 558 km range extension of the Amazonian aroid Dracontium nivosum (Lem.) G.H.Zhu into semi-arid Northeast Brazil is confirmed. This species occurs in Ceará in threatened fragments of brejo forest at ca. 580–870 m elevation. An illustrated taxonomic description is provided. The species’ Extent of Occurrence (EOO) is estimated as 356,392 km2 (meets Least Concern); the Area of Occupancy (AOO), 60 km2 using a 2×2 km cell (Endangered). Within Ceará the EOO is 41.4 km2 (Critically Endangered) and the AOO is 16 km2 (Endangered).

Desempenho produtivo e econômico de cordeiros de diferentes genótipos terminados em confinamento

RESUMO Objetivou-se avaliar o desempenho produtivo e a margem bruta de lucro de cordeiros de diferentes genótipos terminados em confinamento. Foram utilizados 30 cordeiros, sendo 10 ½ Dorper ½ Sem Padrão Racial Definido (SPRD), 10 ½ Santa Inês ½ SPRD e 10 SPRD, com idade média de 150 dias e peso vivo médio inicial de 19,31 ± 2,6 kg. Foi utilizada uma dieta completa, contendo 15,5% de PB e 2,58 Mcal/kg MS de EM. Os mestiços ½ Dorper½ SPRD e ½ Santa Inês ½ SPRD obtiveram melhores resultados em relação ao peso final, apresentando maior acúmulo tecidual durante o período de confinamento. Não foi observado diferença entre o consumo de matéria seca e água em função dos genótipos. Os mestiços de Dorper x SPRD e Santa Inês x SPRD apresentaram maior ganho de peso diário, total e melhor conversão alimentar. Os cordeiros mestiços de Dorperx SPRD apresentaram maior escore corporal final. Os cordeiros mestiços Dorper x SPRD e Santa Inês x SPRD são recomendados para a terminação em confinamento, apresentando desempenho biológico e econômico semelhantes, sendo uma alternativa de produção de carne no Semiárido Nordestino.

ANTI-Lentivirus, Brucella abortus AND B. ovis ANTIBODIES IN SMALL RUMINANTS RAISED IN PERNAMBUCO AND BAHIA

ABSTRACT: Goat and sheep production in the semi-arid northeast of Brazil has shown great economic potential. However, health problems can compromise the productivity of these animals. Given the scarcity of studies about the occurrence of these diseases, the aim of the present study was to analyze the serological diagnosis of anti-Brucella and anti-lentivirus antibodies among small ruminants in municipalities located in the Brazilian states of Bahia and Pernambuco. The samples were collected from local slaughterhouses and dairy farms. In total, 997 serum samples from animals in slaughterhouses and dairy herds were collected. In order to diagnose the caprine arthritis encephalitis virus (CAEV), the samples underwent agarose gel immunodiffusion (AGID) testing. The buffered acidified antigen test (goats) and agarose gel immunodiffusion test (sheep) were used to detect anti-Brucella abortus and B. ovis antibodies following the methodology recommended by the Institute of Technology of Paraná (TECPAR). With anti-CAEV antibodies, seropositivity rates of 4.1% and 2.2% were recorded for animals from the slaughterhouses and dairy farms, respectively. None of the animals (goats or sheep) were positive for anti-B. abortus antibodies. With B. ovis, a seropositivity rate of 6.5% (n = 13) was recorded among the 199 sheep serum samples. Results of the present study confirmed the presence of the CAE virus in the meat and dairy herds studied, although the prevalence was low. Natural infection by B. abortus did not occur in the goat and sheep herds assessed. Seropositivity for B. ovis was confirmed, although prevalence was low. Direct tests are required to diagnose ovine brucellosis.

Gross composition, fatty acid profile and sensory characteristics of Saanen goat milk fed with Cacti varieties.

The use of cactus is an alternative for sustainable production systems in Northeast Brazil. The objective of this research was to evaluate the influence of supplying five cacti species from the Brazilian semi-arid northeast region on the physical-chemical sensory characteristics and the profile of fatty acids of Saanen goat milk. Five multiparous goats were used, confined, and distributed in a Latin square 5 × 5 design, with five experimental diets and five periods. Treatments consisted of 473 to 501g/kg of a cactaceous mix (Pilosocereus gounellei, Cereus jamacaru, Cereus squamosus, Nopalea cochenillifera, or Opuntia stricta) added to 187.8 to 197.9g/kg of "Sabiá" (Mimosa caesalpiniifolia) hay and 311 to 329g/kg of concentrate. No effects of experimental diets (P > 0.05) were evidenced in the physical and chemical composition of milk for fat, total solids, or salt levels. However, protein, lactose, solids-not-fat levels, and cryoscopy point were influenced by diet (P < 0.05). There was no significant difference (P > 0.05) in the profile of fatty acids between treatments for all acids found, except for butyric acid. Diets also did not (P > 0.05) confer sensory changes in milk characteristics. The use of the native cacti in the dairy goats' diet did not influence the sensory characteristics or lipid profile of milk.

Assessment of schistosomiasis in the semi-arid Northeast region of Brazil: the São Francisco River large-scale water transposition project.

INTRODUCTION Risk of schistosomiasis expansion to semi-arid northeastern Brazil under the influence of the Integration Project of the São Francisco River (IPSFR) was assessed. Stool examinations of schoolchildren, epidemiological investigation, and survey of the local host snail Biomphalaria straminea were performed in five IPSFR municipalities. RESULTS Six of 4,770 examined schoolchildren were egg-positive for Schistosoma mansoni. Biomphalaria straminea was widespread, but not naturally infected with S. mansoni. Snails experimentally exposed to two laboratory S. mansoni strains yielded infection indices of 1-4.5%. There is evidence of active schistosomiasis transmission in the area; thus, intensive surveillance actions are required.

Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs?

The aim of our study was to assess whether cyanotoxins (microcystins) can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers). Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001), but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = - 0.01; P > 0.01) with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001). The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass) do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers). These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

Morfologia urbana e a (ir)regularidade fundiária: uma abordagem no semiárido nordestino

O crescimento urbano desordenado decorrente da falta de planejamento e estruturação do espaço geográfico dá origem ao processo de formação de periferias e a ocupação imprópria de assentamentos. As cidades brasileiras estão marcadas pela desigualdade social: enquanto uns vivem em lugares altamente privilegiados, outros residem em bairros com condições de habitação e saneamento decadentes. O objetivo deste artigo é descrever os problemas decorrentes do crescimento e ocupação urbana desordenada no Brasil e a situação de cinco municípios do Semiárido Potiguar no âmbito de (ir)regularidade fundiária. Foi estudada a realidade habitacional de cidades brasileiras, observando-se os contrastes existentes entre os espaços ocupacionais que foram planejados e aqueles que se constituíram de forma indevida e analisados cinco municípios do alto oeste potiguar, especificamente no quesito regularização fundiária. Verifica-se que há uma divisão do espaço urbano do Brasil em regiões com excelente infraestrutura disponível aos seus ocupantes e locais com a ausência de condições mínimas de dignidade, além de um alto índice de irregularidade dominial. Porém, é possível fazer uma reestruturação urbana por meio de programas que visem a regularização fundiária e a, consequente, reformulação das cidades.

Hydrological Processes and Climate Change in Hydrographic Regions of Brazil

The objective of this work is to assess the impacts of IPCC AR5 climate change scenarios on water resources and hydrological processes across the entire Brazilian territory. Hydrological simulations are carried out in total drainage area of about 11,535,645 km2 and average stream flow of about 272,460 m3/s. The study area consists of different climates and land covers such as the Amazon Forest, Northeast Semiarid, Brazilian Savannah, Pantanal wetlands and temperate climate in the South. The atmospheric forcing to drive the large-scale hydrological model MGB-IPH is derived from the downscaling of two global climate models, HadGEM2-ES and MIROC5, by the Eta Regional Climate Model, at 20 km resolution. The Eta model provided the downscaling of the baseline (1961-1990) and three time-slices (2011-2040, 2041-2070 and 2071-2099). These projections adopted two emission scenarios, the RCP 4.5 and RCP 8.5. The change in the average and extremes of precipitation, evapotranspiration, rates of river discharge and soil moisture were assessed. The simulations showed the response of the hydrographic regions due to change of precipitation and potential evapotranspiration in the scenarios. Water availability decreases in almost the entire study area (exception for the South) and the major basins for hydroelectric power generation are affected. The Northwest, Amazon and a small area along the Northeast Atlantic coast exhibited intensification of the extremes discharges, where the anomaly is positive for high-flow (Q10) and negative for low-flow (Q95). The results highlight the most climatic sensitive regions in Brazil in terms of hydrological variables and water resources.

Early Pleistocene lineages of Bagre bagre (Linnaeus, 1766) (Siluriformes: Ariidae), from the Atlantic coast of South America, with insights into the demography and biogeography of the species

ABSTRACT Coastal and marine environments are characterized by a lack of evident physical barriers or geographic isolation, and it may be difficult to understand how divergence can arise and be sustained in marine environments. The identification of 'soft' barriers is a crucial step towards the understanding of gene flow in marine environments. The marine catfishes of the family Ariidae are a demersal group with restricted migratory behavior, no pelagic larval stages, and mechanisms of larval retention, representing a potentially useful model for the understanding of historical processes of allopatric speciation in the marine environment. In the present study, two lineages of the Coco sea catfish, Bagre bagre , were recognized from their complete segregation at both mitochondrial and morphological levels. One lineage is distributed between Venezuela and the northern coast of Brazil, including the semiarid northeast coast, while the second lineage is found on the eastern coast of Brazil, including the humid northeast coast. Based on distribution area, habitats preference, and genetic variability, inferences are made in relation to biogeography and demography of lineages in Atlantic coast of South America.

ATRIBUTOS ECOLÓGICOS DA BIOINVASORA &lt;i&gt;Nicotiana glauca&lt;/i&gt; GRAHAM (SOLANACEAE) E AVALIAÇÃO DA SUSCEPTIBILIDADE DE SUA OCORRÊNCIA NO BRASIL

http://dx.doi.org/10.5902/1980509820650Nativa da Bolívia e Argentina, Nicotiana glauca Graham, atualmente é encontrada crescendo espontaneamente em zonas áridas e semiáridas de diferentes partes do globo, sendo que, em alguns países, é considerada uma importante exótica invasora. No Brasil, a espécie ainda não havia sido reportada como invasora, mas nas áreas do Projeto de integração do Rio São Francisco (PISF), Nicotiana glauca pode ser observada formando aglomerados de indivíduos com altas densidades (mais de 37.000 indivíduos ha). Com isso, o objetivo do presente estudo foi inferir sobre a situação citada por meio de aspectos da estrutura (densidade, biometria e diversidade), reprodução (produção de frutos, propágulos e germinabilidade), presença de substâncias alelopáticas (extratos com concentrações de 0, 5, 10, 15 e 20%) e da susceptibilidade de ocorrência da espécie no Brasil. A densidade estimada para a espécie foi de 37.280±2.442,3 indivíduos ha. A planta pode produzir mais de 1.300.000 sementes por indivíduo. A partir da primeira concentração dos extratos (5%), a germinação das sementes, tamanho e biomassa de plântulas de Lactuca sativa foram afetados significativamente. A espécie apresentou alta probabilidade de ocorrência nas regiões de clima semiárido e subúmido do Brasil. Os resultados deste estudo demonstram a necessidade do controle imediato da espécie nas áreas do PISF e, subsidiam a formulação de meios para evitar novos casos de invasão biológica por Nicotiana glauca em outras partes do Brasil.

Pluriatividade e sustentabilidade em comunidades rurais do semiárido nordestino

O ambiente rural e a agricultura brasileira vêm apresentando um processo intenso de transformações nas últimas décadas. Tais transformações têm gerado muitos debates nos meios político, econômico e acadêmico, dentre os quais está a noção de pluriatividade, um termo recente que designa o agricultor familiar que, residindo no meio rural, combina atividades agrícolas com atividades não agrícolas, como forma de complementar a renda familiar. A pesquisa buscou analisar como a pluriatividade se apresenta em comunidades rurais do semiárido nordestino e como essa prática interfere na sustentabilidade social, econômica e ecológica das comunidades estudadas. Para alcançar este objetivo, utilizou-se o método dialético como método científico e, como procedimentos metodológicos, entrevistas semiestruturadas com representantes de órgãos públicos locais e com as famílias pluriativas das comunidades. Dentro do cenário de semiárido nordestino, a referência empírica do estudo foram três comunidades rurais do município de Brejinho/PE: Sítio Caldeirão, Sítio Lagoa dos Campos e Vila de Fátima. A análise dos resultados indica que a pluriatividade tem um papel fundamental na sustentabilidade social, econômica e ambiental das comunidades pesquisadas. No entanto, não pode ser considerada como a solução para os problemas rurais, visto que muitas famílias do semiárido ainda têm sua reprodução social e econômica ameaçada e solos em processo de degradação. Logo, muitos desafios ainda precisam ser vencidos para se ter um semiárido sustentável.

Effect of pFSH dose reduction on in vivo embryo production in Dorper ewes

&lt;p&gt;To evaluate the effect of pFSH dose on the &lt;em&gt;in vivo &lt;/em&gt;embryo production of Dorper ewes in the semi-arid northeast of Brazil, 40 sheep females were distributed into two groups of 20 animals that received intravaginal CIDR for 14 days, and two days before device removal, they received one of the following treatments: in the FSH200 group, the ewes received 200 mg of pFSH; and in the FSH128 group, the ewes received a total of 128 mg in decreasing doses every 12 h. Beginning 12 h after the conclusion of the treatments, estrus detection was performed every four hours using two Dorper rams of proven fertility. The ewes were mated at estrus onset and 24 hours later. Seven days after intravaginal device removal, the superovulatory response was evaluated, and embryo collection was performed using the laparotomy method. The recovered flushings were subjected to embryo searches under a stereomicroscope and classified according to their qualities. Analyses of variance (ANOVAs) and LSD tests were used to compare the different parameters. The data expressed as percentages were analysed by chi-square test. The ovulation rate was higher in the FSH200 group, which had 16.3 ± 0.3 corpora lutea (CL), than in the FSH128 group, which had 11.3 ± 0.3 CL (P&amp;lt;0.05). However, higher fertilization rate (83.6% vs. 62.4%) and higher transferable (86.0% vs. 71.6%) and freezable (67.9% vs. 40.8%) embryo rates were observed in the FSH 128 group compared with the group that received 200 mg. Furthermore, no significant differences in the remaining parameters were observed between the experimental groups (P&amp;gt;0.05), demonstrating that pFSH dose reduction promoted a greater production of freezable and transferable embryos in Dorper ewes subjected to MOET.&lt;/p&gt;

Effect of pFSH dose reduction on in vivo embryo production in Dorper ewes

To evaluate the effect of pFSH dose on the in vivo embryo production of Dorper ewes in the semi-arid northeast of Brazil, 40 sheep females were distributed into two groups of 20 animals that received intravaginal CIDR for 14 days, and two days before device removal, they received one of the following treatments: in the FSH200 group, the ewes received 200 mg of pFSH; and in the FSH128 group, the ewes received a total of 128 mg in decreasing doses every 12 h. Beginning 12 h after the conclusion of the treatments, estrus detection was performed every four hours using two Dorper rams of proven fertility. The ewes were mated at estrus onset and 24 hours later. Seven days after intravaginal device removal, the superovulatory response was evaluated, and embryo collection was performed using the laparotomy method. The recovered flushings were subjected to embryo searches under a stereomicroscope and classified according to their qualities. Analyses of variance (ANOVAs) and LSD tests were used to compare the different parameters. The data expressed as percentages were analysed by chi-square test. The ovulation rate was higher in the FSH200 group, which had 16.3 ± 0.3 corpora lutea (CL), than in the FSH128 group, which had 11.3 ± 0.3 CL (P&lt;0.05). However, higher fertilization rate (83.6% vs. 62.4%) and higher transferable (86.0% vs. 71.6%) and freezable (67.9% vs. 40.8%) embryo rates were observed in the FSH 128 group compared with the group that received 200 mg. Furthermore, no significant differences in the remaining parameters were observed between the experimental groups (P&gt;0.05), demonstrating that pFSH dose reduction promoted a greater production of freezable and transferable embryos in Dorper ewes subjected to MOET.

Analytic Modeling of Rainwater Harvesting in the Brazilian Semiarid Northeast

AbstractDuring the past two decades, government efforts to provide water access to rural communities in Brazil's semiarid Northeast region have focused on building systems to capture and store rainwater, most importantly through the One Million Cisterns Program (P1MC). This article presents an analytic model based on daily precipitation data to evaluate the sustainability of rainwater capture. Application of this model to analysis of the P1MC reveals the heterogeneous climate in this region causes large spatial variability in the effectiveness of this program. In addition, the size of the area of capture, the run‐off coefficient of the roofs, and the amount of first‐flush diversion also have important effects. This analysis demonstrates while rainwater capture can offer sufficient water for drinking, as a stand‐alone solution it cannot meet P1MC objectives of guaranteeing sustainable and universal access to water for drinking, cooking, and basic hygiene in all regions and years.

Biochar to Climate Change Adaptation

Rain-fed agriculture in the semi-arid northeast of Brazil faces stronger challenges regarding water for agriculture. Biochar is recognized to promote soil water holding capacity. Its properties vary widely with feedstock material and processing conditions, so it is recognized the importance of its characterization and performance evaluation, before use. The objective of this study was to identify best regional available biochar for soil water-holding capacity increase, based on laboratory tests and microstructural porosity evaluation. Types of biochar were compared, according to wood source. Cashew tree and two species from caatinga biome were used, jurema-preta (Mimosa tenuiflora (Willd.) Poir. and marmeleiro (Croton sonderianus Müll. Arg.). For water holding evaluations, both biochar were submitted to Hainnes Funel. Samples were crushed and brought to the laboratory and separated using sieves of 16 mm; 8 mm; 4 mm; 2 mm; 1 mm; 0.5 mm; 0.25 mm; 0.12 mm and &lt;0.12 mm mesh. Samples with particle size diameters of 2 mm and 4mm were submitted to Hainnes Funel. Transversal sections of both biochars were prepared to be observed under a scanning electron microscope, identifying macropores and micropores. Caatinga wood biochar demonstrated greater water holding capacity than cashew wood one in all evaluated diameters. Greater levels are observed related to caatinga wood biochar, 1.89 g g-1 for to particle size diameter of 2 mm and 2,27 g g-1 for 4mm and cashew wood biochar demonstrated water holding capacity of 0.57 and 0.53 g g-1 to 2mm and 4 mm particle size diameters respectively. The fewer quantity of macropores and larger number of micropores may give caatinga wood biochar higher water holding capacity, while thickly lignified cell walls of cashew wood biochar supports the idea that a hydrophobic effect may contribute to its lower holding capacity.

Decomposition of Mongolian pine litter in the presence of understory species in semi-arid northeast China

The effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter.

An approach to assess the impact of landscape connectivity and effective catchment area upon bedload sediment flux in Saco Creek Watershed, Semiarid Brazil

Sediment flux in semi-arid drainage networks is influenced by landscape connectivity, wherein natural landforms and hydro infrastructure networks such as low order dams impede the downstream transfer of sediment. This study analyzes how drainage impediments affect bedload transport within Saco Creek watershed, in semi-arid northeast Brazil. Geomorphology and land use maps are constructed to assess changes to short term landscape connectivity. Bedload conveyance is appraised for precipitation/runoff events of variable magnitude-frequency relationships. From this, ‘effective’ rainfall events are determined. Analysis of the type and location/pattern of drainage impediments is used to assess effective catchment area under three distinct runoff scenarios. In the low magnitude event scenario, only 33.8% of the watershed area contributed effectively to sediment flux. In moderate and high magnitude events this value increased to 61.6% and 70.8% respectively. The relatively small variation from moderate to high magnitude events reflects the operation of dams which store bedload sediments. Findings from this study can be used to show how landscape connectivity analysis can support dam management in semiarid agrarian landscapes.

Brazilian inland water bio-optical dataset to support carbon budget studies in reservoirs as well as anthropogenic impacts in Amazon floodplain lakes: Preliminary results

Abstract. This work presents ongoing efforts and preliminary results for building a dataset that represents the first and most comprehensive bio-optical information available on Brazilian inland waters to support the development of remote sensing algorithms for monitoring aquatic systems. From 2012 to 2014 optical and limnological data was gathered along thirteen field campaigns in five Brazilian reservoirs, in an irrigation and domestic water supply reservoir located in semi-arid northeast of the country and in Amazonian floodplain lakes, thus covering the diversity of Brazilian inland waters. At each site 20 stations, on average, were sampled to acquire profiles of the following optical variables: absorption, attenuation, scattering, and backscattering coefficients and radiances/irradiances spectra above and in-water. Alongside these measurements, water samples were collected for determining concentrations of chlorophyll-a (Chl-a), Total Suspended Solid (TSS), Total Dissolved Carbon (TDC) and its organic/inorganic fractions, CDOM absorption, phytoplankton specific absorption [aph*] and Non-Algal Particles absorption [aNAP*]. Preliminary results show that Chl-a concentrations ranged from 0.6 to 243μg/L in reservoirs and 0.90 to 92μg/L in Amazonian lakes, while TSS concentrations ranged from 0.3 to 31mg/L in reservoirs and 0.5 to 162mg/L in Amazonian lakes. In situ beam attenuation coefficients ranged from 1.4 to 16m-1 in reservoirs and 12.5 to 38m-1 in Amazonian lakes, while diffuse attenuation coefficients of downwelling irradiance over the Photosynthetically Active Radiation (Kd(PAR)) extended from 0.35 to 4.5m-1 in reservoirs and 1.69 to 13.30m-1 in Amazonian lakes. Our research group is building this dataset anticipating future demands for algorithm validation regarding OLI/Landsat8 data and ESA Sentinel missions to be launched as of 2015.

Nitrogen symbiotically fixed by cowpea and gliricidia in traditional and agroforestry systems under semiarid conditions

The objective of this work was to estimate the amounts of N fixed by cowpea in a traditional system and by cowpea and gliricidia in an agroforestry system in the Brazilian Northeast semiarid. The experiment was carried out in a randomized complete block design, in a split-plot arrangement, with four replicates, in the semiarid region of the state of Paraíba, Brazil. Plots consisted of agroforestry and traditional systems (no trees), and split-plots of the three crops planted between the tree rows in the agroforestry system. To estimate N fixation, plant samples were collected in the fourth growth cycle of the perennial species and in the fourth planting cycle of the annual species. In the agroforestry system with buffel grass and prickly-pear cactus, gliricidia plants symbiotically fix high proportions of N (&gt;50%) and contribute with higher N amounts (40 kg ha-1 in leaves) than in the traditional system (11 kg ha-1 in grain and 18 kg ha-1 in straw). In the agroforestry system with maize and cowpea, gliricidia plants do not fix nitrogen, and N input is limited to the fixation by cowpea (2.7 kg ha-1), which is lower than in the traditional system due to its lower biomass production.

Germinação in vitro de Hyptis leucocephala Mart. ex Benth. e Hyptis platanifolia Mart. ex Benth.

Hyptis leucocephala e Hyptis platanifolia (Lamiaceae) são espécies aromáticas endêmicas do semiárido nordestino e possuem grande importância econômica devido ao seu potencial medicinal. O presente trabalho teve por objetivo obter o protocolo para o estabelecimento inicial in vitro das espécies H. leucocephala e H. platanifolia. O meio de cultura WPM promoveu a maior porcentagem de germinação (96,81%) para H. leucocephala, porém não diferiu estatisticamente dos resultados obtidos no MS½ na última semana de cultivo. Para a germinação de sementes de H. platanifolia, o MS½ foi o meio que proporcionou a maior porcentagem (40,83%). O tipo de esterilização não interferiu na germinação in vitro para as duas espécies. Para a espécie H. platanifolia, quando se utilizou o fechamento dos tubos de ensaio com tampão de algodão, a hiperidricidade foi eliminada; porém, a porcentagem de germinação das sementes foi menor. Avaliando-se o tipo de meio de cultura no crescimento in vitro de H. leucocephala observou-se que este fator não influenciou no número de brotações, nem o comprimento de parte aérea e da matéria seca de raiz. O meio MS proporcionou incremento para o número de folhas, matéria seca da parte aérea, e comprimento da maior raiz, enquanto o meio MS½ foi o que promoveu maior número de raízes. O meio de cultura ideal para a germinação de H. leucocephala e H. platanifolia foi o MS½, podendo ser esterilizado com hipoclorito de sódio, enquanto que o MS foi o melhor meio de cultura para o crescimento in vitro de H. leucocephala.