ABSTRACT For the successful application of phytosanitary products, it is essential to understand the spraying process well. The present work aims to evaluate the spectrum and speed of the droplets produced by different spray nozzle models with air induction, working under different operating conditions. The experiment was conducted using an entirely randomized design with five repetitions in a 3 × 3 × 3 factor scheme that incorporates three nozzle models (ADIA, AIXR, and GA), three nominal flows (0.76, 1.14, and 1.51 L min−1), and three operating pressures (200, 300, and 400 kPa). The spectrum and speed of the droplets were determined directly using a real-time droplet analyzer based on high-resolution image analysis. The spray nozzle model interfered with the results. The ADIA promoted Dv0.5 (VMD) higher than AIXR and GA, reaching differences of up to 90%. The increase in pressure promoted a reduction in the droplet size; however, there was no well-defined behavior for the relationship between the flow rate and droplet size. The ADIA and AIXR gave rise to greater uniformity of the droplets in most of the evaluated conditions. The increase in pressure promoted an increase in the speed of the droplets. However, the effect of the nozzle model on this parameter was dependent on the flow.
Abstract 20. Infectious bursal disease (IBD), represents one of the main pathologies that affects backyard poultry populations. Infection is produced by a highly contagious virus that causes significant economic losses, mainly associated with immuno-suppression. The objective of this work was to evaluate antibody levels in backyard hens of Curuguaty City, Paraguay. Blood samples were obtained from 16 healthy birds, without distinction of sex, age and that did not received vaccination. The serological technique was indirect ELISA. Of the total samples analyzed, 37.5% had antibody titers against IBD. Considering the sex, 100% and 16.3% were reported as positives in males and females, respectively. The largest number of cases was reported in young birds from 3 to 6 months of age. Results show that there are circulating strains of IBD virus in the field. The necessity of the implementation of adequate control programs in order to eradicate the causal agent, is emphasized.
Resumen 16. La enfermedad infecciosa bursal (EIB), representa una de las principales patologías que afecta a las poblaciones avícolas de traspatio. La infección es producida por un virus altamente contagioso que ocasiona importantes pérdidas económicas, principalmente asociada con inmunosupresión. El objetivo de este trabajo fue evaluar niveles de anticuerpos en gallinas de traspatio de la ciudad de Curuguaty, Paraguay. Se obtuvieron muestras de sangre de 16 aves aparentemente sanas, sin distinción de sexo ni edad, que no habían recibido vacunación. La técnica serológica utilizada fue ELISA de tipo indirecto. Del total de muestras analizadas un 37,5% presentó títulos de anticuerpos contra la EIB. Considerando el sexo, machos y hembras revelaron 100% y 16,3% de positividad, respectivamente. La mayor cantidad de casos se reportó en aves jóvenes de 3 a 6 meses de edad. Los resultados obtenidos demuestran la existencia de cepas circulantes del virus de la EIB a campo, por lo cual es necesaria la implementación de programas de control capaces de erradicar el agente causal.
Abstract The ethanol crude extract from cashew (Anacardium occidentale L. Anacardiaceae) displayed significant antiplasmodial activity (IC50 0.577 µg/ml). Liquid chromatography-high resolution Mass spectrometry analysis was performed to identify the main compounds existing in the ethanol extract. The occurrence of anacardic acids, cardols, and 2-methylcardols derivatives was confirmed in the extract. The IC50 obtained, when the main isolated compounds were evaluated in Plasmodium falciparum D6 strain, ranged from 5.39 µM to >100 µM. Tested here for the first time, the data showed that cardol triene 1 (IC50 = 5.69 µM) and 2-methylcardol triene 4 (IC50 = 5.39 µM) demonstrated good antimalarial activity. In conclusion, Anacardium occidentale nuts presented relevant biological potential, and further studies should be considered.
Abstract Asian soybean rust (Phakopsora pachyrhizi – ASR) is one of the major diseases that occur in soybean and causes great damage to commercial crops. Therefore, the goal of this work was to investigate the relationship between biochemical and photosyntetic parameters in soybean with ASR. Two experiments were performed in a randomized complete block with three treatments (water, Tween 20, and methyl jasmonate). The evaluated traits were: severity, chlorophyll pools, concentration of phenolic compounds content, enzyme activity, and photosyntetic parameters. Based on Pearson correlation, correlation network and path analysis it was verified that the severity had high correlation with almost all traits evaluated meanwhile photosynthesis is weakly related with almost all traits. Therefore, the occurrence of ASR affects directly the traits related to enzymatic activity and phenolic compounds content in soybean plants inoculated with ASR. The management of ASR is important to keep in normal levels the rates of photosynthesis carried out by the plant, and thus not affect the yield. Besides that, understanding the biochemical mechanisms and ecophysiological responses that occur during the soybean-P. pachyrhizi interaction has a great importance for breeding programs, as it will help for obtaining resistant cultivars or efficient methods in fungus control.
Abstract Yarrow (Achillea millefolium L., Asteraceae) is an important medicinal plant used worldwide for its medicinal properties such as the analgesic, antioxidant and anti-inflammatory ones. The aim of this study was to evaluate the growth and production of photosynthetic pigments and of volatile constituents of Achillea millefolium L. under different irrigation depths. The treatments were the application of 55, 110, 220, 440 and 880 mm of water for a period of 110 days. Data were submitted to polynomial regression analysis at 5% probability, while the volatile constituents were analyzed by standard deviation. Different irrigation depths provided quadratic growth responses being the highest dry matter production at the depth of 440 mm. The contents of chlorophyll a, b, total and carotenoids were higher at the lower depth tested (55 mm). The major volatile compounds identified were sabinene, 1,8-cineol, borneol and β-caryophyllene. Increased water availability reduced the complexity of the volatile fraction of essential oil. Thus, it is recommended that the species be cultivated at 440 mm irrigation depth to have a higher production of dry matter and lower variation in the volatile profile of the essential oil.
ABSTRACT: Stem cells are undifferentiated cells with a high proliferation potential. These cells can be characterized by their in vivo ability to self-renew and to differentiate into specialized cell lines. The most used stem cell types, in both human and veterinary fields, are the mesenchymal stem cells (MSC) derived from bone marrow and adipose tissue. Nowadays, there is a great interest in using stem cells derived from fetal tissues, such as amniotic membrane (AM) and umbilical cord tissue (UCT), which can be obtained non-invasively at delivery time. Due to the scarcity of studies in bovine species, the aim of this study was to isolate, characterize, differentiate and cryopreserve MSC derived from the mesenchymal layer of amniotic membrane (AM), for the first time, and umbilical cord tissue (UCT) of dairy cow neonates after assisted delivery (AD) and from fetus at initial third of pregnancy (IT) obtained in slaughterhouse. Cells were isolated by enzymatic digestion of the tissue fragments with 0.1% collagenase solution. Six samples of AM and UCT at delivery time and six samples of AM and UCT at first trimester of pregnancy were subjected to morphology evaluation, imunophenotype characterization, in vitro osteogenic, adipogenic and chondrogenic differentiation and viability analysis after cryopreservation. All samples showed adherence to plastic and fibroblast-like morphology. Immunocytochemistry revealed expression of CD 44, NANOG and OCT-4 and lack of expression of MHC II in MSC from all samples. Flow cytometry demonstrated that cells from all samples expressed CD 44, did not or low expressed CD 34 (AM: IT-0.3%a, AD-3.4%b; UCT: 0.4%, 1.4%) and MHC II (AM: IT-1.05%a, AD-9.7%b; UCT: IT-0.7%a, AD-5.7%b). They were also capable of trilineage mesenchymal differentiation and showed 80% viability after cryopreservation. According to the results, bovine AM and UCT-derived cells, either obtained at delivery time or from slaughterhouse, are a painless and non-invasive source of MSC and can be used for stem cell banking.
RESUMO: As células tronco mesenquimais (CTMs) estão presentes na maioria dos tecidos adultos e possuem grande capacidade de multiplicação. Quando cultivadas in vitro são capazes de se auto renovar e dar origem a novos tipos celulares. As células tronco mais utilizadas, tanto na medicina humana como na medicina veterinária são as células tronco mesenquimais derivadas da medula óssea e do tecido adiposo. Atualmente, uma grande tendência para a utilização de CTMs obtidas de tecidos fetais, como a membrana amniótica (MA), matriz extravascular do cordão umbilical (TCU) e sangue do cordão umbilical (SCU) pode ser observada, já que estas fontes podem ser colhidas no momento do parto por uma técnica não invasiva. Dessa forma, o objetivo deste estudo foi isolar, caracterizar, diferenciar e criopreservar CTMs obtidas de MA e TCU de fetos bovinos colhidos no momento do parto e de fetos do terço inicial da gestação em abatedouro-frigorífico. As células foram recuperadas por meio de digestão enzimática tecidual, realizada com solução de colagenase 0,1%. Foram colhidas amostras de MA e TCU no momento do parto (n=6) e de MA e TCU no terço inicial de gestação (n=6), as quais foram submetidas às análises morfológicas, imunofenotípica por imunocitoquímica e citometria de fluxo, diferenciações in vitro nas linhagens osteogênica, adipogênica e condrogênica e ainda, avaliação da viabilidade após a criopreservação por citometria de fluxo. Todas as amostras dos diferentes grupos demonstraram adesão ao plástico e morfologia fibroblastóide. No ensaio imunocitoquímico todas as amostras foram imunomarcadas para CD44, NANOG e Oct-4, com ausência de marcação para MHC II. Na análise imunofenotipica por citometria de fluxo, todas as amostras apresentaram marcação para CD44, ausência de marcação para ou baixíssima expressão de CD34 (MA: TI-0,3%a, PA-3.4%b; TCU: TI-0,4%, PA-1.4%) e nula ou baixa expressão de MHC II (MA: TI-1.5%a, PA-9.7%b; UCT: TI-0.7%a, PA-5.7%b. Apresentaram também capacidade de diferenciação in vitro nas três linhagens mesodermais e quando analisadas pós criopreservação por citometria de fluxo, todas as amostras apresentaram viabilidade de 80%. Estes resultados indicam que MA e TCU, obtidos tanto no momento de parto como em abatedouro, de fetos bovinos podem ser utilizados como fonte não invasiva e indolor de CTMs e possibilitam a formação de bancos de armazenamento de células.
ABSTRACT: The platelet-rich plasma (PRP) consists of a high concentration of platelets in a small volume of plasma, four times greater (average) than the serum concentration. The use of PRP is justified by the high concentration of growth factors present in granules in the platelets, which have several functions such as cell proliferation, chemotaxis, angiogenesis and differenciation, which extend the power of tissue repair. There are several protocols to obtain PRP in horses described in the literature, among which are highlighted the double centrifugation, automated and filters. There are substantial differences in the PRP content depending on its method of production, especially when it concerns the amount of leukocytes, platelets and concentration of growth factors. Thus, the aim of this study was to compare the use of platelet concentrates obtained by double centrifugation protocol and obtained by the filter E-PET (Equine Platelet Enhancement Therapy) taking into account the platelet and leukocyte final concentration, the quantification of growth factors (TGFβ and PDGF-BB) and the facility to do those methods. Nine horses were used to obtain PRP by double centrifugation and through the E-PET filter, with no statistical difference (p>0.05) between the methods relative to the platelet and leukocyte concentration; however, there was statistical difference (p=0.002 and p=0.004 respectively) compared with the concentration of TGFβ and PDGF-BB. It was concluded that the E-PET filter proved to be a more effective method possible to use in the field and to provide a higher concentration of growth factors (TGFβ and PDGF-BB).
RESUMO: O plasma rico em plaquetas (PRP) consiste em uma alta concentração de plaquetas em um pequeno volume de plasma, sendo, em média, quatro vezes maior que a concentração sérica. O uso de PRP é justificado pela alta concentração de fatores de crescimento presentes em grânulos no interior das plaquetas, que possuem diversas funções como proliferação celular, quimiotaxia, angiogênese e diferenciação celular, que ampliam o poder de reparação tecidual. Há diversos protocolos para obtenção do PRP em equinos descritos na literatura, dentre os quais destacam-se os de dupla centrifugação, os automatizados e os filtros. Há diferenças substanciais no conteúdo do PRP dependendo do seu método de obtenção, principalmente no que se diz respeito à quantidade de leucócitos, plaquetas e concentração de fatores de crescimento. Sendo assim, o objetivo deste estudo foi comparar a utilização do concentrado de plaquetas obtido por protocolo de dupla centrifugação e o obtido pelo filtro E-PET (Equine Platelet Enhancement Therapy), levando-se em consideração a concentração plaquetária e leucocitária final, a quantificação de fatores de crescimento (TGFβ e PDGF-BB) e a facilidade de realização entre tais métodos. Utilizou-se nove animais para a obtenção de PRP por dupla centrifugação e através do filtro E-PET, não havendo diferença estatística (p>0,05) entre os métodos de obtenção em relação à concentração plaquetária e leucocitária, entretanto, houve diferença estatística (p=0,002; p=0,004, respectivamente) em relação a concentração de TGFβ e PDGF-BB. Dessa forma, concluiu-se que o filtro E-PET mostrou-se um método mais efetivo, sendo possível sua utilização à campo, além de proporcionar uma maior concentração de fatores de crescimento TGFβ e PDGF-BB.
Abstract The present study investigated the solvent extraction of uranium from sulfate acid solutions using Alamine 336 as an extractant dissolved in commercial kerosene Exxsol D-100 and 5% v/v of tridecanol as a modifying agent at room temperature (25±2) ºC and an aqueous/organic volumetric ratio of unity. Experiments were carried out at typical concentration levels like those used at the uranium plant of INB (Indústrias Nucleares do Brasil), Brazil. Data fitting using the slope analysis method revealed that uranium is extracted by Alamine 336 as UO2SO4 and UO2(SO4)22- species, forming (R3NH+)2UO2(SO4)22- in the organic phase; the extraction of the species UO2(SO4)34- seems improbable for the operating conditions investigated. The extraction of uranium is significantly reduced when the concentrations of sulfate and chloride ions in the aqueous phase are increased.
ABSTRACT This paper aimed to evaluate the occurrence of Gonodonta larvae defoliating sugar apple (Annona squamosa) and atemoya fruits (Annona squamosa x Annona cherimolia L. Mill.) in northern state of Minas Gerais. Larvae were collected between December 2007 and January 2008 in Annonaceae plantation in the rural area of the municipality of Janaúba, MG. Adults obtained have been sent for identification. The species identified were Gonodonta bidens Geyer, G. nutrix Stoll and G. pyrgo Cramer. The infestation level observed in the orchard was 85% of plants with the presence of Gonodonta larvae and the average defoliation percentage was 30%. These are the first records of Gonodonta species defoliating sugar apple and atemoya in Brazil.
RESUMO Esta comunicação tem como objetivo registrar a ocorrência de lagartas de Gonodonta desfolhando pinha (Annona squamosa L.) e atemoia (Annona squamosa L. x Annona cherimolaMill.), no norte de Minas Gerais. As lagartas foram coletadas entre dezembro/2007 e janeiro/2008, em área de plantio de pinheira e atemoieira, na área rural do município de Janaúba, MG. Os adultos obtidos foram enviados para a identificação. As espécies identificadas foram Gonodonta bidens Geyer, Gonodonta nutrix(Stoll) e Gonodonta pyrgo (Cramer). O índice de infestação observado no pomar foi de 85% dasplantas com presença de lagartas de Gonodonta e a porcentagem média de desfolha foi de 30%. Estes são os primeiros registros de espécies de Gonodonta desfolhando pinheira e atemoieira no Brasil.
Abstract Cyanobacteria is a remarkable group of prokaryotic photosynthetic microorganisms, with several genera capable of fixing atmospheric nitrogen (N2) and presenting a wide range of morphologies. Although the nitrogenase complex is not present in all cyanobacterial taxa, it is spread across several cyanobacterial strains. The nitrogenase complex has also a high theoretical potential for biofuel production, since H2 is a by-product produced during N2 fixation. In this review we discuss the significance of a relatively wide variety of cell morphologies and metabolic strategies that allow spatial and temporal separation of N2 fixation from photosynthesis in cyanobacteria. Phylogenetic reconstructions based on 16S rRNA and nifD gene sequences shed light on the evolutionary history of the two genes. Our results demonstrated that (i) sequences of genes involved in nitrogen fixation (nifD) from several morphologically distinct strains of cyanobacteria are grouped in similarity with their morphology classification and phylogeny, and (ii) nifD genes from heterocytous strains share a common ancestor. By using this data we also discuss the evolutionary importance of processes such as horizontal gene transfer and genetic duplication for nitrogenase evolution and diversification. Finally, we discuss the importance of H2 synthesis in cyanobacteria, as well as strategies and challenges to improve cyanobacterial H2 production.
Abstract: The platelet-rich plasma (PRP) is characterized by its anabolic, anti-inflammatory and gelling capability. Nowadays, the PRP is considered effective in the repair of cartilage defects, and its gelling capability is proper to filling chondral defects. So, the aim of this study was to investigate the use of activated PRP as a fibrin gel scaffold, such as support for the use with mesenchymal stem cells (MSC), on the treatment of experimentally chondral articular defects. Twelve horses were subjected to an arthroscopic surgery at time zero of the experiment (T0). A chondral defect of 15 mm diameter was created on the medial femoral trochlea and these 12 joints were divided into two groups each with six joints in each group (GA and GB). The joints of the GA were treated with implantation of MSC and PRP-gel. GB joints were the control group. MSCs were cultivated from adipose tissue and PRP-gel was obtained by double centrifugation protocol followed by addition of lyophilized thrombin. After five months (T150) was performed new arthroscopy for macroscopic evaluation of the defect local, collect samples of tissue repair for electron microscopy assessment and also was implemented a magnetic resonance images and computed tomography on GA. It was observed that the PRP-gel associated with CTMs showed a suitable treatment of experimental chondral defects in horses. GA showed a better macroscopic and microscopic appearance of the tissue repair. GB showed smaller number of chondrocytes and increased collagen fibers disorganization. At the magnetic resonance and computed tomography imaging only the local of chondral defect was viewed. The PRP-gel scaffold was satisfactory to use and support MSCs implantation. It showed an easy handling and it was effective, showing a promising results in the repair of induced chondral defects.
Resumo: O plasma rico em plaquetas (PRP) é conhecido por apresentar propriedades anabólicas, anti-inflamatórias e capacidade de gelificação. Atualmente o PRP é considerado eficaz na reparação da cartilagem, sendo sua capacidade de formação de gel indicada para o preenchimento de defeitos condrais. O objetivo desse estudo foi analisar o uso do PRP ativado, no formato de arcabouço, como suporte para o implante de células tronco mesenquimais (CTM), no preenchimento e tratamento de lesões condrais induzidas em equinos. Doze equinos foram submetidos a uma cirurgia artroscópica no tempo zero do experimento (T0), onde foi induzida uma lesão condral de 15 mm de diâmetro na tróclea medial femoral dos membros pélvicos direito. As 12 articulações foram divididas em dois grupos distintos com seis articulações cada (GA e GB). As articulações do GA foram submetidas ao tratamento com o implante de CTM em gel de PRP. As articulações de GB foram o grupo controle do experimento. As CTMs foram extraídas do tecido adiposo e o PRP em gel foi obtido por protocolo de dupla centrifugação seguido da adição de trombina liofilizada. Após cinco meses (T150) foi realizada nova artroscopia para avaliação macroscópica do local, coleta de amostras do tecido de reparação para análises de microscopia eletrônica, sendo realizadas imagens ressonância magnética e tomografia computadorizada no local do implante no GA. Observamos que o gel de PRP associado às CTM demonstrou ser adequado no tratamento de defeitos condrais experimentais dos equinos. GA evidenciou um melhor aspecto macroscópico e microscópico do tecido de reparação, sendo que GB mostrou maior desorganização das fibras colágenas. Nas imagens de ressonância magnética e tomografia computadorizada apenas foi relevante o local da lesão condral. O arcabouço de gel de PRP demonstrou ser apropriado no suporte do tratamento com as CTMs, sendo de fácil aplicação e efetivo, demonstrando resultados promissores na reparação de lesões condrais induzidas.
ABSTRACTPyometra is a common disease in dogs with a hormonal etiology associated with a bacterial infection and leading to accumulation of uterine exudates. Acid-base and electrolyte disturbances are complications that contribute to disease progression, worsening the condition of the patient, possibly leading death. The aim of this study was to characterize the acid-base and electrolyte disturbances in dogs with pyometra, and to evaluate whether preoperative fluid therapy (Ringer's lactate) is effective in correcting these imbalances. Twenty bitches with pyometra were subjected to blood gas analysis in eight pre-set times. It was concluded that the acid-base disorder was the most frequent respiratory alkalosis and fluid therapy in the preoperative Ringer 's lactate solution was effective in the correction of metabolic acidosis, although this has not corrected metabolic alkalosis frames and has provided improved alkalosis breathing .
RESUMOA piometra é uma afecção comum em cadelas com uma etiologia hormonal associada à infecção bacteriana, levando ao acúmulo de exsudato uterino. Desequilíbrios ácido-base e hidroeletrolíticos são complicações que contribuem para a progressão da doença, o que piora o estado geral da paciente e pode levá-la ao óbito. O objetivo do presente trabalho foi caracterizar os distúrbios ácido-base e eletrolíticos em cadelas com piometra, além de avaliar se a terapia hídrica pré-cirúrgica (Ringer lactato) é efetiva na correção desses desequilíbrios. Vinte cadelas com piometra foram submetidas à hemogasometria em oito tempos preestabelecidos. Concluiu-se que o distúrbio ácido-base mais frequente foi a alcalose respiratória e que a terapia hídrica no pré-cirúrgico com solução Ringer lactato foi efetiva na correção da acidose metabólica e proporcionou melhora na alcalose respiratória, embora não tenha corrigido quadros de alcalose metabólica.
OBJECTIVE: The aim of this study was to evaluate overall genetic damage induced by total sleep deprivation in obese, female Zucker rats of differing ages. METHOD: Lean and obese Zucker rats at 3, 6, and 15 months old were randomly distributed into two groups for each age group: home-cage control and sleep-deprived (N = 5/group). The sleep-deprived groups were deprived sleep by gentle handling for 6 hours, whereas the home-cage control group was allowed to remain undisturbed in their home-cage. At the end of the sleep deprivation period, or after an equivalent amount of time for the home-cage control groups, the rats were brought to an adjacent room and decapitated. The blood, brain, and liver tissue were collected and stored individually to evaluate DNA damage. RESULTS: Significant genetic damage was observed only in 15-month-old rats. Genetic damage was present in the liver cells from sleep-deprived obese rats compared with lean rats in the same condition. Sleep deprivation was associated with genetic damage in brain cells regardless of obesity status. DNA damage was observed in the peripheral blood cells regardless of sleep condition or obesity status. CONCLUSION: Taken together, these results suggest that obesity was associated with genetic damage in liver cells, whereas sleep deprivation was associated with DNA damage in brain cells. These results also indicate that there is no synergistic effect of these noxious conditions on the overall level of genetic damage. In addition, the level of DNA damage was significantly higher in 15-month-old rats compared to younger rats.
In this work the in vitro antimycobacterial activity of the ethanolic extract obtained from the wood of Bulnesia sarmientoi Lorentz ex. Griseb and its chemical composition were studied. The preliminary phytochemical analysis of the extract showed the presence of steroids and/or triterpenes and tannins, and a GC/MS fingerprint analysis identified guaiol and bulnesol as main volatile components of the extract, based on their retention index and the comparison of their mass spectra with those contained in NIST libraries. The extract showed activity against Mycobacterium tuberculosis H37Rv strain with a minimal inhibitory concentration (MIC) of 50 µg/mL, using the microplate Alamar Blue assay. These results suggest that the extract could be a source of antimicrobial substances against M. tuberculosis.
En el presente trabajo se evaluó la actividad antimicobacteriana in vitro y se estudió la composición química del extracto etanólico obtenido de la madera de Bulnesia sarmientoi Lorentz ex. Griseb. El estudio fitoquímico preliminar mostró la presencia de taninos y esteroides y/o triterpenos. Los componentes volátiles del extracto fueron además analizados por cromatografía gaseosa acoplada a espectrometría de masas (CG/EM) e identificados por comparación con las librerías NIST 21 y 107 del equipo y además con base en sus índices de retención. Este último análisis identificó a los sesquiterpenos guaiol y bulnesol como los principales componentes volátiles del extracto. La evaluación de la actividad antimicobacteriana usando el ensayo de microtitulación con Azul de Alamar mostró que el extracto es activo frente a la cepa H37Rv de Mycobacterium tuberculosis con una CMI de 50 µg/mL. Esto demuestra que el extracto puede ser fuente de sustancias con actividad frente a M. tuberculosis.
The objective of this study was to evaluate the effect of water and thermal stress on the germination and vigor of carrot seeds. Two experiments were performed in the Universidade Federal de Viçosa; three lots of carrot seeds were used, lot 1 of cv. "Carandaí " and the lots 2 and 3 of cv. "Brasília ". In experiment 1 - Water stress - Four osmotic potentials, 0.0; -0.3; -0.6 and -0.9 MPa were used to humidify the paper substratum, with a solution of PEG 6000 in concentrations of 0; 17.16; 25.68 and 32.16 g L-1. Germination and vigor were estimated. For experiment 2 - Thermal stress - Three temperatures were used, 15°, 20° and 35° C, to evaluate the quality of the seeds. It A paper towel humidified with water was used as substratum, in the proportion of 2.5 times the weight of the paper. It is concluded that the germination of the carrot seeds was not affected by potentials of -0.3 MPa. The length of the roots and the first germination count were efficient to evaluate the vigor of the carrot seeds, under water and thermal stress, allowing the classification of the tested lots. Temperatures of 15° and 35° C influenced the germination and the vigor of the carrot seeds negatively.
O objetivo deste trabalho foi avaliar o efeito do estresse hídrico e térmico na germinação e no vigor de sementes de cenoura. Foram conduzidos dois experimentos na Universidade Federal de Viçosa, utilizando-se três lotes de sementes de cenoura, sendo o lote 1 do cv. "Carandaí", os lotes 2 e 3 do cv. "Brasília". No experimento 1 - Estresse hídrico - Quatro potenciais osmótico, 0,0; -0,3; -0,6 e -0,9 MPa foram utilizados para o umedecimento do papel substrato, com uma solução de PEG 6000 nas concentrações de 0; 17,16; 25,68 e 32,16 g L -1. As sementes foram, então, avaliadas quanto à germinação e ao vigor . Para o experimento 2 - Estresse térmico - Três temperaturas, 15, 20 e 35 foram utilizadas na condução dos testes para avaliação da qualidade das sementes. Utilizou-se como substrato para as sementes o papel toalha umedecido com água, na proporção de 2,5 vezes o peso do papel. Conclui-se que a germinação das sementes de cenoura não foi afetada até potenciais de -0,3 MPa. O comprimento da radícula e a primeira contagem de germinação foram eficientes para avaliar o vigor das sementes de cenoura, sob estresse hídrico e térmico, permitindo a classificação dos lotes testados. Temperaturas de 15 e 35 oc influenciaram negativamente a germinação e o vigor das sementes de cenoura.