Viability of recently harvested and stored Xylopia aromatica (Lam.) Mart. (Annonaceae) seeds

Xylopia aromatica is a native species from Brazil's "Cerrado", recommended for restoration ecology and also as a medicine. Its seeds have embryos with morphophysiological dormancy, making nursery propagation difficult. The objective of this study was to verify the efficiency of X-ray and tetrazolium tests for evaluating the viability of three seed lots, stored for different periods. All seeds were X-rayed (13 kV, 350 seconds) and samples used for tetrazolium and germination tests. In the tetrazolium test, seeds were submitted to six treatments at two temperatures (25 and 30 °C) with imbibition in distilled water and immersion in three concentrations of tetrazolium solution (0.5, 0.75 and 1%) at the two imbibition temperatures. Seeds for the germination test were placed for imbibition in distilled water and a 500 ppm Promalin® (6-Benzyladenine + GA4 + GA7) solution and later sown in sterilized sand. The embryo could not be observed with the X-ray test. However, those seeds observed with an undamaged endosperm did not differ in the percentages of seeds with firm and stained endosperms observed in the tetrazolium test for all the lots. The tetrazolium test is efficient for evaluating seed viability, principally if imbibed at 30 °C and immersed in a 0.5% solution at 30 °C.

Features of neighbourhood environments associated with obesity and related health behaviours in children: using multiple statistical approaches to identify obesogenic environments

Contexte: L'obésité chez les jeunes représente aujourd’hui un problème de santé publique à l’échelle mondiale. Afin d’identifier des cibles potentielles pour des stratégies populationnelles de prévention, les liens entre les caractéristiques du voisinage, l’obésité chez les jeunes et les habitudes de vie font de plus en plus l’objet d’études. Cependant, la recherche à ce jour comporte plusieurs incohérences. But: L’objectif général de cette thèse est d’étudier la contribution de différentes caractéristiques du voisinage relativement à l’obésité chez les jeunes et les habitudes de vie qui y sont associées. Les objectifs spécifiques consistent à: 1) Examiner les associations entre la présence de différents commerces d’alimentation dans les voisinages résidentiels et scolaires des enfants et leurs habitudes alimentaires; 2) Examiner comment l’exposition à certaines caractéristiques du voisinage résidentiel détermine l’obésité au niveau familial (chez le jeune, la mère et le père), ainsi que l’obésité individuelle pour chaque membre de la famille; 3) Identifier des combinaisons de facteurs de risque individuels, familiaux et du voisinage résidentiel qui prédisent le mieux l’obésité chez les jeunes, et déterminer si ces profils de facteurs de risque prédisent aussi un changement dans l’obésité après un suivi de deux ans. Méthodes: Les données proviennent de l’étude QUALITY, une cohorte québécoise de 630 jeunes, âgés de 8-10 ans au temps 1, avec une histoire d’obésité parentale. Les voisinages de 512 participants habitant la Région métropolitaine de Montréal ont été caractérisés à l’aide de : 1) données spatiales provenant du recensement et de bases de données administratives, calculées pour des zones tampons à partir du réseau routier et centrées sur le lieu de la résidence et de l’école; et 2) des observations menées par des évaluateurs dans le voisinage résidentiel. Les mesures du voisinage étudiées se rapportent aux caractéristiques de l’environnement bâti, social et alimentaire. L’obésité a été estimée aux temps 1 et 2 à l’aide de l’indice de masse corporelle (IMC) calculé à partir du poids et de la taille mesurés. Les habitudes alimentaires ont été mesurées au temps 1 à l'aide de trois rappels alimentaires. Les analyses effectuées comprennent, entres autres, des équations d'estimation généralisées, des régressions multiniveaux et des analyses prédictives basées sur des arbres de décision. Résultats: Les résultats démontrent la présence d’associations avec l’obésité chez les jeunes et les habitudes alimentaires pour certaines caractéristiques du voisinage. En particulier, la présence de dépanneurs et de restaurants-minutes dans le voisinage résidentiel et scolaire est associée avec de moins bonnes habitudes alimentaires. La présence accrue de trafic routier, ainsi qu’un faible niveau de prestige et d’urbanisation dans le voisinage résidentiel sont associés à l’obésité familiale. Enfin, les résultats montrent qu’habiter un voisinage obésogène, caractérisé par une défavorisation socioéconomique, la présence de moins de parcs et de plus de dépanneurs, prédit l'obésité chez les jeunes lorsque combiné à la présence de facteurs de risque individuels et familiaux. Conclusion: Cette thèse contribue aux écrits sur les voisinages et l’obésité chez les jeunes en considérant à la fois l'influence potentielle du voisinage résidentiel et scolaire ainsi que l’influence de l’environnement familial, en utilisant des méthodes objectives pour caractériser le voisinage et en utilisant des méthodes statistiques novatrices. Les résultats appuient en outre la notion que les efforts de prévention de l'obésité doivent cibler les multiples facteurs de risque de l'obésité chez les jeunes dans les environnements bâtis, sociaux et familiaux de ces jeunes.

Development and Integration of Biocontrol Products in Branched Broomrape (Phelipanche ramosa) management in Tomato

Parasitic weeds of the genera Striga, Orobanche, and Phelipanche pose a severe problem for agriculture because they are difficult to control and are highly destructive to several crops. The present work was carried out during the period October, 2009 to February, 2012 to evaluate the potential of arbuscular mycorrhizal fungi (AMF) to suppress P. ramosa on tomatoes and to investigate the effects of air-dried powder and aqueous extracts from Euphorbia hirta on germination and haustorium initiation in Phelipanche ramosa. The work was divided into three parts: a survey of the indigenous mycorrhizal flora in Sudan, second, laboratory and greenhouse experiments (conducted in Germany and Sudan) to construct a base for the third part, which was a field trial in Sudan. A survey was performed in 2009 in the White Nile state, Sudan to assess AMF spore densities and root colonization in nine fields planted with 13 different important agricultural crops. In addition, an attempt was made to study the relationship between soil physico-chemical properties and AMF spore density, colonization rate, species richness and other diversity indices. The mean percentage of AMF colonization was 34%, ranging from 19-50%. The spore densities (expressed as per 100 g dry soil) retrieved from the rhizosphere of different crops were relatively high, varying from 344 to 1222 with a mean of 798. There was no correlation between spore densities in soil and root colonization percentage. A total of 45 morphologically classifiable species representing ten genera of AMF were detected with no correlation between the number of species found in a soil sample and the spore density. The most abundant genus was Glomus (20 species). The AMF diversity expressed by the Shannon–Weaver index was highest in sorghum (H\= 2.27) and Jews mallow (H\= 2.13) and lowest in alfalfa (H\= 1.4). With respect to crop species, the genera Glomus and Entrophospora were encountered in almost all crops, except for Entrophospora in alfalfa. Kuklospora was found only in sugarcane and sorghum. The genus Ambispora was recovered only in mint and okra, while mint and onion were the only species on which no Acaulospora was found. The hierarchical cluster analysis based on the similarity among AMF communities with respect to crop species overall showed that species compositions were relatively similar with the highest dissimilarity of about 25% separating three of the mango samples and the four sorghum samples from all other samples. Laboratory experiments studied the influence of root and stem exudates of three tomato varieties infected by three different Glomus species on germination of P. ramosa. Root exudates were collected 21or 42 days after transplanting (DAT) and stem exudates 42 DAT and tested for their effects on germination of P. ramosa seeds in vitro. The tomato varieties studied did not have an effect on either mycorrhizal colonization or Phelipanche germination. Germination in response to exudates from 42 day old mycorrhizal plants was significantly reduced in comparison to non-mycorrhizal controls. Germination of P. ramosa in response to root exudates from 21 day old plants was consistently higher than for 42 day-old plants (F=121.6; P<.0001). Stem diffusates from non-mycorrhizal plants invariably elicited higher germination than diffusates from the corresponding mycorrhizal ones and differences were mostly statistically significant. A series of laboratory experiments was undertaken to investigate the effects of aqueous extracts from Euphorbia hirta on germination, radicle elongation, and haustorium initiation in P. ramosa. P. ramosa seeds conditioned in water and subsequently treated with diluted E. hirta extract (10-25% v/v) displayed considerable germination (47-62%). Increasing extract concentration to 50% or more reduced germination in response to the synthetic germination stimulants GR24 and Nijmegen-1 in a concentration dependent manner. P. ramosa germlings treated with diluted Euphorbia extract (10-75 % v/v) displayed haustorium initiation comparable to 2, 5-Dimethoxy-p-benzoquinon (DMBQ) at 20 µM. Euphorbia extract applied during conditioning reduced haustorium initiation in a concentration dependent manner. E. hirta extract or air-dried powder, applied to soil, induced considerable P. ramosa germination. Pot experiments were undertaken in a glasshouse at the University of Kassel, Germany, to investigate the effects of P. ramosa seed bank on tomato growth parameters. Different Phelipanche seed banks were established by mixing the parasite seeds (0 - 32 mg) with the potting medium in each pot. P. ramosa reduced all tomato growth parameters measured and the reduction progressively increased with seed bank. Root and total dry matter accumulation per tomato plant were most affected. P. ramosa emergence, number of tubercles, and tubercle dry weight increased with the seed bank and were, invariably, maximal with the highest seed bank. Another objective was to determine if different AM fungi differ in their effects on the colonization of tomatoes with P. ramosa and the performance of P. ramosa after colonization. Three AMF species viz. GIomus intraradices, Glomus mosseae and Glomus Sprint® were used in this study. For the infection, P. ramosa seeds (8 mg) were mixed with the top 5 cm soil in each pot. No mycorrhizal colonization was detected in un-inoculated control plants. P. ramosa infested, mycorrhiza inoculated tomato plants had significantly lower AMF colonization compared to plants not infested with P. ramosa. Inoculation with G. intraradices, G. mosseae and Glomus Sprint® reduced the number of emerged P. ramosa plants by 29.3, 45.3 and 62.7% and the number of tubercles by 22.2, 42 and 56.8%, respectively. Mycorrhizal root colonization was positively correlated with number of branches and total dry matter of tomatoes. Field experiments on tomato undertaken in 2010/12 were only partially successful because of insect infestations which resulted in the complete destruction of the second run of the experiment. The effects of the inoculation with AMF, the addition of 10 t ha-1 filter mud (FM), an organic residues from sugar processing and 36 or 72 kg N ha-1 on the infestation of tomatoes with P. ramosa were assessed. In un-inoculated control plants, AMF colonization ranged between 13.4 to 22.1% with no significant differences among FM and N treatments. Adding AMF or FM resulted in a significant increase of branching in the tomato plants with no additive effects. Dry weights were slightly increased through FM application when no N was applied and significantly at 36 kg N ha-1. There was no effect of FM on the time until the first Phelipanche emerged while AMF and N application interacted. Especially AMF inoculation resulted in a tendency to delayed P. ramosa emergence. The marketable yield was extremely low due to the strong fruit infestation with insects mainly whitefly Bemisia tabaci and tomato leaf miner (Tuta absoluta). Tomatoes inoculated with varied mycorrhiza species displayed different response to the insect infestation, as G. intraradices significantly reduced the infestation, while G. mosseae elicited higher insect infestation. The results of the present thesis indicate that there may be a potential of developing management strategies for P. ramosa targeting the pre-attachment stage namely germination and haustorial initiation using plant extracts. However, ways of practical use need to be developed. If such treatments can be combined with AMF inoculation also needs to be investigated. Overall, it will require a systematic approach to develop management tools that are easily applicable and affordable to Sudanese farmers. It is well-known that proper agronomical practices such as the design of an optimum crop rotation in cropping systems, reduced tillage, promotion of cover crops, the introduction of multi-microbial inoculants, and maintenance of proper phosphorus levels are advantageous if the mycorrhiza protection method is exploited against Phelipanche ramosa infestation. Without the knowledge about the biology of the parasitic weeds by the farmers and basic preventive measures such as hygiene and seed quality control no control strategy will be successful, however.

Post-abscission, pre-dispersal seeds of Digitalis purpurea remain in a developmental state that is not terminated by desiccation ex planta

Seed quality may be compromised if seeds are harvested before natural dispersal (shedding). It has been shown previously that slow or delayed drying can increase potential quality compared with immediate rapid drying. This study set out to investigate whether or not there is a critical moisture content, below which drying terminates maturation events for seeds harvested after mass maturity but before dispersal. Seeds of foxglove (Digitalis purpurea) in the post-abscission pre-dispersal phase were held at between 15 and 95 % RH for 4 or 8 d, with or without re-hydration to 95 % RH for a further 4 d, before drying to equilibrium at 15 % RH. In addition, dry seeds were primed for 48 h at -1 MPa. Subsequent seed longevity was assessed at 60 % RH and 45 degrees C. Rate of germination and longevity were improved by holding seeds at a wide range of humidities after harvest. Longevity was further improved by re-hydration at 95 % RH. Priming improved the longevity of the seeds dried immediately after harvest, but not of those first held at 95 % RH for 8 d prior to drying. Maturation continued ex planta in these post-abscission, pre-dispersal seeds of D. purpurea dried at 15-80 % RH at a rate correlated positively with RH (cf. ageing of mature seeds). Subsequent re-hydration at 95 % RH enabled a further improvement in quality. Priming seeds initially stored air-dry for 3 months also allowed maturation events to resume. However, once individual seeds within the population had reached maximum longevity, priming had a negative impact on their subsequent survival.

Emergence of Chenopodium album and Stellaria media of different origins under different climatic conditions

The emergence behaviour of weed species in relation to cultural and meteorological events was studied. Dissimilarities between populations in dormancy and germination ecology, between-year maturation conditions and seed quality and burial site climate all contribute to potentially unpredictable variability. Therefore, a weed emergence data set was produced for weed seeds of Stellaria media and Chenopodium album matured and collected from three populations (Italy, Sweden and UK). The seeds were collected in two consecutive seasons (1999 and 2000) and subsequently buried in the autumn of the same year of maturation in eight contrasting climatic locations throughout Europe and the USA. The experiment sought to explore and explain differences between the three populations in their emergence behaviour. Evidence was demonstrated of synchrony in the timing of the emergence of different populations of a species at a given burial site. The relative magnitudes of emergence from the three populations at a given burial site in a given year were generally similar across all the burial sites in the study. The resulting data set was also used to construct a simple weed emergence model, which was tested for its application to the range of different burial environments and populations. The study demonstrated the possibility of using a simple thermal time-based model to describe part of the emergence behaviour across different burial sites, seed populations and seasons, and a simple winter chilling relationship to adjust for the magnitude of the flush of emergence at a given burial site. This study demonstrates the possibility of developing robust generic models for simple predictions of emergence timing across populations.

Clinical risk factors for osteoporotic fractures in Brazilian women and men: the Brazilian Osteoporosis Study (BRAZOS)

The Brazilian Osteoporosis Study (BRAZOS) is the first epidemiological study carried out in a representative sample of Brazilian men and women aged 40 years or older. The prevalence of fragility fractures is about 15.1% in the women and 12.8% in the men. Moreover, advanced age, sedentarism, family history of hip fracture, current smoking, recurrent falls, diabetes mellitus and poor quality of life are the main clinical risk factors associated with fragility fractures. The Brazilian Osteoporosis Study (BRAZOS) is the first epidemiological study carried out in a representative sample of Brazilian men and women aged 40 years or older with the purpose of identifying the prevalence and the main clinical risk factors (CRF) associated with osteoporotic fracture in our population. A total of 2,420 individuals (women, 70%) from 150 different cities in the five geographic regions in Brazil, and all different socio-economical classes were selected to participate in the present survey. Anthropometrical data as well as life habits, fracture history, food intake, physical activity, falls and quality of life were determined by individual quantitative interviews. The representative sampling was based on Brazilian National data provided by the 2000 and 2003 census. Low trauma fracture was defined as that resulting of a fall from standing height or less in individuals 50 years or older at specific skeletal sites: forearm, femur, ribs, vertebra and humerus. Sampling error was 2.2% with 95% confidence intervals. Logistic regression analysis models were designed having the fragility fracture as the dependent variable and all other parameters as the independent variable. Significance level was set as p < 0.05. The average of age, height and weight for men and women were 58.4 +/- 12.8 and 60.1 +/- 13.7 years, 1.67 +/- 0.08 and 1.56 +/- 0.07 m and 73.3 +/- 14.7 and 64.7 +/- 13.7 kg, respectively. About 15.1% of the women and 12.8% of the men reported fragility fractures. In the women, the main CRF associated with fractures were advanced age (OR = 1.6; 95% CI 1.06-2.4), family history of hip fracture (OR = 1.7; 95% CI 1.1-2.8), early menopause (OR = 1.7; 95% CI 1.02-2.9), sedentary lifestyle (OR = 1.6; 95% CI 1.02-2.7), poor quality of life (OR = 1.9; 95% CI 1.2-2.9), higher intake of phosphorus (OR = 1.9; 95% CI 1.2-2.9), diabetes mellitus (OR = 2.8; 95% CI 1.01-8.2), use of benzodiazepine drugs (OR = 2.0; 95% CI 1.1-3.6) and recurrent falls (OR = 2.4; 95% CI 1.2-5.0). In the men, the main CRF were poor quality of life (OR = 3.2; 95% CI 1.7-6.1), current smoking (OR = 3.5; 95% CI 1.28-9.77), diabetes mellitus (OR = 4.2; 95% CI 1.27-13.7) and sedentary lifestyle (OR = 6.3; 95% CI 1.1-36.1). Our findings suggest that CRF may contribute as an important tool to identify men and women with higher risk of osteoporotic fractures and that interventions aiming at specific risk factors (quit smoking, regular physical activity, prevention of falls) may help to manage patients to reduce their risk of fracture.

Adequação do teste de condutividade elétrica para determinar a qualidade fisiológica de sementes de jacarandá-da-bahia (Dalbergia nigra (Vell.) Fr.All. ex Benth.)

Para testar o efeito da temperatura e do tempo de embebição nos valores de condutividade elétrica e verificar sua aplicabilidade para determinar a qualidade fisiológica de sementes de Dalbergia nigra (jacarandá-da-bahia), foram utilizadas sementes colhidos em três anos (lote I _ 1998; lote II _ 1997 e lote III - 1994). Inicialmente determinou-se o teor de água e depois conduziu-se os testes de germinação em laboratório e viveiro, utilizando-se quatro repetições de 25 sementes. Para estudar a condutividade elétrica (CE) foram utilizadas quatro repetições de 50 sementes. Cada subamostra foi colocada em recipiente contendo 75ml de água deionizada, embebidas por 6, 12, 18, 24, 30 e 36 horas, a 20, 25 e 30ºC. Sementes do lote II apresentaram maiores valores na primeira contagem da germinação, diferindo significativamente dos demais lotes. O lote III apresentou qualidade inferior. Com o aumento do período e da temperatura de embebição ocorreu aumento nos valores de CE das sementes dos três lotes. O lote III mostrou qualidade fisiológica inferior a dos lotes I e II, que apresentaram valores mais elevados de CE. Não houve diferenciação entre os lotes I e II. Concluiu-se que o teste de CE foi eficiente para diferenciar os lotes de sementes de Dalbergia nigra, com alto grau de associação com o teste de germinação.

Testes bioquímicos para avaliação do vigor em sementes de Mimosa caesalpiniaefolia Benth

Mimosa caesalpiniaefolia Benth. is a forest species of the Mimosaceae family, recommended for recovery of degraded areas. The evaluation of vigor by biochemical tests have been an important tool in the control of seed quality programs, and the electrical conductivity and potassium leaching the most efficient in the verifying the physiological potential. The objective, therefore, to adjust the methodology of the electrical conductivity test for seeds of M. caesalpiniaefolia, for then compare the efficiency of this test with the potassium in the evaluation of seed vigor of different lots of seeds M. caesalpiniaefolia. To test the adequacy of the electrical conductivity were used different combinations of temperatures , 25 °C and 30 ºC, number of seeds , 25 and 50, periods of imbibition , 4 , 8 , 12 , 16 and 24 hours , and volumes deionized water, 50 mL and 75mL. For potassium leaching test, which was conducted from the results achieved by the methodology of the adequacy of the electrical conductivity test, to compare the efficiency of both tests , in the classification of seeds at different levels of vigor, and the period 4 hours also evaluated because the potassium leaching test can be more efficient in the shortest time . The best combination obtained in experiment of electrical conductivity is 25 seeds soaked in 50 mL deionized or distilled water for 8 hours at a temperature of 30 ° C. Data were subjected to analysis of variance, the means were compared with each other by F tests and Tukey at 5 % probability, and when necessary polynomial regression analysis was performed. The electrical conductivity test performed at period eight hour proved to be more efficient in the separation of seed lots M. caesalpiniaefolia at different levels of vigor compared to the potassium test

Desempenho de sementes de algodão tratadas quimicamente e armazenadas

Considerando que o armazenamento desempenha papel decisivo na manutenção da qualidade da semente, desenvolveu-se este trabalho com o objetivo de avaliar a qualidade fisiológica e fitossanitária de sementes de algodão, tratadas quimicamente e armazenadas por doze meses. Foram utilizados dois lotes de sementes de algodão cv. DeltaPine-AC90, deslintados quimicamente, que foram submetidos aos tratamentos fungicidas e inseticidas: testemunha; Disulfoton + Carboxin + Thiram; Carbofuran + Carboxin + Thiram; Imidacloprid + Tolylfluanid + Pencycuron. As sementes foram armazenadas em armazém sem controle de temperatura e umidade relativa do ar. Foram retiradas amostras de sementes no início do armazenamento e a cada dois meses e avaliadas quanto ao teor de água, à porcentagem de germinação, ao vigor (testes de envelhecimento acelerado e de germinação à baixa temperatura), à sanidade e à emergência das plântulas. O delineamento utilizado foi o inteiramente casualizado, em esquema fatorial, com quatro repetições. Verificou-se redução da germinação e do vigor de sementes em função do armazenamento. A redução da qualidade fisiológica associou-se com o aumento na ocorrência de Aspergillus sp. e Penicillium sp. nas sementes. A manutenção da qualidade de sementes de algodão foi obtida até o oitavo mês de armazenagem, podendo-se concluir que: a eficiência do tratamento químico de sementes de algodão depende da combinação de produtos utilizados; não se deve tratar com fungicida sementes de algodão com baixo nível de vigor; a ocorrência dos fungos Aspergillus sp. e Penicillium sp. aumentou com o período de armazenamento nas sementes sem tratamento e que a manutenção da qualidade de sementes de algodão para comercialização depende da sua qualidade inicial e do período de armazenamento.

Efeito de diferentes períodos de irrigação no desenvolvimento, produção e qualidade de sementes na cultura do milho (Zea mays L.)

O presente trabalho foi realizado em área demonstrativa de irrigação do Departamento de Engenharia Rural da Faculdade de Ciências Agrárias e Veterinárias, da Universidade Estadual Paulista (FCAV/UNESP), Jaboticabal - SP, tendo como objetivo avaliar os efeitos da deficiência hídrica no desenvolvimento da planta, na produção e na qualidade fisiológica de sementes da cultura do milho (Zea mays L.). O delineamento experimental foi o inteiramente casualizado, com os tratamentos em esquema fatorial 2 x 3, com quatro repetições. Os tratamentos consistiram da utilização de sementes de milho híbrido BR201 e DINA-70, com três períodos de irrigação: 1) durante todo o ciclo; 2) após o período vegetativo (após a emissão da 12ª folha), e 3) até 20 dias após o florescimento (antes do período de enchimento dos grãos). Concluiu-se que a deficiência hídrica durante o período vegetativo (irrigação após a emissão da 12ª folha) foi a mais prejudicial à cultura e à produção; essa deficiência hídrica não afetou a qualidade fisiológica das sementes produzidas, e o híbrido DINA-70 apresentou melhores resultados para os parâmetros fisiológicos e de produção que o híbrido BR201.

Detecção, transmissão e efeito de Xanthomonas campestris pv. campestris na qualidade fisiológica de sementes de brócolis

A detecção, a transmissão e o efeito de Xanthomonas campestris pv. campestris (Xcc) na qualidade fisiológica de sementes de brócolis (Brassica oleracea var. italica) foram avaliados, a partir de sementes obtidas de plantas (Baron, Flórida, Hana Midori Sakata, Precoce Piracicaba de Verão, Ramoso Santana e Sabre) inoculadas com a bactéria, em condições de campo. Para a detecção do patógeno nas sementes foram utilizados os meios de cultura semi-seletivos: SX ágar, NSCAA e BSCAA; a taxa de transmissão da bactéria pelas sementes às plântulas foi avaliada usando semeadura em areia e meio de cultura contido em tubo de ensaio. Para a avaliação da qualidade fisiológica de sementes foram realizados o teste padrão de germinação e os testes de vigor: envelhecimento acelerado, índice de velocidade de emergência, crescimento de plântulas e massa seca. de acordo com os resultados, o meio de cultura semi-seletivo NSCAA foi mais eficaz para detectar Xcc em sementes de brócolis; não houve diferença significativa entre os genótipos na taxa de transmissão da bactéria pelas sementes e Xcc não afetou a germinação e o vigor das sementes.

Teste de condutividade elétrica em sementes de Albizia hassleri (Chodat) burkart. fabaceae-mimosoideae

Este trabalho teve por objetivo verificar o uso do teste de condutividade elétrica para avaliar a qualidade fisiológica de sementes de Albizia hassleri (Chod) Burkart. provenientes de diferentes matrizes. O teste de condutividade elétrica foi realizado a 25 ºC, com cinco repetições de 20 sementes embebidas em 75 mL de água destilada por 2, 4, 6, 12, 24, 48, 72, 96 e 120 h. O teste de germinação foi conduzido a 25 ºC com cinco repetições de 20 sementes por 19 dias. Os dados foram submetidos à análise de variância e as médias de matrizes, comparadas pelo teste de Scott-Knott a 5% de probabilidade. Adicionalmente, procedeuse ao estudo de correlações entre os resultados de condutividade elétrica com os do teste de germinação e ao ajuste de regressões entre os valores de sementes com protrusão de radícula e de plântulas normais em função dos valores de condutividade elétrica, em cada período de embebição das sementes. Verificou-se grande variabilidade entre as matrizes, tanto no teste de germinação quanto no de condutividade elétrica. Os resultados de condutividade elétrica apontaram baixas estimativas de correlações com os obtidos no teste de germinação. As equações de regressão apresentaram baixos valores de coeficiente de determinação, denotando-se a grande variabilidade dos resultados. Pode-se concluir que o teste de condutividade elétrica não foi adequado para discriminação da qualidade fisiológica de sementes de A. hasslerii provenientes de diferentes árvores-matriz.

Envelhecimento acelerado de sementes de espécies oleráceas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Testes de vigor para avaliação de sementes de pepino

Dentro de um programa de controle de qualidade, a avaliação do vigor de sementes é fundamental e necessária para o sucesso da produção. O trabalho teve por objetivo comparar diferentes métodos para avaliação do potencial fisiológico de sementes de pepino. Para tanto, cinco lotes de sementes do híbrido Safira foram submetidos aos seguintes testes: germinação, primeira contagem de germinação, condutividade elétrica (4x50 sementes; 25ºC; 50 e 75mL; 12, 18 e 24h), germinação a baixa temperatura (4x50 sementes; 18ºC; contagens aos quatro e oito dias após a semeadura); envelhecimento acelerado tradicional (41ºC; 48, 72 e 96h) e com solução saturada de NaCl (41ºC; 72 e 96h). Pelos resultados obtidos, pode-se concluir que os testes de condutividade elétrica (50 e 75mL; 12, 18 e 24h) e de envelhecimento acelerado com o uso de solução salina (41ºC, por 72h), possibilitam a melhor identificação de lotes com diferentes níveis de qualidade fisiológica.

Metodologia alternativa para condução do teste de envelhecimento acelerado em sementes de milho

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)