Maria Laene Moreira de Carvalho

Avaliação de métodos para quebra da dormência e para a desinfestação de sementes de canafístula (Peltophorum dubium (Sprengel) Taubert

Este trabalho teve como objetivo testar a eficiencia de diferentes tratamentos para quebra da dormencia e desinfestacao de sementes de canafistula na realizacao do teste de germinacao. O experimento foi realizado em esquema fatorial com tres lotes × cinco tratamentos para quebra da dormencia × quatro tratamentos de desinfestacao das sementes. As sementes utilizadas foram coletadas nos municipios de Lavras-MG, em 1986 e 1998, e em Lins-SP, em 1998. Os tratamentos para quebra da dormencia foram constituidos por escarificacao manual com lixa, agua quente (a- fervura das sementes por 3 minutos com imersao por 24 horas, fora do aquecimento; e b - imersao das sementes em agua quente por 24 horas, fora do aquecimento) e acido sulfurico (imersao por 15, 17, 20 e 30 minutos). Para desinfestacao das sementes foram testados os tratamentos, utilizando Polyfluanide (0,2% por 30 minutos), Benomyl (0,02% por 1 minuto) e hipoclorito de sodio (2% por 3 minutos). Foram utilizadas quatro repeticoes de 25 sementes em cada tratamento. O teste de germinacao foi instalado sobre areia, na temperatura de 25 oC, sob luz branca constante. As contagens de germinacao (plântulas normais) foram realizadas diariamente. O tratamento de imersao das sementes de canafistula em agua quente (95 oC) e posterior permanencia na mesma agua por mais 24 horas, fora do aquecimento, e eficiente na promocao da germinacao, sendo pratico e dispensando o uso de tratamentos de desinfestacao.

Utilização do teste de raios-X na avaliação da qualidade de sementes de canafístula (Peltophorum dubium (Sprengel) Taubert

Leguminous seeds are common targets for mechanical injury, many times invisible to the human eye. Because of this, it was found necessary to utilize tests, such as the X-ray test, which makes possible the evaluation of this type of injury. The objectives of this project were: to verify the efficiency of the X-ray tests in relationship with physical damage to canafistula seed, to verify the effect of this damage to germination and also to evaluate the regularity that machine should be used. Seeds collected in Lavras-MG in 1986 and 1998, and Lins-SP in 1998 were utilized. Seeds from three groups were placed in an acrylic support with 100 partitions and exposed to radiation for various amounts of time and intensity, utilizing equipment 43855 A X-Ray System (Faxitron-HP). Four partitions of 100 seeds were used for each group. The seeds were divided into three categories according to their internal anatomy visualized by radiographs in full seeds, seeds with little physical damage and seeds with severe physical damage. Subsequently, seed dormancy was broken and then submitted to germination tests. The results obtained provided that a time of 60 seconds and an intensity of 25 KVp allowed the brighter internal visualization of seeds. Severe internal damage detected by radiographs might effect the germination of canafistula seeds, and its justify the remotion of those seeds to improve the physical and physiological quality of canafistula lots.

Adequação do teste de raios X para avaliação da qualidade de sementes de Embaúba (Cecropia pachystachya Trec.)

The x-ray test was studied to evaluate the quality of embauba seeds and verify the influence of the internal morphology on the seed germination. Seeds of a lot harvested in 2005 were used from the Bio Flora company. The seeds were exposed to radiation for various amounts of time and intensity, using Faxitron X-Ray equipment, model MX-20. The seeds were divided into three categories according to their internal structure visualized by radiographs in totally formed, partially formed and not formed seeds. Soon after, seeds were submitted to the germination test. The results showed that the time of 360 seconds and 10kV intensity are recommendable for visualizing internal seed structures. The x-ray test is efficient to evaluate development level of embauba seed structure. There is correlation between seed formation and the germination test results.

Avaliação da qualidade de sementes de Tabebuia serratifolia Vahl Nich. e T. impetiginosa(Martius ex A. P. de Candolle) Standley - (Bignoniaceae) pelo teste de raios X

4RESUMO - Para estudar a eficiencia do teste de raios X na avaliacao de defeitos internos em sementes de ipe-amarelo (Tabebuia serratifolia) e ipe-roxo (T. impetiginosa), bem como verificar a consequencia destes defeitos na germinacao, as sementes foram submetidas a diferentes intensidades e tempos de exposicao a radiacao. Definida a intensidade de 55 kV por 25 segundos como sendo a que permitiu melhor visualizacao das estruturas internas, as sementes das duas especies foram divididas em tres categorias de acordo com a sua analise radiografica em: Sem Defeitos, Com Defeitos e Vazias. As Sementes Com Defeitos foram divididas em tres subcategorias: Com Pequenos Danos (menos de 50% do embriao danificado), Com Danos Severos (mais de 50% do embriao danificado) e Deformadas. As sementes foram, entao, submetidas ao teste de germinacao em substrato sobre areia, a 30 o C, sob luz constante. O teste de raios X e eficiente na avaliacao de defeitos em sementes de ipe-amarelo e ipe-roxo. Defeitos internos detectados nas radiografias afetam a germinacao dessas sementes, reduzindo a qualidade do lote.

Armazenamento a vácuo de semente de milho doce

This study evaluated the effect of different packaging types and storage environments on sweet corn quality after 18 months of storage. Three types of packaging were evaluated: three-layered Kraft paper package, plastic package and vacuum conditioning (0.1 atm). Seeds stored in paper package were treated with fungicides and insecticides. Two moisture contents were evaluated in the seeds stored in impermeable (plastic) package: 8 and 11%. The seeds were stored in a cold room or in a conventional warehouse. Seed quality was evaluated using the tests of germination, emergence speed index, cold test, sanitary test and the evaluation of changes in ADH and MDH enzyme systems. Storage in a cold room was more effective in preserving the physiologic quality of sweet corn seeds, and in this environment, storage of treated seeds in paper or plastic packages was more adequate for seed preservation. Storing sweet corn seeds in a conventional warehouse, packaging under vacuum or in plastic package assured smaller reductions in seed physiologic quality after 18 months. The incidence of the fungi Fusarium moniliforme and Aspergillus sp. in the cold room and Aspergillus sp. In the conventional storage was favored regardless of the type of package in the storage of sweet corn seeds that were not treated with fungicides.

Classificação de sementes de espécies florestais dos gêneros Nectandra e Ocotea (Lauraceae) quanto ao comportamento no armazenamento

Studies on seed storage behaviour allow the establishment of suitable conditions to maintain seed viability, in order to support programs of ex situ conservation and seedling production. Thus, this study aimed to investigate the seed storage behavior of five species of the Lauraceae family which grow in South of Minas Gerais State, Brazil. Seeds of Nectandra grandiflora, Nectandra lanceolata, Nectandra oppositifolia, Ocotea corymbosa and Ocotea pulchella were assessed regarding germination and moisture content before and after artificial drying. The seeds show recalcitrant behaviour due to their desiccation sensitivity.

Teste de condutividade elétrica individual na avaliação da qualidade fisiológica de sementes de café (Coffea arabica L.)

O teste de condutividade eletrica e usado para medir os exsudatos das sementes, que certamente refletem a integridade do sistema de membranas. O teste e rapido e de operacao simples, mas a metodologia necessita ser testada para cada especie individualmente para obter uma melhor precisao e exatidao dos resultados. Este trabalho foi conduzido visando determinar o ponto de particao na realizacao do teste de condutividade eletrica em sementes de cafe. Dez lotes de sementes de Coffea arabica sem pergaminho, cultivar Acaia foram usados nesse estudo. Para a avaliacao do ponto de particao as sementes foram embebidas por 96 horas e submetidas ao teste de germinacao, correlacionando os valores de condutividade observados com os valores obtidos no teste de germinacao. O ponto de particao e de 120,5µS.cm-1, considerando 70% de germinacao.

Eletrical conductivity test to evaluate physiological quality of castor bean seeds

The increasing demand for castor bean seeds in Brazil has promoted more interest in the development of tests to assess seed lots with superior quality. To investigate the possibility of using the electrical conductivity test for evaluation of the physiological quality of castor bean seed, ten seed lots from the cultivars AL Guarany 2002 and IAC 80 were used. The seeds were submitted to the bulk and individual conductivity test in four imbibition periods (6, 12, 18 and 24 hours). The lots were characterized by the germination test, first count, seedling emergency, initial emergency, emergence speed index and tetrazolium test. The moisture content of the seeds, the imbibition curve and seed health were also determined. The bulk conductivity test was carried out by using plastic cups with 25 seeds each in 75 ml deionized water, incubated in a BOD at a constant temperature of 25°C. The individual conductivity was determined by an SAD-9000S automatic seed analyzer. In contrast to the determination of seed physiological quality using the individual conductivity test, the bulk conductivity test was efficient in the detection of differences in castor seed lot quality and the period of 6 hours was the imbibition time indicated for the test.

Adequação do teste de germinação para sementes de nabo forrageiro

O estabelecimento de condicoes ideais para conducao do teste de germinacao de sementes de nabo forrageiro e extremamente util para avaliacao da qualidade de lotes. Para definir a temperatura otima e substrato ideal para a avaliacao da germinacao de sementes de nabo forrageiro, foram utilizadas sementes de diferentes lotes das cultivares CATI AL-1000 e IPR 116. A semeadura foi efetuada nos substratos papel e areia, e as sementes, mantidas em seis regimes de temperatura constante (15oC; 20oC; 25oC; 30oC; 35oC) e um alternado (20oC-30oC). A qualidade das sementes de nabo forrageiro foi avaliada pelas determinacoes do grau de umidade, teste de germinacao, primeira contagem da germinacao, indice de velocidade de germinacao, emergencia, estande inicial, indice de velocidade de emergencia e teste de sanidade. A temperatura de 20oC-30oC e o substrato areia sao condicoes adequadas para a realizacao do teste de germinacao das sementes de nabo forrageiro das cultivares CATI AL-1000 e IPR 116.

Morphophysiological development of Tabeluia serratifolia Vahl Nich. seeds

Tabebuia serratifolia is used for the reforestation of degraded areas. Despite protection by law for permanent preservation, the species is in danger of extinction due to improper exploitation. With the objective to aid preservation and long term storage of the species we evaluated morphophysiological alterations of T. serratifolia seeds during the maturation process in order to identify markers that can be used for harvesting and storage. Fruits were collected at anthesis and seven developmental stages from trees growing in Lavras, state of Minas Gerais, Brazil. At each harvest, fruits and seeds were evaluated for color and size, moisture content, dry matter, internal morphology (by X-ray analysis), germination parameters (in vitro and ex vitro), as well as sugar and polyphenol content and heat resistant proteins. During the maturation process the initially green fruits changed to a brownish color and grew from a length of 7 to 18 cm; cracks appeared at the beginning of seed dispersal. The seed color varied from leaf-green to brownish and the length from 1 to 3 cm. The first indicatior of physiological maturity should be observed at 39 days post-anthesis, when variations the color and size of both fruits and seeds were observed. Increase in the moisture content, dry matter and germination, percentage of seeds and embryos in vitro, as well as a reduction in sugar content and LEA proteins were also observed. The physiological maturity of T. serratifolia seeds was reached 53 days after anthesis, coinciding with a maximum of dry matter accumulation and germination (and index of germination speed ex vitro), decrease in phenol levels, higher intensity of heat-resistant protein bands and the beginning of fruit opening.