João Paulo Nobre de Almeida

Estresse hídrico e massa de sementes na germinação e crescimento de plântulas de Amburana cearensis (Allemão) A.C. Smith

Amburana cearensis, known locally as Cumaru, is a species found throughout the caatinga biome, being recommended in the reclamation of degraded areas and for use in phytotherapy. The aim of the present work was to determine the levels of tolerance to water stress at germination and on seedling growth in seedlings of the cumaru, as a function of seed weight. The seeds were initially weighed and separated into three classes (light, medium and heavy), then subjected to water stress using solutions of polyethylene glycol 6000 at different potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and left to germinate at 30 °C in germination chambers. The experimental design was a completely randomised 3 x 6 factorial scheme (weight class x water potential). To evaluate germination, first count, final percentage and rate of germination index were determined, while to evaluate seedling growth, the length and dry weight of the epicotyl and of the root axis plus hypocotyl, and the shoot to root ratio were all determined. Data were tested for normality, and if normal, variance analysis, means comparison and regression were carried out. A decrease in water potential impairs the germination and growth of seedlings derived from medium and heavy seeds in relation to light seeds, with potentials of -0.6 MPa or more strictly limiting the formation of normal seedlings of A. cearensis.

Tetrazolium test for the viability of gherkin seeds

The tetrazolium test is a quick and effective method for evaluating viability in seeds. The aim of this study was to determine a methodology for using the tetrazolium test, and its efficiency in verifying viability in seeds of the gherkin (Cucumis anguria L.). Consequently, five batches of gherkin seed were initially evaluated by the tests for germination, first count and speed of germination. The batches were then subjected to treatments in order to adjust the methodology for the tetrazolium test, evaluating three concentrations of tetrazolium solution (0.100, 0.075 and 0.050%), kept in the dark for two, four and six hours, under temperatures of 35 °C and 40 °C, with four replications of 25 seeds per treatment. At the end of the staining period, the seeds were washed in running water, split lengthways between the cotyledons, and classified as viable and non-viable. Evaluation of viability in seeds of the gherkin by tetrazolium test is efficient when carried out at a concentration of 0.050%, either for six hours at 35 °C or four hours at 40 °C.

Teste de condutividade elétrica na avaliação da qualidade fisiológica de sementes de coentro

Os testes de germinacao e de vigor sao componentes essenciais do processo de controle de qualidade das empresas produtoras de sementes. Diante disso, nesta pesquisa o objetivo foi estudar a metodologia do teste de condutividade eletrica, verificando sua eficiencia na identificacao de diferentes niveis de vigor de lotes de sementes de coentro. Para tanto, utilizaram-se quatro cultivares (Portugues, Super Verdao, Tabocas e Verdao), cada uma representada por quatro lotes de sementes, que inicialmente foram submetidas as avaliacoes do grau de umidade, germinacao, primeira contagem de germinacao e emergencia de plântulas. O teste de condutividade eletrica foi realizado com 25 e 50 sementes embebidas em 50 e 75 mL de agua destilada, a 25 oC, por 2, 8 e 24 horas. O teste de condutividade eletrica e eficiente para a avaliacao do potencial fisiologico de sementes de coentro quando conduzido com 50 sementes imersas em 50 mL de agua destilada, a 25 oC, apos duas horas de embebicao.

Armazenamento e qualidade pós-colheita de frutos de figueira cv. Roxo de Valinhos no Oeste Potiguar

Fig tree fruit have a relatively short shelf life due to their fragile structure and high metabolism, which requires enormous storage. This study aims to evaluate the physical and chemical attributes in the different storage times in post-harvest conservation of fig tree cv. Purple of Valinhos. A completely randomized experimental design was used in a 5 × 3 factorial scheme (5 storage times: 0, 4, 8, 12, 16 days) and (3 harvest points: 50, 75 and 100% mature) with four replicates and 8 fruits per treatment. The fruits were stored in a cold room, with a temperature of 10 ± 2°C and 80-90% relative humidity. These storage conditions were an efficient alternative to maintain fruit quality for up to 4 days for fresh mass and vitamin C characteristics, while soluble solids content (°Brix) had its best values at 16 days of storage. The stage of maturation III obtained greater length and diameter as well as smaller loss of fresh mass and firmness of the fruits.