Germination test for papaya seeds demands thirty days to obtain the results, which is a long period for decision-making. Thus, rapid tests become essential tools to evaluate seed viability, and the tetrazolium test is an alternative for this purpose. Hence, this study aimed to establish the adequate procedure to apply this test, in order to reduce the time of evaluation of papaya seeds. For that, four tetrazolium solution concentrations (0.05, 0.1, 0.5 and 1%) and three staining times (3, 6 and 9 hours) were tested at temperatures of 35 and 40 ºC. The experimental design was completely randomized in 4 × 3 + 1 factorial scheme (concentrations × staining times + one control = germination test). It was found that the tetrazolium test allows to evaluate the physiological quality of papaya seeds, thus reducing the time for decision-making. For the test, we recommend using the concentrations of 0.1% for 9 hours or 1% for 6 hours of staining, at temperature of 40 ºC.

The purpose of this research was to verify the efficiency of physical and biochemical indices in determining the physiological maturity of Tabebuia aurea seeds, as well as to evaluate the post-harvest storage of fruits with different maturation stages on germination and vigor. For this, 200 fruits were classified as dark green (stage I), light green (stage II), and light brown (stage III) epicarp. Freshly harvested fruits were evaluated for length, width, and weight and their seeds for length, width, thickness, thousand-seed weight, water content, electrical conductivity, and chemical composition. Subsequently, a factorial consisting of three maturation stages and four storage periods of fruits (0, 5, 10 and 15 days) were used, and water content, germination, germination speed index, root length, shoot length, and seedling dry matter were evaluated. Physical and biochemical indices can be used as maturation indicators in T. aurea seeds, except fruit length, seed thickness, electrical conductivity, and protein content. The maximum germination and vigor of T. aurea seeds were obtained in fruits at stages I (dark green) or II (light green) associated with post-harvest storage of fifteen days.

Water availability influences plant metabolism during the various stages of development, especially in the period between germination and seedling emergence. The aim of this study was to evaluate the effect of water deficit during the germination process on seeds of A. oleracea. The experiment was carried out in a completely randomised design, with four replications of 50 seeds. The treatments were arranged in a 5 x 2 factorial scheme, with the first factor consisting of the osmotic potentials (-0.2, -0.4, -0.6, -0.8 and distilled water for the potential 0.0 MPa) and the second factor consisting of two lots of seed. The germination test was carried out on substrates moistened with solutions of mannitol and polyethylene glycol (PEG 6000) at the various potentials, in a Biochemical Oxygen Demand (BOD) germinator at a temperature of 30°C and under constant light. The test was evaluated daily for 14 days, considering the seeds that had a root length equal to or greater than two millimetres as having germinated. The variables under analysis were germination, germination speed index, seedling length and seedling dry weight. The germination process of A. oleracea is compromised at water potentials of -0.2 MPa and -0.4 MPa when submitted to PEG and mannitol respectively. Seeds from Lot 1 were more tolerant to the water deficit than were those from Lot 2.

IntroduçãoPiptadenia moniliformis Benth. é uma espécie arbórea pertencente a família Fabaceae, nativa do Nordeste brasileiro mais conhecida popularmente como catanduva. Destaca-se na alimentação animal como forragem e alto valor apícola, além do potencial madeireiro para lenha e carvão para a comunidade de baixa renda. Também é indicada para composição de reflorestamentos heterogêneos para fins preservacionistas, uma vez que, possui rápido crescimento e pode atingir até 10 metros de altura (LORENZI, 2002;MAIA, 2004).A salinidade é um dos principais estresses abióticos que afeta a produção de culturas em regiões áridas e semi-áridas. A germinação de sementes e o crescimento de plântulas podem ser comprometidos devido à redução de disponibilidade de água, mudanças na mobilização de reservas armazenadas e afetando a organização estrutural de proteínas (IBRAHIM, 2016).Neste sentido, algumas técnicas alternativas devem ser utilizadas para amenizar os efeitos negativos da exposição ao sal, dentre elas, o condicionamento fisiológico (MARCOS-FILHO, 2015) que consiste na embebição controlada das sementes, suficiente para promover a ativação das fases iniciais da germinação (fases I e II), sem que ocorra protusão da raiz primária (fase III) (BEWLEY;BLACK, 1994). Os principais tipos de condicionamento utilizados são o hidrocondicionamento (com uso de água para hidratação das sementes) e o condicionamento osmótico (emprego de soluções de polietilenoglicol, manitol, sais) já empregado principalmente para espécies de hortaliças.

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