Emanoela Pereira de Paiva

Condicionamento fisiológico e vigor de sementes de maxixe

Priming is a technique for controlling seed hydration that allows activation of germination metabolic processes but avoiding the emission of the primary root and providing uniformity and better plant performance in the field. The objective of this study was to evaluate the effects of hydropriming on germination, emergence and seedling development in gherkins. Gherkin seeds of the Do Norte and Nordeste cultivars, represented by three lots, were primed at 20 °C on paper towels until they reached 33.5% (Nordeste) or 36.6% (Do Norte) water content. Part of the seeds were dried at room temperature (28-34 ° C) and a relative humidity of 45-55% until water content was 7.0 to 8.5%. The physiological potential of the seeds was determined in the laboratory by evaluating germination rate and speed. Later, the percentage and emergence speed index, height and dry mass of seedlings 14 days after sowing were determined in the greenhouse. Hydropriming benefitted the germination and vigor characteristics of both cultivars.

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.

Qualidade fisiológica de sementes de girassol avaliadas por condutividade elétrica

The seed quality evaluation is essential in quality control programs. Thus, vigor tests have been developed to differentiate seed lots, due to the limitations of the germination test. This study aimed at evaluating the electrical conductivity test efficiency for determining the physiological quality of sunflower seeds. Ten lots of sunflower seeds (Catissol and Multissol cultivars) were used. Initially, the quality of each lot was determined, besides the seeds moisture content, by using tests of germination, first counting and seedling emergence, in a greenhouse. Then, the seeds were submitted to the electrical conductivity test, for four soaking periods (6, 12, 18 and 24 hours), by using disposable plastic cups containing 25 and 50 seeds, in 50 mL and 75 mL of deionized water, at 25°C and 30°C. The experimental design was completely randomized, in a 5x4 factorial scheme (five lots and four soaking periods), separately for each cultivar, with four replications. It was possible to conclude that the electrical conductivity test combining 25°C, 75 mL of deionized water and 50 seeds was sufficiently sensitive to evaluate the physiological quality of sunflower seeds.

Water Stress Affect Germination, Seed Vigor and Seedlings Growth of Bidens subalternans

The beggartick (Bidens subalternans L.) is one of the main weeds present in agricultural crops, capable of adapting to different environmental conditions. The water stress caused by water deficiency can affect the germination of weed seeds and, consequently, their capacity to colonize the agroecosystem. Knowledge of germination under water stress can be important to obtain an adequate management of the species in the agricultural systems. The objective of this study was to determine the effects of water stress on the germination process and vigor of two batches of Bidens subalternans seeds under different osmotic agents. It was completely randomized experimental design was used, with four replicates of 25 seeds. The treatments were arranged in factorial 6 × 2, with the first factor corresponding six levels of osmotic potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and the second the batches (Pernambuco and Ceara). For the simulation of the water stress, the test of germination was installed in substrate paper blotting, moistened with solutions of polyethylene glycol (PEG 6000) and mannitol. The analyzed variables were germination, germination speed index, length and seedling dry mass. Water stress reduced germination, seed vigor and growth of seedlings in all batches of B. subalternans. Seeds of B. subalternans presented greater tolerance to stress induced by mannitol than to PEG-6000 in terms of germination and germination speed index. Regardless of the osmotic agent used for stress induction, B. subalternans seeds did not tolerate water stress higher than -0.4 MPa.

Accumulation of salts in the soil and growth of cowpea under salinity and phosphorus fertilization

Cowpea is widely grown in the Brazilian semiarid region, however, due to excess salts in the soil and irrigation water constantly low crop productivity has been observed. Accumulation of salts in the soil, growth and biomass partition of cowpea under salt stress and phosphorus fertilization was evaluated in this study. The assay was conducted in a greenhouse in Mossoro, State of Rio Grande do Norte, Brazil, from September to December 2015, using a Alfissol Latosolic with low phosphorus content. The experiment was carried out in a randomized block design in a factorial 5 x 3 arrangement, consisting of five water salinity levels (0.5, 1.5, 2.5, 3.5 and 4.5 dS m-1) and three doses of superphosphate (60, 100 and 140% of the recommended dose for crop - 60 kg ha-1 of P2O5), with five repetitions. The plants of cowpea cv. Paulistinha were cultivated for 49 days after sowing in lysimeters with 8 dm3 capacity. During this period was determined the accumulation of salts in the soil, growth and biomass partition plants. Water with salinity higher than 1.5 dS m-1 increased soil salinity above the crop’s threshold of 4.9 dS m-1, 21 days after sowing. Increased salinity impaired growth and biomass partition of cowpea plants, with greater accumulation of dry matter in the leaves and stem in comparison to the root. Hinghest dose of superphosphate promoted greater growth of cowpea plants.

GERMINAÇÃO E CRESCIMENTO DE Salvia hispanica L. SOB DIFERENTES SUBSTRATOS E VOLUMES DE ÁGUA

Salvia hispanica L. pertence à família das Lamiaceae, distribuídas por varias regiões do mundo, originaria da região que se estende do centro-oeste do México até o norte da Guatemala, além das regiões como o Sul da África, América Central, América do Norte, América do Sul e Ásia Sul-Oriental (AYERZA; COATES, 2004), é utilizada no combate a redução de doenças cardiovasculares, colesterol, triglicerídeos, obesidade e regulação do intestino, bem como prevenção de doenças como a diabetes do tipo II e de alguns tipos de câncer (JIN et al., 2012).

Crescimento de porta-enxertos de goiabeira influenciado por doses de biofertilizante, tipo e volume de substrato

Objetivou-se avaliar os efeitos do emprego de esterco bovino em associacao com biofertilizante liquido, aplicado em dois tipos de solo, para producao de porta-enxerto de goiabeira. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 5 x 2 x 2, sendo avaliados os fatores doses de biofertilizante (0,0; 2,5; 5,0; 7,5 e 10,0% v/v), 2 tipos de solos (S 1 :Neossolo Fluvico e S 2 :Luvissolo Haplico) e 2 volumes de solo (1 L e 2 L), com tres repeticoes, totalizando 60 unidades experimentais. O biofertilizante bovino foi aplicado ao solo depois de diluido em agua, na proporcao de 1:3 (v/v), 24 horas antes da semeadura, 25 dias apos a emergencia das plântulas e, posteriormente, em intervalo de 30 DAS.O maior crescimento e o acumulo de materia seca foram obtidos nos porta-enxertos cultivados em recipientes com capacidade para 2 L. De maneira geral, doses de biofertilizante proximas a 5% do volume do substrato proporcionaram o maior desenvolvimento dos porta-enxertos de goiabeira. Os tipos de solo afetaram o crescimento dos porta-enxertos, sendo o Neossolo o mais promissor para producao de porta-enxertos de goiabeira.