RESUMO
The use of an alternative technique to increase the germination of an legume species used in animal feed was investigated based on the effects of low-pressure plasma on the wettability, imbibition, and germination of seeds of Desmanthus virgatus. A conventional nitriding reactor with an argon atmosphere (Ar) and controlled temperature at 30º C was used to apply three different exposure times: 1, 3, and 5 minutes, with a set of intact seeds considered as the control. The experimental design was completely randomized, and the means were compared by the Tukey test at 5% probability to analyze the different experimental conditions tested. The statistical analyses were performed with the software Origin 8.0. The apparent contact angle indicated an increase in the wettable surface with the treatment time, verifying the hydrophilic character of the plasma on the seed. Seeds treated for 3 and 5 minutes showed higher germination than the 1-minute treatment and untreated seeds. In the imbibition test, the leached solution showed lower conductivity in the treated samples than in the untreated sample, indicating less nutrient loss to the solution. The pH remained within the neutral range among the treated samples. The superficial changes in the seeds caused significant gains in the germination parameters, promoting improvement in the indices and rate of germination and contributing to the uniformity of the seed lot with the use of low-pressure plasma as a tool for breaking dormancy.(AU)
Foi investigado o uso de técnica alternativa com fins ao aumento da germinação de uma espécie de leguminosa empregada na alimentação animal, a partir dos efeitos do plasma em baixa pressão na molhabilidade, embebição e germinação de Desmanthus virgatus. Utilizou-se reator de nitretação convencional com atmosfera de argônio (Ar) e temperatura controlada em 30º C sob tratamento de três diferentes tempos de exposição 1, 3 e 5 minutos, considerou-se conjunto de sementes intac-tas como controle. O delineamento utilizado foi inteiramente casualizado, os resultados submetidos ao teste de Tukey à 5% para análise das médias entre as condições experimentais testadas, as análises estatísticas foram realizadas no programa Origin 8.0. O ângulo de contato aparente indicou aumento da superfície molhável com o tempo de tratamento comprovando cará-ter hidrofílico do plasma na semente. Sementes tratadas por 3 e 5 minutos apresentaram germinação superior ao tratamento por 1 minuto e em relação as sementes sem tratamento. A solução lixiviada, no teste de embebição apresentou condutividade das amostras tratadas menor que a amostra sem tratamento, indicando menor perda de nutrientes para a solução. O pH per-maneceu-se dentro da faixa de neutralidade para as amostras tratadas. As modificações superficiais nas sementes ocasionaram ganhos significativos nos parâmetros germinativos, promovendo melhoria nos índices e percentagem de germinação, e contri-buindo na uniformidade do lote de sementes com o uso do plasma a baixa pressão como ferramenta para quebra de dormência.(AU)
Assuntos
Sementes/fisiologia , Germinação/fisiologia , Fabaceae/fisiologia , Métodos de Embebição , MolhabilidadeRESUMO
In this work, the plasma was used in the dielectric barrier discharge (DBD) technique for modifying the high-density polyethylene (HDPE) surface. The treatments were performed via argon or oxygen, for 10 min, at a frequency of 820 Hz, voltage of 20 kV, 2 mm distance between electrodes, and atmospheric pressure. The efficiency of the plasma was determined through the triple Langmuir probe to check if it had enough energy to promote chemical changes on the material surface. Physicochemical changes were diagnosed through surface characterization techniques such as contact angle, attenuated total reflection to Fourier transform infrared spectroscopy (ATR-FTIR), X-ray excited photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Plasma electronics temperature showed that it has enough energy to break or form chemical bonds on the material surface, impacting its wettability directly. The wettability test was performed before and after treatment through the sessile drop, using distilled water, glycerin, and dimethylformamide, to the profile of surface tensions by the Fowkes method, analyzing the contact angle variation. ATR-FTIR and XPS analyses showed that groups and bonds were altered or generated on the surface when compared with the untreated sample. The AFM showed a change in roughness, and this directly affected the increase of wettability.