ABSTRACT The use of cold plasma is effective in overcoming seed dormancy. However, its effects, both in the long-term and during storage, is still not fully understood. The aim of this study, therefore, was to evaluate the immediate and post-storage effect of atmospheric plasma on the seeds of Pityrocarpa moniliformis in overcoming seed coat dormancy. The seeds were treated with plasma for 0, 1.0, 2.0, 3.0, 4.0 and 5.0 minutes. Following application, 50% of the seeds were stored for two years while the remainder were submitted to immediate analysis. The seeds were evaluated for germination and the germination speed index, in addition to seedling length and dry weight. The experimental design was completely randomised, and included regression analysis. The plasma treatment resulted in an increase in the germination rate and vigour of the seeds, both immediately after exposure and after two years of storage. In particular, the seeds treated for five minutes showed around 39% germination, which was outstanding compared to seeds from other exposure times. Plasma is effective in overcoming seed coat dormancy in seeds of P. moniliformis treated for five minutes and tested immediately. The effect of plasma on the seeds of P. moniliformis after storage was less for all the conditions under test. However effects longterm long term understood study therefore poststorage post 0 10 1 1.0 20 2 2.0 30 3 3.0 40 4 4. 50 5 5. application analysis index weight randomised particular 39 times P test 1. 2. 3.

Resumo: A tecnologia de aplicação do plasma atmosférico consiste em um método rápido e prático, que apresenta potencial de modificação da superfície tegumentar de sementes com dureza tegumentar. O objetivo desta pesquisa foi avaliar o efeito da aplicação do plasma frio atmosférico em sementes de Pityrocarpa moniliformis, verificando suas implicações sobre a impermeabilidade do tegumento, germinação e vigor. As sementes foram submetidas ao plasma por 1,5; 2,0; 3,0; 4,0 e 5,0 minutos, utilizando-se como controle, sementes sem nenhum tratamento. Após a aplicação, determinou-se a molhabilidade do tegumento, curva de embebição e condutividade elétrica da solução de embebição. As sementes também foram submetidas ao teste de germinação, tendo-se, a partir dos seus resultados determinado a viabilidade, mediana, uniformidade e assimetria da germinação. As sementes submetidas ao plasma por 4,0 e 5,0 minutos apresentaram os menores ângulos de contato aparente, 64 e 61°, respectivamente, caracterizando maior molhabilidade do tegumento, entre os tratamentos testados. Maior germinação foi observada nos tratamentos com aplicação do plasma quando comparado com o controle. A tecnologia de aplicação do plasma atmosférico tem potencial para ser utilizada como acelerador da germinação de sementes de P. moniliformis.

Abstract: Atmospheric plasma application technology consists of a fast and practical method, which has the potential to modify the surface of seeds with integumentary hardness. The aim of this research was to evaluate the effect of applying atmospheric cold plasma on Pityrocarpa moniliformis seeds, assessing its implications on the seed coat impermeability, germination and vigor. Cells were subjected to plasma for 1.5, 2.0, 3.0, 4.0 and 5.0 minutes, using seeds without any treatment as a control. After application, the seed coat wettability, imbibition curve and electrical conductivity of the soaking solution were determined. Seeds were also subjected to the germination test, and its results were used to determine viability, median, uniformity and asymmetry of germination. Seeds subjected to plasma for 5.0 and 4.0 minutes showed the lowest apparent contact angles, 64 and 61°, respectively, characterizing greater wettability of the seed coat among the treatments tested. Higher germination was observed in the treatments with plasma application when compared to the control. Atmospheric plasma application technology has the potential to be used as an accelerator of P. moniliformis seed germination.