The effect of plasma applied to mulungu (Erythrina velutina) seeds was studied to verify its influence on the germination, water absorption, wettability and structure of the seeds. The plasma jet used in this study was produced by dielectric barrier discharge (DBD) in a helium gas flow of 0.03 L/s at a distance of 13 mm for 60 s. The plasma treatment significantly affected the seed germination rate, which was approximately 5% higher than that of the untreated group. Micropyle and hilum contributed a greater proportion to uptake. When sealed in the hilar or micropyle regions the amount of water absorbed into the seed decreased approximately 75% compared to the unsealed seed. This difference suggests that these two regions together act cooperatively in the water absorption. However, when plasma treated seed was blocked in the micropyle region, water absorption was higher higher than in seeds blocked hilum. This difference suggests that the plasma treatment changed the wettability of the hilum more effectively than it changed the micropyle. These results indicate that plasma can significantly change the hydrophilicity, water absorption and percentage of seed germination in E. velutina.

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Seeds of ‘sabiá’ (Mimosa caesalpiniifolia Benth.) have coat dormancy, which hampers the absorption of water and oxygen, thereby delaying germination. Thus, this study aimed to evaluate methods for overcoming dormancy associated with priming on germination and vigor of seeds of ‘sabiá’, considering the efficiency, practicality and cost of treatment. The experimental design was completely randomized, in a 4 x 5 factorial scheme (four methods for overcoming dormancy x five types of priming), constituting 20 treatments with four replicates of 25 seeds. The methods for overcoming dormancy used were tip removal, seed immersion in hot water at 100 °C for three minutes, immersion in sulfuric acid for 10 minutes and intact seeds. For the determination of physiological conditioning of seeds, the imbibition curve with the different priming agents was constructed. Priming was done on filter paper moistened with solutions of mannitol at the potentials of -0.2 MPa (16 hours), -0.4 MPa (24 hours) and -0.6 MPa (36 hours) and only with distilled water for the hydropriming (12 hours) and seeds without priming. The variables analyzed were first count of germination, germination, root length, shoot length and dry weight of seedlings. The data were subjected to analysis of variance by F test and Tukey test at 5% probability. The dormancy of M. caesalpiniifolia seeds should be overcome with the use of hot water (100 °C) for three minutes, without the need for priming.

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