Evaluation of white-oat seed viability by the tetrazolium test

White-oat seed shows dormancy when recently harvested, but this is normally overcome after storage, which sometimes makes the germination test for evaluating their viability unreliable. The objective of this study was to evaluate different methodologies for performing the tetrazolium test with white-oat seeds, to rapidly determine their viability. Five white-oat seed lots of "Louise" and "IAC-7" cultivars were used to test the following procedures for the tetrazolium assay: a) hydration between moistened paper towels and in soaked water at 20 °C, for 18 h; b) coloring for 2 h, on paper moistened with reagent and direct immersion in the reagent; c) tetrazolium solutions of 0.1%, 0.5% and 1.0%. There were two types of seed preparation: seeds were cut longitudinally through the embryo, and one half was immersed in tetrazolium solution at 30 °C or both halves were placed on filter paper moistened with tetrazolium solution, at 40 °C. Results showed that the tetrazolium test is promising for the rapid determination of seed viability, with hydration between paper (18 h, at 20 °C), and by the coloring on moistened paper (2 h, at 40 °C) with 1% tetrazolium solution.