Adequacy of the tetrazolium test methodology for Stylosanthes capitata Vogel seeds

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Abstract: The seed sector is increasingly dynamic and therefore demands rapid decision-making. The tetrazolium test is a rapid test that determines the viability of seeds, especially from species that show slow germination or dormancy. The methodology described in the Rules for Seed Testing for Stylosanthes sp. is not applied effectively to the Stylosanthes capitata Vogel species. Three seed lots of S. capitata seeds with different quality levels were used to fit the tetrazolium test methodology. In order to determine the physiological quality of seeds, the tests of germination, first count germination, emergence speed index, initial and final seedling emergence percentage, electrical conductivity, respiratory activity and seed moisture content were performed, besides the imbibition curve for the establishment of pre-imbibition periods of the seeds to perform the tetrazolium test. The pre-imbibition and staining periods of 6, 12 and 18 h, and 3, 6, 12 and 24 h at concentrations of 0.075%, 0.1% and 0.5% tetrazolium solution were tested. It was concluded that the 12-h pre-imbibition period and 6-h staining at the 0.1% tetrazolium solution is ideal for evaluating the viability of S. capitata seeds.