Tetrazolium test adjustment for wheat seeds

Abstract

The assessment of the germination test in wheat seeds varies from 4 to 15 days, because the species normally presents dormancy in freshly harvested seeds. The tetrazolium test can characterize seed viability in less than 24 hours including lots with dormancy seeds. The objective of this study was to develop a practical and efficient procedure for evaluating the viability of wheat seeds using the tetrazolium test. Five seed lots of the BRS 208 cultivar were used, where the following were tested: a) pre-conditioning between moist paper towels or direct immersion in water for 18 hours, at 20 °C; b) longitudinal section of the embryo and the endosperm; c) coloration on paper or by immersion for 2 and 3 hours, at 30 and 40 °C; and d) concentrations of tetrazolium solution at 0.075%, 0.1%, 0.5% and 1.0%. The tetrazolium test may be efficiently used to evaluate wheat seed viability by pre-conditioning the seeds between paper towels (18 hours, at 20 °C) and adopting the following combinations of preparation and coloration: coloration of both halves of the seed on paper (2 hours, at 30 °C), in a 1.0% tetrazolium solution; or coloration of one half of the seed by immersion (3 hours, at 30 °C), in a 0.1% tetrazolium solution; or coloration of one half of the seed by immersion (2 hours, at 40 °C), in a 0.075% tetrazolium solution. This latter procedure is recommended for identifying and discarding lots with lower viability.