Physiological Potential of Seeds of Handroanthus spongiosus (Rizzini) S. Grose (Bignoniaceae) Determined by the Tetrazolium Test.

Tetrazolium test (TZT) can quickly evaluate in detail the viability and vigor of seeds. This study aimed to determine the optimal conditions for conducting the TZT on seeds of Handroanthus spongiosus. For this purpose, seeds from three lots were pre-soaked in water for 16 h, followed by extraction of the tegument and immersion in tetrazolium salt solutions at different concentrations (0.01–0.1%), for increasing periods (1–4 h) and at 30 °C in the dark. The experimental design was completely randomized with a 4 × 4 factorial scheme with 25 seeds per repetition. We applied generalized linear models and the Tukey test for pairwise comparisons of the means at 5% probability. The viability/vigor results were compared with data obtained from the germination test at 25 °C using a subsample of seeds from the same lots. The time (1 h to 4 h) of immersion of the seeds in tetrazolium salt solutions did not cause a clear coloration difference. The seeds subjected to all treatment concentrations for 3 h presented average viability greater than 60%, with no difference in germination percentage. The TZT at 0.01% tetrazolium salt solution for 3 h was most efficient in assessing the viability of the Handroanthus spongiosus seeds. [ABSTRACT FROM AUTHOR]