Physiological quality evaluation of Piptadenia stipulacea (Benth.) Ducke seeds by tetrazolium test

Resumo

The tetrazolium test is one of the promising alternatives to determine the viability of dormant, recalcitrant and
slow-germinating seeds. The objective of this study was to adapt the tetrazolium test methodology to estimate the viability
and vigor of Piptadenia stipulacea (Benth.) Ducke seeds. For this, a sample of seeds was classified into three sublots using
round sieves, corresponding to six, five and four millimeters in diameter, respectively. Moisture content, imbibition curve,
germination, emergence, germination and emergence speed indices, mean germination time and seedling emergence were
initially evaluated. The second stage was conducted using a completely randomized experimental design, in 3 x 9 factorial
scheme, corresponding to three sublots and nine combinations between concentrations and time of immersion in tetrazolium
salt (0.05%/2 h; 0.05%/4 h; 0.05%/6 h; 0.075%/2 h; 0.075%/4 h; 0.075%/6 h; 0.1%/2 h; 0.1%/4 h; 0.1%/6 h), totaling twentyseven treatments with four replicates of 25 seeds, evaluated separately at 35 and 40 °C. For each treatment, the seeds were
divided into four classes: viable and vigorous seeds (class I), viable and non-vigorous (class II), unviable (class III) and dead
(class IV). The period of 8 h of pre-imbibition and 4 h of staining in tetrazolium solution at 0.075%, under 35 or 40 °C, is
adequate to estimate the viability and vigor of P. stipulacea seeds.