Rapid viability analysis in Pterogyne nitens Tul. by the tetrazolium test

Abstract

Pterogyne nitens Tul., also known as brave peanut, is a native tree species, with economic and ecological importance, occurring from the Northeast to the South of Brazil. For most forest species, the standard germination test requires a relatively long time to obtain results, which is why tests such as the tetrazolium test have been widely used, as they are a quick and low-cost test. Therefore, the objective of the present work was to establish the most appropriate procedure for conducting the tetrazolium test to evaluate the viability of Pterogyne nitens seeds. The trial was conducted at the Phytotechnics Laboratory, at the Engineering and Agricultural Sciences Campus, at the Federal University of Alagoas, Rio Largo, AL, Brazil. To define the most appropriate methodology for the tetrazolium test and ensure the viability of Pterogyne nitens seeds, a completely randomized experimental design was used, in a 2x3+1 factorial scheme, with two concentrations of the tetrazolium solution, three periods of coloring, plus a control treatment represented by the germination test, with four replications of 25 seeds. Only the cotyledons containing the embryo were placed in 50 mL plastic cups, and immersed in a solution of 2,3,5-triphenyl tetrazolium chloride salt, at concentrations of 0.05 and 0.075%, for staining periods of 2. 4 and 6 hours, in a Biochemical Oxygen Demand (B.O.D.) chamber at 30 ºC in the dark. For the germination test, the seeds were placed equidistant in plastic boxes with blotting paper and a volume of water equivalent to 2.5 times the weight of the substrate, and placed in a B.O.D. chamber. regulated at 30 ºC and a 12-hour photoperiod. Based on tissue color and health standards, seeds whose embryonic axis was pink in color were classified as viable, and seeds with a discolored embryonic axis or yellow or intense red color were classified as non-viable. In general, the results of the percentage of viable seeds of Pterogyne nitens obtained in the tetrazolium test presented values below 78%, showing significant differences in relation to the germination test with 95%, except for the concentration of 0.05% for 6 hours presenting 90% viability. The tetrazolium test proved to be efficient in evaluating the viability of Pterogyne nitens Tul. seeds, being recommended to be immersed in a tetrazolium solution at a concentration of 0.05% for 6 hours.