Viabilidade de sementes de Cordia trichotoma (Vellozo) Arrabida ex Steudel (louro-pardo) pelo teste de tetrazólio

Abstract

The present work was carried out with the aim of determining a specific protocol for tetrazolium test procedure for Cordia trichotoma (Vellozo) Arrabida ex Steudel seeds. Diaspores were harvested in august of 2000 in the UNESP campus, Jaboticabal-SP, Brazil. All seeds were evaluated as to infested seeds, moisture content, weight of 1000 seeds, and germination test. Tetrazolium test was conducted whith the preconditioning in moist germination following methodologies: paper towel and imersion in water (8, 12, 16, 20 and 24 hours) at 25oC; seven different tissues exposure for evaluation (intact diaspore, intact seed, decoated seed, incision in a non embryonic area of the a diaspore, a transversal cut of the diaspore, a longitudinal cut of the diaspore discarding one half part, longitudinal bisection through the middle of the embryo and approximately three quarters of length of its cotyledon); three tetrazolium solutions (0.10; 0.25 and 0.50%); three staining times (2, 3, and 4 hours) at 40oC. Reliable results were obtained when half seeds from longitudinal bisection were exposed to 0.25% solutions. The bisection of ¾ of the cotyledon yielded equally good results. Desuniform and intense color were observed in all staining time that used 0.50% of tetrazolium concentration. The results allowed to conclude that 16 hours