Influência da temperatura e do substrato na germinação de sementes de itaubarana (Acosmium nitens (Vog.) Yakovlev) - Leguminosae, Caesalpinoideae

Abstract

Acosmium nitens (Vog.) Yakovlev (Itaubarana), Leguminosae Caesalpinoideae, is an important timber species, which occurs in "varzea" (annualy flooded) Amazonian forests. This paper deals with germination rates of itaubarana, which were determined for seeds sown under different temperature and substrate conditions. The mean time lenght for germination was also included as measurement parameters. The experiment was carried out using a two-factor design with balanced data considering the effects of constant temperatures (20, 25, 30 e 35°C) and substrates (sand, paper and vermiculite) on the germination rates. Each level was replicated four times, and each replication contained twenty-five seeds. The results showed that seeds did not germinated when they were sown over paper at temperatures of 30 and 35°C. High seed germination rates were observed on the substrate over vermiculite at all temperatures tested, with rates ranging from 87 to 97%. The combination of temperature of 30°C and substrate over vermiculite showed to be adequate for seed germination; under this condition, the highest germination rate (97%) was obtained with a mean time lengh of approximately 5,0 days. For substrate over sand, temperatures of 20, 25 and 30°C provided the highest seed germination rates when compared with a temperature of 35°C. For temperatures of 30 and 35°C, the substrate over vermiculite provided the highest germination rate when compared with the other substrates.