Luminosidade e embebição de água para sementes de espécies florestais

Abstract

In forest species, the environmental conditions can be favorable or not to promote the germination of the seeds and with this they are considered dormant. In order for the germination to take place, the presence of water, luminosity, oxygen and temperature are required. The objective of this study was to verify the effect of luminosity (light and dark) on germination and to determine the three — phase imbibition pattern of of the species of Bowdichia virgilioides Kunth (Sucupira), Leucaena leucocephala (Lam.) De Wit (Leucena) and Tecoma stans Kunth (Ipê). The seeds of Sucupira and Leucena underwent a mechanical scarification process using sandpaper No. 80 on the opposite side to the thread and the seed of Ipé had no scarification. The seeds were distributed on germitest paper moistened with distilled water and packed in germinating chambers of the type B.O.D. at 30 º C in a 24-hour daily light and dark photoperiod regime. 80 seeds were used, distributed in 8 replicates with 10 seeds each. For the imbibition curve, the seed weights were weighed in one-hour intervals and then starting from zero hours to completion of 12 hours, then at 12-hour intervals, after weighing when at least 50% of seeds emitted radicles. The results showed that germination influence was only observed in TI treatment for the seeds studied, characterizing them as positive photoblast. The species that presented the three-phase pattern in the imbibition curve was the Ipê, whereas the species of Leucena and Sucupira were not observed in Phase II of the imbibition curve, being characterized only with Phases I and III (biphasic pattern).