Germination of Quercus humboldtii Bonpl. (Fagaceae) seeds: vulnerable species of the high Andean forest

Abstract

The Colombian oak (Quercus humdoldtii) is an endemic dominant and vulnerable species of the high Andean forest. The wood and fruits have traditionally been used on a small scale by rural populations. A greater synchrony of the germination process might facilitate the production of seedlings for conservation plans. In a forest nursery, the emergence was evaluated according to immersion of seeds in four solutions of gibberellic acid (GA₃) during 24 h (0, 150, 300 and 600 mg L^-1), at 4 °C. A completely randomized design was adopted, with four replications of 25 seeds. The mean emergence time was 32 days, without differences between doses. There was no effect of GA₃ for the emergence of seedlings up to a dose of 300 mg L^-1 (mean= 92 %); however, there was a negative effect with 600 mg L^-1 (20 %). Fresh seeds of the Andean oak have a high moisture content (38 %), perhaps indicative of a recalcitrant behavior. This study confirms, as in most white oaks in the tropic, the absence of dormancy and the high viability of their seeds. The use of GA₃ is not a useful pre-germinative treatment for accelerating and synchronizing seedling emergency in this species.