Emergência de plântulas de tucumã (astrocaryum aculeatum) em função do pré-tratamento das sementes e da condição de semeadura

This research evaluates the effects of different conditions of seed soaking, associated with different substrates and shade levels on the emergence of tucumã (Astrocaryum aculeatum) seedlings. The experimental design was entirely randomized with three replicates and 25 seeds. The treatments form a factorial of 2 conditions of seed soaking (shade and full sun) x 3 sowing substrates (sand, sawdust and sand + sawdust) x 3 levels of shade (30%, 50% and 70%), The seeds were sown in plastic boxes containing the substrate and covered with transparent polyethylene film, forming mini greenhouses. The emergence and emergence velocity index (EVI) showed interaction between the factors "soaking condition" and "sowing substrate". Seeds soaked in the shade (26-27 °C) and sown in sawdust showed 73% emergence and an EVI of 0.710, values significantly higher than those (58% and 0.578) obtained for seeds soaked in full sun (26-42 °C). The 30% and 50% shade levels gave the same percentage of emergence (68%) which was higher than the 44% emergency obtained with 70% shade. Environments with a higher temperature range (13-14 °C) and higher average temperatures (38-39 °C) promoted the process of seed germination. Thus, the best emergence of tucumã seedlings was achieved with seeds pre-soaked in the shade, sown in sawdust, under transparent polyethylene film and kept at 30% or 50% shade