Aspectos ecofisiológicos da germinação de sementes e do estabelecimento de plântulas de Euterpe edulis Mart.

Abstract

Euterpe edulis Mart. is the most abundant native palm and extremely exploited species of Atlantic Forest, being confirmed as an endangered species, in the list 2008 of the Ministry of Environment. The aspects of abiotic (temperature, dehydration, soil water content, submersion) and biotic (presence of the outer layers of the fruit, seed position in the litter and predation) were analyzed on seed germination and seedling establishment. Germination tests were conducted at constant temperatures of 15 º, 20 º, 25 º, 30 º and 35 º C and 20-30 ° C, photoperiod of 8 hours. Dehydration of the seeds was evaluated using different moisture contents 10, 15, 17, 20, 25, 27, 30, 35, 37, 39 and 42%. The effect of soil water content was evaluated using different moisture contents 11, 14, 19, 22, 26, 32, 37 and 42%. To evaluate the submersion, were made two withdrawals monthly, and one withdrawal with fifteen days. Fruits and seeds were evaluated for differences in germination. To evaluate the effect of predation, the seeds were divided into three weight classes, and then cut, removing 25% and 50% of the endosperm, and seed uncut. The shoot was completely removed from seedlings with two different stages of development. To assess the position in the litter seeds were placed under and on the litter in three conditions of light intensity. The best germination temperatures for this species are a constant 25 ° C and 20-30 ° C. Reducing the water content in the seed promoted the decline in seed germination. The soil water contents of 11 and 42% caused a drastic reduction in germination. Seeds stored in water for 30 days showed a reduction of approximately 50% germination, and 75 days was drastically reduced. The presence of the outer layers of the fruit affected significantly the germination. The seeds were able to germinate even with removal of the endosperm. Furthermore, plants were able to resprout after removal, for the two stages of development testing. Seeds in the litter showed better germination in the three conditions of light intensity. We conclude that the seeds of palm present requirements for seed germination, relative to dehydration, soil water content, the time storage in water, and the importance of interaction between species and animal dispersers, that remove the outer layers of the fruit. Regarding the simulation of predation, large reserve nutrient allows the seeds to germinate and the seedlings are established even with the removal of 50% of the endosperm, and the total removal of the shoot, and the presence of litter has a favorable environment, especially in relation moisture for germination of seeds of the palm.