ALTERAÇÕES FISIOLÓGICAS E BIOQUÍMICAS DE SEMENTES DE Dipteryx alata VOG. NO PROCESSO DE GERMINAÇÃO E ARMAZENAMENTO

Abstract

One of the most viable means to preserve native vegetation and maintain genetic characteristics is the creation of seed banks. This strategy allows, besides the species maintenance, to promote the knowledge about physiological quality and seeds’ vigor for a certain time. This study aimed to evaluate the behavior of Dipteryx alata Vog. seeds (baru) in the germination process resumption, observing the phases in the soaking period. For this purpose, the activity of the α-amylase and β-amylase enzymes was evaluated at soaking intervals of 0 to 196 hours, as well as histochemical studies of the compounds present in the seeds and their changes during the germination were carried out. To evaluate the seeds’ resistance of this species, the accelerated aging was carried out in four times, under temperature and controlled relative humidity. During the test, oxidative stress was estimated using the catalase (CAT), superoxydodismutase (SOD), peroxidase (POX), and total proteins enzymes. In addition, tests of respiration, electrical conductivity, germination, and germination speed index were made to evaluate seeds’ vigor under the submitted conditions. To establish new protocols of physiological tests for forest seeds, tetrazolium test was carried out under different concentrations and soaking times, determining various vigor classes for this species. As for storage, the seeds were kept in hermetically sealed glass jars for 12 months under 10 and 20 ºC temperatures. Evaluation period occurred every three months. In these intervals, the seedling emergence, X-ray test, germination, and electrical conductivity were evaluated. It was possible to conclude that the baru seeds in the germination resumption express the activity of the main enzymes related to the synthesis of "new", promoting the reserves mobilization to the embryonic axis under soaking for approximately 50 hours, making possible to characterize the three-phase pattern during seed soaking at germination phase. After 196 hours, end of the third curve’s stage, it was observed a great carbohydrates and proteins consumption, culminating with the primary root formation. It was also concluded that, even under unfavorable conditions, baru seeds have efficient biochemical devices in the defense of free radicals and in the lipid peroxidation. Seeds stored for 12 months under 10 and 20 °C temperatures remained viable with good physiological quality, verified by vigor tests. The use of the X-ray images allowed seeds evaluation during all the storage period, and no damage from the storage process was detected, nor even to the seeds structure itself.