Germinação de sementes de Rubus sellowii e micropropagação de Morus nigra
Abstract
Sexual and vegetative propagation are the main methods of perpetuating plant
species. Despite its importance in propagation, seeds of some species do not
germinate even under favorable conditions, as is the case of seeds of the genus
Rubus, situation called dormancy. Experiments were carried out to characterize and
overcome dormancy in R. sellowii seeds. During the seed imbibition process, was
observed a barrier for water absorption. For the chemical scarification of the seeds,
NaClO and H2SO4 were evaluated. NaClO was not efficient for tegument scarification.
Treatment with H2SO4 for 20 min showed 50% seed germination and a higher rate of
germination. It was also carried out the sowing, without scarification, in a tray
containing substrate the base of pinus bark and kept in greenhouse. Seedling
emergence started 70 days after sowing, reaching 50% after 370 days. Experiments
were also carried out with the micropropagation of Morus nigra, considering the nonviability of commercial seed propagation. It was observed that in vitro cultivation of
explants in the absence of phyto-regulators produced seedlings ready for the
acclimatization phase. In the acclimatization, we tried to verify the best growing
environment (growth room or greenhouse) and in vitro culture time. Growing for 28
days in the growing room resulted in plants with higher height (9.2 cm), number (4.8)
and leaf diameter (3.23 cm), an essential condition for efficient acclimatization. For the
somatic embryogenesis, calli of nodal explants of M. nigra were obtained with the use
of naphthalene-acetic acid (ANA) or benzyladenine (BA), under light or dark conditions.
Both presented similar callus induction rates. For the induction of somatic
embryogenesis, twelve culture media were used for the induction of embryogenic calli.
It was possible to obtain them in media containing BA, 2,4-D and coconut water. These
were cultivated in liquid medium of maturation, in which they presented the
development of globular structures of cream coloring. These globular structures have
multiplied, acquiring green pigmentation when grown on sucrose or glucose as aviii
carbon source. However, there was no subsequent development or regeneration in
seedlings.