| dc.description.abstract | Yerba mate seeds have embryonic dormancy due to the presence of a rudimentary
embryo, in addition to the mechanical dormancy of the woody endocarp that hinders
embryonic growth. In addition, dormancy is possibly linked to the origin of the matrices,
and in places with a lower average temperature, the seeds need more time to develop
their embryos. In this way, the work was divided into two experiments, the first aimed
at characterizing the embryonic stages of six mother trees grown in Santa Maria - RS
and comparing them with a matrix from Chapecó-SC. The second experiment aimed
to apply seed preconditioning to accelerate the embryonic development process. In
the first experiment, the seeds collected in Santa Maria and received from Chapecó,
were evaluated for their biometric measurements (length, width and thickness), their
weight of a thousand seeds, viability, visible embryos and embryo size, and these
evaluations were made on seeds before and after stratification. In the second
experiment, three factors were used, namely: pre-conditioning time (5, 10, 15 days),
three levels of the solution factor (water, 0.02% KNO3 and 0.1% gibberellic acid) and
four levels stratification time factor (0, 65, 140, 200 days). In the first experiment, it was
observed that the seeds embryonic development was similar for all the studied mother
trees, being that the number 4 mother tree was the only one to present torpedo-sized
embryos. In the second experiment, the preconditioning favored germination, reaching
16% of germination in the preconditioned seeds for 15 days in 0.1% gibberellic acid
and stratified for 200 days. It is concluded all the seeds of mother trees cultivated in
Santa Maria - RS showed viability and percentage of visible embryos lower than the
seeds of Chapecó - SC, and the embryos of the seeds of the latter did not present a
more developed shape and size than the from mother tree 4 (Santa Maria - RS), which
presented the most developed embryo among all mother trees. Seed pre-conditioning
in 0.1% gibberellic acid for 15 days was efficient to increase the germination of yerba
mate seeds after 200 days of stratification. | |
