Drying on the viability and embryonic development of Ilex paraguariensis seeds

Abstract

Yerba mate germination has been pointed as low, irregular and slow, with different degrees of dormancy, making the production of seedlings a great challenge. Studies to clarify the main mechanisms of dormancy present in yerba mate seeds are of great importance, but scarce. Therefore, we evaluated the effects of drying on the viability and the embryonic development of the species seeds. We evaluated the drying effect by determining the water content, tetrazolium test and embryo development. In order to evaluate the desiccation tolerance, the seeds were stored in a plastic tray without lid, placed on a cold and dry chamber (CFS) shelf, regulated with 25 ± 3% relative humidity and a temperature of 10 ± 1 ° C, for 70 days. Every seven days the seeds were removed from the CFS and submitted to tetrazolium test and water content evaluation. Embryo development was evaluated from excised embryos, originated from tetrazolium test. The germination test was conducted on sand substrate, in gerbox boxes placed in a growth chamber regulated at 25 °C and photoperiod of 12 hours. From seeds not subjected to drying, only 8% germinated, as a result of embryo immaturity of newly harvested seeds. Drying for 70 days promoted the embryonic development, but affected the viability of the seeds. Therefore, we recommend drying for up to 49 days to improve the germination and the subsequent seedling productions.

Keywords:
Dormancy; Desiccation; Brazilian native species; Yerba mate