Effect of stratification in sterilized substrate in the sanitary quality of Ilex paraguariensis seeds

Abstract

The stratification of Ilex paraguariensis seeds (yerba mate) in wet sand for periods of four to six months is a common practice in nurseries, used to overcome their dormancy. However, this process may present difficult phytosanitary control due to the high moisture content and the high concentration of seeds in the same place. Thus, the present work had the objective of verifying the influence of the stratification in autoclaved sand on the sanitary quality of yerba mate seeds from different lots. Seeds of four lots were submitted to wet stratification for three and six months, and their sanity was evaluated at the end of these periods, as well as seeds that did not undergo stratification. At the end of the stratification period, the seeds had a darkened surface appearance, which may be related to the action of the fungi in the degradation of the endocarp. These ones were identified: Fusarium graminearum, Fusarium oxysporum, Fusarium guttiforme, Paecilomyces sp., Aspergillus sp., Penicillium sp. Already Aureobasidium melanogenum, Trichoderma sp., Curvularia sp., Rhizopus sp., Alternaria sp., Cladosporium sp. and Bipolaris sp. had fewer occurrences. Observed reduction of Fusarium graminearum, Fusarium oxysporum, Fusarium guttiforme, Aspergillus sp. and Penicillium sp. after stratification and the genera Paecilomyces was only observed at 180 days of stratification, and may be related to the degradation of the endocarp of Ilex paraguariensis seeds.

Keywords:
Yerba mate; Overcoming dormancy; Seed pathology