Longevity and germination of Syagrus romanzoffiana (Arecaceae) seeds and its ecological implications
Syagrus romanzoffiana is a palm tree native and widely distributed of South America. The present study investigated the longevity and germination of the buried seeds of this species in an experimental seed bank. Laboratory germination and viability tests were performed for comparison with field results. Pyrenes (seeds enclosed by the endocarp) were buried in a forest fragment edge in July (dry season) in July 2012 and exhumed monthly during one year, for the assessment of water content and percentage of germinated and viable seeds. Germination tests were conducted in a Mangelsdorf-type germinator at 30°C under constant light and the viability was assessed by the tetrazolium test. An additional sample of pyrenes was buried to evaluate the percentage of seedling emergence and survival. Climatic and soil moisture data were recorded. In the laboratory, the pyrenes were stored for one year in a temperature-controlled room at 20ºC and 75% (±10%) relative air humidity to assess changes in the percentage of germination and viability over time. In the field, a reduction in seed viability was observed over the study period, with a total loss of viability of non-germinated seeds at seven months after burial. The maximum germination (close to 26%) was observed in the samples that were exhumed between five and seven months after burial. In the field, seedling emergence did not exceed 10% and seedling mortality was not observed. The percentages of germination and of viable seeds decreased both in burial and stored seeds. The stored seeds maintained viability at up to six months, with marked reduction thereafter. After the germination tests (four months) in the laboratory, all of the remaining seeds were nonviable. The ecological, physiological and reproductive characteristics of the species are discussed, and we concluded that S. romanzoffiana seeds have short longevity after imbibition, and low potential for soil seed bank formation.
Keywords: palm tree, queen palm, viability, seed bank, seed storage