Seasonal Variations in Seed Viability and Vigor of Hancornia speciosa Under Osmoprotective Storage Conditions

Artículo

Storage of desiccation-tolerant seeds is one of the most effective germplasm conservation strategies; however, various species from tropical and subtropical humid forests have seeds that are sensitive to desiccation, recalcitrant seeds, making conservation a challenge. Recalcitrant seeds deteriorate during storage due to high respiration rates and metabolic activity, and protocols employing osmoprotective solutions aim to minimize those effects to maintain seed viability for a longer period. Hancornia speciosa, a fruit tree considered a priority for research in Brazil, is a desiccation-sensitive species of biannual harvest. Thus, the objective of this study was to assess the physiological parameters of viability, vigor, and enzymatic activity of H. speciosa seeds of two harvest seasons, stored in an osmoprotective solution. Germination percentage, water content, electrical conductivity, shoot, root, and seedling length, peroxidase concentration, and heat-resistant protein concentration were all determined for seeds collected during the summer and winter harvests. In addition, gene sequences were explored through gene ontology using Blast analysis to identify the biological and molecular processes associated with enzymatic action during storage. Summer-collected seeds performed better in terms of viability and vigor, with the highest development of shoot, root, and seedling length. The summer-harvest seeds had an initial germination of 80% and maintained a 15% germination rate until 90 days of storage. The seeds collected in the winter had lower initial germination and vigor; however, improved in those parameters during storage in the protective solution, with an increase of 12.5% in germination rate after 90 days. H. speciosa seeds harvested in the summer or winter and stored in the osmoprotective solution remain viable for up to 90 days. The solution has an osmopriming effect on low-vigor seeds, increasing viability and vigor, and the summer-harvest seeds are recommended for storage in the osmoprotective solution. Peroxidase and heat-resistant proteins are active during storage in the solution; the regulation of the expression of these enzymes should be investigated further.