Abstract in English:ABSTRACTBackground: The germination ecology of P. guajava seeds collected in two regions of Brazil was investigated aiming to (1) characterize the seed batches; (2) determine the best temperature for germination; and (3) assess variations in seed desiccation tolerance (DT). For each batch, we determined seed water content and initial germination. To evaluate temperature effects, we tested seed germination. After, we generated the imbibition curves for the two provenance. To evaluate the loss of DT, the seeds were left to germinate along different time intervals. We monitored water loss by regularly weighing the seeds until achieving stabilization, keeping them under these conditions for 72 hours. After drying, the seeds were pre-hydrated and submitted to the germination test. Results:We identified variations in physiological characteristics between the seeds from north and southeast batches. At the temperature extremes, the seeds from both provenance failed to germinate. The highest germination percentages were observed at 20 and 25 °C (constant) and between 20-30 °C (alternating) for the two batches and, for the southeast batch specifically, at 30 °C. The imbibition curve displayed a triphasic pattern with a rapid increase in seed fresh weight in the first 48 hours. Conclusion: The southeast provenance seeds lost DT abruptly, until its complete loss after radicle protrusion, which occurred in both batches. The highest values of germination speed index (GSI) of both provenance were observed after a 9-day imbibition period, suggesting seed hydration memory. Drying resulted in necrosis of the root tissue and death of the seeds with visible roots.
Abstract in English:ABSTRACT Background: Curitiba prismatica (D.Legrand) Salywon & Landrum belongs to the Myrtaceae family and it is popularly known as murta. Endemic to the Mixed Ombrophilous Forest of south Brazil, is predominant in Faxinal System, which is a traditional agricultural system in the State of Paraná. This species also has several uses and potentials, such as wood for fence posts and essential oils with pharmacological properties. For this reason, this study aimed to select molecular markers and assess whether the Faxinal System contributes to the maintenance of the genetic diversity of the species, helping in its management and conservation. As such, 120 adult reproductive individuals were sampled, 60 in two areas managed in the Faxinal System, and 60 in two conservation areas. Results: Initially, 30 ISSR markers were selected, but only eight showed considerable variability, resulting in 68 polymorphic loci. The results show that the average diversity within populations is 80.54%. The Shannon (I) and Nei’s (He) diversity indices were 0.53 and 0.36, respectively. According to Nei’s genetic identity, the populations form two groups. With the analysis of the genetic structure of the populations, which indicated the existence of two distinct genetic groups (K = 2). Conclusion: Thus, the populations in the Faxinal System had higher rates of genetic diversity, despite constant human activity within the system. Therefore, the Faxinal System contributes to the conservation of C. prismatica genetic diversity; however, considering the economic potential of the species and to minimize impacts on the existing fragments, there is a need to work with the local population to ensure sustainable forest management of the species.