Estudo da longevidade de sementes florestais

Abstract

Several factors influence the longevity of forest seeds; therefore, evaluating seed behavior during storage is essential, as is using longevity prediction techniques for better management of germplasm banks. Additionally, it is important to obtain information on the relationships between morphological and genetic characteristics in species survival, as well as physiological and biochemical changes related to seed degradation, to better understand defense mechanisms and adopt possible strategies for the conservation of plant genetic resources. This study was divided into two parts, with the aim of classifying the seed longevity of forest species, relating it to morphophysiological characteristics, and investigating physiological and biochemical changes during natural and artificial aging in Handroanthus serratifolius seeds. In Article 1, for longevity classification, the seeds were subjected to accelerated aging (saturated sodium chloride (NaCl) solution, 75% RH, and a temperature of 35 °C) and evaluated through a germination test to obtain p50 estimates via Probit analysis. Additionally, the lipid content (L), seed coat thickness (ET), presence of endosperm (END), and ratio between the seed coat and internal seed tissues (TT) were quantified/determined. For Article 2, H. serratifolius seeds stored in a cold chamber (8,0 °C; 40% UR) and freshly harvested seeds artificially aged via the accelerated aging test (35 °C and 75% RH) were used. The vigor, viability, and biochemical changes were subsequently determined. All the experiments were conducted in a completely randomized design (CRD), and the data were analyzed using analysis of variance (ANOVA), polynomial regression, Pearson correlation, and principal component analysis (PCA). The p50 varied widely among the evaluated species and was influenced by factors such as seed coat thickness and lipid content. Seeds from the Fabaceae family presented greater longevity and a thicker seed coat, whereas seeds from the Bignoniaceae family presented greater lipid content and lower longevity. In H. serratifolius, seeds maintained high viability for up to five years in dry and cold storage, with a significant reduction in vigor and germination after 15 days of accelerated aging. The accumulation of H₂O₂ and MDA was negatively correlated with the vigor and viability indices, whereas antioxidant enzymatic activity did not significantly influence the loss of seed viability. The accelerated aging test is a useful tool for classifying the longevity of forest species seeds, and morphophysiological characteristics influence the longevity of the studied seeds. H. serratifolius seeds presented significant physiological and biochemical changes during both natural and artificial storage.