Functional seed traits of the endangered native oak (Amburana cearensis Allemao) from Northwestern Argentina

Abstract

Seed traits influence the success of establishing a new individual and vary between and within provenances as an ecological strategy. Amburana cearensis Allemao is an endangered species from Argentina, with natural populations declining primarily due to logging. We studied the morphological and physiological seed traits of three provenances from Argentina (Libertador, Orán, and Piquirenda) and the relationship between seed traits, geographic, and climatic variables. Fifty seeds from each provenance were characterized by measuring their weight, length, width, and thickness. Germination requirements were assessed through two factorial experiments: (1) with temperature (10, 15, 20, 25, 30, and 35 °C) and provenance as factors, (2) with water potential (0, -0.2, -0.4, -0.6, -0.8, -1.2, and − 1.6 MPa) and provenance as factors. A generalized linear model was employed to assess the impact of these factors on germination. Graphic modeling and probit regression were utilized to determine thermal and hydro parameters of germination. Orán seeds (from a lower elevation) were larger than Piquirenda seeds (from a higher elevation), and the variability in morphological traits was greater in the latter provenance. Seeds germinated at temperatures ranging from 15 to 35 °C, with the highest germination percentages observed between 15 and 25 °C. Thermal parameters and hydrotime were similar between provenances, while the base water potential varied among them. Libertador seeds were more sensitive to water potential, and Piquirenda seeds germinated under water restriction conditions. Each provenance exhibits specific traits that offer ecological advantages. This information is crucial for selecting germplasm for conservation and restoration efforts.