Seed traits of species from South Brazilian grasslands with contrasting distribution

Abstract

South Brazilian grasslands are among the most species-rich grasslands worldwide yet they have been suffering ongoing degradation due to land-use. Little is known about the reproductive ecology of the native species of these grasslands. Thus, our goal was to characterize seed traits and germination requirements of three native species of the tribe Tigridieae (Iridaceae, Iridoideae) due to its richness in the Pampa biome and the contrasting morphology, cytogenetics, and geographic distributions of its representatives. We tested if closely related species possess similar seed traits and whether species with wider distributions have broader germination requirements. Seed production and mass were estimated, and morphological analyses, germination experiments and viability tests were performed. Principal component analysis (PCA) was used to describe correlations between seed traits and species' distributions. Germination was assessed using time-to-event analysis and the Cox model. All seed traits differed among the analyzed species/cytotypes. Final germination percentage (FGP) averaged 39.1 % and with overall viability of 89.9 %. Germination tests showed that seeds benefit from negative photoblasty. Species/cytotypes with wider distributions and heavier and larger seeds generally had better germination performances than narrower distributed species/ cytotypes with lighter and smaller seeds.

IAPT chromosome data 40

“…The chromosome number 2n = 42 was previously reported in samples from Argentina (Moreno & al., 2009), Brazil (Moraes & al., 2015, Chile , and Uruguay (Moreno & al., 2009), whereas the chromosome number 2n = 56 was previously reported in populations from Argentina (Moreno & al., 2009) and Brazil . The spatial distribution of H. lahue populations in the Pampas is complex, ranging from mixed populations, where the three ploidy levels are found in sympatry, as well as parapatric and allopatric distributed populations (Stiehl-Alves & al., 2016;Martins & al., 2020).…”