Seed quality of the Sino–Himalayan endemic genus Cyananthus (Campanulaceae) increases with elevation and varies with life histories

Abstract

Background: Seed quality can directly determine the survival and population dynamics of alpine plant species. However, how the quality of seeds is affected by elevation-related stress in the Hengduan mountains in the South-western China remains unclear.Aims: To determine how the seed quality of species of Cyananthus varies with elevation, life history and adaptive strategies.Methods: Nine species, including three annuals and six perennials, in the Himalaya-Hengduan Mountains from ca. 2500 m to ca. 4700 m a.s.l. were selected. For each population, seeds from at least 25 individuals were collected. After air-drying, we related seed mass and per cent germination with elevation and compared these parameters between life histories.Results: Results showed that seed mass (annual species) and germinability (annual and perennial species) were positively correlated with elevation. In addition, seeds from higher elevation exhibited explosive germination within a short period. No correlation was found between seed germination and seed mass.Conclusions: These findings indicate that selective pressure (e.g. low temperature and short growing season) might favour the formation of larger seeds in species from higher elevation, as well as a higher germination percentage and more rapid seed germination. These traits further confer high seed quality at higher elevation. We suggest that elevation is the main determinant of seed quality for Cyananthus species, but seed quality does differ between life histories.