Earthworm-mediated maternal effects on seed germination and seedling growth in three annual plants

Many ecological studies have pointed out maternal effects in plants and shown that plant maternal environment influences germination of their seed and subsequent seedling growth. However, few have tested for maternal effects induced by soil macroorganisms. We tested whether two earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) trigger such maternal effects on seed germination and seedling growth of three plant species (Veronica persica, Poa annua and Cerastium glomeratum). Our results show that, through maternal effects, A. caliginosa enhanced seed germination (V. persica and P. annua) and seedling growth (C. glomeratum and P. annua) while L. terrestris reduced seed germination only in V. persica. In some cases, the increase in germination rates of seeds produced in the presence of earthworms was associated with a reduction of nitrogen content in seeds. These results show that earthworms induce maternal effects in plants and that the size and direction of these effects depend on the combination of plant and earthworm species.