Breaking seed dormancy in Opuntia rastrera from the Chihuahuan desert

In this paper, we investigated if germination of after-ripened seeds of Opuntia rastrera Weber could be enhanced using chemical (acid) and mechanical scarification pretreatments. O. rastrera seeds need an after-ripening period to germinate (≈50%) after 1 year and no germination occurs in younger seeds. Germination of 3-year old seeds of O. rastrera was evaluated using sulphuric acid (H2SO4) for different lengths of time, and mechanical scarification treatments (dry heating at 80 °C for 12 h and washing, immersion in water for 12 h and washing, and seed coat cutting with pliers). Similar to other wild Opuntia species, germination of O. rastrera seeds was not enhanced by any scarification pretreatment, demonstrating that an after-ripening period is the best-if not the unique-way to overcome physiological dormancy for this species.