Rice encrusting with small-seeded native species for reintroduction in agroecosystems: a case study in Lindernia procumbens

Seed coating is commonly applied in agricultural seed industry to alleviate biotic and edaphic barriers and improve seed germination, seedling emergence and establishment. Recently, this seed enhancement technology has been tested and applied to seeds of native species for ecological restoration and conservation. This work presents a novel application of seed coating for the reintroduction of species with dust-like seeds that render direct seeding and cultivation unfeasible. Here we have used seed coating on Lindernia procumbens (Krocker) Philcox (Linderniaceae), a threatened annual species of paddy fields. Lindernia procumbens seeds were encrusted to the surface of rice seeds that acted as carrier to spread the species along rice sowing. We first tested how two selected concentrations of binder affected L. procumbens germination, then we investigated sowing depth (i.e. surface level-light, and buried-darkness) effect. Rice encrusting is a feasible and valuable tool for preserving threatened species with tiny seeds, since binder did not limit L. procumbens germination. Light increased L. procumbens seedlings emergence compared to buried conditions. Although L. procumbens emergence was limited in a paddy field trial, we promoted the formation of a soil seed bank for the species. As such, this should not discourage the possibility to reintroduce rare species with tiny seeds in agroecosystems. This pioneering technique can be extended to ecological restoration, where there is an urgent need for new seed-based approaches and seed-coating technologies to improve seedling establishment and restoration efficacy.