Influence of Palea and Lemma Removal On Seed Viability in Long Term Storage of Paspalum Spp.

One of the greatest challenges in managing a germplasm collection is the loss of seed viability during long term storage.  Many factors influence viability in long term storage including seed condition at harvesting (ripeness, vigor), drying seed prior to storage, and storage conditions (temperature, humidity, etc).  In addition, seed cleaning can greatly influence viability.  Cleaning seeds to remove chaff, dirt, insects, broken seeds and other contaminants is done prior to storage.  Removal of the palea and lemma of grass seeds during the cleaning process, particularly Paspalum seeds, is often desired because if left intact, it can mask the fact that no caryopsis has developed inside.  This will result in reduced germination of samples and lead to inaccurate seed counts.  Additionally, removal of the palea and lemma has been shown to increase germination in Paspalum spp.  However, the palea and lemma can act as a protective barrier during long term storage and removal prior to storage may reduce viability.  Research was conducted to determine the effect on seed germination of palea and lemma removal prior to and after long term storage in Paspalum spp.  Results indicate that removal prior to storage dramatically reduces germination while seeds with intact palea and lemma have significantly higher germination rates.  Removal of the palea and lemma after storage did not have a beneficial effect on germination rates.  It is suggested that the palea and lemma are left intact during storage and that only a small subset of each sample is cleaned to the caryopsis to confirm that the majority of seeds do have a fully developed caryopsis.