| Switchgrass (Panicum virgatum L.) shows potential for use in the biofuels industry, but establishment can be unreliable due to seed dormancy. Typically, after seeding it may take up to three years to reach a proper stand for maximum yield. It has been shown that scarification, stratification periods and/or the use of chemicals help break dormancy and increased germination. The current protocol for testing seeds may require up to 28 days. These methods result in a 50-70% germination rate, including a positive tetrazolium test in non-germinated seeds. Stripping the palea and lemma (floral parts) from the seed typically result in higher germination rates. This may suggest that the floral parts are blocking the exit of chemical inhibitors. As of the present, the mechanism that causes dormancy in switchgrass is not known. Tests monitoring seed weight increases provide data that water enters floral parts but dormancy still occurs. This indicates that water uptake is not the sole mechanism of dormancy. Tissue cultures of excised embryos show a high rate of germination that corroborate with TZ results. Abscisic acid (ABA) is known to be involved in seed dormancy in other plant species and may be a chemical inhibitor in switchgrass. Immunoassays were performed to examine levels of ABA in the seeds. ABA was detectable in switchgrass seeds and was found in external media associated with germinating seeds. ABA is not thought to be the sole mechanism for dormancy but to work antagonistically with ethylene. |
