Skip to main content
ARS Home » Research » Publications at this Location » Publication #308529
Title: Breaking seed dormancy of switchgrass (Panicum virgatum L.): A review

Author
item KIMURA, EMI - Washington State University
item FRANSEN, STEVEN - Washington State University
item Collins, Harold
item GUY, STEPHEN - Washington State University
item JOHNSTON, WILLIAM - Washington State University

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2015
Publication Date: 5/4/2015
Citation: Kimura, E., Fransen, S.C., Collins, H.P., Guy, S.O., Johnson, W.J. 2015. Breaking seed dormancy of switchgrass (Panicum virgatum L.): A review. Biomass and Bioenergy. 80:94-101.

Interpretive Summary: Switchgrass (Panicum virgatum L.) is a perennial herbaceous crop that is selected as model species for cellulosic biomass production. Switchgrass is native to North America, has a high yield and C-sequestration potential that reduces atmospheric CO2 when used as a renewable energy feedstock. Switchgrass is resilient to environmental stresses once successfully established; however, native warm season grasses, such as switchgrass produces small seeds with high degree of dormancy, creating sporadic seedling emergence in the field. Breaking seed dormancy of switchgrass is an important step to reduce the risk of establishment failure and costs associated with reseeding. Many studies have been reported to break seed dormancy of switchgrass with chemical, mechanical, thermal, and hormonal seed treatments. Seed storage duration, storage conditions (e.g., temperature and humidity), and agricultural practices (e.g., soil salinity and fertilizer rates) affect switchgrass seed dormancy. Strong interactions exist among germination, seedling emergence, and soil conditions; therefore, seed testing protocols are need to accurately predict the breaking of dormancy.

Technical Abstract: Switchgrass (Panicum virgatum L.) is a perennial warm-season grass identified as a model species for bioenergy feedstock. Established switchgrass stand are very resilient to environmental fluctuations, however, seed dormancy and weak seedling vigor make establishment difficult. Seeds with high level of dormancy provide low germination percentage, resulting in sporadic seedling emergence in the field. Reseeding cost was estimated to be 36 % of the total establishment cost in switchgrass, which cannot be paid off easily by increasing yield. Currently, the Association of Official Seed Analysts (AOSA) recommends a moist pre-chill treatment at 5°C for 14 days for switchgrass seeds. Pre-chill may mimic the wintering of the seeds and stimulate a seed carbohydrate reserves and lipid by moist and cold stratification. Although the moist pre-chill treatment breaks seed dormancy of switchgrass seeds, the effect are limited under a condition where seeds remain wet. Seed storage at subfreezing temperatures increased germination of switchgrass. Germination of switchgrass was improved from 10 to 76 % after storing at 4°C for 49 days from 30 to 53 % at 4°C for 300 days, from 78 to 90 % after storing at 23°C for 90 days, from 43 to 69 % after storing at 23°C for one year, and from 27 to 88 % after storing at 25°C for one year. These results indicate that storage temperature between 4°C and ambient temperature may break switchgrass dormancy.