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Identifying the Biophysical, Biochemical, Environmental, and Genetic Factors Associated With Seed Development, Dormancy, Germination, and Establishment of Eastern Gamagrass
Department of Horticulture
Eastern gamagrass is a native, perennial grass that can be used for forage, biofuel and conservation plantings. The seed is encased in a cupule and requires stratification for dormancy release and germination. However, following stratification, laboratory seed germination rarely exceeds 60% and typically field emergence is less than 20%.
Preliminary evidence has shown that seed quality has a major impact on dormancy and germination and suggests that seed quality is strongly influenced by seed production practices. The combination of dormancy, low germination and seed quality limits the widespread adoption of gamagrass for forage, biomass and conservation use.
2010 Project Description
Research from this project has been disseminated at several different venues. Information on eastern gamagrass dormancy was presented at the W1168 multi-state working group on seed biology in Michigan. Physical enhancement treatments to improve eastern gamagrass seed lot quality was presented at the Twenty Eighth International Horticulture Congress, Lisbon, Portugal. It was presented in the Seed Biology and Technology session for which I also acted as co-chair. The presentation generated an electronic poster available to the seed biology community at http://www.ihc2010.org/eposters/results.asp (search Finneseth). An additional presentation was made to the Association of Official Seed Analysts / Society of Certified Seed Technologists annual meeting concerning the association between floret position in eastern gamagrass and caryopsis weight.
The utility of a common laboratory blower in removing unfilled cupules and influence on germination of the derived fractions was completed. Two seed lots were selected based on low and high seed quality, 78 and 100% and 38 and 74%, cupule fill and estimated viability, respectively. Samples were fractioned at gate settings of 40-100 using a South Dakota blower and the number of cupules per fraction, mean cupule and caryopsis weight and percent germination were recorded. In both seed lots, a stepwise increase in air velocity facilitated separation based on cupule fill, cupule weight, caryopsis weight and germination of successive fractions.
Overall, cupule and caryopsis weights were increased by 10.7 and 3.4 g and 4.3 and 1.6 g in the low and high quality seed lots, respectively. Removing inferior cupules improved overall viability and seed lot quality. This research directly impacts seed testing by private and public seed labs and indirectly demonstrates to commercial seed producers the impact of using commercial scale seed conditioning equipment to improve seed lot quality in gamagrass.
Gama-Arachchige, N.S., J.M. Baskin, R.L. Geneve and C.C. Baskin. 2010. Identification and characterization of the water gap in physically dormant seeds of Geraniaceae, with special reference to Geranium carolinianum L. Annals of Botany 105:977-990.
Hartmann, H.T., D.E. Kester, F. T. Davies, Jr., and R. L. Geneve. 2010. Hartmann and Kesters Plant Propagation: Principles and Practices. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Eighth edition.