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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.
2011 Project Description
Research from this project has been disseminated at several different venues. Information on eastern gamagrass seed quality and dormancy was presented at the W1168 mulit-state working group on seed biology in Ames, Iowa. The manuscript "Comparative seed lot quality assessment in 42 commercial seed lots of eastern gamagrass" was accepted for publication in the Native Plants Journal and the manuscript "Physical enhancement improves seed lot quality in eastern gamagrass (Tripsacum dactyloides)" was accepted in Acta Horticulturae. The manuscript "A standard laboratory method to assess purity and germination in eastern gamagrass seed lots" was prepared for submission to the Journal of Seed Technology.
Eastern gamagrass [Tripsacum dactyloides (L.) L. (Poaceae)] seed is highly variable across and within populations, which subsequently influences the quantity and quality of seed lots available for purchase. Seed quality and dormancy are barriers to establishment in cultivars, selections and ecotypes of this seed kind.
Forty-two commercially available seed lots were acquired to investigate seed lot parameters that contribute to inconsistent stand establishment of eastern gamagrass. Seed fill and germination potential ranged from 78-100 percent and 11-91 percent, respectively. Actual germination and dormant seed ranged from 0-40 percent and 1-85 percent, respectively. Estimated viability based on tetrazolium (TZ) staining was not related to germination, but had a higher relationship with total viable seed. Caryopsis weight had no association with germination, but was related to dormant seed and total viability in these seed lots. Seed count per pound ranged from 3195 to 8344 and was influenced by genotype.
Commercial seed lots are commonly marketed on a Pure Live Seed (PLS) basis, which incorporates composition and viability of the seed lot, but gives no estimation of dormancy. For applications that require an immediate, specific field population, purchasing decisions and planting rates should be based on Pure Actual Germination (PAG), calculated from seed lot purity and actual germination percentages, which may be a much better predictor of stand potential under favorable field conditions.
Paparozzi, E.T., A. W., Kimberly, R.L.Geneve, H. Hatterman-Valenti, C. Haynes, H. Kraus, C. Mc Kenney and P. Pitts. 2011. The AG IDEA alliance and horticulture graduate certificate programs. HortTechnology 21:688-691.
Gama-Arachchige, N.S., J.M. Baskin, R.L. Geneve and C.C. Baskin. 2011. Acquisition of physical dormancy and ontogeny of the micropyle-water gap complex in developing seeds of Geranium carolinianum L. (Geraniaceae). Annals of Botany 108:51-64.
Fulcher, A., T. Steele, E. Wilkerson, R.L. Geneve, and R. S. Gates. 2011. Using transpiration chambers to detect initial transpiration in cuttings and quantify transpiration in seedlings. Acta Horticulturae 893:1037-1042.
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