ASPECTS OF TE GERMINATION ECOLOGY AND BIOMASS PRODUCTION OF EASTERN GAMAGRASS (TRIPSACUM-DACTYLOIDES L)

In eastern gamagrass (Tripsacum dactyloides) seeds, removal of the indurate cupule enclosing the caryopsis resulted in relatively rapid and high levels of germination regardless of seed pretreatment and across a wide range of incubation temperatures during germination. Seeds incubated at room temperatures with cupules removed had 58%-86% germination, compared with 10%-26% germination for seeds with cupules. Enriched levels of 5% CO2 either had no effect on germination, compared with the germination response under ambient levels of CO2, or germination was enhanced as a function of treatment conditions and seed source. Annual seed production was estimated to be ca. 412/m2. Seed predation, almost entirely by small rodents, was estimated to be ca. 95% of the annual seed crop. Peak aboveground green biomass standing crop was estimated as 1,258 g/m2; of this, only 67 g/m2 were allocated to reproduction. It took ca. 6 days (144 h) for caryopses to pass through a cow''s digestive system; 51 of 500 caryopses passed through the digestive system without apparent mechanical damage, and some retrieved seeds germinated.