Germination Requirements of a Perennial Alysicarpus vaginalis Accession

Germination of a perennial alyceclover [Alysicarpus vaginalis (L.) DC.] accession, which has potential value as a grazing-tolerant pasture legume for peninsular Florida and some tropical locations, was evaluated for response to seed storage and scarification treatments. Both practical means of enhancing germination and characteristics of germination limitations were considered. A series of experiments evaluated responses to storage time, storage temperature, physical seed coat disruption with sandpaper, and exposure to steam, hot water, and dry heat. Freshly harvested seed failed to germinate regardless of seed treatment. Seed that had been stored for 3 to 8 yr produced rapid, essentially complete germination when scarified with sandpaper. A storage period of approximately 16 wk was sufficient for rapid germination regardless of storage temperature. At 4 wk of storage, a storage temperature of 7°C resulted in higher germination than storage at 24°C. Steam exposure times of from 40 min to 2 h or exposure to 80°C water for 5 to 10 min produced slow germination rates but greater than 60% germination after 56 d. Exposure to dry heat for 6 or 12 h produced poorer results (48% germination at 56 d) than steam or hot water. These heat treatments could have value either where mechanical scarification is not available or in situations where sporadic, early season rainfall creates high pasture establishment risks for seed lots that have been scarified to provide rapid, complete germination. Failure of scarified, imbibed, fresh seed to germinate indicates a physiological limitation to germination. Rapid, essentially complete germination of these seed lots after storage periods of from 16 wk to a number of years indicates that an afterripening period overcomes this limitation. Physical seed coat impermeability or hardseededness is demonstrated by the need for scarification even in seed that has been stored long enough to meet the after-ripening requirement. Contribution of the Florida Agric. Exp. Stn., Journal Series no. 8276.