The reproductive versatility of eastern gamagrass

Eastern gamagrass [Tripsacum dactyloides (L.) L.], a native, warm-season species, is a nutritious and palatable forage for grazing livestock. The grass has potential for rangeland and pasture improvement. This field study was conducted over 10 yr and one location to determine the reproductive characteristics of the various cytotypes of Tripsacum and identify methods for breeding agronomically superior cultivars. Intra- and interspecific crosses were made and evaluated between several Tripsacum cytotypes. Cytological and polymerase chain reaction-random amplified polymorphic DNA (PCR-RAPD) techniques a ere used to identify methods of reproduction and types of individuals generated. Results of the study identified two methods for facilitating horizontal gene flow among sexual and apomictic cytotypes. Materials with triploid and hexaploid constitutions were essential in the movement of sexual germplasm into apomictic tetraploids and of tetraploid germplasm into sexual diploids, respectively. Triploids and hexaploids were useful materials to introgress and transfer desirable alleles across species, cytotypes, and reproductive barriers. In addition, the generation of triploid and hexaploid genotypes will continue to exert major influences on Tripsacum evolution and speciation. This study identified additional methods and systems for improving Tripsacum germplasm by utilizing its distant relative maize (Zea mays L.) in a breeding or genetic evaluation program.