An Outcrossing Reciprocity Study Between Remnant Big Bluestem (Andropogon gerardii) Populations in the Carolinas

During the 2007-08 growing seasons we conducted an outcrossing reciprocity study with ramets from 5 big bluestem (Andropogon gerardii) populations from North and South Carolina. We established 15 treatments each at 4 garden sites. Seed germination was low and not significantly different for outcrossed (4.6%) and selfed (2.4%) treatments. However, germination was significantly higher for both outcrossed and selfed seeds from ramets from the Suther Prairie population. The overall mean percent seed set for the outcrossed treatments was 5.9%, and 3.6% for the selfed treatments. There were no significant differences in seed set (maternal effect) for the 5 populations. In addition, there were no significant differences in parental effect in either seed germination or seed set among the 5 populations. Ramets from the BlackJacks Heritage Preserve population (paternal) x Suther Prairie population (maternal) and its reciprocal SP x BJ had the highest combined percent seed germination (21.3% and 5.8%, respectively). Ramets from the Suther Prairie population (paternal) x Buck Creek Serpentine Barren (maternal), and its reciprocal BC x SP, had the highest combined percentage of seed set (22.7% and 9.6%, respectively). Results from this study suggest that viable seed production is low or absent in big bluestem populations in the Carolinas, particularly in smaller populations. We recommend vegetative material or seeds from the Suther Prairie big bluestem population for potential restoration and establishment of local big bluestem populations.