J.P. MUIR and W.D. PITMAN

University of Florida, Agricultural Research Center, Ona, Florida, USA

Abstract

Effects of clipping during autumn every 2 weeks for either three and six clipping cycles were compared to an unclipped control. Autumn herbage production of D. virgatus and D. heterocarpon was reduced by clipping, but that of G. elliottii was not. Root mass and non-structural carbohydrate concentration of roots and stem bases of D. virgatus and G. elliotii were reduced by clipping, while root mass of D. heterocarpon was unaffected by clipping. Root and stem-base carbohydrate accumulation of D. heterocarpon was greater for clipped plants than for the unclipped control.
Subsequent spring regrowth was assessed 16 weeks after a winter defoliation. Despite differences in root and stem-base carbohydrate accumulation at the end of autumn ranging from 9.8% for the D. heterocarpon autumn control plants to 33.9% for the G. elliottii autumn control plants, each of the three species produced similar spring yield responses to winter defoliation following the differential autumn treatments. Winter defoliation reduced regrowth only of plants which had not previously been clipped. Despite lack of effects of autumn clipping treatments on spring regrowth of individual species, spring herbage production among species was correlated with carbohydrate levels at the end of autumn.