Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2013
Publication Date: 1/2/2014
Publication URL: http://handle.nal.usda.gov/10113/62473
Citation: Casler, M.D., Robins, J.G., Coblentz, W.K. 2014. Sparse-flowering orchardgrass represents an improvement in forage quality during reproductive growth. Crop Science. 54:421-429.
Interpretive Summary: Orchardgrass is a major component of many pastures in temperate North America. Early and profuse flowering in pastures is a nuisance to graziers, due to livestock refusal of flowering stems, prompting many graziers to simply avoid using this species. This research demonstrated that non-flowering varieties of orchardgrass represent a significant improvement in forage quality, increased protein, decreased fiber, and increased digestibility during spring growth. The increase in quality was due to a severe reduction in the number of stems, which are of lower quality than leaves. There was no change in quality of regrowth harvests. These results will be of value to livestock producers who are interested in growing orchardgrass in pastures and hay fields.
Technical Abstract: Orchardgrass (Dactylis glomerata L.) is a major component of many pastures in temperate North America. Early and profuse flowering in pastures is a nuisance to graziers, due to livestock refusal of flowering stems, prompting many graziers to simply avoid using this species. The objective of this research was to determine the impact of a genetic reduction in flowering on the quality of harvested forage under two harvest managements of orchardgrass. Six cultivars, three normal cultivars and three sparse-flowering cultivars (mean panicle density of 141 vs. 61 panicles m-2, respectively) were evaluated in field experiments at 21 locations in North America under a 3-cut harvest management. These cultivars were also evaluated at seven locations under a 5-cut harvest management. Sparse-flowering cultivars averaged 9% higher in crude protein (CP), 3% lower in neutral detergent fiber (NDF), 2% higher in NDF digestibility, and 2% higher in in vitro dry matter digestibility (IVDMD) compared to normal cultivars. For the two digestibility measures, differential panicle density between the cultivar groups explained a significant portion of variability, indicating that increase in forage quality was proportional to the decrease in panicle density above a threshold of about 50 panicles m-2. Lastly, differences in forage quality of regrowth between cultivar groups were smaller, less consistent, not always in the direction expected, and of lower statistical import than for first harvest. We conclude that selection for sparse flowering in orchardgrass resulted in significant cause-and-effect increases in first-harvest forage quality, as measured by increased CP, NDFD, and IVDMD and by decreased NDF.