Sparse-flowering orchardgrass is stable across temperate North America

Authors: Casler, Michael; Robins, Joseph; Coblentz, Wayne

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2013
Publication Date: 9/1/2013
Citation: Casler, M.D., Robins, J.G., Coblentz, W.K. 2013. Sparse-flowering orchardgrass is stable across temperate North America. Crop Science. 53:1870–1877.

Interpretive Summary: Development of new varieties of non-flowering orchardgrass would greatly simplify management of orchardgrass in pastures because flowers and stems are a nuisance to grazing livestock. This research evaluated non-flowering candidate varieties of orchardgrass at 21 locations across North America. Non-flowering varieties were always consistently lower in flowering than ordinary varieties, but also experienced a consistent loss in forage yield of 10%. The loss in yield is likely due to lost opportunity cost, owing to the fact that these varieties were not selected for improved forage yield during a 40-year time period. Future selection efforts should be able to assist in improving yield potential of these varieties. These results will be of value to the grass seed industry and other breeders.

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 to consume flowering stems, prompting many graziers to avoid use of this species. The objective of this research was to determine the stability and agronomic impact of recently developed sparse-flowering orchardgrass populations across temperate North America. Six cultivars, three sparse flowering and three normal flowering, were grown at 21 locations in temperate North America and evaluated for panicle density, heading date, and forage yield. Sparse-flowering cultivars had 57% fewer panicles than normal-flowering cultivars, but this effect was highly dependent on mean winter temperature, with normal-flowering cultivars showing twice as much temperature sensitivity compared to sparse-flowering cultivars. Forage yield of sparse-flowering cultivars was reduced by approximately 24-32% for first harvest and 2-9% for regrowth harvests compared to normal-flowering cultivars, and this reduction in forage yield was independent of mean winter temperature. The forage yield reduction associated with sparse flowering is most likely due to a combination of physiological load (loss of stems) and opportunity cost (lack of selection pressure for yield), suggesting an opportunity to improve forage yield potential of this sparse-flowering germplasm pool.