Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2014
Publication Date: 1/6/2015
Citation: Robins, J.G., Bushman, B.S., Escribano, S., Jensen, K.B. 2015. Heterosis for protein, digestibility, fiber, and water soluble carbohydrates in nine sources of orchardgrass germplasm. Euphytica. 204:503-511.
Interpretive Summary: Despite its importance as a forage source, orchardgrass exhibits only limited improvement due to its perennial nature and complicated polypoloid genetics. The development of hybrids and the accompanying heterotic effect is a possible method to increase the rate of genetic improvement in orchardgrass. We describe the development of orchardgrass hybrids and the result on forage quality. We conducted this study at a Cache County, UT field site and managed it with supplemental irrigation. Parents of the orchardgrass hybrids came from sites around the world. Evaluated traits included protein, digestibility, fiber, and sugars. We identified differences among the performance of the hybrids, their parents, and the included commercial varieties. Specifically, the hybrids exhibited better protein at the July harvest and better protein, digestibility, fiber, and sugars at the August harvest.
Technical Abstract: Orchardgrass, or cocksfoot, (Dactylis glomerata L.) is one of the most important forage grasses used in temperate agriculture. Yet, genetic gains are slow and complicated owing to the perennial and autotetraploid nature of orchardgrass. The development of orchardgrass population hybrids may be a way to more efficiently make genetic gains through heterosis. In the study reported herein, we describe the results of a three year study of the effect of heterosis on the forage quality of orchardgrass population hybrids managed with supplemental irrigation at a Cache County, UT, USA field site. The population hybrids derived from the orchardgrass cultivars Latar, Paiute, and Potomac; and from six additional germplasm sources from Asia, Europe, and North America. Data reflected July and August harvests from 2008 to 2010 and included crude protein, in vitro true digestibility, neutral detergent fiber, and water soluble carbohydrates. There were differences (P<0.05) among the population hybrids and the included check cultivars for each of the traits at both harvest points. Mid-parent heterosis was relatively common and there were several instances of high-parent heterosis and reciprocal effects. Additionally, the population hybrids possessed better mean phenotypic values than the cultivars for July crude protein (2 g kg-1), and August crude protein (4 g kg-1), IVTD (7 g kg-1), WSC (4 g kg-1) and NDF (-9 g kg-1). Overall, the results suggest that population hybrids may prove a feasible approach for orchardgrass forage quality improvement.