|PEARSON, CALVIN - Colorado State University|
Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2016
Publication Date: 1/1/2017
Citation: Larson, S.R., Pearson, C., Jensen, K.B., Jones, T.A., Mott, I.W., Robbins, M.D., Staub, J.E., Waldron, B.L. 2017. Development and testing of cool-season grass species, varieties, and hybrids for biomass feedstock production in western North America. Agronomy. 7(1):3. doi:10.3390/agronomy7010003.
Interpretive Summary: Breeding of native grass species, varieties, and hybrids has potential to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye is recognized as one of the tallest native grasses in this region, but it has restricted lateral growth. Creeping wildrye is highly rhizomatous with extensive lateral growth and shorter height. Cultivars of basin wildrye and creeping wildrye are used for rangeland revegetation and other conservation uses, but they were developed from wild populations without any breeding for increased productivity. Previous studies have shown that some hybrids of basin wildrye and creeping wildrye produced more biomass than their parents, but seed was not available to rigorously test these hybrids against standard basin wildrye cultivars or other species such as intermediate wheatgrass and tall wheatgrass that have been introduced and bred for high biomass productivity. In this study we developed seed for two different hybrids of creeping wildrye and basin wildrye and evaluated their productivity relative to standard cultivars of basin wildrye, intermediate wheatgrass, and tall wheatgrass across diverse dryland range and irrigated production environments and management systems. In most cases, tall wheatgrass was the most productive species and one of the standard basin wildrye cultivars, 'Trailhead', outperformed these two hybrids. However, a third experimental hybrid, developed using superior parents, produced 75% more biomass than the best basin wildrye cultivar, in dryland range conditions, and has potential for further develpment and testing. These results elucidate opportuity to improve native grass species for the development of new forage and bioenergy feedstocks in western North America.
Technical Abstract: Development and testing of cool-season grasses is needed to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) are native to semiarid environments of western North America. The objectives of this study were to develop interspecific creeping wildrye (CWR) x basin wildrye (BWR) hybrids and evaluate their biomass yield relative to tetraploid 'Trailhead', octoploid 'Magnar', and the interploidy hybrid 'Continental' BWR varieties in comparison with other perennial grasses across diverse single-harvest dryland range and two-harvest irrigated production environments. Two half-sib hybrid populations were produced by harvesting seed from the self-incompatible 'Acc:641.T' CWR genet, which was clonally propagated by rhizomes transplanted into isolated hybridization blocks with two BWR pollen parents, 'Acc:636' and Trailhead. A third full-sib hybrid was also produced from a single cross of two 'Rio' CWR and Trailhead BWR plants. In space-planted dryland range plots, the Rio CWR x Trailhead BWR and Acc:641.T CWR x Acc:636 BWR hybrids displayed high-parent heterosis with 75 and 36% yield advantages, respectively. However, Trailhead BWR produced greater biomass than half-sib hybrids of the Acc:641.T CWR genet in irrigated sward plots. Perennial Triticeae grasses including BWR, CWR x BWR hybrids, intermediate wheatgrass (Thinopyrum intermedium), and tall wheatgrass (Thinopyrum ponticum) performed equal to or significantly greater than switchgrass (Panicum virgatum) in dryland range and irrigated production environments. These results elucidate opportunity to harness genetic variation among native grass species for the development of new forage and bioenergy feedstocks in western North America.