Abstract
Breeding of native cool-season grasses has the potential to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) rank among the tallest and most rhizomatous grasses of this region, respectively. The objectives of this study were to develop interspecific creeping wildrye (CWR) × basin wildrye (BWR) hybrids and evaluate their biomass yield relative to tetraploid ‘Trailhead’, octoploid ‘Magnar’ and interploidy-hybrid ‘Continental’ BWR cultivars in comparison with other perennial grasses across diverse single-harvest dryland range sites and a two-harvest irrigated production system. Two half-sib hybrid populations were produced by harvesting seed from the tetraploid self-incompatible Acc:641.T CWR genet, which was clonally propagated by rhizomes into isolated hybridization blocks with two tetraploid BWR pollen parents: Acc:636 and ‘Trailhead’. Full-sib hybrid seed was also produced from a controlled cross of tetraploid ‘Rio’ CWR and ‘Trailhead’ BWR plants. In space-planted range plots, the ‘Rio’ CWR × ‘Trailhead’ BWR and Acc:641.T CWR × Acc:636 BWR hybrids displayed high-parent heterosis with 75% and 36% yield advantages, respectively, but the Acc:641.T CWR × ‘Trailhead’ BWR hybrid yielded significantly less than its BWR high-parent in this evaluation. Half-sib CWR × BWR hybrids of Acc:636 and ‘Trailhead’ both yielded as good as or better than available BWR cultivars, with yields similar to switchgrass (Panicum virgatum), in the irrigated sward plots. These results elucidate opportunity to harness genetic variation among native grass species for the development of forage and bioenergy feedstocks in western North America.
Highlights
Development of biofuel feedstocks in the United States has been focused on switchgrass (Panicum virgatum) as a model crop system in part because of its performance in herbaceous crop screening trials conducted across Alabama, Iowa, Indiana, New York, North Dakota, Ohio and Virginia; and because decision makers recognized the strategic importance to demonstrate the feasibility of developing a cellulosic biofuel crop with limited funding [1,2,3,4]
For this study, we have proposed a strategy to produce larger volumes of hybrid seed for different creeping wildrye (CWR) × basin wildrye (BWR) hybrids by growing rhizome propagules from one self-incompatible CWR genet, Acc:641.T, in isolated field hybridization plots with different varieties or natural populations of BWR as the only available pollen source
This study demonstrated a useful approach to produce hybrid seed for allogamous perennial grasses, which has been a long-standing problem in perennial grass improvement
Summary
Development of biofuel feedstocks in the United States has been focused on switchgrass (Panicum virgatum) as a model crop system in part because of its performance in herbaceous crop screening trials conducted across Alabama, Iowa, Indiana, New York, North Dakota, Ohio and Virginia; and because decision makers recognized the strategic importance to demonstrate the feasibility of developing a cellulosic biofuel crop with limited funding [1,2,3,4]. Studies have shown that cool-season perennial Triticeae grasses including crested wheatgrass (Agropyron desertorum), intermediate wheatgrass (Thinopyrum intermedium), mammoth wildrye (Leymus racemosus), tall wheatgrass (Thinopyrum ponticum), and native western wheatgrass (Pascopyrum smithii) may be useful for forage and bioenergy feedstock production across the prairie provinces of Canada and the central United. States including Alberta, Kansas, Manitoba, North Dakota, Saskatchewan, and South Dakota [1,4,6,7,8,9,10]. These cool-season perennial Triticeae grasses are well adapted to the high-elevation cold-desert.
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