Date of this Version
Crop Sci. 27:8‑13
Three studies were conducted to evaluate intergeneric wheatgrass hybrids for their potential as range and pasture grasses in the Central Great Plains. Quackgrass [Elytriga-repens (L.) Nevski] X bluebunch wheatgrass [Psueodoroegneria spicata (Pursh) A. LoveJ F5 hybrid lines (RS lines) developed by D.R. Dewey were grown in a space transplanted nursery at Lincoln, NE, to estimate genetic variability for forage yield and quality as measured by in vitro dry matter digestibility (IVDMD) and protein in the RS population. There was significant variability among the RS lines for all traits (broad-sense heritability H > 0.5) except for first harvest IVDMD (H = 0.26). The highest yielding RS lines yielded only about half as much forage as 'Slate' intermediate wheatgrass [Thinopyron intermedium (Host) Barkworth and D.R. Dewey subsp. intermedium], which was included as a check. Slate intermediate wheatgrass, 'Ruff crested wheatgrass [Agropyron cristatum (L.) Gaertner], 'Nordan' crested wheatgrass [A. desertorum (Fisch.) SchultesJ, RS-1 and RS-2 (quackgrass X bluebunch wheatgrass germplasm), and a quackgrass X A. desertorum hybrid designated as RD were then evaluated in sward nurseries in two environments (Mead and Alliance, NE) that differ widely in climate. Intermediate wheatgrass was clearly superior in forage yield and quality as measured by IVDMD in the eastern part (Mead) of the Central Great Plains. In the western part of this area (Alliance) intermediate and the crested wheatgrasses were equal or superior to the RS hybrids in forage yield and intermediate wheatgrass had higher IVDMD. The RD hybrid had lower yields than the other strains at both locations. Yields of the intergeneric wheatgrass hybrids could be improved by breeding to make them more competitive with intermediate and crested wheatgrasses. The same breeding effort could be used to improve these pure species for which substantial genetic variability for both yield and IVDMD has been previously documented and would probably result in greater overall progress. Forages from grasses grown at Mead in swards were analyzed using the detergent system of analyses and there was considerable variation among the grasses in fiber composition and digestibility of the fiber components even though the grasses were very similar in physiological maturity when harvested. The results suggest that there are genetic differences among these wheatgrasses in forage fiber composition and the digestibility of the fiber components.