Variation among and within Smooth Bromegrass Collections from Rural Cemeteries
Smooth bromegrass (Bromus inermis Leyss.) is poorly adapted to management-intensive rotational grazing because of slow and limited regrowth potential. In an effort to find existing germplasm with tolerance to frequent cutting, smooth bromegrass germplasm was collected from fence and sod habitats of 30 rural cemeteries in Iowa, Minnesota, and Wisconsin. Ramets of 25 clones from each habitat of each cemetery were transplanted into a replicated and randomized experiment at Arlington, WI, and evaluated from 1999 to 2002. Within-population genotypic variance was greater in sod populations for plant height and diameter. Across cemeteries, genotypic variances for regrowth vigor of sod and fence populations were positively correlated. These two results suggest that a large amount of genotypic variability is being maintained at some cemeteries by migration into sod populations and disruptive selection favoring different genotypes in the two habitats. Fence populations averaged 7.6% higher in reproductive forage yield, 9.5% higher in vegetative forage yield, 6.0% taller, 8.4% wider plant diameter, 4.7% higher regrowth vigor, and 6.9% higher frequent-harvest forage yield than sod populations. Sod populations tended to be more variable among cemeteries than fence populations, suggesting greater adaptive responses to selection pressure. Two sod populations were highly unusual, one with unusually fast regrowth arising from tillers that initiated obvious growth within 24 h after apical dominance was removed, the other with extremely high reproductive forage yield, but low regrowth vigor. This germplasm may have value in the development of smooth bromegrass germplasm with improved tolerance to frequent cutting or grazing.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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