Get reliable science

Smooth bromegrass (Bromus inermis Leyss.), meadow bromegrass (Bromus riparius Rehm.) and hybrid bromegrass (B. riparius x B. inermis) are widely used for hay and pasture in temperate regions of the world. Three bromegrass species have variable capacities to regrow following defoliation and remobilization of stored energy after defoliation may vary among these grasses. A field study was conducted in 2006 and 2007 in Saskatoon (52 degrees N, degrees W), Canada to determine etiolated regrowth of three bromegrass species after defoliation to a 2.5-cm stubble height at the vegetative, stem elongation, reproductive stages of development, and after plant dormancy in late fall. After 5 and 10 days following defoliation, etiolated regrowth of meadow and hybrid bromegrass was greater than smooth bromegrass at the vegetative stage, and was greatest in meadow bromegrass, intermediate in hybrid bromegrass, and least in smooth bromegrass at the stem elongation stage. By 30 days and thereafter, etiolated regrowth was similar among three bromegrass species when defoliated at any growth stage. Etiolated regrowth was similar among the three species when defoliated at the reproductive stage. Meadow and hybrid bromegrasses produced more etiolated regrowth than smooth bromegrass on dormant plants in a growth chamber. The percentage of total etiolated regrowth to total full light regrowth increased with advanced growth stage in all three bromegrasses, and this percentage was higher in smooth bromegrass than the other two bromegrasses at the stem elongation and reproductive stages. The results of this study suggest that, following defoliation, meadow and hybrid bromegrass can mobilize stored energy more rapidly for regrowth than smooth bromegrass in the early regrowth period, contrary to the greater dependence on stored reserves in smooth bromegrass at the later growth stages.