Dry Matter Production of Orchardgrass and Perennial Ryegrass at Five Irrigation Levels

Within the Great Basin, availability of irrigation water throughout the growing season is the limiting factor in the development of improved pastures. The choice of species and their water requirements are critical factors for providing a stable source of forage throughout the grazing season. A line‐source irrigation system was used from 1995 to 1998 to evaluate dry matter (DM) production and seasonal forage distribution of nine orchardgrass (Dactylis glomerata L.) and perennial ryegrass (Lolium perenne L.) hybrid cultivars along with check cultivars of meadow brome (Bromus riparius Rehm.) and smooth brome (B. inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), and quackgrass [Elytrigia repens (L.) Nevski] × bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) A. Love] hybrids (RS) under five irrigation levels ranging from 41 to 91 cm per year. Mean DM production rankings across water levels combined over years were tall fescue > orchardgrass > meadow brome > RS‐hybrid > smooth brome > perennial ryegrass‐hybrids. The DM production response across water levels was largely linear with a minor but significant quadratic component at lower water rates. Tall fescue was most responsive (i.e., produced more DM production) to increased irrigation rates. At lower water levels, meadow brome outyielded orchardgrass. However, when water was not limited, orchardgrass outyielded meadow brome. The RS hybrid and smooth brome had relatively low DM production at both low and high water levels. All species produced significantly (P < 0.01) more DM than perennial ryegrass at lower water levels. Under limited irrigation, tall fescue and meadow brome will produce more DM.