Dry matter production of orchardgrass and perennial ryegrass at five irrigation levels

Within the Great Basin, availability of irrigation water throughout the gro wing season is the limiting factor in the development of improved pastures. The choice of species and their water requirements are critical factors fo r 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 (Dac tylis glomerata L.) and perennial ryegrass (Lolium perenne L.) hybrid culti vars 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] x bluebunch wheatgrass [Ps eudoroegneria spicata (Pursh) A. Level hybrids (RS) under five irrigation l evels ranging from 41 to 91 cm per year. Mean DM production rankings across water levels combined over gears mere tall fescue > orchardgrass > meadow brome > RS-hybrid > smooth brome > perennial ryegrass-hybrids. The DR I pro duction response across water levels was largely linear with a minor but si gnificant quadratic component at lower water rates. Tall fescue was most re sponsive (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 wat er levels. Ail species produced significantly (P < 0.01) more DM than peren nial ryegrass at lower water levels. Under limited irrigation, tall fescue and meadow brome will produce more DM.