YIELD, NUTRITIVE-VALUE, AND PHENOTYPIC VARIABILITY OF TALL WHEATGRASS GROWN IN A NONSALINE ENVIRONMENT

The phenotypic variation of 10 important botanical traits and 2 traits related to herbage quality was measured in tall wheatgrass (Thinopyrum elongatum) cv. Tyrrell. Five certified lines of Tyrrell were compared among themselves and with cvv. Largo and San Jose. Significant differences, both between cultivars and within lines of Tyrrell, were observed for several traits. The phenotypic variability measured confirms that Tyrrell is distinct from its progenitor, Largo, and has sufficient variability to make it suitable for use in a selection program. In a second experiment, from November 1990 to February 1993, the yield and nutritive value of Tyrrell, Largo, and San Jose were compared with perennial ryegrass (Lolium perenne) cv. Ellett and tall fescue (Festuca arundinacea) cv. Demeter. There were no differences (P>0.05) between cultivars for either total dry matter yield or total yield of digestible dry matter. Seasonal differences in growth and nutritive value were observed. Ellett showed superior growth in winter and early spring, while tall wheatgrass and Demeter were more summer-active. In 6 of the 11 harvests measured for nutritive value, there were no differences (P>0.05) between treatments for yield of digestible dry matter; for 2 of the remaining 5 harvests, Tyrrell yielded more digestible dry matter than Ellett. Dry matter digestibility of tall wheatgrass did not fall below 60%. The results suggest that with appropriate management, tall wheatgrass can produce nutritious forage in quantities sufficient for animal production systems, particularly as a special purpose summer pasture.