Understanding Summer Dormancy in Perennial Cool-Season Grasses.
Dariusz Malinowski1, Jaime Kigel2, Betty A. Kramp3, Haitao Zuo4, Harold B. Rathburn5, Jeff A. Brady3, William E Pinchak3, Lawrence M Angerer3, and Michael J. Burnett3. (1) Texas AgriLife Research, POB 1658, Vernon, TX 76385, (2) Hebrew University of Jerusalem, Faculty of Agriculture, POB 12, Rehovot, 76100, Israel, (3) Texas Agricultural Experiment Station, 11708 H-wy 70S, POB 1658, Vernon, TX 76384, (4) Beijing Academy of Agriculture and Forestry Science, Beijing, 100097, China, (5) Tarleton State University, 1333 W. Washington St., Stephenville, TX 76402
Summer-dormant cool-season perennial grasses originate from Mediterranean environments, where they have developed a drought resistance strategy to survive long and hot summers. Our team has introduced these grasses to semiarid environments of the southern Great Plains with the intention to complement forage from dual-use wheat (Triticum aestivum L) in the autumn and early spring grazing seasons. Mechanisms of summer dormancy are poorly understood in this type of grasses. We present our results that may explain how summer dormancy is induced and released in cool-season perennial grasses and discuss findings of other researchers working on this phenomenon. The mechanism may include, depending on the grass species, total leaf senescence in early summer regardless of soil water availability, accumulation of antioxidants in shoot meristems, an altered pattern of dehydrin expression, and formation of perennating, drought tolerant organs. We also present long-term (2001-2007) biomass productivity data of Grasslands Flecha MaxQ, the first commercially available summer-dormant tall fescue cultivar on the U.S. market.