Obligatory summer-dormant cool-season perennial grasses for semiarid environments of the southern Great Plains
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Introduced cool-season perennial grasses may become an important complementary winter forage to dual-use wheat (Triticum aestivum L.) in high-risk semiarid environments of the southern Great Plains. Currently recommended, summer semidormant cultivars are not adapted to prolonged and severe summer drought and not productive in the autumn grazing season. In an experiment planted at Vernon, TX, on a Miles fine sandy loam (fine-loamy, mixed, thermic Udic Paleustalfs) in October 2000, we evaluated productivity and plant survival of an obligatory summer-dormant 'Grasslands Flecha' and summer semidormant 'Georgia 5', 'Jesup', and 'Kentucky 31' tall fescue (Festuca arundinacea Schreb.); a highly summer semidormant 'Grasslands Maru' hardinggrass (Phalaris aquatica L.); and summer semidormant 'Grasslands Matua' and 'Grasslands Tango' prairiegrass (Bromus wildenowii Kunth) under two defoliation intensities of 7.5 and 15 cm. Georgia 5, Jesup, and Grasslands Flecha were either infected with the novel Neotyphodium coenophialum Glenn, Bacon, and Hanlin endophyte strain AR542, with their endemic endophytes (except for Grasslands Flecha), or noninfected (E-). Only Grasslands Flecha and Grasslands Maru successfully survived summer droughts during 2001-2004. Prairiegrass behaved as an annual but did not reseed in 2003. Aboveground biomass was greater at 15- vs. 7.5-cm defoliation height, except for 2004 growing season. In Grasslands Flecha, the novel endophyte increased tiller survival during summer drought by 150% (2001) and 121% (2002) when compared with E-plants. Obligatory and highly summer semidormant cultivars of perennial cool-season grasses may be productive and persistent in the southern Great Plains and have the potential to complement forage from dual-use wheat pastures.
