Saltgrass [Distichlis spicata (L.) Greene] is a North American native that has only recently been used as a forage crop but only now is being looked at for potential for turf adaptation (Kopec and Marcum, 2001). It is a warm season species with excellent drought and salinity tolerance and commonly appears in salty and alkaline soils throughout the central and western United States (Eppley et al., 1998). With continued population growth and periodic drought in the semiarid western United States, there is an increased public interest in using turf species that can tolerate reduced irrigation and saline soil.
Freezing is the major environmental stress that limits geographic distribution of warm season turfgrass species. Variation in freezing tolerance still exists in most grasses and can be effectively used in breeding (Larsen, 1994). A previous freezing study with six saltgrass clones (Shahha et al., 2003a) indicated variation in freezing tolerance and suggested that freezing tolerance could be associated with origin of clone. Differences in freezing tolerance among cultivars and ecotypes have been found in other warm season turf species such as seashore paspalum (Cardona et al., 1997; Cyril et al., 2002), zoysiagrass (Dunn et al., 1999), buffalograss (Qian et al., 2001), and bermudagrass (Anderson et al., 2003). On the other hand, Busey (2003) observed variation in freezing tolerance among st. augustinegrass cultivars at only two of 24 experimental counties in Florida. In a freezing experiment with buffalograss performed in Colorado, cultivars with better freezing tolerance turned brown earlier in fall, whereas those less tolerant remained green until mid-November (Qian et al., 2001). To develop new cultivars for specific geographic locations, it is important to study freezing tolerance in this species. Thus, this 2-year experiment was initiated to examine relative freezing tolerance of 27 saltgrass ecotypes collected in three U.S. zones of cold hardiness but grown in one location and to determine if there is an association between leaf color retention in fall and freezing tolerance.
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