Cold Hardiness of Southern and Northern Saltgrass Ecotypes.
Mohamed A. Shahba, Sarah Wilhelm, Yaling Qian, and Anthony Koski. Colorado State University, Department of Horticultur and Landscape Arcitecture, Fort Collins, CO 80523-1173
Studies were conducted to assess cold hardiness of saltgrass accessions
collected from southern climates (San Joaquin Valley, CA) vs. accessions
collected from northern climate (the Front Range of Colorado). Plugs of three
northern selections and three southern selections were planted in the field in
Colorado to establish 5 by 5 ft plots. Rhizomes were sampled from the plots
during November and December from 2003 to 2005 and subjected to laboratory
freezing tests to determine freezing temperature resulting in 50% mortality
(LT50). Field color evaluation indicated the northern accessions
started dormancy response about one month earlier than the southern ecotypes.
Significant differences existed between northern and southern ecotypes and
within ecotypes. On average, the northern saltgrass ecotypes survived 7.0 to
13.0 C colder temperature than the southern ecotypes, with LT50
reaching –18 to –23 C during the mid-winter (January). Field winter injury was
only observed during the winter of 2003-2004 when the southern accessions
suffered 85-92% winter injury in the field whereas the northern accessions
exhibited ≤ 10 % winter injury. No difference in field
winter injury among ecotypes was observed in the winter of 2004-2005. In
summary, southern ecotypes are less freeze tolerant than the northern ecotypes.
This information is important in selecting and developing turf-type saltgrass
accessions for regional use.