Root Growth of Artemisia tridentata

We designed a greenhouse study to test the following 2 hypotheses: (1) root growth of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) exceeds that of basin big sagebrush (A.t. ssp. tridentata) and mountain big sagebrush (A.t. ssp. vaseyana) during the first 10 to 40 days after planting, and (2) root length of basin big sagebrush exceeds that of mountain big sagebrush, and root length of mountain big sagebrush exceeds that of Wyoming big sagebrush, at the end of a 174-day growing period. For the first 10 days, Wyoming big sagebrush root growth significantly (p=0.05) exceeded that of basin and mountain big sagebrush. At 20 and 30 days, Wyoming and basin big sagebrush were not significantly different, but both significantly exceeded mountain big sagebrush. At 40 days, basin big sagebrush root growth significantly exceeded that of Wyoming big sagebrush, which significantly exceeded mountain big sagebrush. Basin and Wyoming big sagebrush root lengths at 174 days were not significantly different, but both significantly exceeded mountain big sagebrush. Significant differences in root lengths at 174 days occurred among accessions. We concluded that Wyoming big sagebrush can survive on xeric sites where basin and mountain big sagebrush cannot because of smaller aboveground parts and rapid and long root growth.