• Root growth of Artemisia tridentata

      Welch, B. L.; Jacobson, T. L. C. (Society for Range Management, 1988-07-01)
      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.
    • Seedling growth rate of 3 subspecies of big sagebrush

      Booth, G. D.; Welch, B. L.; Jacobson, T. L. C. (Society for Range Management, 1990-09-01)
      Differences in growth rate among 3 subspecies of big sagebrush (basin big sagebrush, mountain big sagebrush, and Wyoming big sagebrush) for mature plants have been reported by a number of workers. Little has been reported on comparisons of seedling growth rate among these 3 subspecies. Results of this study indicated that (1) over an extended period and in a non-water-limiting environment, the rate of seedling growth In Wyoming big sagebrush approached zero and was less than that of seedlings of basin and mountain big sagebrush; (2) basin and mountain big sagebrush continued to have nonnegligible growth rates even at the end of the study; and (3) Wyoming big sagebrush reached its point of maximum growth rate approximately 2 weeks earlier than did the other 2 subspecies. It appears that Wyoming big sagebrush has evolved, placing 2 important growth characteristics under genetic control: (1) the maximum growth rate is attained earlier (when more water is available to sustain such growth) than in the other 2 subspecies, possibly enhancing its ability to survive on xeric sites during the early stages of growth; and (2) top growth produces smaller aboveground parts, enhancing survival after the early stages.