Growth Rate Differences among Big Sagebrush (Artemisis Tridentata) Accessions and Subspecies Utah

Abstract

Even-aged plants of 21 big sagebrush (Artemisia tridentata) accessions were grown in a uniform garden to test growth parameter variation. Growth parameters measures (height, crown diameter, yield, and annual nonfloral leader growth) were scored after the 1975, 1976, and 1977 growing seasons. Nested analyses of variance and mean comparison tests showed significant (p<0.05) accession and subspecies differences in each measure, each year. On a subspecies level, basin big sagebrush (A.t. ssp. tridentata) exceeded the other two subspecies (mountain big sagebrush = A.t. vaseyana, Wyoming big sagebrush = A.t. wyomingensis) for each character. In general, the values for the last two subspecies were not significantly different, but mountain big sagebrush tended to have larger values. Using 1975 data for yield and 1976 data for the other growth parameters, basin big sagebrush accessions averaged 147.9 +/- 14.7 (se) cm in height, 193.0 +/- 12.1 cm in maximum crown spread, 2217 +/- 444 g current yield, and 12.7 +/- 1.1 cm in annual leader growth. Corresponding values for mountain big sagebrush were 95.8 +/- 2.2 cm, 157.3 +/- 3.4 cm, 890 +/- 77 g, and 8.8 +/- 0.6 cm. For Wyoming big sagebrush the values were 77.1 +/- 4.1 cm, 129.6 +/- 6.4 cm, 545 +/- 84 g, and 8.5 +/- 1.1 cm. Comparison of three accessions' performances at two uniform gardens and their native sites indicated that growth parameters, while subject to environmental influences, are under genetic control. The fastest growing and largest growing plants of this study were diploid, 2n = 18, whereas, the slowest growing ones were tetraploid, 2n = 36. Growth rate characteristics of big sagebrush should be considered for management purposes and in plant improvement programs.