Seasonal Variation of Monoterpenoids in Big Sagebrush (Artemisia tridentata)

Abstract

Monthly monoterpenoid content was determined for 16 big sagebrush (Artemisia tridentata) plants grown on a uniform garden. These 16 plants were selected at random from 4 accessions of basin big sagebrush (A.t. ssp. tridentata)-4 plants per accession. A composite sample was taken for a fifth accession of mountain big sagebrush (A.t. vaseyana). Monoterpenoid content varied seasonally with the lowest content occurring during May (0.97% of dry matter). Highest monoterpenoid content occurred during July (4.18%) followed by August (3.36%) and September (2.73%). Dove Creek (2.61% of dry matter) and Marysvale (2.64%) basin big sagebrush accessions contained significantly higher pooled levels of monoterpenoids than the Indianola (1.73%) and Loa (1.55%) big sagebrush accessions. The composite samples of the Indian Peaks mountain big sagebrush accession, an accession significantly preferred over the Marysvale and Loa accessions, contained an overall monoterpenoid level of 2.82%. Adverse relationships between monoterpenoid content and the consumption of big sagebrush by wintering mule deer seem weak.