|Remmenga, Marta - NEW MEXICO STATE UNIV|
Submitted to: Wildland Shrub Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 15, 2005
Publication Date: August 1, 2007
Citation: Lucero, M.E., Estell, R.E., Anderson, D.M., Fredrickson, E.L., Remmenga, M. 2007. Differences in volatile profiles between populations of Ceratoides lanata var. subspinosa (Rydb.) J.T.Howell. In: Sosebee, R.E., Wester, D.B., Britton, C.M., McArthur, E.D., Kitchen, S.G., editors. Proceedings: Shrubland Dynamics-Fire and Water; August 10-12, 2004, Lubbock, Texas. US Forest Service RMRS-P-47 p. 142-146. Interpretive Summary: Interpretive summary not required.
Technical Abstract: Ceratoides lanata (Rydb.) J.T. Howell, common winterfat, is valued for its nutrient content and palatability to livestock. However, the subspecies Ceratoides lanata var. subspinosa (Rydb.) J.T. Howell, first described in the Mojave desert, is considered unpalatable. This characterization has been supported by data from livestock grazing studies at the Jornada Experimental Range in southern New Mexico. Curiously, observation of subspinosa revealed several populations in central New Mexico which were heavily grazed. Volatile terpene profiles have frequently been associated with differences in palatability in various plant species. To determine whether differences in volatile profiles between subspinosa populations would correlate with apparent differences in palatability, plants from 13 populations of subspinosa were collected in the fall of 2000. Volatile analysis of ground shoot samples using solid-phase microextraction and gas chromatography-mass spectroscopy consistently identified 33 compounds. Limonene, myrcene, and 3-carene were the most abundant compounds in all populations, comprising 81% and 85% of the volatiles detected in heavily grazed and ungrazed plants, respectively. This is thought to be the first time C. lanata subspinosa volatiles have been described. Compounds present in at least half of either the heavily grazed or ungrazed plants were subjected to a stepwise discriminate analysis of relative quantities. The analysis identified a subset of 14 chromatographic peaks (myrcene, 3-hexenol, 3-carene, AR-curcumene, limonene, n-hexanol, p-cymene, a mixture thought to contain alpha-pinene, alpha-thujene, and tricyclene, a mixture thought to contain n-decanal, and five unknowns) which may distinguish between palatable and unpalatable phenotypes. When a discriminate rule based on these chemicals was applied to chemical data from individual plants at all sites, none of the plants were misclassified. The possibility that these varied oil profiles may be used to distinguish palatable from unpalatable phenotypes is discussed.