U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Main content area

Effect of light intensity and wavelength on concentration of plant secondary metabolites in the leaves of Flourensia cernua

Rick E. Estell, Ed L. Fredrickson, Darren K. James
Biochemical systematics and ecology 2016 v.65 pp. 108-114
Flourensia, carbon, forage production, grasslands, herbivores, leaves, light intensity, livestock, phenolic compounds, rangelands, secondary metabolites, semiarid zones, shade, shrubs, solar radiation, terpenoids, ultraviolet radiation, wavelengths, Chihuahuan Desert
Flourensia cernua (tarbush) is a shrub that has encroached into grasslands in many areas of the northern Chihuahuan Desert and contains high levels of carbon-based secondary compounds. Concentrations of secondary compounds are affected by numerous biotic and abiotic influences, including amount and wavelength of solar radiation. However, responses to shade and ultraviolet light restriction are inconsistent among plant species and compound class. We conducted a three-year study to evaluate the effect of shade and UV light restriction on total phenolic and terpene concentrations in tarbush. Sixty plants were randomly assigned to one of three treatments (control, UV light restriction, or 50% incident light restriction). Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Total phenolics did not differ between UV-restricted and control plants, but were lower in shaded plants than the other treatments (P < 0.05). Total volatiles tended to be greater for the UV-restricted treatment than control plants (P = 0.056), with shaded plants not different from either treatment. Treatment effects were detected for 18 individual compounds (P < 0.05). Our results partially support the hypothesis that UV restriction and shading alter carbon-based secondary chemical concentrations.