J. Penuelas et J. Llusia, EFFECTS OF CARBON-DIOXIDE, WATER-SUPPLY, AND SEASONALITY ON TERPENE CONTENT AND EMISSION BY ROSMARINUS-OFFICINALIS, Journal of chemical ecology, 23(4), 1997, pp. 979-993
Rosmarinus officinalis L. plants were grown under carbon dioxide conce
ntrations of 350 and 700 mu mol/mol (atmospheric CO2 and elevated CO2)
and under two levels of irrigation (high water and low water) from Oc
tober 1, 1994 to May 31, 1996. Elevated CO2 led to increasingly larger
monthly growth rates than the atmospheric CO2 treatments. The increas
e was 9.5% in spring 1995, 23% in summer 1995, and 53% in spring 1996
in the high-water treatments, whereas in low-water treatments the grow
th response to elevated CO2 was constrained until the second year spri
ng, when there was a 47%, increase. The terpene concentration was slig
htly larger in the elevated CO2 treatments than in atmospheric CO2 tre
atments and reached a maximum 37% difference in spring 1996. There was
no significant effect of water treatment, likely as a result of a mil
d low water treatment for a Mediterranean plant. Terpene concentration
increased throughout the period of study, indicating possible age eff
ects. The most abundant terpenes were alpha-pinene, cineole, camphor,
borneol, and verbenone, which represented about 75% of the total. No s
ignificant differences were found in the terpene composition of the pl
ants in the different treatments or seasons. The emission of volatile
terpenes was much larger in spring (about 75 mu g/dry wt/hr) than in a
utumn (about 10 mu g/dry wt/hr), partly because of higher temperature
and partly because of seasonal effect, but no significant difference w
as found because of CO2 or water treatment. The main terpene emitted w
as alpha-pinene, which represented about 50% of the total. There was n
o clear correlation between content and emission, either quantitativel
y or qualitatively. More volatile terpenes were proportionally more im
portant in the total emission than in total content and in autumn than
in spring.