Effects of iron on yield and composition of Rosmarinus officinalis L. essential oil

The effect of iron absorption on yield and composition of the oil of Rosmarinus officinalis L. (Lamiaceae) growing in calcareous soil in the North of Sardinia is reported. The plant material was obtained from two different chemotypes of R. officinalis whose oils were rich in α-pinene (sample A) and 1,8-cineole (sample B) respectively. The effect of foliar iron sprays was investigated in irrigated and non-irrigated plants. During the period of the study, May-November 1995, iron absorption did not produce any significant increase in oil yield but appeared to cause a marked rise in verbenone concentration in the oil of irrigated plants. This is likely to be the result of intensified metabolic oxidative processes which convert α-pinene into verbenyl derivatives. The higher concentrations of verbenone in R. officinalis oil after iron treatment increase its value for the perfume industry. © 1998 Allured Publishing Corp.