) and has been explored as a food preservative and for decreasing aflatoxin B1 in maize grain ( Bluma and Etcheverry, 2008 ). Anise seed essential oil content and composition vary depending on the environment and the genotype ( Leela and Vipin, 2008
, 1973 ). Like with other aromatic plants, A. annua essential oil content and composition is modified by genotype and the environment ( Tzenkova et al., 2010 ), by distillation method ( Scheffer, 1993 ), and by other factors. A recent report ( Ferreira
-metone, citronellyl formate, and geraniol formate ( Peterson et al., 2006 ; Weiss, 1997 ). Market value of rose-scented geranium essential oil is determined by composition (the proportion of the compounds, mainly the citronellol-to-geraniol ratio) and the quantity
distillation ( Topalov, 1962 ). Although there are numerous reports on garden sage essential oil composition, there is no agreement in the literature regarding the optimal steam DT for the extraction of the essential oil from garden sage biomass. We
factors, as reviewed recently by Figueiredo et al. (2008) . It has been demonstrated with some other essential oil species that the length of the DT may affect essential oil yield and composition, but not oil bioactivity ( Cannon et al., 2012
; Ondarza and Sánchez, 1990 ). Because the essential oil composition influences its biological activity ( Karakaya et al., 2011 ), the essential oil yield (content) is important with respect to the economics of production. Oregano essential oil yield and
( Adams, 1979 ), and duration of distillation time ( Zheljazkov et al., 2012a , 2012b ) can affect Rocky Mountain juniper essential oil composition. However, there are no reports on variations of Rocky Mountain juniper essential oil year-round, from
, 1991 ; Zheljazkov et al., 2010b ). We hypothesized that the length of the DT will have an effect on Japanese cornmint essential oil content and composition. Indeed, various authors used different DTs for extraction of Japanese cornmint, ranging from 60
through increasing the number of plants per area. Hence, the main objective of these experiments was to determine the effect of different PBZ concentrations on rose-scented geranium vegetative growth, and essential oil yield and composition. Materials and
beneficial for the existing and future spearmint essential oil industry. There have been various studies aiming to improve essential oil yield and composition of spearmints. For example, previous studies demonstrated that some plant hormones such as MJ may