Volatilome and micromorphological analysis of two rosemary hybrids

The profile of volatile organic compounds (VOC), the composition of the essential oils (EOs) and the micromorphology of the leaf trichomes were investigated in two rosemary hybrids, Salvia×mendizabalii (Sagredo ex Rosúa) Roma-Marzio & Galasso (S × m) and Salvia x lavandulacea (de Noé) Roma-Marzio & Galasso (S × l). The phytochemical analysis highlighted the dominance of monoterpene hydrocarbons in both aroma profiles (65.8 % in S × m and 77.9 % in S × l, respectively), although they displayed different main compounds except for ?-pinene (28.2 % in S × m and 24.5 % in S × l). In S × m the EOs extracted from both fresh and dried leaves exhibited camphor (29.7 % and 25.9 %, respectively), ?-pinene (21.0 % and 18.2 %, respectively) and 1,8-cineole (11.1 % and 13.6 %, respectively) as major compounds. Noteworthy is the occurrence of ?-pinene (2.6 %) in the EO dried samples, whereas sabinene and limonene were exclusive of the fresh samples. In S × l the EOs from the fresh and dried leaves shared the same main compounds: camphor (24.0 % and 27.5 %, respectively), myrcene (14.9 % and 14.8 %, respectively) and ?-pinene (13.1 % and 12.2 %, respectively). The micro-morphological observations on leaves proved the occurrence of non-glandular dendritic hairs with smooth cuticle in both hybrids. The glandular trichomes include three main morphotypes: peltate, short capitate and medium-long capitate. The peltate and the short capitates are common to both hybrids, however in the peltate the number of the head secreting cells is different, eight in S × m and sixteen in S × l. The medium-long capitate occurs exclusively on the leaf adaxial side of S × m.