The floral headspace volatiles of selected orchids

Floral headspace volatiles are a mixture of Plant Volatile Organic Compounds (PVOCs) emitted from the flowers into the surrounding atmosphere. Based on the biosynthesis, floral HS volatiles are grouped mainly into terpenoids, phenylpropanoids and fatty acid derivatives. Floral HS volatiles mediate ecological interactions with microbes, pollinators, insects and herbivores, and significantly contribute to the atmospheric chemistry. In addition, floral volatiles are widely used as components of perfumes, cosmetics, flavorings, and also in therapeutic applications. However, most of the flowers are yet to be investigated for their floral HS volatiles. Orchids are one of the largest groups of flowering plants with extraordinary floral diversification and adaptation strategies especially with regard to the shape, color and fragrance. Along with the intriguing shapes and stunning colours, the fragrance is key determinant in orchid industry.

The current study focuses on the floral headspace profiles of the orchids Dendrobium crumenatum (Pigeon orchid), Grammotiphyllum speciosum (Tiger orchid), Oncidium Jamie Sutton x Honolulu (Dancing girl) and Peristeria elata Hook. (Dove orchid). The HS volatiles were analysed using Shimadzu GC-MS with Headspace Sampler (HS-20) using static headspace method. The volatile compounds were identified by calculating the RRI value, interpreting the mass spectrum, and through library search. The major floral HS volatiles identified are; Dendrobium crumenatum (Pigeon orchid)- β-ocimene, benzaldehyde, methyl benzoate, benzene acetaldehyde and nerolidol; Grammotiphyllum speciosum (Tiger orchid)- E-β-ocimene, β-caryophyllene, linalool, (E,E)-α farnesene and δ-cadinene; Oncidium Jamie Sutton x Honolulu (Dancing girl)- 1, 8-cineole, α-pinene, linalool, benzaldehyde and β-myrcene and Peristeria elata Hook. (Dove orchid)- 1,8-cineole, α-pinene, 2-phenyl ethyl acetate, myrcene and limonene. The reported floral HS volatile have significant role in ecological, medicinal, chemotaxonomical, and horticultural applications.