Leaf Morphology, Protogynous Dichogamy and Leaf Essential Oil Composition of Selected Cinnamomum Species in Sri Lanka

Abstract

The knowledge gap on morphology, floral behaviour and chemical composition of endemic seven wild relatives of cultivated cinnamon (Cinnamomum verum J. Presl) should be addressed for their utilization in cinnamon breeding and industry. This study was carried out to determine the floral behaviour of two wild cinnamon species of Cinnamomum dubium Nees (Cd) and Cinnamomum litseaefolium Twaites (Cl) along with Cinnamomum verum (Cv) variety Sri Gemunu (SG), leaf morphological characters (LMC) and, leaf essential oil composition of Cinnamomum capparu coronde Blume (Cc), Cd and Cl under ex-situ conservation at mid country research station, Dalpitiya, Sri Lanka (GPS: 7.1333031 N, 80.590026 E) along with Cv varieties SG and Sri Wijaya (SW) during February 2019. Floral cycles were determined through visual observation for two consecutive days. Protogynous dichogamy was determined: Cl and SG belonged to type A, while Cd was type B. In all species, the first opening was distinguishable with the fresh white stigma and white petals, while the stigma was brown and anthers were dehiscent during the second opening irrespective of time point of the floral cycle. Partial overlappings of functional male and functional female stages were observed in both type A and B plants, which may lead to self pollination. LMC of length, width, shape, apex, base, texture, venation, petiole length and margin varied among species. Gas Chromatography Mass Spectrometry (GC-MS) revealed of 34, 34, 12, 48, 8 and 18 chemical compounds from Cc, Cd, Cl-1, Cl-2, SG and SW respectively. The highest abundant chemical compound varied as Eugenol in Cc, SG, SW and Cl-1 (33.11%, 82.11%, 90.80% and 42.13% respectively), Eucaliptol in Cd (51.19%) and linalool in Cl-2 (30.93%). Above results will indicate the potential variation among wild relatives of cultivated cinnamon, which needs to be further investigated for insights on future cinnamon breeding.