Seasonal and diurnal variations in leaf aroma volatiles of Cinnamomum tamala (Buch.—Ham.) T. Nees & Eberm as evidenced from metabolite profiling, histochemical and ultrastructural analyses

Abstract Though the leaves of Cinnamomum tamala is extensively employed in culinary applications due to its rich aroma and therapeutic properties, the produce exhibits variability in composition and contents of leaf essential oil due to fluctuations in climatic conditions and harvesting time. This work evaluated the impact of seasonal and diurnal variations on the composition and contents of aroma volatiles in the mature leaves of C. tamala. In summer, the profile of aroma volatile was dominated by phenylpropanoids (112.96 ± 24.11 μg g–1 of freeze-dried [FD] leaf tissue) while in winter monoterpenes (58.45 ± 8.194 μg g–1 of FD leaf tissue) acquired the dominance. The variability in the contents of primary metabolites was shown to be influenced by the harvesting season and time. Organic acids and sugars showed highest accumulation in leaves harvested during summer evening and winter morning, respectively. Histochemical study showed the presence of lipids and terpenes in the secretory cells as revealed through sudan III and NaDi staining. The ontogeny of secretory oil cells that accumulate essential oil were elucidated through ultrastructural study.