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Description
Ceylon cinnamon (Cinnamomun verum) is a globally demanded spice valued for its specific flavor, positioning it as the world’s largest exporter. The Cinnamon Research Centre of Sri Lanka has developed two high yielding cultivars, Sri Gemunu and Sri Wijaya, producing yield up to 600 kg per acre under optimal management conditions. These cultivars are vegetatively propagated for commercial distribution to maintain genetic uniformity. Understanding phenotypic plasticity in vegetatively propagated materials is crucial for cultivar identification and breeding purposes. This study evaluated the environmental stability and phenotypic plasticity of qualitative leaf morphological traits in twenty cinnamon accessions across two agroclimatic zones of the Mid Country Wet Zone (Mid country Research Station [MRS], WM3a) and the Low Country Wet Zone (Thalgampola, Galle, WL2a) in Sri Lanka. Mother plant maintained at MRS were compared with their vegetatively propagated clones established in Thalgampola for approximately 2 years. Standardized leaf sampling from the 5th and 6th nodes below apical shoot tips minimized development variation to assess six qualitative traits of leaf arrangement, shape, apex, base, venation, and margin. Chi-square and Cramer's V coefficients quantified between selected traits and environment associations. Results demonstrated that leaf arrangement (p=1.000, V=0.060), apex (p=0.324, V=0.374), base (p=0.438, V=0.360), and venation (p=1.000, V=0.000) exhibited environmental stability across sites (p>0.05, V<0.5). Conversely, leaf shape displayed moderate phenotypic plasticity (p=0.033, V=0.579), while leaf margin showed strong environmental responsiveness (p<0.001, V=0.951). These findings indicate that environmentally stable traits serve as reliable taxonomic markers for cultivar identification across diverse sites, while phenotypically plastic traits may discuss adaptive advantages under varying agroclimatic conditions, informing both breeding strategies and propagation quality control.
Keywords: Cinnamomum verum, Environmental stability, Leaf morphology, Phenotypic plasticity
