Enhancing Growth, Yield, and Quality of Wild Turmeric (Curcuma aromatica Salisb.) through Rhizome Priming and Chitosan Biostimulation: An Integrative Review

Abstract

Wild turmeric (Curcuma aromatica Salisb.), a rhizomatous member of the Zingiberaceae, occupies a distinctive niche among Curcuma species owing to its camphoraceous aroma, its comparatively modest curcuminoid content set against a rich essential oil fraction, and its long-standing role in traditional cosmetics and medicine across South and Southeast Asia. Commercial cultivation of the crop nevertheless remains constrained by uneven rhizome sprouting, prolonged dormancy, susceptibility to soil-borne rhizome rot, and inconsistent curcuminoid and oil yields across seasons. Rhizome priming and chitosan biostimulation have separately emerged as low-cost, environmentally benign pre-planting and in-season interventions capable of addressing these constraints in Zingiberaceae and related rhizomatous crops. This review draws together evidence from turmeric, ginger and allied medicinal and aromatic species to appraise how hydro-, osmo-, chemo- and bio-priming of rhizomes, together with foliar or rhizome-dip application of chitosan, influence sprouting uniformity, vegetative vigour, rhizome biomass accumulation, and the biosynthesis of curcuminoids and volatile oils. The mechanistic basis of these responses is examined, spanning imbibition kinetics and reserve mobilisation during priming, and pattern-triggered immunity, reactive oxygen signalling and transcriptional activation of phenylpropanoid and curcuminoid pathway genes following chitosan elicitation. Comparative evidence from turmeric, ginger and related medicinal plants is synthesised to identify effective concentration ranges, application windows and combined priming-elicitation strategies. The review closes by outlining priority research directions specific to Curcuma aromatica, principal conclusions for growers and breeders, and the methodological limitations inherent in extrapolating findings from congeneric and heterologous crop systems to this comparatively under-studied species.