Sustainable turmeric production through medicinal and fruit tree-based agroforestry systems

Agroforestry systems offer a sustainable approach to enhance land productivity, ecological stability, and income diversification by integrating high-value trees with economically important crops. This study aimed to evaluate the effects of different medicinal and fruit tree species and distances from tree bases on the growth, yield, and land-use efficiency of turmeric (Curcuma longa L.). The experiment was conducted under a two-factorial randomized complete block design (RCBD) with four replications. Six tree species—Phyllanthus emblica L., Terminalia chebula Retz, Terminalia bellirica (Gaertn. Roxb.), Mangifera indica L., Moringa oleifera, and Citrus sinensis (L.) Osbeck were integrated with turmeric at three distances from the tree base (0–68, 69–136, and 137–204 cm), along with an open-field control without trees. Growth, yield components, light availability, land equivalent ratio (LER), and multivariate relationships were analyzed. Results indicated that turmeric growth performance and yield were significantly (p < 0.05) influenced by tree species, distance from the tree base, and their interaction. Turmeric performed best under open control plots and moderately shaded conditions beneath M. oleifera, P. emblica, and M. indica, producing the highest rhizome yield (31.86–36.43 t ha⁻¹) at 137–204 cm from the tree base. Dense-canopy trees such as T. bellirica and T. chebula reduced turmeric yield due to excessive shading and root competition. Principal Component Analysis (PCA) identified plant height, number of mother rhizomes, and number of secondary fingers as major yield determinants. Light availability showed a strong positive correlation with turmeric yield (r = 0.92, p < 0.001), underscoring the importance of canopy management. Land Equivalent Ratio (LER) values ranged from 1.64 to 1.81, confirming the productivity advantage of tree–turmeric intercropping over monocropping. Overall, integrating turmeric with suitable trees such as M. oleifera, P. emblica, and C. sinensis promotes sustainable, productive, and climate-resilient agroforestry systems in tropical regions.