Turmeric (Curcuma spp.) is widely cultivated in tropical regions for its use in traditional medicine and culinary purposes. This study investigated the bacterial populations in the rhizosphere, stems, and leaves of the Curcuma species and strains at different growth stages. Bacterial population cultivated in the field and plastic house showed variations across growth stages. The rhizosphere possessed the highest bacterial populations in both experiments (1.8 to 11.9 × 10⁶ CFU/g and 1.7 to 24.3 × 10⁶ CFU/g, respectively), with C. amada and Ryudai gold as the highest. Endophytic bacteria in stems and leaves also peaked at the middle growth stage. Principal Component Analysis (PCA) revealed distinct separations among Curcuma species planted in the field and plastic house at different growth stages. C. aromatica and C. longa strain L2 clustered differently under field conditions, while C. zedoaria and C. xanthorrhiza were distinct under plastic house conditions. Combined PCA revealed a clear separation between the field and plastic house, with tighter clustering observed in the plastic house. Leaf-associated bacterial populations were compositionally distinct from those in the rhizosphere and stems. These findings suggest that the Curcuma growth stage and species significantly affect bacterial community structure, supporting the development of targeted cultivation strategies and microbial applications to enhance productivity and sustainability in turmeric farming.

Nitrogen and phosphorus are essential macronutrients that often limit plant growth due to their low bioavailability in soil. Beneficial microorganisms, including nitrogen-fixing and phosphate-solubilizing bacteria, play important roles in improving nutrient availability and supporting plant productivity. This study investigated the populations of nitrogen-fixing and phosphate-solubilizing bacteria associated with different Curcuma species. Samples were collected during the vegetative stage from rhizosphere soil, rhizomes, stems, and leaves. Plant tissues were surface-sterilized to isolate endophytic bacteria, and microbial populations were enumerated using nitrogen-free agar and Pikovskaya agar at 28 °C for 7–14 days. The results revealed clear differences in bacterial populations among plant compartments and Curcuma species. Nitrogen-fixing bacteria were most abundant in the rhizosphere, reaching 3.0–23.3 × 10⁴ CFU/g in field conditions and 3.3–18.3 × 10⁴ CFU/g in the plastic house, followed by rhizomes, stems, and leaves. Similarly, phosphate-solubilizing bacteria showed the highest populations in the rhizosphere (11.3–29.7 × 10⁴ CFU/g in the field and 4.3–25.5 × 10⁴ CFU/g in the plastic house). These findings suggest that Curcuma-associated nitrogen-fixing and phosphate-solubilizing bacteria may contribute to nutrient cycling and potentially enhance plant adaptation to environmental stresses through improved nutrient acquisition, providing a basis for future studies and biofertilizer development in sustainable agriculture.