Spearman rank correlation coefficients (ρ_Spearman) between metallicity gradients (∇_r[Z/H]) and various galaxy properties. The light gray bars represent the direct (zero-order) correlation coefficients, while the dark blue bars indicate the partial correlation coefficients after controlling for galaxy stellar mass (M_⋆). The analyzed properties include stellar mass (M_⋆), H I deficiency parameter (Def_HI), central stellar mass surface density (Σ_cen), morphological T type, local projected number density of galaxies (η_k), light-weighted stellar age (﹩\mathrm{log}({\rm{Age}})﹩), and effective radius (R_e). Error bars denote the 1σ uncertainties estimated via bootstrap resampling. Statistical significance levels based on the full dataset are indicated above the bars: no asterisks for p ≥ 0.05 (not significant), a single asterisk (∗) for p < 0.05, and double asterisks (∗ ∗ ) for p  < 0.001. Notably, stellar age and the H I deficiency parameter maintain statistically significant correlations with the metallicity gradient even after fixing M_⋆, whereas morphological and structural parameters show negligible and statistically insignificant partial correlations.