Variation in the normalised stellar locus position (circles in the left panels) and dispersion (squares in the right panels) with r-band magnitude. The coloured symbols mark the measurements in each J-PLUS EDR pointing. The white symbols show the median and the dispersion of the pointing-based values. The dashed lines mark identity. The top panels show the results assuming no concentration uncertainties (σ_c = 0), and the bottom panels with the uncertainties, computed assuming a covariance ρ = 0.72, properly accounted for.