For the supersymmetric KdV equation, a proper Darboux transformation is
presented. This Darboux transformation leads to the B\"{a}cklund transformation
found early by Liu and Xie \cite{liu2}. The Darboux transformation and the
related B\"{a}cklund transformation are used to construct integrable super
differential-difference and difference-difference systems. The continuum limits
of these discrete systems and of their Lax pairs are also considered.Comment: 13pages, submitted to Journal of Physics
