  Information reconciliation protocol has a significant effect on the secret
key rate and maximal transmission distance of continuous-variable quantum key
distribution (CV-QKD) systems. We propose an efficient rate-adaptive
reconciliation protocol suitable for practical CV-QKD systems with time-varying
quantum channel. This protocol changes the code rate of multi-edge type low
density parity check codes, by puncturing (increasing the code rate) and
shortening (decreasing the code rate) techniques, to enlarge the correctable
signal-to-noise ratios regime, thus improves the overall reconciliation
efficiency comparing to the original fixed rate reconciliation protocol. We
verify our rate-adaptive reconciliation protocol with three typical code rate,
i.e., 0.1, 0.05 and 0.02, the reconciliation efficiency keep around 93.5%,
95.4% and 96.4% for different signal-to-noise ratios, which shows the potential
of implementing high-performance CV-QKD systems using single code rate matrix.
