In this paper we develop backstepping-based boundary sliding mode controllers for coupled time fractional reaction diffusion (FRD) systems governed by time fractional partial differential equations (PDEs) with time varying delay and input disturbances. Here, the diffusion coefficients are spatially varying (nonconstant) and can be same or different. To asymptotically stabilize the system, we first use a backstepping transformation to convert the original dynamics into a target dynamics with a new manipulable input and the perturbation. Then, the sliding mode algorithm is employed to design this discontinuous controller to suppress disturbances. In this case, we obtain the combined backstepping/sliding mode controller of the original dynamics, with which the closed-loop asymptotic stability is proved by the fractional Halanay's inequality. Fractional numerical examples are given to demonstrate the efficiency of the proposed synthesis.