However, it was the home side who took an 18th-minute lead through Fryatt. The striker, who is on loan from Premier League side Hull City, was left with a simple finish after Antonio pounced on uncertainty in the Reading defence to square the ball to the 27-year-old.
The lead was doubled seven minutes later as Antonio cut inside from the right wing and sent a shot underneath the body of Alex McCarthy.
However, Reading grabbed a goal back 10 minutes before the break through Pavel Pogrebnyak's header from Gunter's cross.
The two-goal cushion was restored three minutes before half time when McCarthy's save from a Connor Wickham shot rebounded into the net off the prone Morrison.
Reading looked intent on finding an early goal in the second half, and Danny Guthrie's strike whistled past the post before Robson-Kanu scooped the ball over the bar from just eight yards.
However, Wickham virtually sealed a Wednesday win in the 57th minute with a thunderous finish from Antonio's cross to make it 4-1.
Wickham turned provider six minutes later as he flicked the ball on to Fryatt, who sent a sumptuous chip over the head of McCarthy.