If you fly a conventional light aircraft along hands off trimmed for S & L flight and select full power it will go into a climbing turn- how then is any loading applied if you do not touch the CC, so how does the stalling speed increase?
Because you are no longer trimmed. The excess power is converted into climb with your airspeed more or less constant - assuming no phugoid. If you let the aircraft bank one side or the other, some of that excess power will be converted into higher speed. Higher speed without changing trim or touching the controls means the aircraft wants to pull up, or pull up in a turn. Thus stall speed increases.