A significant proportion of the funding will support the network of dedicated development managers employed at regional level.
Maxwell told the Scottish rugby sponsors' conference at Murrayfield: "This new funding ploughs £752,500 into the future success of Scottish rugby.
"With youth participation growing, there is a real appetite for rugby among young people in Scotland.
"This investment will support the sport at a regional level and capitalise on this growing interest. It will also help talented young players to continue in the sport and provide a welcome boost to the senior game."
SRU chief executive Gordon McKie said: "Our partnership with sportscotland is all about increasing participation and improving performance.
"This investment is integral to the achievement of our strategic plan with the main emphasis being on growing the game in partnership with the many dedicated volunteers in clubs and schools throughout Scotland."