U.S. forward Abby Wambach and a group of fellow players have withdrawn their complaint of gender discrimination over the artificial turf fields to be used for this year’s World Cup in Canada. The artificial turf became a contentious issue with the players, who have claimed that the surface is less forgiving than natural grass and impacts play because of concerns over injury. They also claim that balls travel and bounce differently on turf. But their overriding complaint was one of equity: The men’s World Cup is held on real grass. “Our legal action has ended. But I am hopeful that the players’ willingness to contest the unequal playing fields — and the tremendous public support we received during the effort — marks the start of even greater activism to ensure fair treatment when it comes to women’s sports,” Wambach said in a statement Wednesday. The players’ complaint was filed last fall with the Human Rights Tribunal of Ontario. It named FIFA, the international governing body for soccer, and the Canadian Soccer Association. Neither budged in reconsidering the planned surface for the event. The World Cup will be played in six Canadian cities starting in June, with an expanded field of…