CANADA STOCKS-TSX slides at open as CN Rail, Roots fall

TORONTO, Oct 25 (Reuters) - Canada's main stock index was down shortly after the open as Canadian National Railway fell more than 2.5 percent, and Roots Corp opened 8 percent below its IPO price.

The Toronto Stock Exchange's S&P/TSX composite index fell 37.69 points, or 0.24 percent, to 15,867.45.

Seven of the index's 10 key sectors lost ground. (Reporting by Solarina Ho; Editing by Chizu Nomiyama)