April 16 (Reuters) - Canada's main stock index opened

lower on Tuesday, weighed down by materials shares, while

declines were limited by cementing bets of a June interest rate

cut by the Bank of Canada after a domestic inflation data

reading.

At 9:30 a.m. ET (13:30 GMT), the Toronto Stock Exchange's

S&P/TSX composite index was down 82.59 points, or

0.38%, at 21,657.61.