TORONTO, July 9 (Reuters) - Toronto's main stock index opened higher on Thursday as a rise in commodity prices gave a boost to the resource-heavy index, while forecast-beating results from U.S. bellwether Alcoa helped boost sentiment.

The S&P/TSX composite index .GSPTSE was up 68.33 points, or 0.71 percent, at 9,721.78 at the open after touching a nine-week low on Wednesday.

Six of the TSX's 10 sectors were higher, led by a 1.25 percent gain in the mining-laden materials group and a 1 percent rise in the energy sector. (Reporting by Frank Pingue; editing by Peter Galloway)