Grain futures prices were mostly higher Wednesday on the Chicago Board of Trade ahead of a planting prospects report due Thursday. Corn was off 3/4 to up 5, soybeans were up 3 1/4 to up 6, wheat was up 3 to up 5 1/4 and oats were up 3 1/2 to up 12 3/4. Corn futures were mixed as the dollar index rose 0.4 percent to 83.19 on the International Exchange. Wheat and soybean prices closed higher as traders repositioned holdings ahead of Thursday\'s planting report, which tends to set the tone for trading through the spring. The prices: Corn: May 7.35 1/4 up 5, Jly 7.16 up 3 3/4, Sep 6.03 off 3/4, Dec 5.71 unchanged. Soybeans: May 14.53 3/4 up 6, Jly 14.31 up 4 1/2, Aug 13.85 1/2 up 3 1/4, Sep 13.15 1/4 up 3 1/4. Wheat: May 7.36 3/4 up 5 1/4, Jly 7.36 up 3 3/4, Sep 7.42 1/2 up 3 3/4, Dec. 7.53 1/4 up 3. Oats: May 4.12 1/2 up 12 3/4, Jly 4.07 up 12 1/4, Sep 3.86 up 12 1/4, Dec 3.69 1/4 up 3 1/2.