RIYADH: Gold prices edged higher on Tuesday on the back of a weaker dollar, but were stuck in a tight range as investors refrained from making big bets ahead of a possible aggressive US interest rate hike. Spot gold was up 0.2 percent at $1,721.29 per ounce, as of 0500 GMT. US gold futures gained 0.1 percent to $1,720.30 per ounce. The dollar slipped for a fourth straight session, down 0.1 percent against its rivals, making gold less expensive for buyers holding other currencies. Silver rises Spot silver rose 0.4 percent to $18.48 per ounce, while platinum gained 0.6 percent to $883.98. Palladium climbed 0.2 percent to $2,012.50. Corn climbs 2 percent, hits one-week high Chicago corn jumped more than 2 percent on Tuesday, with prices climbing to their highest in a week, while soybeans rose 1.8 percent after a US government report showed the declining condition of both crops. Wheat gained more ground after a Russian missile strike on the Ukrainian port of Odesa over the weekend raised doubts about the implementation of an agreement to open a corridor for Ukrainian grain exports. The most-active corn contract on the Chicago Board of Trade was up 2.3 percent at $5.97-1/4 a bushel, as of 0356 GMT, after hitting its highest since July 19 at $5.99-1/2 a bushel. Soybeans added 1.8 percent to $13.70-1/4 a bushel and wheat gained 1.9 percent at $7.84-1/4 a bushel. Copper rises Copper prices rose on Tuesday, as supply risks flagged by major producers offset demand concerns, while a softening dollar made the metal cheaper for holders of other currencies. Three-month copper on the London Metal Exchange rose 1.5 percent to $7,591 a ton by 0356 GMT, while the most-traded September copper contract on the Shanghai Futures Exchange advanced 2.1 percent to $8,640.86 a ton. (With input from Reuters)