--Investors reduced risk exposure on fear of slower purchases by China

--Wheat was the weakest leg of the grain complex

--Soybeans ended lower, but remained the strongest leg of the grain complex on export demand

CHICAGO (Dow Jones)--U.S. grain and soybean futures ended lower Friday on broad commodity weakness, as traders were averse to risk amid global economic uncertainty.

The losses were driven by a widespread risk-off trade across asset classes, with declines witnessed in equities, energy and grain futures. The U.S. dollar's surge weighed on grains in general, with traders continuing to take profits after recent gains, helping to extend the losses.

Investors reduced risk exposure on fear of slower purchases by China amid data showing its economy grew slower than expected in the first quarter.

Wheat futures slumped to two-week lows on the global economic weakness, with ample world wheat supplies generating fundamental pressure as well.

Wheat was the weakest leg of the grain complex, as the market is retreating to the lower end of the recent trading range, said Doug Bergman, agricultural derivatives specialist with RCM Asset Management.

"Bullish news for wheat is hard to find and any time corn struggles, wheat struggles more," Bergman said.

China's economy grew at 8.1% in the first quarter, below the 8.3% that economist had forecast. The figure was near a 3-year low and raised doubts about the future buying interest of one the world's largest consumers of commodities.

China's economic data was generally in line with annual GDP growth forecasts, and more attention was being paid to rising bond yields in Spain, a feature that sent European Union stock markets lower, according to analyst at advisory firm AgResource Company.

Wheat essentially erased gains from earlier in the week. Advances on fears of frost damage to crops this week was likely overstated, AgResource added.

CBOT May wheat ended down 15 3/4 cents or 2.5% at $6.23 1/2 per bushel, May KCBT wheat ended 10 cents lower at $6.43 and May MGEX wheat ended down 12 1/4 cents to $8.24 1/4.

Corn futures fell in unison with wheat, pressured by widespread risk off selling. CBOT May corn ended down 8 1/4 cents at $6.29 1/4.

Soybean futures ended lower, but remained the strongest leg of the grain and oilseed complex amid strong underlying export demand. Expectations for tighter world supplies and growing demand continue to provide strength for soybean prices.

An announced sale of 165,000 metric tons of U.S. soybeans to China for delivery in the 2012-13 marketing year provided fresh support to limit losses.

CBOT May soybeans ended 4 1/4 cents lower at $14.36 3/4 a bushel.