Updates for market open, changes byline from PARIS/BEIJING to CHICAGO, adds bullets

By Heather Schlitz

CHICAGO, May 9 (Reuters) - Chicago soybean and corn futures bounced on Friday as traders covered short positions ahead of Saturday's meeting between senior U.S. and Chinese officials and ahead of a widely tracked U.S. Department of Agriculture report on Monday, analysts said.

Front and back month wheat contracts sank to lifetime lows as good weather in the U.S. Plains and lackluster export demand prompted traders and commodity funds to add onto already-large short positions.

Most-active Chicago Board of Trade wheat Wv1 futures fell 6-1/2 cents to $5.23 a bushel as of 1630 GMT, with the July contract WN25 hitting a lifetime low of $5.21-1/2 a bushel.

"The wheat market continues to be on a trainwreck," Terry Linn, vice president at Linn & Associates, said. "Funds are piling on to the short side."

CBOT soy Sv1 was last up 12-1/4 cents to $10.57-1/4 a bushel. CBOT corn Cv1 rose 2-1/2 cents to $4.50 a bushel.

The weekend U.S.-China trade talks in Geneva have been described by White House officials as a step towards de-escalating tensions with China and containing a trade war between the world's two biggest economies.

The soybean market has been particularly sensitive to the tariff stand-off between China, the world's biggest soybean importer, and the United States, the world's second-largest exporter of the oilseed.

Export sales of U.S. corn and soybeans have also given support to prices.

However, ideal planting and growing conditions in the U.S. corn and soy belts have added a lid to prices while the upcoming Brazilian corn harvest is expected to pull global demand away from U.S. corn in the coming weeks.

Improving U.S. winter wheat crop conditions and forecast rain in the Black Sea export region have weighed heavily on wheat prices.

Traders were also positioning ahead of the USDA's world crop report on Monday that will include its first supply and demand balance sheets for 2025–26.

(Reporting by Heather Schlitz in Chicago. Additional reporting by Ella Cao and Lewis Jackson in Beijing and Gus Trompiz in Paris; Editing by Marguerita Choy)

((Heather.Schlitz@tr.com))