* Fiber supported by limited physical demand, weather worry

* Cotton prices inch to second straight weekly gain

(Reuters) - Cotton futures edged down on Friday but eked out a slight gain for the week, largely withstanding pressure from a broad-based commodities selloff on concern over the state of the crop in the United States, the world's top cotton exporter.

The most-active December cotton contract on ICE Futures U.S. closed down 0.2 cent, or 0.2 percent, to settle at 84.52 cents per lb, though the second month inched to its second straight weekly gain.

Fourteen of the 19 commodities markets represented by the Thomson Reuters-Jefferies CRB index were down.

Earlier this week the second month rose the most in a month as the U.S. Federal Reserve's decision to delay cutting back its stimulus program boosted commodities and financial markets.

Stocks and commodities fell on Friday, as those gains were seen as overdone.

"We had a strong response to the Fed announcement, and today everything came unglued," said Sharon Johnson, a cotton specialist with KCG Futures in Atlanta.

Limited physical demand and concerns over the state of the U.S. crop prevented steeper losses.

Beijing made its first purchase of cotton from the 2013 crop. The move was anticipated and failed to boost New York prices significantly this week, but continuation of Chinese stockpiling has underpinned the market.

China's cotton program has led to voracious demand for lower-priced foreign cotton and has put a floor under global prices.

Rains in areas of South Texas became cause for worry this week as they threatened to hamper the harvest. Earlier in the season, rains eased worry over protracted dry conditions that have damaged crops in the top producing state.

The late harvest of a U.S. crop expected to be small has also provided support for futures prices, even with global inventories expected to climb this year.

U.S. weekly export sales were seen as decent by many merchants, even as high prices deterred strong demand for U.S. fiber.

"Some mills did not cover their summertime needs, and now they've had to come to the market," said one U.S. trader.

(Reporting by Chris Prentice; Editing by John Wallace)