* Corn, wheat rise on poor crop weather, weak dollar
* Soybeans up on firmer corn and wheat, weak dollar
* Coming up: CFTC Commitments of Traders report Friday (Recasts, updates throughout, adds byline, changes dateline from HAMBURG)
By Karl Plume
CHICAGO, April 21 (Reuters) - U.S. corn futures rebounded on Thursday from the previous session's 2 percent slide as wet weather delayed the start of planting in the U.S. Midwest and the dollar fell to its lowest point in nearly three years.
Wheat rose 1 percent on worries that dry weather was harming winter crops in the United States and Europe while wet conditions stalled spring wheat seeding in the northern U.S. Plains and Canada.
Soybeans edged higher as the dollar sank and support spilled over from rising corn and wheat.
"We're bouncing back on the weather. Despite forecasts for better conditions by the middle of May, the weather looks to be pretty bad through then. And a lower dollar certainly isn't hurting anything either," said Jack Scoville, analyst with The Price Futures Group.
The U.S. dollar on Thursday fell to a near-three-year low against a basket of currencies as investors fretted over low interest rates and the threat of a U.S. credit rating downgrade.
Dollar-denominated commodities such as grains tend to rise when the greenback sinks, partly because it increases the buying power of those holding other currencies.
Corn prices dropped to their lowest levels in nearly three weeks on Wednesday as investors liquidated long positions on forecasts for drier weather over the U.S. corn belt eased some concerns about delayed spring planting.
But updated forecasts for weekend rains in some areas renewed worries about a late start to seeding at a time when corn stocks are projected to be the tightest since the 1930s.
"It's all weather until we get the crop planted, it's all money trying to outguess the weather," said Paul Haugens, vice president for Newedge USA.
U.S. markets are closed on Friday for the Good Friday holiday.
Chicago Board of Trade corn for May rose 0.7 percent to $7.37-1/2 a bushel by 10:35 a.m. CDT (1535 GMT) while May soybeans were up 0.3 percent to $13.62-1/4 a bushel.
CBOT soft red winter wheat futures for May added 0.9 percent to $7.91-3/4 a bushel. The market was led by gains in higher-protein wheat varieties traded on the Kansas City Board of Trade and the Minneapolis Grain Exchange which have been threatened by adverse weather.
Prolonged drought conditions through Texas, Oklahoma and southern areas of Kansas, the top U.S. winter wheat growing state, have left wheat industry experts fearing there is little hope for much of the new wheat crop due to be harvested this summer.
Meanwhile, soggy conditions have delayed the start of spring wheat seeding in the northern U.S. Plains.
KCBT May hard red winter wheat rose 1.5 percent to $9.34 a bushel, while MGE May spring wheat climbed 1.7 percent to $9.54-1/4.
CBOT wheat was poised to notch its largest weekly gain since late January, while KCBT and MGE wheat were set for their strongest week since early December. (Additional reporting by Naveen Thukral in Singapore, Michael Hogan in Hamburg, and Sam Nelson in Chicago; editing by Jim Marshall)