U.S. grain futures edged higher on previous close, boosted partly by a weaker dollar, although the scope for a significant rebound in prices appeared to be capped by ample supplies. Chicago Board of Trade wheat for May delivery was up 0.5 percent at $4.21-1/4 a bushel at 1034 GMT. The most active contract had dipped to a low of $4.17-1/2 on Wednesday, the lowest since March 31.the market remained weighed by abundant global supplies although the prospect of lower crops in the Black Sea region helped to underpin prices. Wheat crop in Russia was forecast to fall by 9 percent from last year to 66 million tonnes while a decline in production was also anticipated in Ukraine. Lower exports from Russia and Ukraine are likely to help reduce the supply glut witnessed in global grains market. May milling wheat was down by one euro or 0.6 percent at 163.50 euros a tonne.