Fears that the Federal Reserve, the nation's central bank, intended to further tighten credit, combined with expectations that the basic supply of money would rise sharply this week, spurred selling yesterday that sent interest rate futures plunging.

After trading ended for the day, however, the money supply figures showed a much smaller increase than analysts had expected.

T-bond futures closed 10 to 15 points lower at the Chicago Board of Trade, quoted at 96-10 in the current contract and GNMA futures lost 5 to 7 points to end at 93-25 in March 1978 delivery. (The T-bond and GNMA futures prices are quoted as a percentage of par; and when the yield is 8 percent interest, a futures contract would trade at 100-00, or par.)

T-bills traded on the Chicago Mercantile Exchange's International Monetary Market division dropped 2 to 6 points to 93-30 in March 1978 delivery, which reflects an annualized yield of 6.70 percent.

Also reacting to the dollar's downward spiral, as wll as to an increase of 2 1/4 percent in the British Sterling rate, silver futures swelled 3.5 to 6.2 cents a troy ounce on New York's Comex. Gold futures advanced 20 cents to $1.20 an ounce, closing at $180.50 in the February contract.

Meanwhile, wheat futures lost 1 1/2 cents a bushel as farmers sold large amounts of that commodity in western areas of the nation.

A moderate pickup in corn and soy-bean movement was generated by improved weather in the Midwest, but corn prices closed unchanged to just fractions of a cent lower and soybean futures were mixed.

Talk of good export demand boosted soybean oil futures by as much as 30 points.

At the close of grain trade, soybeans were 2 cents a bushel lower to 2 cents higher, with the March contract quoted at $5.67 1/4; wheat was 1 1/4 to 1 1/2 cents lower, March $2.65; cornwas unchanged to 1/2-cent lower, March $2.25 3/4; and oats were 1 to 2 1/2 cents lower, March $1.24 1/4.