By Rick M. Green, Capitol Bureau State general revenues grew last month, but gross production tax collections declined as the oil industry slump continued, Oklahoma finance officials said Thursday. March general revenue fund collections of $424.4 million were $11.5 million, or 2.8 percent, above prior year collections. “While this year’s revenues have been solid to date, we’re seeing clearer signals now of a slowdown ahead,” said Secretary of Finance, Administration and Information Technology Preston L.