David Gartner defended his controversial appointment to the Commodity Futures Trading Commission yesterday before a Senate committee that was more critical of the White House's handling of the affair than of Gartner's possible conflicts of interest.

Several members of the Senate Agriculture Committee said they would not approve Gartner for the $50,000-a-year post if they had it to do over again. But as Chairman Herman Talmadge (D-Ga.) noted, "this committee can do nothing" now that Gartner has been confirmed.

Gartner continued to defy President Carter's demand for his resignation, telling the committee, "If he (the president) called me right after this committee meeting I would have to tell him I won't quit."

Gartner said he told White House staff members in February - three months before he was publicly appointed - that his children had been given $72,000 worth of stock by Dwayne Andreas, chairman of Archer-Daniels Midland Corp., a major grain company.

"The White House didn't seem concerned about the gifts of stock," added Gartner, who has now been asked to step aside because of the gift.

Sen. S.I. Hayakawa (R-Calif.) accused the administration of "turning chicken" on the appointments. He complained that Gartner had been called back before the Agriculture Committee, which approved the nomination, "in order to look good for the press."

Sen. Patrick Leahy (D-Vt.) asked: "Are we looking at whether there are improprieties past, present or potential? Or a foul-up on the part of the committee or the Senate itself? Or are we now in a case where the White House finds it has done some sloppy staff work and they've got to cover themselves?"

But Gartner was also questioned at length by four Senators, who directly or indirectly indicated they want him out of the job.

"In the event we were considering this nomination today I would not vote for it," said Richard Lugar (R-Ind.). Accepting the stock, Lugar said, "raised serious questions of indiscretion for someone of the political experience of Mr. Gartner."

Gartner was the top aide to Sen. Hubert Humphrey when he received the stock from Andreas, a long-time backer of Humphrey, whose daughter worked on Humphrey's staff as Gartner's secretary.

Gartner said Humphrey knew and did not disapprove of the gifts of stock in Archer-Daniels-Midland, which were placed in a trust fund for the education of Gartner's four children, who came to the hearing with him. After his ownership of shares in a grain company was questioned at his original confirmation hearing, Gartner asked the trustee to sell the stock.

Gartner's contention that the stock not influence his role as a regulator of commodity futures trading was greeted skeptically by Sen. Kaneaster Hodges (D-Ark.).

"It troubles me that you don't see the conflict," said Hodges, adding "I, too, would vote against the nomination."

Sen. Orrin Hutch (R-Utah), who is not on the committee joined in the critical questioning. He said CFTC's ethics code would bar a staff member from owning stock in or accepting gifts from a company regulated by the commission.

The commodity futures market was described as "the most speculative investment permitted in this country" and "one that has been abused for many years" by Sen. John Melcher (D-Mont.).

Melcher disputed Gartner's claim that he could insulate himself from any possible conflicts by removing himself from cases "directly" affecting Archer-Daniels-Midland or Andreas.

ADM subsidiaries are members of the major commodity exchanges, Melcher pointed out, and the CFTC has jurisdiction over the operating rules of the exchange, the terms of futures contracts and every other aspect of the business.

Saying "we probably made a mistake in rushing this through" when the committee first approved the appointment, Sen. Robert Dole (R-Kan.) said he saw no way to remove Gartner "unless there's something else."

Gartner was questioned repeatedly about White House inquiries into the stock gifts and he repeatedly stressed that he had reported the gifts voluntarily.

Senators blamed the White House for rushing Gartner's appointment through the Senate in one day. Vice President Mondale was leaving town the following day and wanted to swear in his old friend Gartner before he left, the Senators said.

Although several Senators suggested Gartner ought to acquiesce to Carter's request that he quit, Gartner said he could not do so.

"If I were to resign it would look like an admission of wrong doing. I am not guilty of any wrongdoing."