Southern Republican activists cheered a series of hard-line foreign policy speeches today but were told that GOP growth in Dixie depends much more on attention to down-home concerns such as roads, schools and jobs.

Some 1,400 party workers from 13 states attending the biennial Southern Republican Leadership Conference here applauded a strong statement of support for aid to the rebels fighting the Sandinista government of Nicaragua from Vice President Bush, and endorsements of the Strategic Defense Initiative (SDI) from former secretary of state Henry A. Kissinger, former Senate majority leader Howard H. Baker Jr. (R-Tenn.) and Jeane J. Kirkpatrick, former ambassador to the United Nations.

In the only implicitly critical comment about President Reagan's arms control policy, Kissinger said the United States should not talk simply about research and testing on SDI. "We ought to bite the bullet and say we are going to deploy . . . . If the Soviets had the ability to build their own SDI, you can bet your last cent they would do it," he said.

But the conference host, Tennessee Gov. Lamar Alexander, warned that preoccupation with "the Washington issues of war, welfare, Social Security and debt" will divert Republicans from "addressing the real needs of the South."

"Unless we start talking about the real issues of concern to the South," the popular governor said, citing the environment, health, law enforcement, transportation, education and economic development, "we won't make progress" in reducing Democratic dominance of state and local governments in the 13-state region.

Such an approach, Alexander said, will require Republicans to demonstrate that "we are not the antigovernment party" but are prepared to use government "at least as the catalyst, and often more than that" to meet local needs.

The governor, who is leaving office after his second term ends next January, told the conference Republicans "have barely begun" to challenge Democratic dominance in Dixie.

Using even blunter terms at a news conference, Alexander said that two decades after the birth of "the so-called southern strategy, we have produced a lot of Republican votes for national candidates, but in many respects, we are weaker" than then.

"We have miserable numbers" in southern legislatures, he said. "Tennessee is the only state capitol in the South with an active two-party system," in part because "by and large across the South, Democrats have been better at addressing state and local issues than Republicans."

Alexander's message was endorsed by Republican National Committee Chairman Frank J. Fahrenkopf Jr., who told the conference that the growth of Republicanism in the South has been slowed by "top-down tactics" that emphasized presidential and senatorial and gubernatorial races over courthouse and legislative contests.

But as Bush and Baker led off a parade of 1988 presidential hopefuls and GOP banquet-circuit stars, the emphasis quickly shifted to foreign policy.

The vice president, whose political action committee threw a party for the Dixie delegates tonight, focused his speech on President Reagan's request for $100 million in military and other assistance for the Nicaragua rebels, also known as contras.

Bush said they were "freedom fighters" opposing "a small claque of political terrorists . . . who hijacked the Nicaraguan revolution, betrayed the patriots who fought and died for freedom, and put a communist regime in the place where a democratic government was supposed to be."

Baker set the tone for the foreign policy panel by declaring of Reagan's SDI space-based missile defense, "Anything the Russians don't like that bad must be awful good." Baker also declared that "we would not have meaningful negotiations [with the Soviet Union] were it not for the determination of Ronald Reagan and congressional Republicans that the United States be rearmed . . . to the point that no one can challenge us again . . . . We must persevere in what's begun," he said.

Kissinger warned that current Soviet proposals in the Geneva arms control talks are aimed at "maintaining their advantage at somewhat lower cost."

Defending SDI, he said that "only by balancing offensive and defensive weapons can we make progress toward real elimination of the threat of nuclear war." Kissinger also argued that terrorism must be made part of the negotiations, because "there is no question that terrorist organizations around the world are receiving intelligence, training and financial support either from the Soviet Union or Soviet clients."

With prospects increasing for a multistate southern primary and caucus early in the 1988 political calendar, almost all of the GOP presidential hopefuls scheduled time for the gathering.

The activists will see former Delaware governor Pierre S. (Pete) du Pont IV, former secretary of state Alexander M. Haig Jr., the Rev. Pat Robertson, Senate Majority Leader Robert J. Dole (R-Kan.) and Rep. Jack Kemp (R-N.Y.) on Saturday.