June 6, 1983

Some scientists now suspect that trees can in effect warn one another of danger by releasing chemicals into the air. Researchers are preparing new experiments that they hope will confirm the tentative findings of their initial tests, the National Science Foundation announced yesterday. If they are successful, the science foundation said, they will probably be the first to show that plants emit signals that are received and responded to by other plants.

International Leaders of the O.A.U. will try again, for the third and possibly last time, to end rifts that threaten the role the Organization of African Unity has sought to play for two decades in Africa. There was uncertainly about whether the attempt would succeed as African leaders began arriving in Addis Ababa, Ethiopia, for preliminary negotiations to determine whether the O.A.U. twice-postponed 19th summit meeting can take place. (Page A1, Column 3.) An attempt to stop further sabotage in South Africa by the underground African National Congress will be made by shutting the group's military wing out of neighboring black states, South Africa's highest-ranking military official said. Gen. Constand Viljoen, chief of the Defense Force, said this isolation could be accomplished through a combination of military and diplomatic pressure. (A1:3.)

An article in the Business People column Friday gave an incorrect street number for the New York branch of Creditanstalt-Bankverein. It is at 717 Fifth Avenue.

''There were always a lot of snide implications that we came to Princeton for social reasons.

Any Democratic attempt to modify the 10 percent income tax cut scheduled for July 1 will be defeated, Howard H. Baker Jr. of Tennessee, the leader of the Republican majority in the Senate, predicted. In a television interview, he also supported the reappointment of Paul A. Volcker as chairman of the Federal Reserve, a view that has been opposed privately by some Administration officials. (Page A1.)