A secret Communist Party meeting here Tuesday has tended to: * Confirm that Konstantin Chernenko is still on top of the Kremlin heap. Mr. Chernenko took the leading role at the Central Committee session, adding to the impression created by his interview with the Washington Post last week that he is at least first among equals in a collective leadership. The impression is also supported by reports from East Europe (see Budapest story, below).
* Raise questions about the status of the man who has been widely considered to be Chernenko's heir-apparent, Mikhail Gorbachev.
The Soviet news agency Tass said that the meeting approved plans to improve the Soviet Union's agricultural performance - the area for which Gorbachev, the No. 2 figure in the Kremlin hierarchy, is responsible. But initial reports from Tass, the official Soviet news agency, did not mention his name.
Among the questions Western analysts raised was whether Gorbachev, had been relieved of responsibility for agricultural affairs. He had previously held that portfolio within the Communist Party, and would have been expected to address the Central Committee on the subject during the meeting.
If so, some analysts say, that probably means he is now better positioned to succeed Chernenko as general secretary of the party and de facto head of the Soviet Union.
Others, however, speculate that Gorbachev may have been tarnished somewhat by the country's poor showing in agriculture. They are awaiting further indicators of his standing within the party.
The Soviet Union is facing its sixth consecutive poor harvest and, to deal with the problem, the Central Committee Tuesday approved a plan to expand ''irrigated and drained lands'' by 50 percent.
At the same time, Chernenko said that the party must achieve a ''breakthrough'' during its next five-year economic plan (1986-1990) by striving to raise ''the efficiency of the national economy.''
Analysts wondered whether the Soviet Union, in its drive to irrigate more land, will embark on a controversial scheme to divert the flow of rivers from Siberia to Soviet Central Asia.
The multibillion dollar project, which has been under consideration for a number of years, might radically alter the climate of both Siberia and parts of Asia, according to environmentalists. There were no direct references to the Siberian diversion plan in reports of the meeting, however.
By any measure, the Soviets seem to be planning a major drive to open more areas to irrigation. Prime Minister Nikolai Tikhonov indicated that several million additional acres of Soviet land will be irrigated or drained over the coming decade, bringing the total amount of irrigated land to 74 million acres and drained land to some 50 million acres.
Eric Bourne reports from Budapest:
The Hungarians, in contrast to most Western observers, seem convinced of two points about Soviet President Konstantin Chernenko:
* That he is the effective leader of a collective leadership and is identified with the group that wants a return to East-West detente in order to divert greater resources to stimulating the laggard Soviet economy.
* That he is fully committed to the economic reforms initiated by his predecessor, Yuri Andropov, and will continue them - despite a stricter ideological tone.
In eight months of debate over differences of approach within the top leadership since Mr. Chernenko's succession, not all the details of his economic program have been resolved, it is said here. But the general belief, among East European ''liberals'' here and elsewhere, is that last year's innovations will be enlarged.
''I am sure the reforms will be further developed,'' said an official here who speaks with considerable authority. ''The only question will be how far and how fast and, more important still, how effectively changes can and will be put into actual operation.''
The latter was an allusion to the predictable resistance of conservative groups to changes in management systems that would deprive them of positions and power. It is the kind of problem with which the Hungarians themselves have often had to contend since they embarked on their much wider-reaching reforms at the start of the 1970s.
The Soviet Union, of course, has a very long way to go before it even catches up with Hungary. But the conviction here is that the state of the Soviet economy has finally compelled the Russians to think seriously of reform.
The Hungarians have always kept a careful eye on likely Soviet reactions to their own avant-garde approach. Given the threat the current standoff in superpower relations could pose to Hungary's ''independent'' economic policies, there was considerable relief here at Mr. Chernenko's recent forthright call for better planning, flexible managerial structures, and the kind of linkage of productivity and incentive wages that were introduced by Mr. Andropov.
''The Russians,'' an authoritative Communist source here said, ''are as concerned as anyone about the present costs of the arms race and the simply appalling economic prospect if military rivalry between the superpowers is carried into space.''
Chernenko and his supporters are aware, the Hungarians and others say, that the Soviet Union's prime domestic interests lie in improving the economy and in narrowing the widening technological gap between itself and the East bloc on the one hand, and the United States and other Western powers.
''The Russians know the options,'' it is said. ''They want technology for economic advance and the higher living standards their people are expecting, not for the militarization of space, which would set all other considerations at naught.''
Soviet economic plans are tied to what the Hungarians are themselves emphasizing: making quality products that can compete on the world market and earn the hard currency that alone can help them close their own technology gap.
When Chernenko took over, some ''intensified'' production and management innovations were already being tried in various Soviet industrial sectors, and in republics with better-than-average economic records.