Soviet President Leonid Brezhnev's health "deteriorated seriously" during his recent trip to Uzbekistan, and he was taken on a stretcher from the airport to a hospital upon his return here last week, according to well-informed Soviet sources.

The sources quoted Brezhnev's doctors as saying they expected the 75-year-old Soviet leader to recover but that he would have to remain in the hospital "for weeks." A meeting of the Communist Party Central Committee that was to have been held here this week has been postponed until May 24, the sources said.

The Soviet sources, who also disclosed that Brezhnev suffered a mild heart attack in early February, suggested that he may have had a mild stroke March 25 aboard the plane carrying him to Moscow from Tashkent, the capital of Uzbekistan, one of the Soviet Asian republics.

A spokesman for the Foreign Ministry would not comment on the report.

While reporting a "serious worsening" of his health, the sources did not suggest that the Soviet leader was incapacitated.

The apparent deterioration of his condition, however, has focused new attention on his trusted lieutenant, Politburo member Konstantin Chernenko, who is understood to be currently in charge of day-to-day affairs.

Chernenko, 70, who has been an associate of Brezhnev's since 1950, suddenly appeared near the peak of Kremlin authority last year when he leapfrogged over several other Soviet politicians to fourth ranking at the party congress, after Brezhnev, ideologist Mikhail Suslov and Andrei Kirilenko, a Politburo veteran of more than 20 years. The four were the only ones to be elected both Politburo members and party secretaries.

The death of Suslov earlier this year and Brezhnev's visible weaknesses have raised the question of succession, in which Chernenko thus far appears as a rising star, according to arcane symbols of Soviet politics.

While Kirilenko's appearances have become infrequent in recent weeks, Chernenko has been all over television and the press. He was next to Brezhnev during a visit here by Poland's Gen. Wojciech Jaruzelski.

In describing events leading up to Brezhnev's hospitalization, the Soviet sources said the exceptionally heavy schedule of the previous two weeks as well as climatic and other changes on the trip to Central Asia led to a general weakening of the Soviet leader's condition.

During the past few years, Brezhnev has undergone periodic bouts of poor health. In addition to heart trouble, he is said to suffer from emphysema. People who have seen him personally in recent years have noted a slurring in his speech and also hearing difficulties.

He appeared fit, however, on March 16 when he delivered a major speech at the trade union congress and again when he delivered one at Tashkent on March 24.

The sources said it was obvious toward the end of his visit to Tashkent that Brezhnev's heavy schedule was severely testing his endurance.

His condition began to deteriorate seriously aboard the plane, the sources said. Upon arrival in Moscow, the Soviet leader was carried on a stretcher into an ambulance and taken to the Kremlin hospital. This would explain the absence of the customary arrival photographs in the Soviet news media.

Brezhnev's personal physician, Yevgeny Chazov, canceled a scheduled visit this week to England.

The sources said Brezhnev also had been under "psychological" stress--presumably a reference to the recent deaths of several close associates, including Suslov.

The Soviet decision-making process has well-established procedures for day-to-day matters during the temporary absence of Brezhnev. Suslov, before his death, acted as Brezhnev's deputy at Politburo meetings, and Kirilenko coordinated the activities of the secretariat of the Central Committee.

Since Suslov's death, Chernenko has acted as Brezhnev's deputy at Politburo sessions, according to well-informed sources, and also reportedly has taken over the role of coordinator of the secretariat activities. Regardless of who chairs these meetings, however, all major decisions are made collectively by the Politburo.

Unlike the skillful Brezhnev, who rose to power after riding the current of Soviet politics, Chernenko owes his career entirely to one man--Brezhnev. For years he has held the job of head of Brezhnev's office, sifting information for him, setting his timetable and relaying orders to subordinates.

To be so closely associated with Brezhnev, whose political authority remains unchallenged despite his illness, gives Chernenko a unique position in the leadership. This, however, may not be an asset when Brezhnev leaves the political stage.

Chernenko, a silver-haired, bouncy man of fleshy face and baggy striped suits, was born of a Siberian peasant family 70 years ago. He joined the Communist Party in 1931 and held positions in Krasnoyarsk in Central Asia. In 1948 he was transferred to Moldavia to head the party's propaganda department.

Chernenko and Brezhnev met in 1950, the year Brezhnev was appointed party secretary of the Moldavian Republic. When Brezhnev moved into the powerful secretariat in Moscow in 1956, he took Chernenko along and made him propaganda chief for the country.

In 1965, a year after his patron assumed full power as general secretary of the party, Chernenko was made chief of the general department of the Central Committee--in effect, Brezhnev's chief of staff.

For all practical purposes, Chernenko has remained in that position ever since, although rewarded with new positions and titles. In 1971 he was made a member of the Central Committee. In 1978 he was made a full member of the ruling Politburo.

Since Suslov's death, Chernenko seemed to have been trying--clearly with Brezhnev's blessings--to seize control of the party apparatus and form an independent power base.

Little is known, however, about his own ideas on subjects ranging from foreign policy to agriculture. It is believed here that he has little practical knowledge of economics, having never held an industrial management position. This could be a key weakness. He is said to favor tighter party control over the economy rather than economic reforms. Picture1: Leonid Brazhnev...under 'psychologiscal' stress