A Federal appeals court yesterday rejected the Nixon Administration's appeal for postponement of the deadline for the Department of Health, Education and Welfare to step up desegregation enforcement.

The U.S. Court of Appeals for the District of Columbia issued the ruling less than an hour after government attorneys argued that HEW had shown "good faith" in implementing earlier court-ordered integration plans.

A February 16 ruling by a lower court judge held that by Tuesday, HEW must send letters to 116 secondary and elementrary school districts advising them of hearings on their desegregation plans.

Affected by the order are schools in 17 Southern and Border states.