Consolidated Rail Corp., the federally subsidized northeastern railroad system, said yesterday it will defer plans to abandon certain rail lines for a year in the hope that federal regulation of the industry will be ended during that time.

If the industry is deregulated, Conrail Chairman Edward G. Jordan said yesterday, giving the railroad greater pricing and marketing flexibility, Conrail might be able to turn the losing freight routes into profitable ones. If the industry is not deregulated, however, he warned that Conrail would be forced to go ahead with its abandonment plans.

"If reforms are not made that will improve the railroad's ability to develop an economically sensible basis for designing a selfsustaining system, Conrail will have no choice but to propose substantial abandonments in subsequent years," Jordan said.

"Freedom from economic regulation would allow Conrail to try to find ways to make traffic pay its way before we resort to ending unprofitable service."

Conrail announced a year ago that about 451 miles of freight service rail lines in eight states probably would be abandoned within three years. But now, the rail line said it plans to limit abandonments to about 142 miles of track, most of which are not being used.

Jordan complained that Conrail now carries a significant amount of traffic that does not generate a sufficient return and is losing about 10 cents for every dollar of freight revenue it now takes in. "Obviously, Conrail has too much unprofitable traffic," he said. But the regulatory environment precludes the line from taking the pricing and marketing initiatives that might alter the picture before considering desertion of the lines, he said.