There was a time when the mere thought of opening day at Laurel Race Course would make a horseplayer's pulse quicken. Laurel represented the start of the Maryland racing season, and idle bettors couldn't wait to get back into action.

That, of course, was back in the antediluvian era when there was such a thing as a racing season. With year-round racing now mandated by the legislature, Maryland tracks operate day after day, week after week, year after year, ad infinitum, ad nauseum. But even so, the start of Laurel's 59-day session at 12:30 this afternoon will be an occasion for some enthusiasm, or at least a sense of relief.

This Laurel meeting was preceded by a month of racing in the cavernous gloom of Bowie, which was preceded by seven weeks in the decrepitude of Timonium, which was preceded by the seemingly interminable summer meeting at Pimlico, with its tedious diet of cheap horses and small fields.

Laurel at least offers its patrons interesting sport and ocmfortable facilities. It is not the garden spot of American racing, by any means, but a track that operates in the dismal weather of November and December cannot be. Laurel does have what may be the most pleasant winterized, glass-enclosed grandstand in the country. It is spacious and well-ventillated, bright and cheery, and it is certainly the only grandstand in Maryland where a civilized human being can comfortably enjoy an afternoon of racing.

For the next three weeks, that racing will be the best Maryland has to offer. Today's $146,960 Selima Stakes is one of the nation's premier events for 2-year-old fillies. If Golferette can defeat Candy Eclair, she probably will earn the championship of her age and sex.

Next Saturday, the rich Laurel Futurity will match home town star Spectacular Bid against Secretariat's son, General Assembly, in a race that will resolve the 2-year-old colt championship.

And a week after that, the Washington, D.C. International may entice Seattle Slew to try running on the grass for the first time in a bid to strengthen his claim to the Horse-of-the-Year title.

Despite the quality of its stakes racing and the attractiveness of its facilities, Laurel in recent years has been the despair of Maryland horse players. The source of the problem is its racing strip.

One of its defects is its very shape. The frequent one-mile races are run out of a chute where only parking-lot attendants can witness the start, and bettors who form their handicapping judgments by watching races can only guess what is happening. But the chief problem has been the composition of the track.

Laurel's track was completely rebuilt in 1972. Not only did it look peculiar - it was orangish color - but the result and the times of results often were peculiar, sometimes unfathomable. Post handicapper Clem Florio diagnosed the problem last fall, during the course of his daily jogs around the track.

"As soon as they was any inclement weather," he said, "the track got uneven. I might be running on a hard path for awhile; then it would veer off and disappear. Sometimes the dirt would pile up in one spot and the track would be practically bald in another. It was never consistent. And the conditions would change every day."

Such conditions make rational betting practically impossible. Fortunately, LAurel's management recognized the imperfections, and worked this summer to reshape the base of the track, so that it slopes evenly from the crown of the track to the rail.

Often, in the early stages of a meeting when a racing strip has undergone changes, biases will exist that consistently favor certain types of horses. Handicappers at Laurel today should watch closely to determine if the strip has any pronounced tendency to favor front runners or stretch runners, inside posts or outside posts.

Such biases can offer the most profitable situations in racing. And if Laurel offers money-making opoortunities, along with its other virtues, horseplayers' pulses will have good reason to quicken.