Season openers for the Lab Theatre on the University of Utah campus and Park City Performances' 10th season in the historic Egyptian Theatre get under way this week, along with new shows at the Heritage Theater in Perry and by the Wasatch Playhouse troupe in Layton.

- THE LAB THEATRE opens its 1990-91 season with Paul Zindel's acclaimed Pulitzer Prize-winning drama, "The Effect of Gamma Rays on Man-in-the-Moon Marigolds," with a four-day run, Thursday through Sunday, Oct. 18-21.Director Tim Turner's cast includes Monica Moench as Tillie, Peggy Goodman as Beatrice, Heidi Burnett as Ruth, Gina L. Corina as Nanny, and Chris Woodward as Janice.

The play is a powerful and moving study of an embittered, vindictive widow (Beatrice), living in squalor with her two teenage daughters. The play's title is derived from youngest daughter Tillie's high school science class experiment. Tillie wins a prize for her project, resulting in the shattering climax of the play when her mother cannot accept the girl's success.

When it was produced in the spring of 1970 off-Broadway, the New York Daily News called it "a great human drama." Clive Barnes of The New York Times, said "See this play - it has a compassion all its own."

The play was first presented in 1965 at the Alley Theatre in Houston, Texas, followed by a television version in 1966. In 1970, the New York Drama Critics' Circle named it "the best American play of the year."

Performances will be Thursday through Saturday at 8 p.m. and Sunday at 7 p.m., with a matinee on Friday, Oct. 19, at 5 p.m.

The Lab Theatre is in the Performing Arts Building, adjacent to the campus bookstore. For tickets, contact the Pioneer Memorial Theatre box office at 581-6961.

- PARK CITY PERFORMANCES opens its 10th anniversary season with the off-Broadway musical revue "Personals," a collection of songs and scenes about the sort of people who present themselves in the "lonely hearts" ads - lonely people looking for that certain someone.

"In other words, `Personals' is about most people, about the unending search for love during the post-Me Decade," says director Rafael Colon Castanera, the company's artistic director.

Castanera's six-member ensemble consists of Sarah Anderson, Laura Clayton, Jayceen Craven, Stephen Kerr, Shane Mazafari and Richard Scott.

Assisting with the production are Catherine Owens, lighting; Jennifer Dehner-Serio, costumes; Michael Johnson, musical director, and Jeannie Mathews-Groll, stage manager. Castanera has designed the sets.

"Personals" opens Friday, Oct. 19,and continues on Thursdays-Saturdays at 8 p.m. through Nov. 24.

Castanara cautions that the show is recommended for mature audiences.

The Egyptian Theatre is located at 328 Main St., Park City. For ticket information and reservations, call the Park City Performances box office at 649-9371.

- THE HERITAGE THEATER is getting into the Halloween swing of things with its production of the two-act musical, "The Little Shop of Horrors," directed by Dee Pace.

The show runs Mondays, Fridays and Saturdays at 8 p.m. from Oct. 19 through Nov. 10.

The cast includes Vondel Hathaway as lowly Seymour, a lad who is infatuated by coworker Audrey (Randi Harrington), but who is also worried about Audrey's relationship with Orin (Hyte Johnson), a sadistic dentist.

Vondel discovers an unusual plant (named Audrey II) . . . a plant with a voracious appetite for not your run-of-the-greenhouse plant foot, but flesh and blood - in larger and larger quantities.

Craig Whitaker is the voice of Audrey II, with Melanie Nelson as the puppeteer.

Other cast members are Scott Nelson, Nedra Pace, Michelle Papasian and Cherie Whitaker.

Tickets are $5 for adults, $4 for students and senior citizens and $3 for children, with a family rate of $18 for a family group of no more than six on Monday nights. For reservations, call 723-8392. The theater is located at 2505 S. Highway 89 in Perry, south of Brigham City.

- WASATCH PLAYHOUSE, Layton's community theater company, is adding its playful bit to the Halloween season with the frightfully funny comedy, "Arsenic and Old Lace," the 1941 Broadway hit about the two Brooklyn spinsters who murder and bury bodies, instead of tatting doilies.

The show will be presented Friday and Saturday, Oct. 19-20; Monday, Oct. 22, and Friday and Saturday, Oct. 26-27, at 7:30 p.m. at Central Davis Junior High, 663 Church St., Layton.

Director Paul Naylor's cast includes Doratha Walker and Leone Gurr as Abby and Martha Brewster; Robert Hunt as Jonathan Brewster, their sinister nephew, and Jeff Larson and Kevin Wallin as Teddy and Mortimer Brewster.

Others in the cast are Ralph Murdock, Bobby Moon, Kristi Barker-Chase, Ryan Stark, Brook Chase, Roger Brunker, David Walker and Ned Tilson.

Tickets are $4 for adults, $3 for senior citizens and students (under 18), or $15 per family (maximum of six). Tickets may be purchased in advance at theLayton book store or by calling 544-0806. Discounts are also available for groups of 20 or more.