Maryland's State Board of Education agreed yesterday to offer kindergarten a year earlier than normal - when children are 4 years old - as part of an ambitious attack on reading deficiencies at schools where reading scores are lowest.

In an informal 8-to-1 vote, the board decided to seek $6.34 million to start the extended kindergarten program in the fall of 1979 to 105 elementary schools throughout the state where third graders tested six months or more below grade level in reading.

Enrollment in the program would be voluntary, and the 4-year-olds would attend school for a half-session each day. At 5 years old, the children would go on to the regular half-day kindergarten program.

The plan, board members said, is tied closely to State School Superintendent David W. Hornbeck's Project Basic, a program now underway to make minimum competency in a broad variety of areas a prerequisite for high school graduation.

Dr. Leon Rosenberg, a Johns Hopkins University Medical School psychologist, told the board that "the best predictions of failure later on in school are the reading levels in the early years."

Rosenberg, who conducted a three-year study of 10 kindergarten programs for 4-year-olds already in existence in the state, argued that the study "clearly indicated dramatic growth in basic skills by children who would have been moving toward early childhood school failure." He said he disputes the validity of studies that indicate gains made in such early childhood programs as Head Start were quickly lost.

In studying the 10 experimental kindergarten programs for 4-year-olds scattered around the state, Rosenberg said he found "solid evidenc of cognitive and emotional change" in the children when they were tested against a control group.

Throughout the state, 3,955 4-year-olds are enrolled in public school kindergarten programs, the board was told compared to 6,509 4-year-olds in privately supported programs. Thus, staff members argued, access to early childhood education programs in limited for low income families.

If approved by the Maryland General Assembly, local school districts would be required to offer kindergarten for 4-yearolds in the eligible schools, although no student would be required to attend since state law makes kindergarten attendanc optional.

State officials estimate 7,381 4-year-olds would enroll in the new kindergarten program.

Adoption of both the kindergarten program and the effort to sttess basic skills, both of which would be highly structured, comes as part of an overall effort to emphasize basics in recent years, both in Maryland and elsewhere.

Before autumn, the state board is expected to approve a basic reading test as a condition for high school graduation, effective with the class of 1982.

Adoption of yesterday's program, said board Chairman Richard Schifter, "means that Project Basic is more than just testing."

In a related dealing with test scores, the board took under consideration a study by staff members indicating that schools have higher scores where principals have a high expectation of teachers and students, spend more time in classrooms and less in the office and function as instructional leaders.

That study involved a detailed examination of 30 schools throughout the state where scores on tests of basic skills vary substantially from the predicted level, based on the median IQ of the students. In 18 of the schools, the scores were substantially above what the students' IQs indicated; in 12 of them they were substantially below.

The study found a key difference between the two types of schools to be the principal.

The high scoring schools, as opposed to the low ones, "had a sense of direction and were seen as 'being run' instead of 'running.' Much of this difference in feeling or sense of direction is attributable to the principal's instructional leadership role," the study said.