New fiction and nonfiction briefly noted; Wakefield's likable '40s novel; Under the Apple Tree, by Dan Wakefield. New York: Delacorte Press/Seymour Lawrence. 342 pp. $13.95

This highly readable and likable novel describes the coming-of-age of Artie Garber, from 1941 - when he is 10, and his older brother Roy goes off to help the Marines save the free world - through 1945, when the altered, embittered Roy no longer acts like a hero, and the maturing Artie no longer needs him to be one.

Besides rendering ''the home front'' in affectionate and lively detail - and with virtually total recall of small-town mores, adolescent sexual panic 1940 s-style, and period slang - Wakefield has populated the novel with several thoroughly believable and interesting nice people. It's familiar material all right, but the skillful plotting and adroit deployment of short paragraphs and scenes keep the story humming. A charming book, Wakefield's best since ''Going All the Way'' (1973).