VARIABILITY OF SOMATIC EMBRYOGENIC ABILITY IN THE GENUS PISUM L - EFFECTS OF GENOTYPE, EXPLANT SOURCE AND CULTURE-MEDIUM

The ability of shoot apices, immature cotyledons and embryonic axes ex cised from mature seeds to express somatic embryogenesis was tested in nine garden peas, eleven field peas, two forage peas and seven specie s or subspecies other than Pisum sativum L. Embryonic axes were poorly embryogenic when compared to the two other explants. Shoot apices and immature cotyledons were both cultured on two media differing in thei r sugar composition. Seven garden peas out of nine were more embryogen ic than all the field peas. Many genotypes, 22 out of 29, produced mor e embryos in cultures of shoot apices when fructose substituted sucros e. With immature cotyledons, somatic embryogenesis was also enhanced f or 20 genotypes out of 29 on maltose-supplemented medium compared to s ucrose-containing medium. Thus, exogenous carbohydrate seemed to play an essential role in somatic embryogenesis in pea.