Relative effects of gamma rays, ethyl methane sulphonate and nitroso methyl urea on the meiosis and on pollen and seed fertility in M1 generation of Lathyrus sativus were studied. Radiations were more efficient in inducing meiotic abnormalities than the chemical mutagens. However, chemical mutagens induced greater pollen and seed sterility than radiations. Radiation induced sterility might be the result of chromosomal aberrations which in turn were dose dependent while sterility induced by chemicals might be attributed to cryptic deletions and specific gene mutations. A dose dependent increase in chiasma frequency was observed in physical as well as chemical mutagenic treatments.
