The mutagenic effect of ethylene imine (EI) on the tomato

Air-dry tomato seeds were treated with an ethylene imine dilution series. Most sterile M₁-plants can be detected morphologically at an early stage. Few of the morphological deviants proved to be fertile. Both with regard to M₁^- and to M₂^- growing space the highest concentration leaving fertiles (0.25%) was the most efficient. At this dose the rate of mutation which can be scored on young M₂-plants, reached a value of 1.04 per M₂-family. A small shortage of M₂-families with 1 mutation is suggested by different tests. This may be due to penetrance heterogeneity. The spectrum of chlorophyll mutations changes with the EI concentration, a significantly smaller proportion of chlorodefectios (albinas, etc.) being found at higher concentrations.