Radiation and genetical studies to estimate the number of embryonic initials taking part in the formation of the shoot meristem of Vicia ervilia and Lathyrus sativus

Summary Dry seeds of V. ervilia and L. sativus were irradiated with 60Co gamma rays. The M₁ plants were grown to maturity. During harvest, ten randomly selected plants were arbitrarily numbered (symbols P₁ to P₁₀) and the branches and the pod positions along each branch of each plant were numbered (symbols for branches, B₁ to B₄ and pod positions, p₁ to p₁) from the lowest to the topmost one. The seeds of each pod position were collected, threshed, counted and, the next year, sown separately. Mutants were isolated from among the M₂ population and each mutant could be traced back to the particular topography of the M₁ plant. The seeds from the M₂ plants originating from different sectors of the M₁ plants were grown to M₃ generation to study the pattern of inheritance. The segregation data of L. sativus show that in some cases at least one and in other cases at least two embryonic initials were involved in the formation of the shoot meristem whereas in V. ervilia the number of embryonic initials involved was at least two or three.