Induction of Mutations by Gamma Irradiation at Four Developmental Stages in Castor (Ricinus communis L.)

Abstract

Castor plants (var. 279) were exposed to acute gamma rays (2000, 3000 and 4000 R) at seedling, meiotic, gametic and post-gametic stages. The mean chloro-phyll and morphological mutant frequencies with widest spectra and a substantial increase in phenotypic variability for days to flower, seed yield/plant and harvest-index were observed at gametic stage. The spectrum of chlorophyll mutants at this stage differed significantly from those of other three stages. Certain promising mutants with early maturity, dwarf stature and tetra-locular capsules were also recovered more frequently at gametic stage. Maximum mutagenic effectiveness and efficiency were recorded at the same stage. The data amply indicate that ‘gametic’ stage is the most suitable one for irradiation and recovery of useful mutants.