Abstract:
Epiphytotic conditions and non-availability of resistant germ plasm prompted the use of mutation
induction technique to develop a variety resistant to phytophthora blight caused by Phytophthora
nicotianae var. parasitica in sesame (Sesamum indicum L.). Dry seeds of three varieties were irradiated with
six doses o f60Co gamma rays in the range 100-700 Gy. The mutant line 182/3 of variety MI 3 selected from
200 Gy dose treatment in the M2 showed tolerance to the disease at Angunakolapelessa in the disease
nursery. The mutant line was tested in the advanced yield trial, National Co-ordinated Varietal Trials and
in the National Coordinated Varietal Adaptability Trials. It was superior to MI 3 in yield and plant survival
during the seasons favouring development of the disease and was similar to MI 3 and other recommended
varieties during the other seasons. The variety has cream coloured seeds, branched stem, and recorded
1890 kg ha'1 at Girandurukotte, 1593 kg h a 1 at Maha Illuppallama and 1151 kg ha’1 at Angunakolapelessa
under rainfed conditions. The mutant was released as ANK S2 in 1993 and may be used to increase the
declining sesame area due to low yield of existing varieties and their susceptibility to disease. It should also
serve as valuable parent material in cross-breeding programmes.
