Genetic improvement of two Indian non-basmati aromatic rice landraces through physical and chemical mutagenesis

Purpose Kala Jirga and Ajara Ghansal are the non-basmati aromatic rice landraces having small grains and good cooking qualities. In spite of huge demand these landraces are cultivated in a few pockets of Kolhapur district of India due to micro-climate required for the development of aroma and grain quality. Both the varieties are late maturing (> 160 days), tall (> 140 cm) and highly susceptible to lodging which resulted into low productivity. To overcome these constraints, induced mutation was attempted to improve the traits in these important rice landraces. Material and methods Seeds of two landraces were treated with three concentrations/doses of Ethyl methanesulphonate (EMS), Sodium Azide (SA) and Gamma (gamma) rays. Putative mutants were identified and isolated in M-2 generation for desirable traits by comparing with adjacent untreated control. Putative mutants were grown in three replications to test their breeding behavior and other economical traits in M-3 generation. Results In the present study, differential response of landraces toward mutagenic treatments was observed which resulted into greater number of putative mutants in Ajara Ghansal (56 putative mutants) as compared to Kala Jirga (24 putative mutants). EMS induced the highest mutation frequency followed by Gamma rays and SA. In M-3 generation, fifteen and eighteen mutants of Kala Jirga and Ajara Ghansal respectively exhibited true breeding for mutant traits, while rest of the putative mutants had very poor agronomic traits or reverted back to their normal trait. Desirable mutants of both the landraces viz., dwarf, early, nonlodging and more tillers with high yield were very promising and can be released for commercial cultivation after multi-location testing or used in crossing program as a donor for desirable traits. Conclusions Induced mutations were found to be very useful to improve the specific defect present in both landraces. The desirable mutants with early maturity and high number of tillers may prove useful in the improvement of aromatic rice.