Mutation breeding of butterfly pea

A low-energy nitrogen ion beam at 50 keV was used to induce mutation in butterfly pea (Clitoria ternatea L.) seeds. Ion fluences of 1×10¹⁶ to 12×10¹⁶ N-ions cm^‑2 did not affect the seed survival percentage. However, the 12×10¹⁶ N-ions cm^‑2 caused variegated and deformed leaves on some plants in ‘M₁’ (the 1^st generation of mutation induction) population. The ‘M₁’ population (n=137) also had lower average internode and leaflet lengths than the wild type population (n=50). All ‘M₁’ plants were self-pollinated and their seeds were grown as ‘M₂’ population following the pedigree method. Four dwarf mutant plants derived from one line were found among 516 ‘M₂’ plants, and coded ‘M₂S’. They were self-pollinated and their seeds were grown as ‘M₃S’. All seeds from the ‘M₂S’ plants grew out to be dwarf plants. Characteristics of the ‘M₃S’ plants (n=15) were compared to the wild type plants (n=6) at 70 days after sowing in December 2017. The ‘M₃S’ plants had significant shorter internodes, smaller leaflets, and smaller flowers than the wild type plants (at p<0.05). The mutant plants drastically reduced their climbing habit. Thus, their average height was only 19.3±3.4 cm, while the average plant height of wild type was 53.7±33.6 cm. The dwarf mutants could be developed as a pot plant.