Efficacy of oryzalin as a potent chemical for in vitro induction of polyploids in Asiatic lily (Lilium hybrida L.) var. Polyanna

Abstract

The efficacy of a mitosis inhibiting compound, oryzalin was tested for in vitro induction of polyploidy in Lilium hybrida var. Polyanna. Bulb scale segments were exposed to different concentrations of oryzalin (0.001, 0.003, 0.005, 0.007 and 0.01%) for 2, 4 and 6 h. It was observed that increasing the concentration as well as exposure time to oryzalin lead to reduction in explant survival and delayed regeneration of shoot bud. Though a few shoots per explant were formed in the initial stage of treatment but were with stunted growth. Also upon transferring these shoots on to rooting medium showed delayed root induction with slow growth. The root tips of treated plants were examined for ploidy determination and the highest percentage of tetraploids (45.0) and also the highest efficiency of tetraploid conversion (1.1) were recorded in 0.001% oryzalin treatment with exposure of 6 h. In all the oryzalin treatments, diploids and mixoploid/ aneuploid plants were regenerated, while with the lowest oryzalin concentration (0.001%), only diploids or tetraploids were observed. Thus, this concentration can be used for tetraploid induction in liliums.