Effect of colchicine on in vitro polyploidy induction in African marigold (Tagetes erecta)

Colchicine was used as chemical mutagen for in vitro induction of polyploids. nodal segments of in vitro grown marigold plantlets were cultured on ms medium supplemented with four different concentrations of colchcine (0.0%,0.001%,0.01% and 0.05%) for 12h,separately. after treatment,nodal segment were shifted to colchicine free ms medium for normal growth. highest mortality rate (72.74%) and restricted shoot growth (3.80 cm) was observed in 0.05% colchicine treatment. stomatal size and number used as cytological parameters to identify polyploids. stomatal size was increased in 0.01% (811.34 μm) and 864.70μm in 0.05% treatments while 289.30 μm was in control. the stomatal number was reduced to 9 in 0.05% colchicine treatment as compared to control (16). the polyploids showed an increase in stomatal size and decrease in stomatal number per unit area. thus 0.01% and 0.05% treatments found effective in inducing polyploidy in african marigold.