Effects of Autotetraploidy Induction Using Colchicine on Aanatomical Characteristics of Pot Marigold

In plant breeding programs¡ polyploidy inductions have been used for producing new cultivars with improved vegetative organs in many plants. Polyploid plants typically associated with changes in anatomical¡ morphological¡ physiological and biochemical traits. In this experiment¡ 0.02¡ 0.04 and 0.06 % colchicines concentrations were applied to the cotyledon and two true leaves stages for investigating the effect of autotetraploidy induction on some stem and leaf anatomical traits of pot marigold. Cytometric studies showed that at two true leaves stage¡ sprayed plants with 0.06% colchicin concentration were significantly induced the highest levels of polyploidy (60.06% and 58% in the genotype of yellow and orange flowers respectively). While¡ the highest mortality rate was obtained in treated plants with 0.06% colchicines concentration at cotyledon stage. Results of leaf anatomic traits in diploid plants with tetrapolid plants showed that length¡ width and number of chloroplasts of stomata guard cells were increased in tetraploid plants compared with diploid plants¡ but stomata density per area was declined. Also¡ the vascular bundles length¡ the phloem and xylem thickness and stem diameter to pith length ratio were significantly increased (P