effect of cycocel and daminozide on vegetative growth, flowering and the content of essence of pot marigold (calendula officinalis)

pot marigold (calendula officinalis l.) is a medicinal and ornamental plant. the effect of different concentrations of chlormequat (cycocel), and daminozide, two plant growth retardant, on plant height, flowering, the content of essence and some other traits in pot marigold (calendula officinalis) was assessed. plant growth retardants are commonly applied to limit stem elongation and produce a more compact plant. the experiment was done as a factorial in randomized completely blocks design (r.c.b.d.) with 16 treatments and 3 replications in rasht. cycocel at 4 concentrations (0, 500, 1000 and 1500 mg/l) and daminozide at 4 concentrations (0, 1500, 3000 and 4500 mg/l) were used. investigated characteristics were plant height, leaf number, flower number, flowering time, fresh weight, dry matter, the content of essence and carotenoid in flowers. based on analysis of variance (anova), the effect of different treatments and their interaction on most traits was significant at 0.05 level of probability. the minimum height (24 cm/plant) in treatment of 500 mg/l cycocel + 3000 mg/l daminozide, the largest number of flowers (4.66 flowers/plant) in treatment of 1000 mg/l cycocel + 4500 mg/l daminozide and most essence content (0.154 mg/100 g) in treatment of 4500 mg/l daminozide without cycocel were obtained.