postharvest assessment of lignifying enzymes activity, flower stem lignification and bending disorder of gerbera cut flower

Scape bending disorder is the most important factor affecting postharvest loss of gerbera cut flowers. one of the ultimate reasons for gerbera stem bending is lignin, with deformation structural functions and defensive mechanisms. this postharvest experiment was conducted to evaluate the role of phenylalanine ammonia lyase (pal) and peroxidase (pod) enzymes activity in stem bending of two gerbera cultivars; (‘beaudine’ (sensitive)) and (‘aqua’(resistant)). this experiment was based on a completely randomized design with three replications over eight days. results showed the significant effects of cultivar on stem bending percentage, total phenol content, pal and pod enzyme activities and lignin content (p<0.05). the ‘aqua’ cultivar had the highest phenol and lignin content and the lowest stem bending percentage. the maximum and the minimum pal and pod enzyme activities were observed in resistant and sensitive cultivars, respectively. based on the results, induction of pal and pod enzymes activity, and consequently lignin formation could have direct effects on stem strength and as a result reduce gerbera stem bending disorder.