Influence of photoperiodic conditions on growth and flowering of chrysanthemum (Dendranthema grandiflora Tzvelev) genotypes for off-season flower production

Abstract

Chrysanthemum (Dendranthema grandiflora Tzvelev) is a leading cut flower crop, but its strong photoperiodic sensitivity restricts year-round availability. Expanding production into the off-season requires identification of genotypes that combine adaptability with superior floral traits. In 2023, twenty-one genotypes were evaluated under natural and controlled photoperiodic conditions in a naturally ventilated polyhouse using a factorial Randomized Block Design with three replications. Photoperiod significantly influenced growth and flowering responses. Natural photoperiod promoted vegetative vigour and yield attributes, resulting in higher plant height (134.16 cm), greater spread (40.07 cm), increased stem number (6.83), stem length (81.28 cm), stem weight (35.06 g), flowers per stem (12.14), flower diameter (5.79 cm), flowering duration (29.85 days) and vase life (12.85 days). Controlled photoperiod accelerated reproductive transition, resulting in markedly earlier bud initiation (78.81 days) and flowering (136.07 days), while sustaining yields comparable to natural conditions. Substantial genotypic variability was observed, reflecting differential adaptation to photoperiod manipulation. These findings demonstrate that natural photoperiod enhances vegetative growth and floral quality, whereas controlled photoperiod enables precise crop scheduling with minimal yield penalties. Photoperiod regulation, therefore, represents an effective strategy for aligning chrysanthemum supply with market demand, offering new opportunities for off-season cultivation, resource use efficiency and breeding of genotypes with wider adaptability.