Abstract
A new model to analyse reciprocal transfer experiments to assess stages of photoperiod sensitivity in Antirrhinum has been validated in the present study. Flowering time and leaf numbers data of Antirrhinum cultivars Chimes White, Liberty White, Ariane, Winter Euro Rose, Sonnet and Rocket Orchid were used for the validation of the model. Six plants of each cultivar were transferred from LD to SD and Vice versa at four days interval from emergence until first flower appearance. Plants at juvenile phase (initial phase of development) were insensitive to photoperiod in both inductive (LD) and non-inductive (SD) environment. After juvenile phase when plants were transferred from LD to SD, they recognised the stimulus under inductive environment and induced flowering. However, plants transferred from non-inductive environment to inductive showed a continuous phase of photosensitivity. Rate of flower development was less sensitive to photoperiod. The duration of photoperiod sensitive phases varied with the cultivars. Hence, it is concluded that Antirrhinum cultivars are not sensitive to photoperiod during their entire course of growth and development which is mere wastage of energy. These cultivars require 4-8 days of photoperiod at critical phase to flower that will minimise the production cost of cut flower industry.