Effect of night-break on growth and flower production in Kalanchoe

Abstract

Kalanchoe blossfeldiana is a popular potted flowering plant with extended flowering periods and low demand for nutrients and water. Understanding photoperiodic response is a prerequisite for the management of the flowering period in photoperiodic crops like Kalanchoe. The night-break treatments were provided by an artificial light source (CFL bulbs) starting from 7th October 2019 for 20 (7th October - 26th October), 30 (7th October - 5th November) and 40 (7th October - 15th November) days as night interruption (NI) for 30 min. and 60 min. from 11:30 PM to 00:00 AM and 11:30 PM to 00:30 AM. Exposing the plants to a 60 min. night interruption for 20 days has proven to be crucial in achieving essential qualitative criteria for potted plants, specifically ensuring compact plant growth with minimal plant height (26.20 cm) and a controlled plant spread (19.17 cm). The maximum number of days to flower bud appearance (138.07 days), days to colour break stage (203.79 days) and days to 50% opening of flowers (232.23 days) was under 60 min. of night interruption for 40 days. Therefore, delayed flower production in Kalanchoe for up to 45 days can be achieved by 60 min. of night interruption for 40 days along with acceptable quality pot plants. A significant amount of anthocyanins and total phenols reported with photoperiodic treatment confirms that photoperiod influenced the biosynthesis of anthocyanin and phenoliccompounds in Kalanchoe.