Photosynthetic Daily Light Integral Impacts Growth and Flowering of Several Kalanchoe Species

Abstract

Our objective in this study was to identify the effects of the photosynthetic daily light integral (DLI) on growth and flowering of six kalanchoe (Kalanchoe) species: Kalanchoe glaucescens, christmas tree plant (K. laciniata), chandelier plant (K. manginii), shovel leaf kalanchoe (K. nyikae), common kalanchoe or nentabos (K. rotundifolia), and velvet leaf kalanchoe (K. velutina). Plants were grown under an 8-hour photoperiod with a DLI of 4.3, 8.6, or 17.2 mol·m−2·d−1. Node numbers below the terminal inflorescence on K. glaucescens, K. manginii, K. nyikae, and K. rotundifolia decreased as the DLI increased, whereas node numbers of K. laciniata and K. velutina were unaffected by DLI. Time to first open flower of K. glaucescens, K. nyikae, and K. rotundifolia was unaffected by the DLI, whereas increasing the DLI from 4.3 to 17.2 mol·m−2·d−1 reduced the time to first open flower of K. laciniata, K. manginii, and K. velutina. Total flowers for all species increased as the DLI exceeded 4.3 mol·m−2·d−1. Shoot heights of K. glaucescens and K. rotundifolia increased as the DLI increased from 4.3 to 8.6 mol·m−2·d−1, whereas shoot height of K. nyikae decreased as the DLI increased from 4.3 to 17.2 mol·m−2·d−1; shoot heights of K. laciniata, K. manginii and K. velutina were unaffected by DLI. Dry weight gain increased for all species as the DLI exceeded 4.3 mol·m−2·d−1.