Quantum Flux Density Studies of Chrysanthemum in a Controlled Environment with High-pressure Sodium Lamps. I. Rooting Studies1

Abstract

Abstract Growth of chrysanthemum (Chrysanthemum morifolium Ramat) was studied as a function of quantum flux density (QFD), QFD duration, and temperature. Unrooted cuttings were rooted under high-pressure sodium (HPS) lamps in a controlled environment (CE) at 4 QFD, 3 QFD durations, and 3 temperatures, and plants were grown to flowering in a greenhouse to determine treatment effect on flowering time and plant size at flowering. Increasing QFD duration was more effective in increasing root and shoot dry weight than increasing QFD. Root and shoot dry weights were greatest at 21°C after 13 days rooting. Light treatment during rooting had no effect on flowering time or shoot length at flowering, but there were differences of up to 35% in fresh weight at flowering. A photochlorosis was observed on all treatments irradiated with HPS lamps; the photochlorosis was irreparable at a QFD of 420 μEm−2s−1.