Influence of Intensity and Duration of Cool White Fluorescent Lighting and Fertilizer on Growth and Quality of Foliage Plants1

Abstract

Brassaia actinophylla Endl., Chamaedorea elegans Mart., Dieffenbachia maculata (Lodd.) G. Don ‘Exotica’, Dracaena marginata Lam., and Ficus benjamina L. were grown for 1 year under 13 or 26 μE m−2sec−1 from Cool White fluorescent lamps for 12, 18, or 24 hours daily durations. Increasing light duration to 24 hours daily decreased quality of all plants tested, with Brassaia, Chamaedorea, and Dieffenbachia being most affected. The primary symptoms resulting from constant light were foliar chlorosis and decrease in plant quality, although necrotic spotting appeared at times. By experiment termination, best plants overall were associated with 26 μE m−2sec−1 light for 12 or 18 hours duration and poorest with 26 μE m−2sec−1 light and 24 hours duration. A second factorial experiment with Dieffenbachia and Dracaena tested effects of 3 fertilizer levels (0, 0.67, or 1.30 g Osmocote/3 months per 15-cm pot) under 2 light intensities (13 or 26 μE m−2sec−1) and 2 light durations (12 or 24 hours) on plant quality. Higher fertilizer levels had a limited effect on plant quality, while influence of light intensity and duration was similar to the initial experiment.