Evaluation of Lettuce Growth under Multi-spectral-component Supplemental Solid State Lighting in Greenhouse Environment

Abstract

Light-emitting diodes (LEDs) have been useful in ev aluating plants's physiologic and growth responses to radiation quality and quant ity. In the great majority of these studies, growth rooms (phytotrons) have been used in order t o avoid the influence of external factors such as the daylight radiation. The main objective of this study was to evaluate the growth performance of two LED-based supplemental lighting treatments (LED1, LED2) on lettuce (Lactuca sativa var. crispa L., 'Frillice') cultiva tion in real glass greenhouse conditions. Control plants were grown under conventional high-pressure sodium (HPS) lamps. In LED1 treatment red-orange (RO) and blue LEDs with peak wavelength emissions at 630nm and 460nm, respectively were used while in LED2 an additional yellow component at 594nm was also included. The results had indicated that lettuce gr owth parameters can be improved using supplemental spectral-tailored LED lighting. RO LED s were also effective in promoting biomass accumulation and the addition of a small percentage of yellow photons may further enhance this aspect and increase the number of leaves per plant. The results have also suggested a relation between the amount of blue photons and yellow-green photons in lettuce growth. Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserv ed.