The effect of different spectral LED lights on the phenotypic and physiological characteristics of lettuce ( Lactuca sativa ) at picking stage.

Abstract

Light plays crucial roles in plant morphological and physiological processes. In this study, lettuce plants ( Lactuca sativa L .) were exposed to different spectral LED lights for 16 hd-1 photoperiod under the following eight treatments: white light (W, the control), monochromatic red light (R), monochromatic blue light (B), monochromatic green light (G), monochromatic yellow light (Y), monochromatic purple light (P) and a combination of R and B with R/B ratios of 9/1 and 4/1. Lettuce phenotype and some quality related indices were significantly changed under different LED lights. The vitamin C content of lettuce was increased under most of different light treatments, while the anthocyanin content was significantly increased only under G LED light treatment. In addition, R/B (4/1) increased soluble sugar and protein content and R and B combinations particularly R/B (4/1) improved phenotypic characteristics including plant height, stem diameter, fresh weight above ground, Soil and Plant Analyzer Development (SPAD). These results suggested R/B (4/1) could efficiently improve the lettuce quality which will provide valuable information for optimizing the conditions of lettuce production in the plant factory setting.