AUTHOR=Li Lie , Tong Yu-xin , Lu Jun-ling , Li Yang-mei , Liu Xin , Cheng Rui-feng 

TITLE=Morphology, Photosynthetic Traits, and Nutritional Quality of Lettuce Plants as Affected by Green Light Substituting Proportion of Blue and Red Light

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.627311

DOI=10.3389/fpls.2021.627311

ISSN=1664-462X

ABSTRACT=Green light, as part of the photosynthetically active radiation, has been proven that it has high photosynthetic efficiency once absorbed by plant leaves and can regulate plant physiological activities. However, few studies have investigated the appropriate and efficient way of using the green light for plant production. Thus, the objective of this study was to investigate moderate amount of green light, partially replacing red and blue light, for plant growth and development. In this experiment, four treatments were set up by adjusting the relative amount of green light as 0 (RB), 30 (G30), 60 (G60), and 90 (G90) μmol·m-2·s-1, respectively, with a total photosynthetic photon flux density (PPFD) of 200 μmol·m-2·s-1 and a fixed red to blue ratio of 4:1. Lettuce (Lactuca sativa cv. ‘Tiberius’) plant growth and morphology, stomata characteristics, light absorptance and transmittance, photosynthetic characteristics, as well as nutritional quality were investigated. The results showed that: 1) shoot dry weight increased by 16.3% and 24.5%, and leaf area increased by 11.9% and 16.2% under G30 and G60, respectively, compared with those under RB. Plant stem length increased linearly with increasing green to blue light ratio; 2) Light transmittance of lettuce leaf under treatments employing green light was higher than that under RB, especially in green region; 3) Stomatal density increased while stomatal aperture area decreased with the increase in the relative amount of green light; 4) Carbohydrate accumulation increased under G60 and G90. Soluble sugar contents under G60 and G90 increased by 39.4% and 19.4%, respectively. Nitrate content under G30, G60 and G90 decreased by 26.2%, 40.3%, and 43.4%, respectively. The above results indicated that the moderate amount of green light replacing red and blue light effectively increased the biomass and nutritional quality of lettuce plants.