title: Plant Growth and Photosynthetic Characteristics ofMesembryanthemum crystallinumGrown Aeroponically under Different Blue- and Red-LEDs.
abstract: Mesembryanthemum crystallinumis a succulent, facultative crassulacean acid metabolism (CAM) plant. Plant growth and photosynthetic characteristics were studied whenM. crystallinumplants were grown indoor under light emitting diodes (LED)-lighting with adequate water supply. Plants were cultured aeroponically for a 16-h photoperiod at an equal photosynthetic photon flux density of 350 μmol m-2s-1under different red:blue LED ratios: (1) 100:0 (0B); (2) 90:10 (10B); (3) 80:20 (20B); (4) 70:30 (30B); (5) 50:50 (50B); and (6)100:0 (100B).M. crystallinumgrown under 10B condition had the highest shoot and root biomass and shoot/root ratio while those grown under 0B condition exhibited the lowest values. Compared to plants grown under 0B condition, all other plants had similar but higher total chlorophyll (Chl) and carotenoids (Car) contents and higher Chla/bratios. However, there were no significant differences in Chl/Car ratio among all plants grown under different red- and blue-LEDs. Photosynthetic light use efficiency measured by photochemical quenching, non-photochemical quenching, and electron transport rate, demonstrated that plants grown under high blue-LED utilized more light energy and had more effective heat dissipation mechanism compared to plants grown under 0B or lower blue-LED. Statistically, there were no differences in photosynthetic O2evolution rate, light-saturated CO2assimilation rate (Asat), and light-saturated stomatal conductance (gssat) among plants grown under different combined red- and blue-LEDs but they were significantly higher than those of 0B plants. No statistically differences in total reduced nitrogen content were found among all plants. For the total soluble protein, all plants grown under different combined red- and blue-LEDs had similar values but they were significantly higher than that of plants grown under 0B condition. However, plants grown under higher blue-LEDs had significant higher ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) protein than those plants grown under lower blue-LED. HighAsatandgssatbut very low CAM acidity of allM. crystallinumplants during light period, imply that this facultative CAM plant performed C3photosynthesis when supplied with adequate water. Results of this study suggest that compared to red- or blue-LED alone, appropriate combination of red- and blue-LED lighting enhanced plant growth and photosynthetic capacities ofM. crystallinum.
authors.affiliation: National Institute of Education, Nanyang Technological University Singapore, Singapore.
authors.forename: Jie
authors.initials: J
authors.lastname: He
authors.affiliation: National Institute of Education, Nanyang Technological University Singapore, Singapore.
authors.forename: Lin
authors.initials: L
authors.lastname: Qin
authors.affiliation: National Institute of Education, Nanyang Technological University Singapore, Singapore.
authors.forename: Emma L C
authors.initials: EL
authors.lastname: Chong
authors.affiliation: National Institute of Education, Nanyang Technological University Singapore, Singapore.
authors.forename: Tsui-Wei
authors.initials: TW
authors.lastname: Choong
authors.affiliation: National Institute of Education, Nanyang Technological University Singapore, Singapore.
authors.forename: Sing Kong
authors.initials: SK
authors.lastname: Lee
keywords: LED lighting; Mesembryanthemum crystallinum; aeroponics; photosynthesis; plant growth