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BioSource Species<br />
Lactuca sati … BioSource Species<br />
Lactuca sativa L.<br /><br />
Genotypes/Varieties<br />
cv. Banchu Red Fire<br /><br />
Organ specification<br />
The third leaf<br /><br />
Growth conditions<br />
Under white fluorescent light (FL, FLR110H-W1A; Mitsubishi/Osram Co.; Yokohama, Japan), seeds of red-leaf lettuce (Lactuca sativa L. cv Banchu red fire; Takii seed, Kyoto, Japan) were pregerminated [14 hr, 14 days, 23 ± 2ºC, 100 µmol m−2 s−1 photon synthetic photon flux density (PPFD)]. The seedlings were supplied with a nutrient solution (Otsuka hydroponic composition, Otsuka Chemical Co. Ltd., Osaka, Japan) adjusted to an electrical conductivity (EC) of 1.2 dS/m and pH 5.8. It contained 7.0 mmol l-1 NO3-, 0.6 mmol l-1 NH4+, 3.7 mmol l-1 K+, 2.3 mmol l-1 Ca2+, 1.3 mmol l-1 H2PO4-, and 0.9 mmol l-1 Mg2+. The seedlings were transplanted to cultivation panels in a growth chamber (VB1514; Vötsch, Germany), supplied with nutrient solution for the duration of the experiments, and grown at 25ºC [relative humidity (RH) 60%, 900 µmol mol-1 CO2]. The plants were irradiated with different light spectra from LEDs, namely B470 (peak wavelength 470 nm, ISL305X302-BBBB, CCS Co., Kyoto, Japan), G510 (peak wavelength 510 nm, ISL-305X302- GGGG505, CCS Co.), G520 (peak wavelength of 524 nm; ISL-305X302-GGGG525, CCS) and
R680 (peak wavelength of 680nm; ISL-305X302-RRRR68, CCS Co., Kyoto, Japan).
The seedlings were irradiated for 24 hr at PPFD 100 or 300 µmol m−2 s−1 (P100, P300). The wavelength of the light source was determined with a USB2000 spectrometer (Ocean Optics, Dunedin, FL, USA). At 14, 15 and 21 DAS, dry weight (DW) was measured. and 21 DAS, dry weight (DW) was measured.
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