No LED treatment(NL) No LED unit was applied PPFD in Pulsed LED (PL) was 1/2 compared with in Continuous LED (CL) a b a b PL CL ・Introduction Strawberry(Fragaria × ananassa Duch. ‘Benihoppe’) Spinach(Spinacia oleracea L. ‘Hydroseven’) 0 10 20 30 40 50 60 Yeild (g / plant) a a b PL CL NL 0 10 20 30 40 50 60 70 Yield (g / plant) PL CL NL b a a 0 0.01 0.02 0.03 0.04 0.05 0 0.01 0.1 0.4 1 10 100 A / PPFD (mol mol -1 ) Pulse cycle (ms) b a a a a a a 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0 0.01 0.1 0.4 1 10 100 A / PPFD (mol mol -1 ) Pulse cycle (ms) d a a a a b c Excessively low solar radiation during cold season Depression in photosynthesis and crop growth Decline in crop production Energy-saving system for supplemental lighting Pulsed LED irradiation promote light use efficiencies Pulsed LED irradiation promote the crop growth and yield at the same level of continuous LED irradiation There is a possibility that pulsed LED irradiation can supplement a required light efficiently for crop growth and electricity consumption ・Energy use efficiencies No significant difference between PL and CL Yield was increased Pulsed LED irradiation can be expected to promote the crop growth and yield at the same level of continuous LED irradiation Time ( s) 0 Current Turning on Turning off Turning on Turning off Light use efficiency Light use efficiency Light use efficiency in PL was about 1.2 times as large as that in CL Yield Results & Discussion Results & Discussion Yield * Kyushu University ** Postdoctoral Research Fellow of the Japan Society for the Promotion of Science, QST Takasaki Advanced Radiation Research Institute, National Institutes, *** NARO Kyushu Okinawa Agricultural Research Center, **** Kankyou Photonics Co., Ltd. KYUSHU UNIVERSITY Turning on and off at a high rate De-exciting steps of P680 and P700 effect of pulsed LED irradiation Pulsed LED irradiation can be expected to promote the crop growth and yield efficiently under energy saving 0 0.2 0.4 0.6 0.8 LA (m 2 / plant) PL CL NL a a b b a b Dec. Feb. 0 50 100 150 200 250 300 Plant Height (mm) c a b PL CL NL a a b b c c 11/21 12/1 12/12 (PL: duty ratio was 50%, CL: duty ratio was 100%) Reduction of photosynthetic rate in PL was only 20% Spinach PL was 2 times as large as CL Yield was increased No significant difference between PL and CL Pulsed LED irradiation can be expected to promote the crop growth and yield at the same level of continuous LED irradiation ・Summary 0 0.2 0.4 0.6 0.8 PL CL NL a a b LA (cm 2 / plant) Duty ratio; 50% Blinking time; 0.1 ms PPFD; solar radiation + 100 μmol m -2 s -1 Duty ratio; 100% Blinking time; 0 ms PPFD; solar radiation + 140 μmol m -2 s -1 No LED (NL) Treatments LED unit : (KP-E2-RBB, Kankyou Photonics Co., Ltd.) No LED unit was applied Duty ratio; 50% Blinking time; 0.1 ms PPFD; solar radiation + 70 μmol m -2 s -1 Duty ratio; 100% Blinking time; 0 ms PPFD; solar radiation + 200 μmol m -2 s -1 Treatments No LED unit was applied No LED (NL) CL PL Duty ratio 50% Strawberry Spinach LA was increased No difference in Dec (before supplemental lighting) PPFD in PL was 1/2 compared with in CL Light use efficiency in PL was about 1.4 times as large as that in CL (PL: duty ratio was 50%, CL: duty ratio was 100%) Reduction of photosynthetic rate in PL (0.01-1ms) was only 10% CL PL Duty ratio 50% Plant Height No difference Effect of Far-red light ? Term Term Nov.21,2017 -Dec.12,2017 Dec. 2016 - Feb. 2017 PL was increased at same level of CL in Feb (after supplemental lighting) To make dark period during these steps… Strawberry PL was 3 times as large as CL During these steps, light energy is not required P700 + P680 + Photosystem II P680 + 2H 2 0 4H + +O Higher Lower Energy of electron 4 Photons Cytochrome complex 4 Photons Photosystem I 4e - P700 + P680 + P700 + 2NADP + +2H + Pulsed LED irradiation promote energy use efficiencies Leaf area(LA) and Plant Height LA Not included in supplemental light excite excite de-excite de-excite PPFD (μmol m -2 s -1 ) 600 400 200 0 PPFD (μmol m -2 s -1 ) 300 200 100 0 Energy use efficiencies (g kWh -1 ) 1.2 1 0.8 0.6 0.4 0.2 0 0.5 0.4 0.3 0.2 0.1 0