Effects of Supplemental LED Light on a Strawberry Plant on the Bottom Bed When Cultivated on a Two-floor Bed System

Over the past decade in Republic of Korea, growing system of strawberry (Fragaria ☓ ananassa Duch.) was begun to change by high bed bench cultivation from soil cultivation. The strawberry plant on the high bed bench system is cultivated at 12% (about 700ha) of strawberry cultivation area by 2015. In recent, a strawberry is cultivated at the two floor growing-bed system in plastic greenhouse to improve the efficiency of land-use at winter season requiring much operational cost. However, the lack of light on bottom bed is occurred by shadows of upper bed. So, the bottom bed is needed supplemental light for effective photosynthesis of strawberry. We conducted this study to confirm the effects of supplemental LED light to illuminate strawberry under planting on bottom bed. The experiment was irradiated three different supplemental LED light such as blue plus red (448 and 661 nm), blue (448 nm) and red (448 nm) at the strawberry plants on bottom bed. The light intensity of supplemental LED light at each treatments on crops was about 75 µmol·m^-2·s^-1 and light illumination time was four hours a day. The control was not supplemental light treatment. In the experiment, fruit yield was significantly increased at the strawberry plant grown under blue or blue plus red LED light than grown under red LED light or control. The soluble sugar contents in strawberry fruit were decreased at strawberry plant grown under red supplemental LED light compared with other treatments. The antioxidant activities of fruit such as DPPH, ABTS were not significant by light treatments.