The use of horticultural LED improves hydroponic lettuce
Researchers in China and in the UK studied the effects of horticultural LED on lettuce (Lactuca sativa L.) grown in hydroponic systems to determine if this culture method could reduce the accumulation of nitrates and what consequences it may have on phytochemical levels.
« The plants, especially leafy vegetables, grown hydroponically can accumulate high levels of nitrates and other harmful substances, » said Qi-Chang Yang and Lu Chungui, authors of the study published in the Journal of American Society for Horticultural Science.
« Previous research on the effects of continuous light on photosynthesis and plant growth have focused primarily on the circadian rhythm and induced injuries. We know little about the effects of continuous LED light on the response of photosynthetic system and changes in antioxidant and phytochemicals concentrations. »
Researchers developed experiments with continuous light (CL) and / or a combination of green LED light (G) with red-blue (RB) to determine whether certain mixtures could reduce nitrate levels and increase nutrient levels in the hydroponically grown salad. These tests were including white horticultural LED and 5 combinations of red-blue LED light (with or without green LED light).
« Our results clearly show that continuous light composed of RB and RBG LEDs dramatically affect the nitrate levels in pre-harvest stages lettuce, » conclude the authors of the study. « Nitrate levels are significantly reduced in the RB-CL and CL-RBG light, with 0-24 hours’ exposure times. »
Results also demonstrate that the RB LED light was more effective than the white LED regarding lettuce growth. « Continuous exposure to Horticultural LED for 24 hours consequently improves anti-radical activity and increases phenolic compounds concentration » according to the study writers. They recommend continuous exposure of 24 hours to RBG LED light to reduce nitrate levels and improve the quality of lettuce.
Complete study here.
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