Nitrate accumulation and mineral nutrition of lettuce under varied light emitting diode lighting

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This study aims to investigate strategies to minimize nitrate accumulation in lettuce to mitigate its potential harmful effects on human health. Lettuce cultivation under light-emitting diode lighting (LED) is becoming increasingly popular, and determining the effects of different LED sources on lettuce nutrition and nitrate accumulation is an important topic. The effects of different nitrate levels in the nutrient solution and different LED sources on lettuce nutrition and nitrate accumulation have been investigated under controlled conditions. Lettuce plants were grown for 48 days under White (W), Blue (B), Blue + Far Red (B + FR), Red (R), Red + Blue (R + B), Red + Far Red (R + FR), Red + Blue + Far Red (R + B + FR) LED lights using nutrient solutions containing 20, 24, and 28 mM nitrate. The highest marketable yield was obtained under B lighting, followed by R, R + B, R + FR, and R + B + FR. To reduce nitrate accumulation, lighting setups using W, R + B + FR, R + B, and R have proven to be advantageous. In these treatments, nitrate levels were determined to be 1039, 1118, 1167, and 1170 mg kg−1, which were lower compared to the other treatments. The concentrations of measured nutrients in plants were highest under B + FR, R + FR, and R + B lighting. The total chlorophyll concentration increased with the N dose, with the highest levels observed in the B, B + RF, and R + B + FR treatments. In conclusion, LED lighting influences lettuce nutrition and nitrate accumulation, with W, R + B + FR, R + B, and R treatments most effective in reducing nitrate levels. These findings should be validated in commercial greenhouse conditions to assess their practical applicability for large-scale production.