Increasingly, vegetables are being efficiently grown using soilless techniques such as hydroponics. Hydroponic systems are favored for their ability to improve water and nutrient use efficiency and crop yields, and have the added benefit of allowing growers to use fewer chemical fertilizers. Researchers in China and United Kingdom studied the effects of LED light combinations on lettuce grown in hydroponic systems to determine whether the treatments could reduce nitrate accumulation, and to find out what effect the treatments might have on phytochemical levels.