LEDs increase the yield of crops, blue light, red light

Research into the application of LED lighting to plant and vegetable production systems has been ongoing, and researchers are trying to figure out how LED lighting affects plant growth and crop yields. Recently, scientists from the Department of Horticulture Science at Chungbuk National University in South Korea published a research report on Hort Science, revealing the impact of LED lighting on lettuce cultivation.

The use of LED lighting in an environmentally controlled, closed plant production system allows crop production to be unaffected by external climatic conditions. According to the authors Ki-HoSon and Myung-MinOh, LED lighting has certain advantages over traditional light sources in plant cultivation. They pointed out that LEDs have the advantages of high light energy conversion rate, low radiant heat output and light weight. In addition, LED lights can be applied to a variety of narrow bands. Therefore, we can optimize light quality while increasing crop yield and quality. They explain that blue LEDs and red LEDs are commonly used for plant growth because chlorophyll a and b are effective in absorbing light in the blue and red bands.

In the study, the scientists used red leaf lettuce and green leaf lettuce and six LED lights for experiments. Scientists studied their growth characteristics including fresh weight and dry weight of shoots and roots, specific gravity of shoots and roots, total leaf area and chlorophyll content. In this study, scientists also measured chlorophyll fluorescence, antioxidant capacity, phenolic concentrations, and flavonoid concentrations, respectively. The report shows that different ratios of blue and red light (blue and red light ratios of 0:100, 13:87, 26:74, 35:65, 47:53, 59:41.) are illuminated by LED lamps. Different growth results were obtained, indicating that red LEDs are the main reason for increasing the growth rate of lettuce. The ratio of blue and red light in the best experimental group of lettuce growth was 35:65, 47:53, 59:41.

This experiment confirmed that blue LED and red LED have positive effects on the accumulation of antioxidant phenolic compounds and lettuce growth in plants, respectively. Scientists say that red LED illumination alone can stimulate lettuce plants to increase biomass accumulation, but this single illumination induces abnormal leaf shape and negatively affects polyphenols and antioxidant levels. They recommend using a blend of blue LEDs and red LEDs in a closed plant production system to improve the quality and yield of lettuce crops.